Volume 21 ‐ February 2017

Contents

Editorial Board

R. V. Apshankar

Energy Systech

Vijay Chavan

V-Smart Thermotech Pvt. Ltd.

Kishor Dukare

Jayahind Montupet Pvt. Ltd.

Pramod Gajare Consultant

Aniruddha Inamdar Consultant

Mrs. N. S. Kadam

Met. Dept., Govt. Polytechnic

R. T. Kulkarni

Arkey Conference Service Cell

U. M. Nadgar

Consultant

Prof. S. K. Paknikar

Consultant

A. B. Sane

Consultant

Anand Joshi - EditorConsultant

Aluminium Extrusion & Foundry

Volume 21 - FEBRUARY 2017

Disclaimer - The editor and the Editorial Board do not accept any responsibility for the statements, contents, opinions and point of views expressed by the authors.

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Note: Some images in some articles may not be clear. Interested readers may contact the author

...looking forward always!

Non-destructuve Examination 01

In Manufacturing Industry

Mr. Amit V Deshpande,

Insight Quality Services

How We Failed Competency Frameworks 06

Rahoul Joshii, Elementz People Systems (P) Ltd

Pyrotek's Starburst Rotor Displays 08

Efficient Performance and Long Life

Compared to Other Rotors in Testing

Jay Fritzke, Pyrotek Foundry Technical Manager;

Gordon Albers, Pyrotek General Manager

Western Europe

Design Optimization of Heat Treatment 10

Support Frames for Aluminum Alloy

Structural Cast Parts Using Virtual

Experimentation 1 1Heinz-Jürgen Gaspers , Jesper Thorborg

1MAGMA Gießereitechnologie GmbH, Aachen, Germany

Statistical Techniques for Industry 18

Pramod Gajare, Consultant.

Metallography of Aluminium Alloys 21

Through Questions - Answers

Prof. S. K. Paknikar, Consultant

1 Introduction:

Non-destructive Testing, the testing carried out

without impairing the final usefulness of the product is

becoming more alive in todays world than ever before.

New and newer techniques are being developed. The

latest machines, carefully developed procedures and

qualified manpower are always striving for the

reliability of product through NDT. NDT is not only

encompassing the industrial field like material testing,

service inspection, corrosion monitoring, laser

technology, process control, instrument development,

nuclear power but it also covers equally the health

physics and medicine. X-rays and Ultrasound are very

common methods used in medical field.

When we talk about welding industry, the NDT plays a

vital role in the evaluation of weldments. Many

techniques are developed to find out the soundness of

the weld at different stages of manufacturing cycle.

NDT is also used in raw materials as well as service

inspection.

This paper takes you for a tour of different Non-

destructive testing techniques applicable for welding

industry alongwith their principle, application and

selection criteria. It also covers the very important

factors for a meaningful NDT which are – qualified

manpower, calibrated machines and correct

procedures. At the end, it poses the areas of concern

in today’s context.

2. NDT techniques used in Welding Industry:

Considering the definition of NDT, needless to say that

Visual Testing becomes first technique of NDT. Some

of the commonly used NDT techniques are :

Visual Testing (VT)

Liquid Penetrant Testing (PT)

Magnetic Particle Testing(MT)

Ultrasonic Testing (UT)

Radiographic Testing (RT)

Eddy Current Testing (ET)

Leak Testing (LT)

The basic principle, equipment required, applications

and advantages / limitations are as given in Annexure

A.

It is important to mention here that NDT cannot

eliminate the need for Destructive Testing. The

different NDT techniques also do not substitute each

other. However, they can compliment each other.

Further, the techniques like Acoustic Emission,

Neutron Radiography, Thermal Emission and

Vibration Analysis are also used for the evaluation of

material and weldments.

3. Importance of Training :

The success of NDT always depends on the

knowledge and skill level of the operator. NDT results

are operator dependant and cannot be cross checked

by the simple alternatives. The moment a probe is

removed from the surface there are no indications and

one has to go by the operator’s report. This operator

dependability has forced the technical societies to

formulate the norms for training, qualification and

certification of NDT personnel. The worldwide used

standard is ASNT’s SNT- C T-1A : The international

standard ISO 9712 is also used. Indian Standard

applicable is IS13805. These standards give the

requirements for Training and Certification of NDT

personnel. It divides the personnel into 3 categories

for each technique namely, level I (operator level)

level II (supervisory level) and level III (managerial

level). One has to ensure that the candidate meets the

requirements of Education, Training, Eye test and

minimum grade in Examination (Theory + Practical).

