increasing the pie for the european self adhesive tape ... · opportunities to increase the pie for...

Increasing the pie for the European self adhesive tape industry

... an insight in the opportunities to replace alternative joining methods

October 2009

Meijer + Voermans Consulting Goldschrütifeld 2 [email protected] Tel +41 41 410 60 62 CH-6017 Ruswil www.mvconsulting.ch

Meijer + Voermans Consulting innovation evaluation implementation

Increasing the pie for the European self adhesive tape industry Afera

October 2009 |

Increasing the pie for the European self adhesive tape industry

... an insight in the opportunities to replace alternative joining methods

Sponsored by

The European Association for the Self Adhesive Tape Industry

Afera 2009. All rights reserved. No part of this report may be reproduced in any form or by any means

without permission in writing from Afera, PO Box 85612, NL 2508 CH The Hague, Netherlands.

Tel: +31 (0) 70- 312.39.16, [email protected], www.afera.ch

This study contains information gathered professionally and in good faith from sources within the public

domain, expert interviews and internal databases. While every step has been taken to ensure that the data

presented is accurate and information is based on expert knowledge, neither Meijer + Voermans Consulting

nor Afera accepts responsibility for any consequences arising from the application of data and information

presented in this document. Expert advice should always be taken on the application of analyses.



October 2009 |

Table of content

1 Summary ................................................................................................................................. 8

2 Introduction ............................................................................................................................ 10

2.1 Target and objectives .................................................................................................... 11

2.2 Scope ............................................................................................................................ 12

3 Methodology .......................................................................................................................... 13

4 Joining methods ..................................................................................................................... 14

4.1 Categorization of joining methods .................................................................................. 14

4.2 Strength-weakness analysis of joining method: methodology ........................................ 15

5 Pressure sensitive adhesive tapes ......................................................................................... 17

5.1 Adhesive - PSA tape - Solvent based ............................................................................ 18

5.2 Adhesive - PSA tape - Dispersion .................................................................................. 20

5.3 Adhesive - PSA tape - Hotmelt ...................................................................................... 22

6 Physically hardening adhesives ............................................................................................. 24

6.1 Adhesive - Physical hardening - Hotmelt ....................................................................... 25

6.2 Adhesive - Physical hardening - Organic solvent ........................................................... 27

6.3 Adhesive - Physical hardening - Water based ............................................................... 29

6.4 Adhesive - Physical hardening - Plastisol ...................................................................... 32

7 Chemically curing adhesives .................................................................................................. 34

7.1 Adhesive - Chemical curing - 1K .................................................................................... 35

7.2 Adhesive - Chemical curing - 2K .................................................................................... 37

8 Mechanical joining - Fasteners ............................................................................................... 40

8.1 Mechanical - Fasteners - Nuts & Bolts ........................................................................... 41

8.2 Mechanical - Fasteners - Screws ................................................................................... 43

8.3 Mechanical - Fasteners - Pins & Rivets ......................................................................... 45

8.4 Mechanical - Fasteners - Stitching & Stapling ................................................................ 47

9 Mechanical joining - Integral ................................................................................................... 49

9.1 Mechanical - Integral Joints - Joining by forming ........................................................... 50

9.2 Mechanical - Integral Joints - Snap fit ............................................................................ 52



October 2009 |

10 Brazing and soldering ............................................................................................................ 54

10.1 Brazing .......................................................................................................................... 55

10.2 Soldering ....................................................................................................................... 57

11 Welding .................................................................................................................................. 59

11.1 Welding - Metal ............................................................................................................. 60

11.2 Welding - Plastic ............................................................................................................ 62

12 New developments in joining methods ................................................................................... 65

12.1 Adhesives ...................................................................................................................... 65

12.2 Mechanical Joining ........................................................................................................ 66

12.3 Brazing / Soldering ........................................................................................................ 67

12.4 Welding ......................................................................................................................... 67

13 Comparison of joining methods .............................................................................................. 69

14 Survey .................................................................................................................................... 75

14.1 Introduction and scope .................................................................................................. 75

14.2 Joining methods in consumer electronics ...................................................................... 76

14.3 Selection criteria in consumer electronics ...................................................................... 78

14.4 Development and future requirements ........................................................................... 80

14.5 Conclusions ................................................................................................................... 82

15 Acknowledgements ................................................................................................................ 83



October 2009 |

List of tables

Table 1: Judgement criteria for strength-weakness analysis of joining methods ............................ 15

Table 2: Strength-Weakness analysis of PSA tape - solvent based .............................................. 19

Table 3: Strength-Weakness analysis of PSA tape - dispersion .................................................... 21

Table 4: Strength-Weakness analysis of PSA tape - hotmelt ........................................................ 23

Table 5: Strength-Weakness analysis of physical hardening - hotmelt .......................................... 26

Table 6: Strength-Weakness analysis of physical hardening - organic solvent .............................. 28

Table 7: Strength-Weakness analysis of physical hardening - water based .................................. 31

Table 8: Strength-Weakness analysis of physical hardening - plastisol ......................................... 33

Table 9: Strength-Weakness analysis of chemical curing - 1K ...................................................... 36

Table 10: Strength-Weakness analysis of chemical curing - 2K .................................................... 39

Table 11: Strength-Weakness analysis of nuts & bolts .................................................................. 42

Table 12: Strength-Weakness analysis of screws ......................................................................... 44

Table 13: Strength-Weakness analysis of pins & rivets ................................................................. 46

Table 14: Strength-Weakness analysis of stitching & stapling ....................................................... 48

Table 15: Strength-Weakness analysis of joining by forming ........................................................ 51

Table 16: Strength-Weakness analysis of snap fit ......................................................................... 53

Table 17: Strength-Weakness analysis of brazing ......................................................................... 56

Table 18: Strength-Weakness analysis of soldering ...................................................................... 58

Table 19: Strength-Weakness analysis of welding - metal ............................................................ 61

Table 20: Strength-Weakness analysis of welding - plastic ........................................................... 64



October 2009 |

List of figures

Figure 1: Overview joining methods .............................................................................................. 14

Figure 2: PSA tape-solvent ........................................................................................................... 18

Figure 3: Mirror fixation ................................................................................................................. 19

Figure 4: Mirror fixation DIY .......................................................................................................... 19

Figure 5: PSA tape - dispersion .................................................................................................... 20

Figure 6: Packaging tape .............................................................................................................. 20

Figure 7: Masking tape.................................................................................................................. 20

Figure 8: PSA tape - hotmelt ......................................................................................................... 22

Figure 9: Self adhesive labels ....................................................................................................... 23

Figure 10: Hygiene products ......................................................................................................... 23

Figure 11: Physical hardening - hotmelt ........................................................................................ 25

Figure 12: Furniture production ..................................................................................................... 26

Figure 13: Textile lamination ......................................................................................................... 26

Figure 14: Physical hardening - organic solvent ............................................................................ 27

Figure 15: Furniture laminate ........................................................................................................ 28

Figure 16: Flooring ........................................................................................................................ 28

Figure 17: Physical hardening - water based ................................................................................ 29

Figure 18: Construction ................................................................................................................. 30

Figure 19: Parquet flooring ............................................................................................................ 30

Figure 20: Plastisol ....................................................................................................................... 32

Figure 21: Automotive ................................................................................................................... 32

Figure 22: Construction - brick filling ............................................................................................. 32

Figure 23: Chemical curing - 1K .................................................................................................... 35

Figure 24: Electronics PCB ........................................................................................................... 36

Figure 25: Glass construction ....................................................................................................... 36

Figure 26: Chemical curing - 2K .................................................................................................... 37

Figure 27: Window frame .............................................................................................................. 38

Figure 28: Structural glazing ......................................................................................................... 38

Figure 29: Nuts & bolts.................................................................................................................. 41

Figure 30: Bridge construction ...................................................................................................... 41

Figure 31: Pipe connection ........................................................................................................... 41

Figure 32: Screws ......................................................................................................................... 43

Figure 33: Electronic components ................................................................................................. 43

Figure 34: Wood construction ....................................................................................................... 43

Figure 35: Pins & rivets ................................................................................................................. 45

Figure 36: Aircraft construction ..................................................................................................... 46

Figure 37: Metal construction ........................................................................................................ 46

Figure 38: Stitches & stapling ....................................................................................................... 47

Figure 39: Construction ................................................................................................................. 47

Figure 40: Cable fixation ............................................................................................................... 47

Figure 41: Joining by forming ........................................................................................................ 50



October 2009 |

Figure 42: Cable connection ......................................................................................................... 51


Figure 44: Snap fit ......................................................................................................................... 52

Figure 45: Snap fit - glove box ...................................................................................................... 53

Figure 46: Snap fit - phone assembly ............................................................................................ 53

Figure 47: Brazing ......................................................................................................................... 55

Figure 48: Car manufacturing........................................................................................................ 55

Figure 49: Bicycle frame ............................................................................................................... 55

Figure 50: Soldering ...................................................................................................................... 57

Figure 51: PCB fixation ................................................................................................................. 57


Figure 53: Welding - metal ............................................................................................................ 60

Figure 54: Pipe welding................................................................................................................. 60

Figure 55: Robot welding - industrial parts .................................................................................... 60

Figure 56: Welding - plastic ........................................................................................................... 62

Figure 57: Filter components ........................................................................................................ 63

Figure 58: Packaging .................................................................................................................... 63

Figure 59: Worksheet “Comparison”: select joining methods to compare ...................................... 70

Figure 60: Worksheet “Comparison”: comparison of two selected joining methods ....................... 71

Figure 61: Worksheet “Comparison”: major strengths and weaknesses ........................................ 71

Figure 62: Worksheet “Criteria comp”: select specific criteria for comparison ................................ 72

Figure 63: Worksheet “Criteria comp”: performance of joining methods on selected criteria ......... 73

Figure 64: Worksheet “Criteria comp”: Top 5 joining methods on selected criteria ........................ 73

Figure 65: Worksheet "Criteria comp": Overall best on selected criteria ........................................ 73

Figure 66: Applied joining methods - consumer electronics ........................................................... 76

Figure 67: Top 3 - Most applied joining methods - consumer electronics ...................................... 76

Figure 68: The most applied joining method - consumer electronics ............................................. 77

Figure 69: Reasons for choice of joining methods - consumer electronics .................................... 78

Figure 70: Awareness of PSA tapes as joining method - consumer electronics ............................ 79

Figure 71: Current use of PSA tape as joining method - consumer electronics ............................. 79

Figure 72: Research investment for selection of joining methods - consumer electronics ............. 80

Figure 73: Key requirements joining methods - consumer electronics ........................................... 81



October 2009 |

1 Summary

The Afera marketing committee has commissioned Meijer + Voermans Consulting to study the

opportunities to increase the pie for the European self adhesive tape industry by replacing

alternative joining methods.

Knowledge about the performance of current joining methods and the comparison with self

adhesive tape is a first step in a successful replacement of these joining methods by self adhesive

tape.

Today, many different processes or methods are used to fasten or join materials.

The joining methods can be categorized in four main groups:

adhesive bonding

mechanical joining

brazing / soldering

welding

For the decision which joining method to use in a specific application, several factors are relevant.

In order to have a complete assessment of the joining method, this study considers criteria related

to the feature of the joint (e.g., stress distribution, sealing function) and production related criteria

(e.g. assembly time, equipment). A strength-weakness analysis of all joining methods is conducted

through the judgement of these factors.

Meijer + Voermans Consulting developed a tool that allows a direct comparison of all joining

methods on the evaluated criteria. The comparison tool includes data of 19 joining methods judged

on joint features and production related aspects.

The tool allows comparison in two directions:

Comparison of joining methods: showing the performance of the selected joining methods on

25 criteria

Comparison of the performance on specific criteria: showing the top 5 joining methods

performing best on selected criteria

The results of the comparison are be visualised in graphs and the major strength and weaknesses

for the comparison of the specific joining methods are summarised.