4. Latest Developments :

The developments in NDT are very fast. Flexible

borescopes, remote visual inspection, video cameras

for visual inspection are the latest things in Visual

Testing In Magnetic Particle Testing and in Penetrant

Testing fluorescent inspection methods are catching

over visible methods. In Japan fluorescent penetrant /

magnetic particle testing has become very common.

In ultrasonic testing the recording systems are

developed and one can transmit the data through

internet and view it from a distant place without loss of

time. In addition to the automatic on-line Ultrasonic

tube testing machines, new ultrasonic inspection

machines for remote inspection for tube wall thinning

are very common now. In radiography the filmless

radiography and development in detecting media is

taking over conventional radiography. In eddy current

testing new techniques are coming up in service

inspection. In Helium leak testing, leak detection of the -9order of 10 std. cc/sec. is possible.

NON-DESTRUCTUVE EXAMINATION IN MANUFACTURING INDUSTRY

Mr. Amit V Deshpande,

Insight Quality Services, support@iqs-ndt.org

01February 2017

02February 2017

SILCARB HEATING ELEMENTS P. LTD. enters into manufacturing of Dosing Furnaces for aluminium GDC Tech Forum spoke to Mr. K. V. Chandrashekar, M.D.

to enlighten our readers regarding this development

5. Selection of a particular NDT technique :

(Annexure B is tabulating NDT technique selection

w.r.t. welding discontinuity and Annexure C gives the

generally applicable NDT w.r.t weld joint types.

Advantages / Limitations of the NDT Method :

The advantages and limitations of the NDT method

can be used to determine which method will provide

the best results for a particular test. For example

radiography can detect cracks whose major planes

are aligned parallel with the radiation beam; such

cracks are usually normal to the plate surfaces.

Radiography, however, usually cannot detect

laminations in plate or cracks oriented parallel to the

plate surface. On the other hand, Ultrasonic can more

readily detect cracks oriented in either direction

provided the proper scanning technique is used.

Acceptance standards :

The statement “the weld shall be of radiographic

quality” has no meaning unless acceptance standards

are stated. Acceptance standards define different

types of characteristics of discontinuities and whether

particular types of discontinuities are permissible. If a

particular type of discontinuity is permissible, then the

acceptance standards must specify the maximum

size at which that discontinuity is acceptable.

Acceptance standards are an integral part of most

codes and specifications and are commonly used as

reference in purchase specifications.

Cost :

Different inspection methods have different costs in

any particular situation. Two basic cost factors, which

should be considered in the selection of a

nondestructive method, are the initial equipment

availability cost and the cost of performing the

inspection. Visual inspection is almost always the

least expensive, but it is also limited to the detection of

surface discontinuities. In general, costs of

Radiographic, Ultrasonic, Eddy current and Helium

Leak testing inspections are greater than those of

Visual, Magnetic and Liquid Penetrant inspections. X-

ray films are generally imported which constitutes the

major consumable cost in Radiography.

Selection of the proper NDT method can be quite

complex. It involves manufacturing technology,

possible discontinuities, orientation of discontinuities,

accessibility for testing, physical condition of the job

and so many other factors. To meet the intended

purposes and minimize cost, it is suggested that help

be obtained from a qualified nondestructive testing

engineer or technician.

6. Case Studies :

While going through the tour of the different NDT

techniques it is worthwhile to spend some time to have

a look on some of the case studies which will

emphasize on the basic advantage / limitations of

NDT techniques and it will convey the subject in right

sense. The case studies are the events happened in

last few years and they are to be considered as

representative types

6.1 New porosities were revealed in the space

science motor shell radiography after increasing

the density of radiograph from 2.5 to 3.5. This was

due to increased contrast at higher densities.

This shows that, for a specific purpose the outer

limits of parameters given by specification are not

sufficient. One has to design new limits to suit the

purpose.

6.2 In Aluminium weld radiography a black band was

observed in the weld zone. This was due to weld

material composition different than parent metal

composition. Investigation proved that there was

no discontinuity. One can easily get misled with

such situations unless proper study of materials

and consumables is taken up.

6.3 New defects were revealed due to change of

shooting direction in high thickness Pressure

Vessel Radiography . This emphasizes operators

to follow procedures religiously and also

demands a good record keeping.

6.4 Comparison of UT & RT results to 3”, 4” and 5”

thickness pressure vessels. This data was

collected to compare RT and UT results for the

welds. The data indicates that RT & UT results

are not interchangeable and they cannot replace

each other.

6.5 The results of Ultrasonic Testing of welds with 2

MHz frequency probe and 4 MHz frequency

probe are not matching. This demands the

procedure be to be followed religiously.

6.6 Cracks after back chipping seen by PT and not

seen by RT in groove spot. This shows PT can be

superior to RT when it comes for surface defects.

6.7 Narrow gap welding techniques demand the

ultrasonic testing procedure to be totally changed

with tandem technique. This shows study of

configuration is a must before selecting a

technique and one has to change the testing

procedure if weld configuration is changed.

7. Areas of concern :

Availability of trained / qualified manpower :

03February 2017

NDT is an operator dependant technique and

demands highly skilled and trained personnel. This is

a concern of the day . The improperly trained

manpower cannot give justice to the NDT techniques

and can lead to misleading results.

Adequate Machinery :

This is an important factor contributing to the success

of the NDT. If the machine is not capable of producing

results the test will not be meaningful. Calibration of

the machines is an important issue.

Adequacy of Procedures :

Even though the trained manpower and adequate

machinery is available, one cannot get fruitful NDT

results unless the correct procedures are adopted.

The correctness of procedures will be verified by cross

checking, demonstration of techniques and ensuring

that the procedure is reviewed and approved by a

person having authority in the subject.

While going through the above concerns one has to

realize that ‘Cheapest is not the Best Bye’.

The careful selection of NDT subcontractor (the

subcontracting of NDT is very common) is very

important and monitoring the subcontractor’s work is

also recommended. The subcontractor cannot put

properly qualified manpower and adequate machines

and correct procedures unless it is paid for. So the

important thing always remains in the following three

aspects.

- Is the NDT requirement clear?

- Is subcontractor capable of fulfilling the

requirement?

- Is subcontractor actually fulfilling the

requirement?

Unless this monitoring is taken up seriously the

reliable results cannot be guaranteed.

Non-destructive testing is a serious business. The

health and lives of people and money is at stake. Even

experienced technicians can also encounter

problems. Hence technicians starting a career in NDT

shall get the best possible training and never take

routine test results granted. New technicians should

always be teamed up with experienced personnel and

the doubtful results shall be concluded with the

guidance of expects.

04February 2017

05February 2017

MACHINING OF ALUMINIUM CASTING

CONFERENCE ON

...looking forward always!

5 - 6 (Fri-Sat) May 2017 at Hotel Sun-n-Sand, Pune

There was a time when fascination to build

competency frameworks hit India Inc like a tsunami.

Every other organization wanted to do it. From my

involvement with over a dozen such initiatives I

gathered that knowing what skills, capabilities

organizations had and grooming leaders were the

most common reasons reported. There were those

who went competency way because it was the most

cutting edge, progressive thing to do at that time while

some others did it because everyone around was

doing it. As a part of IT industry at that time, I witnessed

scores of them did it to acquire some certification like

P-CMM, that helped create certain impressions on

existing and potential customers or provided a

structure to the over-grown software engineer called

Mr CEO who looked for mechanistic approach to

people and organization development. Then, there

were some who did it without much conceptual clarity

to differentiate between skill and competence. For

them .NET and Java were competencies. Thus, on

one hand they expected this intervention to deliver the

objective of organization and people development,

there was also some vagueness and frivolity

attached to the whole exercise.

I witnessed some interesting phenomenon. Many

organizations built their competency frameworks

bottom-up. Entry level competencies were identified

first and a simple logical progression was applied as

we got up the ladder. For instance, if communication

was a competency identified, it was defined at various

levels and applied to, let's say, junior staff with level

descriptor reading as `organizes thoughts and

articulates in a manner that....' The same competency

was then applied to strategic leadership as

`communicates unit/ function/ department strategy

from time to time'. In some other cases,

competencies were unscientifically picked from

an `off the shelf' universal set of some consulting

company by applying collective wisdom and best

judgment. They were loosely validated using tools like

BEI.