October 2009 |

The objective of the second part of this study is a detailed market research concerning joining

methods in consumer electronics, identifying

Main joining methods currently used

Reasons for the choice of joining methods

Unmet needs related to current joining methods

The consumer electronics market is defined as any device containing an electronic circuit board

that is intended for everyday use by individuals. This encompasses a large category of electronics

that includes televisions, cameras, digital cameras, PDAs, calculators, VCRs, DVDs, clocks, audio

devices, headphones, camcorders, and many other home products.

The data is based on primary research (questionnaire) with experts in the consumer electronics

industry mainly including design engineers and mechanical engineers.

Mechanical joining methods are the dominant joining method for consumer electronics. Most used

are fasteners (screws) and integral joints (snap fit).

The main reasons to use these methods are:

Cost

Fast assembly

Easy disassembly

Bond strength

Previous experiences

Today the general awareness for PSA tapes as joining method in consumer electronics is with

63% relatively low. Only 30% of those who are familiar with PSA tapes currently use PSA tapes as

joining method.

It can be concluded that there is clearly a need to raise the awareness level for self adhesive tape

as joining method to ultimately increase the use of self adhesive tape in the consumer electronics

market.

This study and the accompanying Excel tool were especially developed in order to help the Afera-

members raise the awareness level of PSA tape as a joining method with their customers and

prospects. With the use of this report and tool the Afera organisation hopes that its members will

be able to eventually increase the pie for the European self adhesive tape industry.



October 2009 |

2 Introduction

The Afera marketing committee has commissioned Meijer + Voermans Consulting to study the

opportunities to increase the pie for the European self adhesive tape industry by replacing

alternative joining methods.

Knowledge about the performance of current joining methods and the comparison with self

adhesive tape is a first step in a successful replacement of these joining methods by self adhesive

tape.

The approach taken in this study can be described as a pragmatic approach. The main focus was

on the comprehensive and technical analysis of the different joining methods. All information

collected was integrated in a simple working tool, which can be used directly for new business

development activities in your company.

This working tool is considered to be valuable in a wide range of situations, including following:

Detailed discussions with your (potential) customer in case of problems with the existing joining

method

The knowledge provided with this tool could be used to increase the awareness at your

(potential) customer of self adhesive tape as an interesting joining method

Execute a Strength-Weakness analysis of your product(s) on the relevant criteria, in order to

position your current product next to alternative joining methods

The comparison of the Strength-Weakness analysis of self adhesive tape or your product in

particular with one or more alternative joining methods could drive new product development to

match the precise market needs

For internal education purposes to raise the knowledge level about joining methods in order to

be a competent partner for discussions with your (potential) customer

As a supporting tool for brainstorming sessions in order to define the specific market

development activities (e.g. the potential markets and/or joining methods) for your products



October 2009 |

2.1 Target and objectives

The purpose of this study is to provide, by means of a comprehensive analysis, relevant

information for the assessment and exploration of opportunities to replace alternative joining

methods by self adhesive tapes.

The study’s principal objectives are to provide an accurate and complete (technical) evaluation of

the joining methods, including the following:

An overview of the available joining methods, identifying the main groups

Strength-Weakness analysis of each joining method considering features of the joint and

production related aspects

Comparison of the different joining methods, identifying the main advantages and

disadvantages of self adhesive tapes over alternative joining methods

An Excel-based working tool to compare different joining methods. This tool should trigger and

initiate ideas for new business opportunities related to the replacement of alternative joining

methods by self adhesive tape

This evaluation is relevant for all markets and applications of joining methods.

The objective of the second part is a detailed market research concerning joining methods in

consumer electronics, identifying




This research work is executed by primary research in the consumer electronics market.



October 2009 |

2.2 Scope

The scope of this study includes the main joining categories and considers the main technologies

within each category. It includes the technical assessment of joining methods, currently used in the

industry.

The market related research is limited to the “consumer electronics” segment.

The selection of the “consumer electronics” segment was made by the Afera marketing committee.

This study is not intended to make decisions for its readers. Rather, it provides a basis and

framework for decision-making, and can improve the probability of making better, more informed

decisions based on a sound understanding of the current joining methods in the industry. This

study (including the working tool) is therefore expected to be a valuable tool in steering the strategy

and innovation of companies and driving the industry forward.

This study contains information gathered professionally and in good faith from sources within the

public domain, expert interviews and internal databases. While every step has been taken to

ensure that the data presented is accurate and information is based on expert knowledge, neither

Meijer + Voermans Consulting nor Afera accepts responsibility for any consequences arising from

the application of data and information presented in this document. Expert advice should always be

taken on the application of analyses.



October 2009 |

3 Methodology

Meijer + Voermans Consulting used a research methodology based on primary and secondary

data collection, in-house information, and access to a wide range of industry contacts.

The primary research information in this study was collected through a survey combined with in-

depth interviews with a range of industry experts, professionals and design engineers.

Secondary research is based on a wide range of sources, including:

A review of all available published information on joining methods in general and joining

methods in consumer electronics in particular

On-line databases and internet searches

Analysis of relevant industry statistics

Other industry sources

In the survey and interviews, it was indicated that the study is conducted for Afera, i.e. promoting

the self adhesive tape industry.



October 2009 |

4 Joining methods

4.1 Categorization of joining methods

Today, many different processes or methods are used to fasten or join materials.

The joining methods can be categorized in four main groups:

adhesive bonding

mechanical joining

brazing / soldering

welding

A further break-down of these groups can be made as outlined in Figure 1.

The next sections give a detailed description and analysis of each joining method.

Figure 1: Overview joining methods

Joining methods

Adhesive Mechanical

Solvent based

Dispersion

Hotmelt

Brazing / Soldering

Hotmelt

Organic solvent

Water based

Plastisol

1K

2K

Nuts & Bolts

Screws

Pins & Rivets

Stitching & Stapling

Joining by forming

Snap fit

Physically

hardening

Chemical

curingPressure

sensitive tapes

Metal - metal

Plastic - plastic

Fastener Integral joints

Brazing

Soldering

Welding



October 2009 |

4.2 Strength-weakness analysis of joining method: methodology

For the decision which joining method to use in a specific application, several factors are relevant.

In order to have a complete assessment of the joining method, this study considers criteria related

to the feature of the joint (e.g., stress distribution, sealing function) and production related criteria

(e.g. assembly time, equipment).

The complete list of judgement criteria, considered in this study, is shown in Table 1 below.

Table 1: Judgement criteria for strength-weakness analysis of joining methods

A strength-weakness analysis of all joining methods (as mentioned in Figure 1) was conducted

through the judgement of these factors. The judgements are based on the available secondary

market research data combined with industry expert opinions.

Nr. Judgement criteria Explanation

Part 1: Feature of joint

1.1 Removable Is the joint designed to be permanent or removable

1.2 Stress and stress distribution Does the joint have points of high stress or is the stress evenly distributed. Does the joining method induce stress

into the substrate due to heat or mechanical damage (e.g. hole, tapping)

1.3 Appearance / aesthetic Judgement of joint appearance: is the joint visible and/or do surface discontinuities exist

1.4 Temperature resistance (in end use) Is the joint resistant to high temperatures

1.5 Mechanical (fatigue) resistance Is the joint resistant to fatigue

1.6 Solvent resistance Is the joint resistant to solvents

1.7 Sealing function Does the joining method seal the joint (air/water-tight): continuous joint and ability to adapt to substrate

1.8 Strength-to-Weight ratio Bond strength of the joint related to the weight of the joining method

1.9 Transmission of structure-borne noise and vibrations Is the joining method able to damp and/or insulate the structure-borne noise and vibrations

1.10 Bond strength How high is the strength of the joint with respect to load and creep resistance

1.11 Corrosion resistance and prevention Is the joining method resistant to corrosion, can the joining method prevent corrosion

1.12 Recyclability Does the joining method allow easy recycling: either by disassembly or disposal as single material

Part 2: Production related aspects

2.1 Materials joined Is the joining method able to connect a great variety of substrates: similar/dissimilar materials, shapes and

thicknesses

2.2 Rate of strength development How much time is needed for the joint to reach final bond strength

2.3 Distortion of assembly How high is the risk for distortion of the assembly due to temperature and/or applied joining forces

2.4 Preparation of joint Does the substrate need to be cleaned (pollutants) and prepared (hole, tapping) before joining

2.5 Post-processing Is processing required after applying the joining method: cleaning, joint dressing, retightening

2.6 Equipment What equipment (cost, portable) is involved to create the joint (assumption: continuous process)

2.7 Consumables How high is the cost for the materials used to create the joint

2.8 Production rate / assembly time How high is the speed of the joining method (assumption: continuous process)

2.9 Quality assurance How easy and reliable is the quality inspection of the joint

2.10 Level of skill required / assembly complexity How much skill is required to create the joint and execute the joining method

2.11 Ease of repair Is it easy to repair the joint when the joint is damaged/broken

2.12 Heat requirements Are the substrates exposed to heat during assembly: temperature, duration, area of exposure

2.13 Health & safety risks What is the risk for the operator during assembling with respect to elevated temperature, emissions, dangerous

equipment



October 2009 |

A rating is given to each criterion on a scale from -5 to +5.

“-5” in case the concerned criterion is judged as a severe weakness.

“+5” in case the concerned criterion is judged as a high strength.

The relevance of all criteria is set at 1 as this study includes a comparison of the joining methods in

general. The final score of a criterion is calculated by multiplying the rating with the relevance of

each criterion.



October 2009 |

5 Pressure sensitive adhesive tapes

The special feature of pressure sensitive adhesives is that they do not solidify to form a solid

material, but remain viscous. As a result, they remain permanently tacky and have the ability to wet

surfaces on contact. Bonds are made by bringing the adhesive film in contact with the substrate

and applying pressure.

To produce PSA tapes the polymer is coated on a release liner (or directly on a substrate) after

which the coating is dried (cooled and/or crosslinked) to produce a PSA film. This film can be

transferred to a carrier material to produce a PSA tape. The carrier material may be covered on

one side or on both sides with the PSA film to create a tape. Single side coated PSA tapes are

typically used for covering and connecting substrates whereas double side coated PSA tapes are

mainly used for mounting substrates The PSA film without carrier material is called transfer tape.



October 2009 |

5.1 Adhesive - PSA tape - Solvent based

5.1.1 Definition and description

For solvent based PSA tapes, polymers are diluted in organic

solvent(s). This liquid is coated on a substrate after which the solvent

is dried and the polymer is crosslinked to produce a PSA film. The

solid content before coating is typically < 50%.

Within the group of pressure sensitive adhesives, solvent-based, pure

acrylic adhesives are the premium choice for applications where a

combination of high shear, temperature, chemicals and aging

resistance is required.

Figure 2: PSA tape-solvent

Solvent-based, pure synthetic rubber adhesives are unequalled with regard to a high-level mix of

shear, initial tack and adhesion to low-energy surfaces.