When competencies are attached to roles and when

India Inc reports as high as 70% variation in what

people write as role descriptor or job description and

what they actually do, are those competencies

realistic, idealistic or hypothetical? When job content

is a largely a variable entity, if targets change six

times a year, how could competencies hold much

validity? We need to be mindful of the fact that

competency concept was imported from that part of

the world where job content is more or less a static

entity which is not the case here. Sadly survival and

growth oriented organizations didn't have the time to

do it right, they had to do it fast (`as of yesterday' as the

popular expression goes). They also had compulsions

to show themselves as a part of/ replica of ̀ that'.

Owing to the lack of clarity of its purpose,

understanding of the real concept and it's potential,

competency assessments today have merely

become tools to make operational decisions such

as promotions, salary increments, transfers,

deputations etc. It is time we did cost-benefit analysis

of it and made bold decisions. Considering the overall

cost in terms of its development, annual

administration and the cost arising out of resultant

impact such as attrition, replacement, low morale etc

(if any), I believe this intervention is not just unviable

but actually quite counter-productive in most cases; a

reality no one would dare own up! I find HR

departments first create processes that bleed

organizations and then create more expensive ones

to stop bleeding. Assessments bleed and

engagement surveys and everything emanating from

them are attempts to stop that bleeding.

In the 28 competency frameworks of small and large

organizations including three of India's top 10

business houses that I got an opportunity to work with,

I distinctly remember thinking that it's not worth the

effort if we have communication, listening, team

building, decision making, problem solving,

commercial/ business acumen or even strategic

thinking as competencies beyond higher middle

management (i.e. barring top two or three levels of the

organizations depending on the size and structure).

These things should be a `given' at strategic

leadership. Such competencies at that level keep

06February 2017

How We Failed Competency Frameworks Rahoul Joshii, Elementz People Systems (P) Ltd

rahoul@elementz.co.in

leaders stuck to operations excellence which may not

help our cause of leadership development. They are

about performance not about transformation. Sadly,

since businesses have become mechanistic, most

competency frameworks are built to address only

current and occasionally future operational

challenges and hence those skills. Further I feel a

need to remind the readers that competencies are

about differentiating behaviours not the common/

standardised behaviours for a grade/ level/

designation.

I have come to believe that leadership

competencies should be linked to organization's

leadership philosophy and its core ideology; its

ethos. Because that's what top leaders ought to be

focusing on primarily. Aspects such as being

empathic, self aware, environmental sensing need to

make their way into the list along-with strategy,

problem solving etc without worrying whether or not

they could be assessed/ measured and without

worrying whether or not such behaviours would

always lead to tangible commercial success. A deep

look into your organization's philosophy, ideology will

provide the necessary conviction in having these as

leadership competencies. There are some

progressive Indian organizations already doing that.

With that in place, we could say that we want all our top

leaders to be problem solvers but only those who have

empathy and environmental sensing make the cut

because those are the real differentiators. Just having

strategy and problem solving does not differentiate a

potentially successful leader from a transformational

one.

Centre for Creative Leadership recommends that

leadership competencies are derived from business

strategy, vision and organization's leadership

philosophy. `Derived from' are the key words here.

Daniel Goleman also indicates that 67% of leadership

abilities are emotional abilities. Yet sadly they don't

make it to the list of leadership competencies simply

because these things are difficult to measure. And

what's easy to measure is not the stuff leadership

is made of.

Operationally, this is another big challenge.

Competency frameworks are not adequate tools for

leadership development. We have ended up calling

managerial skills as leadership competencies and

have ended up weakening our infrastructure for a

meaningful development of leadership abilities.

07February 2017

Mr. Deepak Mahajan & Ms. Anushree Ghorpade

Anchor : Anuja Ramdasi

COFFEE TALK ON : Gulzar ‐ The Poet (Gulzar’s bollywood songs on musical tracks)

7 th December 2016 (Wednesday)

Felicitating GDC TECH Journal Release

The combination of gas injection and fluxing improves

the quality of aluminium alloys and reduces operating

costs. Pyrotek offers a line of degassing systems and

related products to improve metal and casting quality,

including STAR and CALGAS equipment.