5.1.2 Delivery form

Rolls

Spool

Die-cut parts / stripes

5.1.3 Application method

Manual

Automatic dispensing

Pick & place for small (die-cut) parts

5.1.4 Typical applications

Graphics (flying splices, decorative films etc)

Automotive

Electronics

Medical



October 2009 |

5.1.5 End-product examples

Figure 3: Mirror fixation Figure 4: Mirror fixation DIY

5.1.6 Strength-Weakness analysis

Table 2: Strength-Weakness analysis of PSA tape - solvent based

Strengths Weaknesses

Good stress distribution

Good appearance / Aesthetics

Avoids galvanic corrosion

Easy assembly of different materials

Easy and fast assembly

Difficult to repair / remove

Recyclability

Temperature resistance

Bond strength

Preparation of joint

Nr. Judgement criteria Type PSA tape - Solvent based


1.1 Removable Weakness Permanent; difficult to remove without damaging the construction

1.2 Stress and stress distribution StrengthGood uniform load distribution over joint area (except in peel); no induced stress (no heat

or mechanical damage)

1.3 Appearance / aesthetic Strength Very good joint appearance; joint not visible, no discontinuities

1.4 Temperature resistance (in end use) Weakness Poor temperature resistance due to organic adhesive

1.5 Mechanical (fatigue) resistance StrengthVery good mechanical resistance; good stress distribution combined with excellent fatigue

properties

1.6 Solvent resistance Weakness Medium - poor solvent resistance due to polymer

1.7 Sealing function Strength Good - very good sealing; continuous joint, good ability to adapt to substrate

1.8 Strength-to-Weight ratio Strength Medium - low strength and low weight

1.9Transmission of structure-borne noise

and vibrationsStrength Good - very good because of the viscoelastic behaviour of the PSA

1.10 Bond strength Weakness Poor bond strength; medium load and very poor creep resistance

1.11 Corrosion resistance and prevention Strength Very good corrosion resistance and corrosion prevention

1.12 Recyclability Weakness Very poor; difficult disassembly, joint material is typically different from substrate


2.1 Materials joined Strength Joins any combination of similar or dissimilar materials, shapes and thicknesses

2.2 Rate of strength development Strength Medium - fast; final strength developed over minutes - hours

2.3 Distortion of assembly Strength Very low risk for distortion; no heat or forces during assembly

2.4 Preparation of joint Weakness Surface treatment and/or cleaning often required

2.5 Post-processing Strength Typically not required

2.6 Equipment Strength Fairly simple dispensing equipment: low cost

2.7 Consumables Weakness High material cost

2.8 Production rate / assembly time Strength Very high speed

2.9 Quality assurance Weakness Difficult; limited non destructive tests (NDT) methods available

2.10Level of skill required / assembly

complexityStrength No special skill required; easy application, typically use of automated processes

2.11 Ease of repair Weakness Difficult to repair after joint has been created

2.12 Heat requirements Strength No exposure during assembly

2.13 Health & safety risks Strength Very low risk; no emissions, no elevated temperature, simple equipment

PSA tape - Solvent based

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

5.2 Adhesive - PSA tape - Dispersion


For dispersion based PSA tapes, polymers are dispersed in water. This liquid

is coated on a substrate after which the solvent is dried and the polymer is

crosslinked to produce a PSA film. The solid content before coating is typically

> 50%. The molecular weight of the polymer is usually lower compared to

solvent borne PSA adhesives.

Figure 5: PSA tape - dispersion

5.2.2 Delivery form

Rolls

Spool



Manual




Packaging

Masking

Label


Figure 6: Packaging tape Figure 7: Masking tape



October 2009 |


Table 3: Strength-Weakness analysis of PSA tape - dispersion








Recyclability


Bond strength


Nr. Judgement criteria Type PSA tape - Dispersion








properties

1.6 Solvent resistance Weakness Medium - poor solvent resistance due to polymer





1.10 Bond strength Weakness Poor - very poor bond strength; medium-poor load and very poor creep resistance


















PSA tape - Dispersion

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

5.3 Adhesive - PSA tape - Hotmelt


A hotmelt PSA is a 100% solid system and is processed at

elevated temperatures. The basic PSA polymer is melted and

subsequently coated as a thin film on a release liner or carrier

material. After cooling (and crosslinking) of the polymer the hotmelt

PSA becomes solid again.

Figure 8: PSA tape - hotmelt

Rubber based hotmelt PSA (HMPSA) are most common and are the most economical choice to

manufacture adhesive tapes with regard to the capital investment, infrastructure, and space.

Rubber based HMPSA have impressive peel performance and excellent adhesion to low-energy

surfaces.

The scope of applications for rubber based HM PSA is limited as a result of

thermoplastic properties

poor resistance to UV-light

Acrylic HMPSAs provide better oxidative resistance and UV stability than rubber based HMPSAs.

5.3.2 Delivery form

Rolls

Spool



Manual




Packaging tape

Label

Hygienic products



October 2009 |


Figure 9: Self adhesive labels

Figure 10: Hygiene products


Table 4: Strength-Weakness analysis of PSA tape - hotmelt








Solvent resistance

Bond strength


Difficult to repair

Nr. Judgement criteria Type PSA tape - Hotmelt


1.1 Removable Neutral Permanent; however removable when using heat to disassemble




1.4 Temperature resistance (in end use) Weakness Very poor (lowest) temperature resistance due to use of hotmelt


properties

1.6 Solvent resistance Weakness Very poor solvent resistance due to polymer


1.8 Strength-to-Weight ratio Neutral Low strength and low weight



1.10 Bond strength Weakness Very poor bond strength; poor load and very poor creep resistance


1.12 Recyclability Weakness Poor; removable when using heat, joint material is typically different from substrate
















PSA tape - Hotmelt

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

6 Physically hardening adhesives

Physically hardening adhesives are adhesives which, on application, are already present in their

final chemical state. Only polymers that can be liquefied can be used for this category of adhesive,

namely thermoplastics that can be melted, soluble thermoplastics or elastomers, or polymer

dispersions.



October 2009 |

6.1 Adhesive - Physical hardening - Hotmelt


Hot melt adhesives are generally 100% solids formulations based on

thermoplastic polymers. They are solid at room temperature and are

activated upon heating above their softening point, at which stage they are

liquid, and can be processed. After application, they retain the ability to wet

the substrate until they solidify. Upon solidification, they return to a physical

state that has structural integrity and can function as an adhesive.

Figure 11: Physical hardening - hotmelt

6.1.2 Delivery form

Rod (stick) for handheld hot melt glue guns

Block, granular, powder for bulk melt processors

Film


Application of the hotmelt in liquid state by:

Extruding (die, nozzle)

Rolling / printing

Spraying

Joining is carried out immediately after application or after reheating the solidified layer.


Packaging

Printing

Textile, non woven, hygiene

Shoe

Furniture / wood processing

Automotive

Electronics



October 2009 |


Figure 12: Furniture production Figure 13: Textile lamination


Table 5: Strength-Weakness analysis of physical hardening - hotmelt




Good sealing function

No post processing required


Very poor temperature resistance

Solvent resistance

Bond strength


Ease of repair

Nr. Judgement criteria Type Physical hardening - Hotmelt



1.2 Stress and stress distribution StrengthGood uniform load distribution over joint area (except in peel); induced stress small (limited

heat during assembly)


1.4 Temperature resistance (in end use) Weakness Very poor (lowest) temperature resistance due to use of hotmelt


properties

1.6 Solvent resistance Weakness Very poor solvent resistance due to polymer

1.7 Sealing function Strength Very good sealing; continuous joint, good ability to adapt to substrate

1.8 Strength-to-Weight ratio Neutral Low strength and low weight


and vibrationsStrength Good - very good because of the viscoelastic behaviour of the polymer

1.10 Bond strength Weakness Very poor bond strength; poor load and very poor creep resistance


1.12 Recyclability Neutral Poor; removable when using heat, joint material is typically different from substrate



2.2 Rate of strength development Strength Fast; final strength developed after seconds - minutes (cooling time)

2.3 Distortion of assembly Strength Medium - low risk for distortion; heat of hotmelt, no forces during assembly



2.6 Equipment Weakness Heating and dispensing equipment: medium - high cost

2.7 Consumables Neutral Medium material cost

2.8 Production rate / assembly time Strength Medium - high speed



complexityStrength Some skill required for correct application: speed, temperature


2.12 Heat requirements Neutral Medium exposure; medium temp, short duration of heat exposure on joint only

2.13 Health & safety risks Strength Low risk; some emissions possible due to elevated temperature

Physical hardening - Hotmelt

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

6.2 Adhesive - Physical hardening - Organic solvent


Adhesives are formulated from solvents containing polychloroprene,

polyurethane, acrylic, and natural and synthetic rubbers (elastomers). Solvent

based adhesives contain significant levels of volatile organic compounds

(VOCs). They are available with a variety of drying and bonding times to match

the application method and assembly process.

Figure 14: Physical hardening - organic solvent

Two major classes exist:

1. Wet bonding adhesives

These adhesives build strength through the evaporation of the solvent. After application of the

adhesive, the substrates must be bonded while the adhesive is still liquid. Final bond strength is

obtained after the remaining solvent evaporates from the bond line.

2. Contact adhesives

Both substrates are coated with adhesive and any solvent present is allowed to evaporate before the

bond is made. The bond is formed by bringing the two coated substrates together using enough

pressure to insure intimate contact of the two adhesive films, the adhesive having sufficient tack or

auto-adhesion to provide early bond strength. Bond strength builds over time.

6.2.2 Delivery form

Liquid

Spray

Paste (beads or ribbons)


Manually or automatically apply by

Brush / roller

Spray

Beads or ribbons


Furniture (laminates)

Footwear

Flooring



October 2009 |


Figure 15: Furniture laminate Figure 16: Flooring


Table 6: Strength-Weakness analysis of physical hardening - organic solvent








Recyclability

Rate of strength development

Health & safety risks / VOC (solvents)


Nr. Judgement criteria Type Physical hardening - Organic solvent



1.2 Stress and stress distribution StrengthGood uniform load distribution over joint area (except in peel); induced stress small (heat

required for drying)




properties

1.6 Solvent resistance Weakness Poor solvent resistance due to polymer





1.10 Bond strength Weakness Poor bond strength; medium load and poor creep resistance





2.2 Rate of strength development Weakness Slow; final strength developed over hours - days (evaporation / curing time)

2.3 Distortion of assembly Strength Low risk for distortion; heat for drying, no forces during assembly



2.6 Equipment Weakness Dispensing, drying and ventilation equipment: medium - high cost

2.7 Consumables Weakness Medium material cost

2.8 Production rate / assembly time Weakness Slow speed due to bond strength build up



complexityWeakness Some skill required for correct application: speed, temperature, drying


2.12 Heat requirements Weakness Medium; low - medium temp, medium duration of heat exposure on total assembly

2.13 Health & safety risks Weakness High risk; evaporation of solvents

Physical hardening - Organic solvent

-5 -4 -3 -2 -1 0 1 2 3 4 5

http://homeimprovement.lovetoknow.com/Image:Linoleum_Flooring.jpg



October 2009 |

6.3 Adhesive - Physical hardening - Water based


Water based physical hardening adhesives include a wide variety of

polymeric materials (usually thermoplastics or elastomers) dispersed or

dissolved in a continuous aqueous phase.

Water based products can be classified as either solutions or

dispersions:

Figure 17: Physical hardening - water based

Solutions

Water-based solution adhesives are based on natural and synthetic polymers that can be dissolved

in water. Bonds are formed by the evaporation of water or by absorption of water into the substrate.

These adhesives are used in bonding paper and paper products as well as in moistenable adhesives

such as those used on stamps, envelopes, labels, and packing tape.

Polymer dispersions / emulsions

Water based dispersion adhesives are typically formulated from compounds including vinyl acetate

polymers and copolymers (PVAC), ethylene vinyl acetate (EVA), acrylics, styrene-butadiene rubber

(SBR), natural rubber latex and synthetic elastomers, and polyurethane (PUR). Like latex paint,

these adhesives are heterogeneous systems comprising a solid polymer phase dispersed in an

aqueous phase.

Similar to solvent based physical hardening adhesives the polymer dispersions can be divided in two

major classes:

1. Wet bonding adhesives:

After adhesive application, substrates are joined while the adhesive is still wet. The bond forms as a

result of water being lost either by evaporation or absorption by the substrate. These adhesives are

often used in the paper processing industry, in the packaging sector and in furniture-making.



October 2009 |

2. Contact adhesives:

As with solvent based contact adhesives, both substrates are coated with adhesive. The water is

then allowed to evaporate before the bond is made. The bond is formed by bringing the two

coated substrates together using only enough pressure to insure intimate contact of the two

adhesive films, the adhesive having sufficient tack or auto-adhesion to provide early bond

strength. Bond strength builds over time as the two adhesive surfaces remain in contact and the

films co-mingle.

6.3.2 Delivery form

Liquid

Spray

Paste (bead / ribbon)


Manually or automatically apply by

Brush

Roller

Spray

Beads or ribbons


Wood (furniture making, construction)

Paper

Fabrics

Leather

Other porous substrates


Figure 18: Construction Figure 19: Parquet flooring



October 2009 |


Table 7: Strength-Weakness analysis of physical hardening - water based

Strengths

Weaknesses







Recyclability




Nr. Judgement criteria Type Physical hardening - Water based



1.2 Stress and stress distribution StrengthGood uniform load distribution over joint area (except in peel); induced stress small (heat

required for drying)




properties











2.2 Rate of strength development Weakness Slow; final strength developed over hours - days (evaporation / curing time)

2.3 Distortion of assembly Strength Low risk for distortion; heat for drying, no forces during assembly








complexityWeakness Some skill required for correct application: speed, temperature, drying


2.12 Heat requirements Weakness Medium; low - medium temp, medium duration of heat exposure on total assembly

2.13 Health & safety risks Neutral Medium risk; elevated temperature

Physical hardening - Water based

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

6.4 Adhesive - Physical hardening - Plastisol


Plastisols are single-component adhesives (coatings) that are applied as a

paste to the substrate. The paste consists of solid polyvinylchloride (PVC)

particles dispersed in plasticizer. In order to form a bond, the applied

adhesive is heated so that the thermoplastic PVC swells and can take up the

plasticizer. Acrylic plastisols are dispersions of an acrylic polymer (usually

based on methyl methacrylate) in a plasticizer, which are heat cured.

Figure 20: Plastisol

They are halogen-free replacements for PVC plastisol sealants. The two-phase system (sol)

converts to a single-phase system (gel) by incorporating plasticizer in the swollen polymer which

occurs at a temperature between 150 and 180°C and results in an adhesive film consisting of a

plasticized polymer. The cured product may be a soft, rubber-like material or a tough, hard solid.

6.4.2 Delivery form

Paste / Gel


Dip coat

Coating

Spraying


Automotive

Construction

Textile and carpet industries

Fabric coating / Laminating


Figure 21: Automotive Figure 22: Construction - brick filling



October 2009 |


Table 8: Strength-Weakness analysis of physical hardening - plastisol



Good mechanical / Fatigue resistance


Good dampening of structure borne noise and

vibrations



Recyclability


Production / assembly time


Nr. Judgement criteria Type Physical hardening - Plastisol



1.2 Stress and stress distribution NeutralGood uniform load distribution over joint area (except in peel); induced stress medium

(heat required for curing, 150-180°C)


1.4 Temperature resistance (in end use) Weakness Poor temperature resistance due to polymer


properties





and vibrationsStrength Very good because of the viscoelastic behaviour of the plastisol





2.1 Materials joined StrengthJoins any combination of similar or dissimilar materials, shapes and thicknesses; high

temperature required for curing limits choice of substrate material

2.2 Rate of strength development Weakness Medium - Slow; final strength developed over hours - days (curing time)

2.3 Distortion of assembly Weakness Medium risk for distortion; heat for drying, no forces during assembly










2.12 Heat requirements Weakness High; medium - high temp, medium duration of heat exposure on total assembly

2.13 Health & safety risks Neutral Medium risk; elevated temperature

Physical hardening - Plastisol

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

7 Chemically curing adhesives

Chemically curing adhesives are reactive materials that require chemical reaction to convert them

from liquid (or thermoplastic) to solid. Once cured, these adhesives generally provide high

strength, flexible to rigid bond lines that resist temperature, humidity, and many chemicals.



October 2009 |

7.1 Adhesive - Chemical curing - 1K


With single component adhesives, the adhesive components are

premixed in their final proportions. They are however chemically

blocked. As long as they are not subjected to the specific

conditions which activate the hardener they will not cure. They

require either, high temperature, substances or media (light,

humidity) from the surroundings to initiate the curing mechanism.

Figure 23: Chemical curing - 1K

The containers in which this type of adhesive are transported and stored must be carefully chosen

to prevent any undesired reactions.

The four major classes are:

1. Anaerobic: cure under the absence of oxygen

2. Heat cure: require high temperatures for a specified period of time to achieve cure

3. Moisture cure: require moisture to trigger the curing reaction

4. Radiation cure: require light waves of defined wavelength

7.1.2 Delivery form

Liquid

Paste

Film


Spray

Lamination


Automotive

Electronics

Wood structures / Composites

Dental technology

Bonding and sealing glass and metal



October 2009 |


Figure 24: Electronics PCB

Figure 25: Glass construction


Table 9: Strength-Weakness analysis of chemical curing - 1K





Good strength to weight ratio

No post processing



Difficult quality assurance (structural joints)


Nr. Judgement criteria Type Chemical curing - 1K



1.2 Stress and stress distribution StrengthGood uniform load distribution over joint area (except in peel); induced stress small

(exothermic reaction heat)


1.4 Temperature resistance (in end use) Neutral Medium temperature resistance due to the crosslinking and polymer


properties

1.6 Solvent resistance Neutral Medium solvent resistance due to the crosslinking and polymer


1.8 Strength-to-Weight ratio Strength Medium - high strength and low weight



1.10 Bond strength Strength Medium bond strength; medium-good load and medium creep resistance





2.2 Rate of strength development Weakness Medium; final strength developed over hours - days (reaction time)

2.3 Distortion of assembly Neutral Medium risk for distortion; heat from exothermic reaction, no forces during assembly



2.6 Equipment Strength Fairly simple and low cost dispensing equipment

2.7 Consumables Weakness Medium - high material cost

2.8 Production rate / assembly time Neutral Medium speed due to curing time





2.12 Heat requirements Weakness Medium exposure; medium temp, short duration of heat exposure on total assembly

2.13 Health & safety risks Neutral Medium risk; emissions depend on type of polymer and reaction

Chemical curing - 1K

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

7.2 Adhesive - Chemical curing - 2K


Two component adhesives are 100% solids systems that obtain

their storage stability by separating the reactive components.

They are supplied as “resin” and “hardener” in separate

containers. It is important to maintain the prescribed ratio of the

resin and hardener in order to obtain the desired cure and

physical properties of the adhesive.

Figure 26: Chemical curing - 2K

The two components are only mixed together to form the adhesive a short time before application

with cure occurring at room temperature. Since the reaction typically begins immediately upon

mixing the two components, the viscosity of the mixed adhesive increases with time until the

adhesive can no longer be applied to the substrate or bond strength is decreased due to

diminished wetting of the substrate.

Four major types of two component adhesives include:

1. Epoxies

2. Methyl methacrylates

3. Silicone adhesives

4. Urethanes

1. Epoxies

Are the most widely used structural adhesives. They can be formulated into fast curing systems

with 2 to 5 minute work-life that give rigid bond lines which are somewhat brittle. Two component

epoxy adhesives are used to bond metal, plastic, fibre reinforced plastic (FRP), glass, and some

rubbers.

2. Methyl methacrylates

Provide faster strength build-up than epoxy adhesives and are more tolerant to oil on the

substrate. MMA adhesives are used for bonding plastics to each other and for bonding metals to

plastics. Classic applications for this type of adhesive are in the automotive industry and in rail car

manufacturing.



October 2009 |

3. Silicone adhesives

Are generally used for production line assembly, e.g. in electronics and the electrical industry as

well as in the production of household appliances, in the automotive industry, and for window

manufacture. Two component silicones are used instead of single component silicones when

adhesive film thicknesses of over 6 mm are required or for large bonding areas.

4. Urethanes

Can be formulated with a wide range of cured properties ranging from soft and flexible, to tough

and elastic, to hard and rigid. They are used to bond materials with different flexibility or different

thermal coefficients of expansion including glass to metal, fibre reinforced plastic (FRP) to metal,

and aluminium to steel.

7.2.2 Delivery form

Liquid

Paste


Spray (Manual / automated)

Dispenser (e.g. cartouche)


Construction / Manufacturing

Transportation

Electronics


Figure 27: Window frame

Figure 28: Structural glazing



October 2009 |


Table 10: Strength-Weakness analysis of chemical curing - 2K





Good strength to weight ratio

No post processing



Difficult quality assurance (structural joints)


Nr. Judgement criteria Type Chemical curing - 2K



1.2 Stress and stress distribution StrengthGood uniform load distribution over joint area (except in peel); induced stress small

(exothermic reaction heat)


1.4 Temperature resistance (in end use) Neutral Medium temperature resistance due to the crosslinking and polymer


properties

1.6 Solvent resistance Neutral Medium solvent resistance due to the crosslinking and polymer


1.8 Strength-to-Weight ratio Strength Medium - high strength and low weight



1.10 Bond strength Strength Medium bond strength; medium-good load and medium creep resistance





2.2 Rate of strength development Neutral Medium; final strength developed over hours - days (reaction time)

2.3 Distortion of assembly Neutral Medium risk for distortion; heat from exothermic reaction, no forces during assembly



2.6 Equipment Neutral Dosing, mixing and dispensing equipment: medium cost

2.7 Consumables Weakness Medium - high material cost

2.8 Production rate / assembly time Strength Medium speed due to curing time



complexityWeakness Some skill required for correct application: dosing, mixing, speed, temperature


2.12 Heat requirements Weakness Medium exposure; medium temp, short duration of heat exposure on total assembly

2.13 Health & safety risks Neutral Medium risk; emissions depend on type of polymer and reaction

Chemical curing - 2K

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

8 Mechanical joining - Fasteners

Fasteners are discrete assembly items that are used to join together the various components of a

part. A fastener can be a bolt and nut, a screw, a rivet, or even a staple. However, the majority of

fasteners used in industry are threaded fasteners. These devices typically allow for the assembly

and disassembly of components.



October 2009 |

8.1 Mechanical - Fasteners - Nuts & Bolts


A nut is a type of hardware fastener with a threaded hole. Nuts are

almost always used opposite a mating bolt to fasten a stack of parts

together. The two partners are kept together by a combination of their

threads' friction, a slight stretch of the bolt, and compression of the

parts. In applications where vibration or rotation may work a nut loose.

Adhesives, safety pins, and other tricks are used to prevent fastener

rotation.

Figure 29: Nuts & bolts

The most common shape is hexagonal, for similar reasons as the bolt head - 6 sides give a good

granularity of angles for a tool to approach from (good in tight spots), but more (and smaller)

corners would be vulnerable to stripping/rounding.

8.1.2 Delivery form

Typical materials include

Stainless steel

Steel

Zinc plated

Galvanised

Plastic


Wrench: manual or powered


Construction / Manufacturing


Figure 30: Bridge construction Figure 31: Pipe connection



October 2009 |


Table 11: Strength-Weakness analysis of nuts & bolts


Removable joint

Good bond strength


Ease of repair

Low level of skill required

Stress and stress distribution

Appearance / Aesthetics

Sealing function

Cost for consumables

Mechanical fatigue resistance

Nr. Judgement criteria Type Nuts & Bolts


1.1 Removable Strength Removable

1.2 Stress and stress distribution Weakness Points of high stress; induced stress large (surface damage, holes)

1.3 Appearance / aesthetic Weakness Very poor joint appearance; clearly visible joint (both sides) and surface discontinuities

1.4 Temperature resistance (in end use) Strength Very good temperature resistance due to material used

1.5 Mechanical (fatigue) resistance WeaknessVery poor; points of high stress combined with poor fatigue properties; special provision

required for fatigue and resistance to loosening at joints

1.6 Solvent resistance Strength Very good solvent resistance due to material used

1.7 Sealing function Weakness Very poor sealing; discontinuous joint, no ability to adapt to substrate

1.8 Strength-to-Weight ratio Weakness High strength and very high weight


and vibrationsWeakness Very poor as solid and rigid connection; special provision required

1.10 Bond strength Strength Good - very good bond strength; very good load and good creep resistance

1.11 Corrosion resistance and prevention Weakness Poor corrosion resistance; requires SS or corrosion protection

1.12 Recyclability Strength Very good recycling; similar material and/or easy disassembly


2.1 Materials joined StrengthJoins most combinations of similar or dissimilar materials, shapes and thicknesses;

however hole / tapping limits choice of substrate material (e.g. ceramics, composites)

2.2 Rate of strength development Strength Very fast; immediate final strength

2.3 Distortion of assembly Weakness High risk for distortion; points of high stress during assembly

2.4 Preparation of joint Weakness Hole preparation required

2.5 Post-processing Neutral Usually no post-processing; occasional retightening in service

2.6 Equipment Strength Portable and "on-site" assembly: low - very low cost

2.7 Consumables Weakness Very high material cost

2.8 Production rate / assembly time Weakness Joint preparation and manual tightening: slow; mechanized tightening: fairly rapid

2.9 Quality assurance Strength Medium - good; reasonable confidence in torque control tightening


complexityStrength No special skill required; simple equipment handling

2.11 Ease of repair Strength Very good to repair; easy replacement


2.13 Health & safety risks Strength Low - medium risk; no emissions during assembly but manual equipment handling

Nuts & Bolts

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

8.2 Mechanical - Fasteners - Screws


Mechanical device for fastening things together, consisting essentially of a

cylindrical or conical piece of metal threaded evenly around its outside

surface with an advancing spiral ridge and commonly having a slotted head:

it penetrates only by being turned, as with a screwdriver.

Figure 32: Screws

8.2.2 Delivery form


Stainless steel

Steel

Zinc plated

Galvanised

Plastic


Screw driver: manual or powered

Automated assembly


Construction / manufacturing


Figure 33: Electronic components

Figure 34: Wood construction



October 2009 |


Table 12: Strength-Weakness analysis of screws


Removable joint

Good bond strength


Ease of repair



Appearance / Aesthetics

Sealing function



Nr. Judgement criteria Type Screws


1.1 Removable Strength Removable

1.2 Stress and stress distribution Weakness Points of high stress; induced stress large (surface damage, holes/tapping)

1.3 Appearance / aesthetic Weakness Poor joint appearance; visible joint (1 side) and small surface discontinuities






1.8 Strength-to-Weight ratio Weakness High strength and high weight



1.10 Bond strength Strength Good bond strength; good load and good creep resistance








2.4 Preparation of joint Weakness Hole preparation and/or tapping for threaded fasteners

2.5 Post-processing Neutral Usually no post-processing; occasional retightening in service



2.8 Production rate / assembly time Strength Joint preparation and manual "tightening": slow; mechanized tightening: fairly rapid

2.9 Quality assurance Strength Medium - good; reasonable confidence in torque control tightening



2.11 Ease of repair Strength Very good to repair; easy replacement



Screws

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

8.3 Mechanical - Fasteners - Pins & Rivets


A rivet is a mechanical fastener. Before it is installed it consists of a

smooth cylindrical shaft with a head on one end. The end opposite the

head is called the buck-tail. On installation the rivet is placed in a pre-

drilled hole. Then the tail is "upset" (i.e. deformed) so that it expands to

about 1.5 times the original shaft diameter and holds the rivet in place. To

distinguish between the two ends of the rivet, the original head is called

the factory head and the deformed end is called the buck-tail.

Figure 35: Pins & rivets

Because there is effectively a head on each end of an installed rivet it can support tension loads

(loads parallel to the axis of the shaft); however, it is much more capable of supporting shear

loads (loads perpendicular to the axis of the shaft).

8.3.2 Delivery form


Steel

Zinc plated

Galvanised

Aluminium


Manual rivet tools

Air powered rivet tools

Inserter presses


Automotive

Aerospace

Furniture

Restoration

Construction

http://upload.wikimedia.org/wikipedia/commons/6/6d/Blindnieten.JPG



October 2009 |


Figure 36: Aircraft construction

Figure 37: Metal construction


Table 13: Strength-Weakness analysis of pins & rivets




No post processing

Solvent resistance

Heat requirement

Permanent / difficult to repair


Sealing function



Nr. Judgement criteria Type Pins & Rivets




1.3 Appearance / aesthetic Weakness Poor joint appearance; clearly visible joint (both sides) and surface discontinuities






1.8 Strength-to-Weight ratio Weakness High strength and high weight











2.4 Preparation of joint Weakness Hole preparation required




2.8 Production rate / assembly time Weakness Joint preparation and manual "tightening": slow; mechanized tightening: fairly rapid

2.9 Quality assurance Strength Medium; non destructive tests (NDT) methods applicable



2.11 Ease of repair Weakness Difficult to repair; labour intensive to replace pins/rivets



Pins & Rivets

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

8.4 Mechanical - Fasteners - Stitching & Stapling


A U-shaped metal loop with pointed ends, driven into a surface to

hold a bolt, hook, or hasp or to hold wiring in place.

Figure 38: Stitches & stapling

8.4.2 Delivery form


Metal

Plastic

Fabric (stitching)


Staple gun: manual or powered

Stitching equipment


Fabric

Paper

Wood


Figure 39: Construction

Figure 40: Cable fixation



October 2009 |


Table 14: Strength-Weakness analysis of stitching & stapling




No post processing

Solvent resistance

Heat requirement



Sealing function


Distortion of assembly

Nr. Judgement criteria Type Stitching & Stapling




1.3 Appearance / aesthetic Weakness Poor joint appearance; visible joint (2 side) and small surface discontinuities

1.4 Temperature resistance (in end use) Strength Good temperature resistance; depends on material used (e.g. plastic)



1.6 Solvent resistance Strength Good solvent resistance; depends on material used (e.g. plastic)


1.8 Strength-to-Weight ratio Weakness Medium - low strength and medium weight



1.10 Bond strength Strength Medium bond strength; medium load and good creep resistance

1.11 Corrosion resistance and prevention Weakness Poor corrosion resistance; requires SS or corrosion protection unless plastic is used

1.12 Recyclability Weakness Medium - poor recycling; difficult disassembly, depends if joint material is similar material






2.4 Preparation of joint Strength No cleaning and preparation required



2.7 Consumables Strength Medium material cost

2.8 Production rate / assembly time Strength Medium - high speed; slow in case of manual assembly




2.11 Ease of repair Weakness Difficult to repair; labour intensive reparation


2.13 Health & safety risks Strength Medium risk; no emissions during assembly but dangerous equipment (high forces)

Stitching & Stapling

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

9 Mechanical joining - Integral

The term mechanical integral joining is used to describe the joining of two components without

additional “material”. One or both components are deformed to create a permanent joint or the two

components have integrated locating and locking features (constraint features). In the latter case

joining requires the (flexible) locking features to move aside for engagement with the mating part,

followed by return of the locking feature toward its original position to accomplish the interference

required to latch the components together. Locator features, the second type of constraint feature,

are inflexible, providing strength and stability in the attachment. This type of integral joints is called

“snap-fit”.



October 2009 |

9.1 Mechanical - Integral Joints - Joining by forming


The term “joining by forming” is generally used for technologies and processes

for manufacturing permanent connections between two or more work-pieces by

transforming at least one of the work-pieces This includes joining by mechanical

deformation without additional parts.

Figure 41: Joining by forming

Technologies included are:

Crimping

Hemming

Clinching

Lock forming

Joining by expanding

Joining by grooving and centre punch

Joint extrusion

Bulge forming

The joining by forming technology always requires overlapping areas of work-pieces.

9.1.2 Delivery form

Sheet

Tubes


Pressing / shaping tools


Automotive

HVAC

Ship building / Container building

Appliances

Piping



October 2009 |


Figure 42: Cable connection Figure 43: Pipe connection


Table 15: Strength-Weakness analysis of joining by forming


Strength to weight ratio


No post processing

No consumables

No heat required


Transmission structure-borne noise, vibrations

Corrosion resistance

Quality assurance


Nr. Judgement criteria Type Joining by forming



1.2 Stress and stress distribution NeutralGood uniform load distribution over joint line; induced stress medium (mechanical

deformation)

1.3 Appearance / aesthetic Neutral Medium joint appearance; visible but smooth joint


1.5 Mechanical (fatigue) resistance Neutral Medium due to good stress distribution but poor fatigue properties


1.7 Sealing function Neutral Medium sealing; continuous joint, no ability to adapt to substrate

1.8 Strength-to-Weight ratio Strength High strength and very low weight; material from structure is used for joint





1.12 Recyclability Strength Very good recyclability; single material, no disassembly required


2.1 Materials joined Weakness Limited to materials which can be pressed in shape (e.g. metal, some plastics)


2.3 Distortion of assembly Weakness Medium - high risk for distortion; area of high stress during assembly

2.4 Preparation of joint Strength Little or no cleaning and preparation required


2.6 Equipment Strength Portable and "on-site" assembly: low cost; depends on size of joint

2.7 Consumables Strength Typically no consumables required

2.8 Production rate / assembly time Strength Automated processes: relatively high speed



complexityNeutral Some skill required: (complex) equipment handling



2.13 Health & safety risks Strength Medium risk; no emissions during assembly but dangerous equipment (high forces)

Joining by forming

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

9.2 Mechanical - Integral Joints - Snap fit


Snap fits are commonly used as an assembly method for injection

moulded parts. Snap fits are very useful because they eliminate screws,

clips, adhesives, or other joining methods. The snaps are moulded into

the product, so additional parts are not needed to join them together.

Additionally, if designed correctly, they can be disassembled and

reassembled several times without any problems.

Figure 44: Snap fit

A snap fit can either be designed as a permanent snap or a multiple snap. Permanent fits are

used in disposable parts that are never meant to be disassembled. Multiple snaps are used in

most designs where disassembly for service is expected.

Snap fit connections typically suitable for the following material combinations:

Plastic – plastic

Plastic – metal

Metal – metal

9.2.2 Delivery form

Injection moulded parts

Press formed parts


Manual or automatic


Component assembly in:

Automotive

Electronics

Consumer goods



October 2009 |


Figure 45: Snap fit - glove box

Figure 46: Snap fit - phone assembly


Table 16: Strength-Weakness analysis of snap fit




Production rate / Assembly time

No post processing

Level of skill required

Preparation of joint (investments)

Difficult to repair


Sealing function

Transmission of structure-borne noise and

vibrations

Nr. Judgement criteria Type Snap fit


1.1 Removable Strength Removable in case of an accessible joint

1.2 Stress and stress distribution Weakness Points of high stress at connection; induced stress small (mechanical or heat)

1.3 Appearance / aesthetic Strength Good joint appearance; joint and discontinuities can be hidden by design

1.4 Temperature resistance (in end use) Strength Good temperature resistance; depends on material used (e.g. plastic)

1.5 Mechanical (fatigue) resistance WeaknessPoor; points of high stress combined with medium fatigue properties; special provision


1.6 Solvent resistance Strength Good solvent resistance; depends on material used (e.g. plastic)

1.7 Sealing function Weakness Poor sealing; discontinuous joint, no ability to adapt to substrate

1.8 Strength-to-Weight ratio Strength Medium strength and low weight


and vibrationsWeakness Poor as solid and rigid connection; special provision required

1.10 Bond strength Strength Medium - good bond strength; medium load and good creep resistance

1.11 Corrosion resistance and prevention Weakness Poor corrosion resistance; requires SS or corrosion protection unless plastic is used

1.12 Recyclability Strength Very good recycling; similar material and/or (easy) disassembly


2.1 Materials joined Weakness Limited to flexible materials (e.g. thin construction, plastic)


2.3 Distortion of assembly Strength Low risk for distortion; no heat and low forces during assembly

2.4 Preparation of joint Weakness High investment in equipment, tooling and engineering


2.6 Equipment Strength Typically no tools required


2.8 Production rate / assembly time Strength High speed



complexityStrength No special skill required

2.11 Ease of repair Weakness Very difficult to repair; practically impossible to repair as integrated in substrate


2.13 Health & safety risks Strength Very low risk; no emissions during assembly

Snap fit

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

10 Brazing and soldering

Brazing and soldering are processes in which the (liquid) filler metal is drawn into the joint by

capillary attraction (rather than deposited in the joint as in fusion welding). Brazing is a welding

process in which the filler metal has a melting point higher than 425 °C but lower than that of the

metal of metals being joined. The process known as soldering is generally similar to brazing

except that the filler metals used melt at temperatures below 400 °C. In actual practice, most

brazing alloys melt at temperatures well above 425 °C, most solders at temperatures well below

400 °C.



October 2009 |

10.1 Brazing


Brazing is a joining process whereby a non-ferrous filler metal or alloy is

heated to melting temperature above 450°C and distributed between two or

more close-fitting parts by capillary action. At its liquid temperature, the molten

filler metal and flux interacts with a thin layer of the base metal, cooling to form

an exceptionally strong, sealed joint due to grain structure interaction.

Figure 47: Brazing

10.1.2 Delivery form

Heat source: torch / laser


Brazing alloy: bar

Flux: liquid, gas, or included in brazing alloy


Wiring

Duct work

Piping


Figure 48: Car manufacturing Figure 49: Bicycle frame



October 2009 |


Table 17: Strength-Weakness analysis of brazing


Solvent resistance

Bond strength



Appearance


vibrations

Heat requirements


Post processing

Materials which can be joined

Nr. Judgement criteria Type Brazing



1.2 Stress and stress distribution WeaknessGood uniform load distribution over joint line; induced stress medium-high (heat required

for brazing > 450°C)

1.3 Appearance / aesthetic Strength Good joint appearance; joint barely visible and small surface discontinuities

1.4 Temperature resistance (in end use) Strength Very good temperature resistance; determined by filler material

1.5 Mechanical (fatigue) resistance Neutral Medium; good stress distribution combined with poor fatigue properties


1.7 Sealing function StrengthGood sealing; continuous joint, medium ability to adapt to substrate; requires special

equipment and skills

1.8 Strength-to-Weight ratio Strength High strength and medium weight


and vibrationsWeakness Very poor as solid and rigid connection


1.11 Corrosion resistance and prevention Weakness Poor corrosion resistance; requires corrosion protection

1.12 Recyclability Strength Good recycling; if brazing material is similar to substrate and removable by heat


2.1 Materials joined Weakness Suitable to join metals only; limited capability to join dissimilar metals


2.3 Distortion of assembly Weakness High risk for distortion due to process temperature

2.4 Preparation of joint Weakness Cleaning necessary and prefluxing often required (except for special processes)

2.5 Post-processing Weakness Corrosive fluxes must be cleaned off

2.6 Equipment Weakness Special furnaces and automatic unit: high cost; Manual equipment: low cost

2.7 Consumables Strength Medium - low material cost; some special brazing fillers are expensive


2.9 Quality assurance Weakness Difficult; skill and experience required


complexityWeakness High skill required for high quality joint: equipment handling

2.11 Ease of repair Strength Good to repair; without damaging substrate, with limited labour investment

2.12 Heat requirements Weakness High; high temperature, medium duration of heat exposure on major part of assembly

2.13 Health & safety risks Weakness Medium - high risk; elevated temperature and emissions

Brazing

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

10.2 Soldering


Soldering is the process in which two metals are joined together by means

of a third metal or alloy having a relatively low melting point. Soft soldering

is characterized by the value of the melting point of the third metal or alloy,

which is below 400°C. The third metal or alloy used in the process is called

solder.

Figure 50: Soldering

Soldering is distinguished from brazing by use of a lower melting-temperature filler metal; it is

distinguished from welding since the base metal is not melted during the joining process. In a

soldering process, heat is applied to the parts to be joined, causing the solder to melt and be

drawn into the joint by capillary action and to bond to the materials to be joined by wetting action.

After the metal cools, the resulting joints are not as strong as the base metal, but have adequate

strength.


Solder: bar

Flux: liquid or included in solder


Heat source: torch or soldering iron


Electronics and electronic components (PCB)

Copper pipes (plumbing)

Sheet metal (cans, radiators, rain gutters)


Figure 51: PCB fixation Figure 52: Pipe connection

http://en.wikipedia.org/wiki/File:Fitting1537.JPG



October 2009 |


Table 18: Strength-Weakness analysis of soldering


Solvent resistance

Bond strength



Appearance


vibrations

Heat requirements


Post processing


Nr. Judgement criteria Type Soldering



1.2 Stress and stress distribution NeutralGood uniform load distribution over joint line; induced stress medium (heat required for

soldering < 450°C)

1.3 Appearance / aesthetic Strength Good joint appearance; joint barely visible and small surface discontinuities

1.4 Temperature resistance (in end use) Strength Good temperature resistance; determined by filler material





1.8 Strength-to-Weight ratio Strength Medium - high strength and medium weight




1.11 Corrosion resistance and prevention Weakness Poor corrosion resistance; requires corrosion protection

1.12 Recyclability NeutralMedium recyclability; joint material is typically different than substrate, disassembly by

heat


2.1 Materials joined Weakness Suitable to join metals only; limited capability to join dissimilar metals


2.3 Distortion of assembly Weakness Medium - high risk for distortion due to process temperature

2.4 Preparation of joint Weakness Cleaning necessary and prefluxing often required (except for special processes)

2.5 Post-processing Weakness Corrosive fluxes must be cleaned off

2.6 Equipment Weakness Special furnaces and automatic unit: high cost; Manual equipment: low cost

2.7 Consumables Strength Medium - low material cost


2.9 Quality assurance Weakness Difficult; skill and experience required



2.11 Ease of repair Strength Good to repair; without damaging substrate, with limited labour investment

2.12 Heat requirements Weakness High; high temperature, medium duration of heat exposure on major part of assembly

2.13 Health & safety risks Weakness Medium - high risk; elevated temperature and emissions

Soldering

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

11 Welding

Welding is a method that joins materials, usually metals or thermoplastics, by causing

coalescence. This is often done by melting the work-pieces and adding a filler material to form a

pool of molten material (the weld pool) that cools to become a strong joint, with pressure

sometimes used in conjunction with heat, or by itself, to produce the weld. This is in contrast with

soldering and brazing, which involve melting a lower-melting-point material between the work-

pieces to form a bond between them, without melting the work-pieces.

Many different energy sources can be used for welding, including a gas flame, an electric arc, a

laser, an electron beam, friction, and ultrasound.

http://en.wikipedia.org/wiki/Coalescence_(welding)

http://en.wikipedia.org/wiki/Heat

http://en.wikipedia.org/wiki/Fire



October 2009 |

11.1 Welding - Metal


Welding is the process of permanently joining two or more metal parts, by

melting both materials. The molten materials quickly cool, and the two

metals are permanently bonded. Spot welding and seam welding are two

very popular methods used for sheet metal parts.

Figure 53: Welding - metal


Heat source and filler material


Resistance: e.g. spot welding

Electric arc: e.g. MIG/ TIG

Thermal: e.g. torch


Automotive

Shipbuilding

Piping

Construction


Figure 54: Pipe welding

Figure 55: Robot welding - industrial parts



October 2009 |


Table 19: Strength-Weakness analysis of welding - metal


Bond strength


Recyclability

Solvent resistance


Permanent bond / difficult to repair


vibrations


Equipment investment


Nr. Judgement criteria Type Welding - Metal



1.2 Stress and stress distribution WeaknessGood uniform load distribution over joint line; induced stress very high (heat required for

welding > 3000°C)

1.3 Appearance / aesthetic NeutralMedium joint appearance; visible joint and small surface discontinuities; some dressing

necessary for smooth surfaces

1.4 Temperature resistance (in end use) Strength Very good (highest) temperature resistance due to material used





1.8 Strength-to-Weight ratio Strength Very high strength and high weight



1.10 Bond strength Strength Very good bond strength; very good load and very good creep resistance

1.11 Corrosion resistance and prevention Weakness Very poor corrosion resistance; requires corrosion protection

1.12 Recyclability Strength Very good recycling; single material, no disassembly required


2.1 Materials joined Weakness Limited to join specific metals only


2.3 Distortion of assembly Weakness Very high risk for distortion due to process temperature

2.4 Preparation of joint Strength Little or no cleaning and preparation on thin materials. Edge preparation on thick materials

2.5 Post-processing Weakness Heat transfer (cooling) and dressing for smooth surface are sometimes necessary

2.6 Equipment WeaknessSpecial equipment and automatic unit: very high cost; manual equipment: medium-high

cost

2.7 Consumables Strength Low material cost

2.8 Production rate / assembly time Strength Automated processes: very high speed

2.9 Quality assurance Strength Good; non destructive test (NDT) methods applicable to most processes




2.12 Heat requirements Weakness Very high; very high temp, medium duration of heat exposure on major part of assembly

2.13 Health & safety risks Weakness High risk; elevated temperature and emissions

Welding - Metal-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

11.2 Welding - Plastic


Plastic welding is the process of welding thermoplastic parts together.

There are several techniques with which this can be accomplished.

The techniques can be divided in

A. Welding by external heating

B. Welding by mechanical movement

Figure 56: Welding - plastic

Most important for plastic welding are the semi- crystalline materials, (unreinforced or reinforced

materials) as for example polyamides, and polyethylene, as well as all important materials which

are used for the manufacturing of plastic parts, such as ABS, SAN, PC, PMMA, PBT and Blends,

like PP/EPDM, PC + PBT, PPE + PA, as well as welding of plastic parts with foreign to the

process materials such as textile- or resin-adhered fibre materials and woodstock materials.


Heat source to weld the plastic components


Welding by external heat:

Hot gas welding

Speed tip welding

Contact welding

Hot plate welding

High frequency welding

Laser welding

Welding by mechanical movement:

Ultrasonic welding

Spin welding

Vibration or friction welding



October 2009 |


Automotive

Household appliances

Electronic appliances

Packaging


Figure 57: Filter components

Figure 58: Packaging



October 2009 |


Table 20: Strength-Weakness analysis of welding - plastic


Recyclability

Consumables (cost efficient)


Corrosion resistance

Post processing

Permanent bond / difficult to repair


vibrations


Equipment investment

Quality assurance

Nr. Judgement criteria Type Welding - Plastic



1.2 Stress and stress distribution WeaknessGood uniform load distribution over joint line; induced stress very high (heat and vibrations

required for welding)

1.3 Appearance / aesthetic StrengthMedium - good joint appearance; visible joint and small surface discontinuities can be

hidden by design

1.4 Temperature resistance (in end use) Weakness Poor temperature resistance due to material used; depends on selection of plastic

1.5 Mechanical (fatigue) resistance Strength Medium-good; good stress distribution combined with medium fatigue properties

1.6 Solvent resistance Neutral Medium solvent resistance due to material used



1.8 Strength-to-Weight ratio Strength High strength and low weight


and vibrationsWeakness Poor as solid and rigid connection, however plastic


1.11 Corrosion resistance and prevention Strength Very good corrosion resistance and prevention as plastic is used

1.12 Recyclability Strength Very good recycling; single material, no disassembly required


2.1 Materials joined Weakness Limited to join specific plastics only


2.3 Distortion of assembly Weakness Medium - high risk for distortion due to process temperature

2.4 Preparation of joint Strength Little or no cleaning and preparation required

2.5 Post-processing Strength Typically not required; occasional dressing

2.6 Equipment Weakness Medium - high cost; depends on process used


2.8 Production rate / assembly time Strength Very high - very slow; depends on substrate thickness and process used



complexityStrength Medium - low skill required: equipment handling; most processes are automated

2.11 Ease of repair Weakness Very difficult to repair; complex and very labour intensive reparation

2.12 Heat requirements Weakness Medium; medium temperature, medium duration of heat exposure for joint line

2.13 Health & safety risks Strength Low risk for elevated temperature and emissions

Welding - Plastic-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

12 New developments in joining methods

This chapter gives an overview of the latest innovation and development activities for the different

joining methods.

12.1 Adhesives

12.1.1 Physically hardening

Improvement of recyclability

Biodegradable adhesives are used to improve the recyclability. This new development is

mainly applied for packaging applications.

Improvement of cost efficiency

High speed manufacturing technology (e.g. microwave activation of adhesive) results in lower

production cost.

Improvement of temperature resistance

New curing systems (e.g. PUR) improve the temperature resistance.

Improvement of compatibility of joining materials

Multilayer hotmelt films allow the combination of materials with different adhesive requirements

12.1.2 Chemical curing

Improvement of cost efficiency

Innovation in dosing systems (e.g. design of viscosity for optimal processing of the adhesive)

and in curing systems (e.g. e-beam, UV and electromagnetic waves) increase the curing

efficiency and the curing speed of the adhesives.

Use in optical applications

Development of optically clear and bubble free adhesives allow use in joining contrast

enhancement films and other display applications.



October 2009 |

Improvement of technical properties

New developments in various filler materials (e.g. nano-fillers) improve the technical properties

of adhesives (e.g. temperature stability, flame resistance, electrical conductivity) to allow a

broader application range.

12.2 Mechanical Joining

12.2.1 Nuts & bolts; Screws

Improvement of temperature resistance

The use of ceramic composites improve the temperature resistance of structural joints

Improvement of fatigue resistance

The use of titanium composites improve the fatigue resistance

12.2.2 Pins and rivets

Reduction of labour

Self tapping rivets significantly reduce the labour intensive preparation of the joint as no hole

needs to be drilled.

12.2.3 Joining by forming

Improvement in the forming capability of light weight materials

The improved deformation behaviour of light weight materials enables the use of light weight

materials for joining by forming joints.

12.2.4 Snap fit

Improvement in sealing performance

The increased accuracy (i.e. dimensions) of snap fit components improves the sealing

performance of the joint.



October 2009 |

12.3 Brazing / Soldering

Improvement in flexibility in choice of joining materials

The high temperatures required for brazing and soldering do not permit the use of heat

sensitive materials close to the joint. High temperatures also increase the risk for distortion of

the joint. Laser beam welding with very local heat avoids damage of heat sensitive materials

and distortion of the joining and adjacent materials.

Improvement in joining light weight constructions with aluminium materials

Light weight constructions with aluminium materials can be joined due to the development of

aluminium brazing filler materials with low melting temperatures suitable for joining light weight

constructions.

Improvement in environmental impact

Continuous developments of lead free filler materials for soldering results in a reduction of the

environmental impact.

12.4 Welding

12.4.1 Metal

Improvement of corrosion resistance

Development of new alloys to avoid corrosion of the welded joint

Improvement in joining light weight constructions with aluminium materials

Light weight constructions with aluminium materials can be joined due to the development of

aluminium alloys suitable for joining light weight constructions.

Improvement in joining dissimilar metals

Joining of dissimilar metals is improved due to the development of new filler materials

Metal welding without consumables

Ultrasonic welding (of thin parts) eliminates the need for consumables and results in a clean

and aesthetic joint



October 2009 |

12.4.2 Plastic

Improvement in joining of complex shapes

The use of laser beam welding technology allows joining of complex shapes due to the use of a

very local heat source. Laser beam welding allows clean welding (aesthetics) of complex

shapes.



October 2009 |

13 Comparison of joining methods

As one of the principal objectives, Meijer + Voermans Consulting developed a tool that allows a

direct comparison of all joining methods on the evaluated criteria. The comparison tool includes

data of 19 joining methods judged on joint features and production related aspects.

The tool allows comparison in two directions:

Comparison of joining methods: showing the performance of the selected joining methods on

25 criteria

Comparison of the performance on specific criteria: showing the top 5 joining methods

performing best on selected criteria

The results of the comparison are visualised in graphs and the major strength and weaknesses for

the comparison of the specific joining methods are summarised.

Two practical examples illustrate the possibilities with this comparison tool: Section 13.1.1

describes the direct comparison of “solvent based PSA tape” versus “snap fit” and section 13.1.2

illustrates the performance of the joining methods on two specific criteria.



October 2009 |

13.1.1 Comparison of joining methods: PSA - solvent based versus snap fit

The worksheet “comparison”, as illustrated in Figure 59 below, allows the selection of two desired

joining methods for comparison. All joining methods are listed in the selection boxes and are

activated by clicking the circle behind the joining method.

Figure 59: Worksheet “Comparison”: select joining methods to compare

For this specific example “PSA - solvent based” is selected in the first box and “integral joint - snap

fit” is selected in the second box.

The result of this selection is a direct comparison between PSA - solvent based and integral joint -

snap fit on 25 criteria. This comparison includes the explanation of the judgement and the absolute

rating for each criterion. The rating is multiplied by the relevance of this criterion, giving the score

of the joining method. The scores are illustrated in the graph and the performance differences

between the two joining method are calculated on the right side of the graph providing a quick

overview of the major differences.

Nr. Judgement criteria Relev. Score


1.1 Removable 0

1.2 Stress and stress distribution 0

1.3 Appearance / aesthetic 0

1.4 Temperature resistance (in end use) 0

1.5 Mechanical (fatigue) resistance 0

1.6 Solvent resistance 0

1.7 Sealing function 0

1.8 Strength-to-Weight ratio 0


and vibrations0

1.10 Bond strength 0

1.11 Corrosion resistance and prevention 0

1.12 Recyclability 0


2.1 Materials joined 0

2.2 Rate of strength development 0

2.3 Distortion of assembly 0

2.4 Preparation of joint 0

2.5 Post-processing 0

2.6 Equipment 0

2.7 Consumables 0

2.8 Production rate / assembly time 0

2.9 Quality assurance 0


complexity0

2.11 Ease of repair 0

2.12 Heat requirements 0

2.13 Health & safety risks 0

0

-5 -4 -3 -2 -1 0 1 2 3 4 5

Score D

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0 0

0

-5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

The comparison is illustrated in Figure 60 below.

Figure 60: Worksheet “Comparison”: comparison of two selected joining methods

The main differences between the selected joining methods are also summarised below the graphs

as major strengths and major weaknesses. The joining method selected in box 1 is compared to

the joining method selected in box 2 as illustrated in Figure 61 below.

Figure 61: Worksheet “Comparison”: major strengths and weaknesses

Nr. Judgement criteria Relev. Score


1.1 Removable -5.0 1 -5

1.2 Stress and stress distribution 5.0 1 5

1.3 Appearance / aesthetic 5.0 1 5

1.4 Temperature resistance (in end use) -3.0 1 -3

1.5 Mechanical (fatigue) resistance 5.0 1 5

1.6 Solvent resistance -2.0 1 -2

1.7 Sealing function 4.0 1 4

1.8 Strength-to-Weight ratio 1.0 1 1


and vibrations4.0 1 4

1.10 Bond strength -3.0 1 -3

1.11 Corrosion resistance and prevention 5.0 1 5

1.12 Recyclability -5.0 1 -5


2.1 Materials joined 5.0 1 5

2.2 Rate of strength development 2.0 1 2

2.3 Distortion of assembly 5.0 1 5

2.4 Preparation of joint -3.0 1 -3

2.5 Post-processing 5.0 1 5

2.6 Equipment 3.0 1 3

2.7 Consumables -3.0 1 -3

2.8 Production rate / assembly time 5.0 1 5

2.9 Quality assurance -3.0 1 -3


complexity4.0 1 4

2.11 Ease of repair -3.0 1 -3

2.12 Heat requirements 5.0 1 5

2.13 Health & safety risks 5.0 1 5

Difficult; limited non destructive tests (NDT) methods available

No special skill required; easy application, typically use of automated

processes

Difficult to repair after joint has been created

No exposure during assembly

Very low risk; no emissions, no elevated temperature, simple

equipment

Surface treatment and/or cleaning often required

Typically not required

Fairly simple dispensing equipment: low cost

High material cost

Very high speed

Medium - fast; final strength developed over minutes - hours

Very low risk for distortion; no heat or forces during assembly

Very poor; difficult disassembly, joint material is typically different from

substrate

Joins any combination of similar or dissimilar materials, shapes and

thicknesses

Good - very good sealing; continuous joint, good ability to adapt to

substrate

Medium - low strength and low weight

Good - very good because of the viscoelastic behaviour of the PSA

Poor bond strength; medium load and very poor creep resistance

Very good corrosion resistance and corrosion prevention

PSA tape - Solvent basedPSA tape - Solvent based

Permanent; difficult to remove without damaging the construction

Good uniform load distribution over joint area (except in peel); no

induced stress (no heat or mechanical damage)

Very good joint appearance; joint not visible, no discontinuities

Poor temperature resistance due to organic adhesive

Very good mechanical resistance; good stress distribution combined

with excellent fatigue properties

Medium - poor solvent resistance due to polymer

-5 -4 -3 -2 -1 0 1 2 3 4 5

Score D

3.0 1 3 -8

-3.0 1 -3 8

3.0 1 3 2

2.0 1 2 -5

-2.0 1 -2 7

3.0 1 3 -5

-3.0 1 -3 7

3.0 1 3 -2

-3.0 1 -3 7

2.0 1 2 -5

-1.0 1 -1 6

2.0 1 2 -7

-2.0 1 -2 7

5.0 1 5 -3

3.0 1 3 2

-5.0 1 -5 2

5.0 1 5 0

5.0 1 5 -2

5.0 1 5 -8

5.0 1 5 0

-3.0 1 -3 0

5.0 1 5 -1

-5.0 1 -5 2

5.0 1 5 0

5.0 1 5 0

Very difficult to repair; practically impossible to repair as integrated in

substrate

No exposure during assembly

Very low risk; no emissions during assembly

Typically no tools required

Typically no consumables required

High speed

Difficult; limited non destructive tests (NDT) methods available

No special skill required

Limited to flexible materials (e.g. thin construction, plastic)

Very fast; immediate final strength

Low risk for distortion; no heat and low forces during assembly

High investment in equipment, tooling and engineering

Typically not required

Poor corrosion resistance; requires SS or corrosion protection unless

plastic is used

Very good recycling; similar material and/or (easy) disassembly

Good solvent resistance; depends on material used (e.g. plastic)

Poor sealing; discontinuous joint, no ability to adapt to substrate

Medium strength and low weight

Poor as solid and rigid connection; special provision required

Medium - good bond strength; medium load and good creep resistance

Removable in case of an accessible joint

Points of high stress at connection; induced stress small (mechanical

or heat)

Good joint appearance; joint and discontinuities can be hidden by

design

Good temperature resistance; depends on material used (e.g. plastic)

Poor; points of high stress combined with medium fatigue properties;

special provision required for fatigue and resistance to loosening at

joints

Snap fitSnap fit

-5 -4 -3 -2 -1 0 1 2 3 4 5

PSA tape - Solvent based vs. Snap fit

Major Strength D Value

Stress and stress distribution 8

Sealing function 7

Transmission of structure-borne noise

and vibrations7

Mechanical (fatigue) resistance 7

Materials joined 7

PSA tape - Solvent based vs. Snap fit

Major Weakness D Value

Consumables -8

Removable -8

Recyclability -7

Solvent resistance -5

Bond strength -5



October 2009 |

13.1.2 Comparison of the performance on specific criteria

The worksheet “Criteria comp”, as illustrated in Figure 62 below, allows the selection of two desired

criteria. The performance of all joining methods will be compared on these criteria. All criteria are

listed in the selection boxes and are activated by clicking the circle behind the joining method.

Figure 62: Worksheet “Criteria comp”: select specific criteria for comparison

For this specific example “stress and stress distribution” is selected in the first box and “solvent

resistance” is selected in the second box.

This comparison includes the explanation of the judgement and the absolute rating for each joining

method. The rating is multiplied by the relevance of this criterion giving the score for the

performance of all joining methods on this criterion. The total score for each joining method based

on the addition of the score for both criteria is presented on the right side of the figure. The scores

are illustrated in the graph as shown in Figure 63.

Nr. Evaluated joining methods Score Score Score

Judgement of selected criteria Judgement of selected criteria Total 1+2

1 PSA tape - Solvent based 0 0 0

2 PSA tape - Dispersion 0 0 0

3 PSA tape - Hotmelt 0 0 0

4 Physical hardening - Hotmelt 0 0 0

5 Physical hardening - Organic solvent 0 0 0

6 Physical hardening - Water based 0 0 0

7 Physical hardening - Plastisol 0 0 0

8 Chemical curing - 1K 0 0 0

9 Chemical curing - 2K 0 0 0

10 Nuts & Bolts 0 0 0

11 Screws 0 0 0

12 Pins & Rivets 0 0 0

13 Stitching & Stapling 0 0 0

14 Joining by forming 0 0 0

15 Snap fit 0 0 0

16 Brazing 0 0 0

17 Soldering 0 0 0

18 Welding - Metal 0 0 0

19 Welding - Plastic 0 0 0

0 0

-5 -4 -3 -2 -1 0 1 2 3 4 5 -5 -4 -3 -2 -1 0 1 2 3 4 5



October 2009 |

Figure 63: Worksheet “Criteria comp”: performance of joining methods on selected criteria

The five joining methods performing best (top 5) for the selected criteria are summarised below the

graph as illustrated in Figure 64 below.

Figure 64: Worksheet “Criteria comp”: Top 5 joining methods on selected criteria

All scores are added and the “Top 5” joining methods based on both criteria are listed in the

“Overall best” overview as illustrated below.

Figure 65: Worksheet "Criteria comp": Overall best on selected criteria

Nr. Evaluated joining methods Stress and stress distribution Rating Relev. Score Solvent resistance

Judgement of selected criteria Judgement of selected criteria

1 PSA tape - Solvent based Good uniform load distribution over joint area (except in peel); no induced stress (no heat or mechanical damage) 5 1 5 Medium - poor solvent resistance due to polymer

2 PSA tape - Dispersion Good uniform load distribution over joint area (except in peel); no induced stress (no heat or mechanical damage) 5 1 5 Medium - poor solvent resistance due to polymer

3 PSA tape - Hotmelt Good uniform load distribution over joint area (except in peel); no induced stress (no heat or mechanical damage) 5 1 5 Very poor solvent resistance due to polymer

4 Physical hardening - Hotmelt Good uniform load distribution over joint area (except in peel); induced stress small (limited heat during assembly) 3 1 3 Very poor solvent resistance due to polymer

5 Physical hardening - Organic solvent Good uniform load distribution over joint area (except in peel); induced stress small (heat required for drying) 3 1 3 Poor solvent resistance due to polymer

6 Physical hardening - Water based Good uniform load distribution over joint area (except in peel); induced stress small (heat required for drying) 3 1 3 Poor solvent resistance due to polymer

7 Physical hardening - Plastisol Good uniform load distribution over joint area (except in peel); induced stress medium (heat required for curing, 150-180°C) 0 1 0 Poor solvent resistance due to polymer

8 Chemical curing - 1K Good uniform load distribution over joint area (except in peel); induced stress small (exothermic reaction heat) 3 1 3 Medium solvent resistance due to the crosslinking and polymer

9 Chemical curing - 2K Good uniform load distribution over joint area (except in peel); induced stress small (exothermic reaction heat) 3 1 3 Medium solvent resistance due to the crosslinking and polymer

10 Nuts & Bolts Points of high stress; induced stress large (surface damage, holes) -5 1 -5 Very good solvent resistance due to material used

11 Screws Points of high stress; induced stress large (surface damage, holes/tapping) -5 1 -5 Very good solvent resistance due to material used

12 Pins & Rivets Points of high stress; induced stress large (surface damage, holes) -5 1 -5 Very good solvent resistance due to material used

13 Stitching & Stapling Points of high stress; induced stress large (surface damage, holes) -5 1 -5 Good solvent resistance; depends on material used (e.g. plastic)

14 Joining by forming Good uniform load distribution over joint line; induced stress medium (mechanical deformation) 0 1 0 Very good solvent resistance due to material used

15 Snap fit Points of high stress at connection; induced stress small (mechanical or heat) -3 1 -3 Good solvent resistance; depends on material used (e.g. plastic)

16 Brazing Good uniform load distribution over joint line; induced stress medium-high (heat required for brazing > 450°C) -1 1 -1 Very good solvent resistance due to material used

17 Soldering Good uniform load distribution over joint line; induced stress medium (heat required for soldering < 450°C) 0 1 0 Very good solvent resistance due to material used

18 Welding - Metal Good uniform load distribution over joint line; induced stress very high (heat required for welding > 3000°C) -3 1 -3 Very good solvent resistance due to material used

19 Welding - Plastic Good uniform load distribution over joint line; induced stress very high (heat and vibrations required for welding) -2 1 -2 Medium solvent resistance due to material used


-5 -4 -3 -2 -1 0 1 2 3 4 5

Criteria 1 Stress and stress distribution

Top 5 joining methods Score

PSA tape - Hotmelt 5

PSA tape - Solvent based 5

PSA tape - Dispersion 5

Physical hardening - Hotmelt 3

Chemical curing - 1K 3

Criteria 2 Solvent resistance

Top 5 joining methods Score

Nuts & Bolts 5

Screws 5

Brazing 5

Soldering 5

Pins & Rivets 5

Overall best - Criteria 1 and 2

Top 5 Total score

Soldering 5

Joining by forming 5

Brazing 4





October 2009 |

13.1.3 Technical details of the comparison tool The Excel based tool is available in two versions: Excel 97-2003 and Excel 2007.

Detailed instructions on how to use this tool are included as a separate worksheet.

The tool may be customised in order to design your individual case for a specific application and /

or materials combination.

Add criteria to include application specific requirements

Assign relevancies to these new criteria

Complete the judgement for these new criteria



October 2009 |

14 Survey

14.1 Introduction and scope

The objective of the second part of this study is a detailed market research concerning joining

methods in consumer electronics, identifying




The consumer electronics market is defined as any device containing an electronic circuit board

that is intended for everyday use by individuals. This encompasses a large category of electronics

that includes televisions, cameras, digital cameras, PDAs, calculators, VCRs, DVDs, clocks, audio

devices, headphones, camcorders, and many other home products.

The data in the following sections is based on primary research (questionnaire) with experts in the

consumer electronics industry mainly including design engineers and mechanical engineers.

Analyses and conclusions from the questionnaire were verified by interviews with industry experts.



October 2009 |

14.2 Joining methods in consumer electronics

The figure below shows the distribution for the use of different joining methods in the consumer

electronics industry.

Figure 66: Applied joining methods - consumer electronics

All joining methods are used in the consumer electronics industry

Welding is used least

The following figures show the results for the questions:

“What are the three most applied joining methods in your products?”

“What is the most applied joining method in your product?”

Figure 67: Top 3 - Most applied joining methods - consumer electronics

13%

21%

25%23%

19%

0%

10%

20%

30%

40%

Welding Soldering / brazing

Mechanical fastener

Integral joint Adhesive bonding

Applied joining methods

10% 10%

33%

23%

18%

5%

0%

10%

20%

30%

40%


Mechanical fastener


Other

Most applied joining methods - Top 3



October 2009 |

Figure 68: The most applied joining method - consumer electronics

Mechanical fastening and integral joint are by far the most common joining methods for

consumer electronics.

The main reasons mentioned why integral joints are used most often are:

Cost

Fast assembly

Easy assembly

The main reasons mentioned why mechanical fasteners are used most often are:

Cost

Fast assembly

Good disassembly

Bonding strength


7%

0%

43%

36%

7% 7%

0%

10%

20%

30%

40%

50%


Mechanical fastener


Other

The most applied joining method - Nr.1



October 2009 |

14.3 Selection criteria in consumer electronics

Evaluation of the selection criteria for joining methods in consumer electronics results in the

following overview:

Figure 69: Reasons for choice of joining methods - consumer electronics

Assembly, disassembly and cost play an important role when selecting joining methods

Also positive previous experiences meaning “copy-paste” from previous models is very

common for the selection of joining methods in consumer electronics

Self adhesive tape is quick and easy to assemble BUT most often not removable and easy to

disassemble. This is a significant disadvantage when equipment needs to be repaired and for

recycling.

0% 20% 40% 60% 80%

high production rate / quick assembly

easy assembling / low level of skill required

good disassembly

low cost

low emissions (e.g.no fumes, organic solvents etc.)

it is a frequently used joining method in our company

positive previous experiences

Reasons for choice of joining method



October 2009 |

14.3.1 Awareness The general awareness with respect to PSA tapes as joining method for consumer electronics is

not very high as illustrated in the result below.

Figure 70: Awareness of PSA tapes as joining method - consumer electronics

Only 63% of the respondents are aware of PSA tapes as joining method

When asking the respondents who are aware of PSA tapes as joining method if they actually use

PSA tapes in their products the number is again relatively low as illustrated in the figure below.

Figure 71: Current use of PSA tape as joining method - consumer electronics

Only 30% of those who are familiar with PSA tapes currently use PSA tapes as joining method

Based on these results it can be concluded that there is clearly a need to raise the awareness level

for self adhesive tape as joining method to ultimately increase the use of self adhesive tape.

62.5%

37.5%

Awareness of PSA tapes as joining method

aware not aware

20%

50%

30%

Current use of PSA tape as joining method

no in special cases only yes



October 2009 |

14.4 Development and future requirements

In order to understand the development activities and opportunities for PSA tapes in consumer

electronics the respondents were asked:

When is research invested in the selection of the joining method?

What should a new joining method do to raise your interest?

The results are summarised in the following figures.

Figure 72: Research investment for selection of joining methods - consumer electronics

From these responses it can be concluded that there is a clear split between active and proactive

development work with respect to joining methods. Some companies are focussed on new

developments and actively invest resources to investigate new potential techniques whereas other

companies only act when they have to.

A significant part of the engineers is open for new joining methods

An entry for self adhesive tape is easiest in case of a current problem

7%

50%

43%

0%

20%

40%

60%

never; always “copy-paste” in case production/quality problems w. previous method

continuous activity

When is research invested in the selection of the joining method?



October 2009 |

Figure 73: Key requirements joining methods - consumer electronics

Key requirements respondents are looking for in new developments are:

Easier to assemble and disassemble

Lower thickness / volume of the joint

Lower cost

Higher bond strength, durable and robust

Easier joining of dissimilar materials

With respect to the performance of current self adhesive tapes, quick / easy assembly and low

thickness (volume) of the joint are strong assets, whereas the fact of not being removable and

easy to disassemble is the weakest aspect of current PSA tapes. This might require specific

developments to ultimately increase the use of self adhesive tape in consumer electronics.

0% 5% 10% 15% 20%

easy to disassemble

low thickness/volume

low cost

high bonding strength

reliable/durable/robust

easy to assemble

join dissimilar materials

other

A new joining method should be …



October 2009 |

14.5 Conclusions

Mechanical joining methods are the dominant joining method for consumer electronics.

Most used are fasteners (screws) and integral joints (snap fit).

The main reasons to use these methods are:

Cost

Fast assembly

Easy disassembly

Bond strength


Easy and quick assembly, disassembly and low cost play an important role when selecting joining

methods. Also positive previous experiences meaning “copy-paste” from previous models is very

common for the selection of joining methods in consumer electronics.

Self adhesive tape is quick and easy to assemble BUT most often not removable and easy to

disassemble. This is a significant disadvantage when equipment needs to be repaired and for

recycling.

The general awareness for PSA tapes as joining method for consumer electronics is with 63%

relatively low. Only 30% of those who are familiar with PSA tapes currently use PSA tapes as

joining method.

Although a significant part of the engineers is open for new joining methods, an entry for self

adhesive tape is easiest in case of a current problem.

The key requirements for new developments in joining methods are:

Easier to assemble and disassemble

Lower thickness / volume of the joint

Lower cost

Higher bond strength, durable and robust

Easier joining of dissimilar materials

In summary it can be concluded that there is a need to raise the awareness level for PSA tape as

joining method to ultimately increase their use. With respect to the performance of current PSA

tapes, quick / easy assembly and low thickness (volume) of the joint are strong assets, whereas

the fact of not being removable (easy to disassemble) is the weakest aspect of current PSA tapes.

This might require specific developments to ultimately increase the use of PSA tape in consumer

electronics.



October 2009 |

15 Acknowledgements

Meijer + Voermans Consulting would like to thank Afera for their co-operation. In particular, we

thank Astrid Lejeune and Eric Pass for their support and valuable input as well as the constructive

discussions throughout the course of this project.

Finally, input and support were provided by several companies in the industry. Meijer + Voermans

Consulting would like to thank those companies for their valuable contributions.

increasing the pie for the european self adhesive tape ... · opportunities to increase the pie for...

Documents