The Starburst® rotor is a key component to Pyrotek's

STAR degassing systems. Machined from graphite

and treated using Pyrotek's proprietary process, it

offers excellent strength at elevated temperatures, is

resistant to oxidation and thermal shock and is non-

fatiguing, showing no property changes due to age or

cyclical operation.

Pyrotek STARBURST rotor

An eroded STARBURST rotor that performed

better than the competitor

Typically, in Pyrotek's spinning-rotor degassing and

fluxing systems, a metered amount of inert gas is

injected through the shaft and Starburst rotor. The

rotor shears the inert gas into tiny bubbles and

disperses them evenly throughout the melt. Hydrogen

gas and non-metallic inclusions are attracted to the

bubbles and rise to the surface as dross.

Atmosphere temperature and relative humidity have a

major influence on hydrogen content. The

atmosphere can contain water vapour, while humidity

can derive from furnace linings and tools. Other

factors include corroded charge materials, oily

circulation materials such as chips or scrap, salts and

treatment agents and combustion gases.

Hydrogen causes porosity in the metal, which leads to

poor surface quality, surface blistering after heat

treatment, leakage problems and reduced

mechanical properties.

Effective degassing produces many small bubbles,

has good mixing action, distributes bubbles through

an entire vessel and reduces surface turbulence and

“vortexing.”

A Comparison

Pyrotek recently conducted tests comparing the

performance of the Starburst rotor to other rotors on

the market. Results showed that the Starburst rotor,

whether new or at end-of-life, removes as much or

more hydrogen during the degassing process than its

counterparts.

Rotors tested included a new Pyrotek Starburst rotor

and an eroded model, as well as three competitor

rotors made by two separate manufacturers.

The testing was performed using a 500 kilogram (1100

pound) electrical heated crucible furnace containing

aluminium alloy 226 (A38) AlSi9Cu3 at 700°C

(1290°F). The average ambient temperature was

15°C (60°F), while the average relative ambient

humidity was 51 percent.

Hydrogen curves were recorded continuously with an

ABB AlSCAN hydrogen analyzer unit, which monitors

dissolved hydrogen content in molten aluminium and

offers real-time readings.

In tests starting with high hydrogen levels in the bath,

08February 2017

Jay Fritzke Gordon Albers

Pyrotek's Starburst Rotor Displays Efficient

Performance and Long Life Compared to Other Rotors in Testing

Jay Fritzke, Pyrotek Foundry Technical Manager;

Gordon Albers, Pyrotek General Manager, Western Europe

09February 2017

the eroded Pyrotek Starburst rotor removed 50

percent of the hydrogen after 80 seconds and reached

0.1 milliletre of hydrogen per 100 grams of aluminium

after 120 seconds, while the new Starburst rotor

removed half the hydrogen after 150 seconds and

reached 0.1 milliletre of hydrogen per 100 grams of

aluminium after 320 seconds.

The three other rotors removed 50 percent of the

hydrogen in the melt after 140–240 seconds and

reached 0.1 milliletre of hydrogen per 100 grams of

aluminium after 220–380 seconds.

In tests starting with low hydrogen levels, the used

Pyrotek Starburst rotor removed 50 percent of the

hydrogen after 140 seconds and reached hydrogen

levels of 0.03 milliletres per 100 grams of aluminium,

while the new Starburst rotor removed half the

hydrogen after 300 seconds and reached 0.05

milliletres of hydrogen per 100 grams of aluminium

One of the competitor rotors removed 50 percent of

the hydrogen in the bath after 240 seconds, reaching

levels of 0.05 milliletres of hydrogen per 100 grams of

aluminium. The two remaining rotors did not remove

half the hydrogen yet both reached levels of 0.06

milliletres of hydrogen per 100 grams of aluminium.

Results showed that Pyrotek's Starburst rotor

performs efficiently until the end of its life. The

Starburst rotor can be operated at lower revolutions

per minute than the competitors' rotors due to its

unique design, which causes less surface turbulence,

vortexing and graphite erosion.

Further testing at individual customer plants can yield

more definitive results.

About Pyrotek

Pyrotek is a global engineering leader and innovator

of technical solutions, integrated systems and

consulting services for materials processing

industries including aluminium, steel, glass and more.

Founded in 1956, Pyrotek offers expertise in high-

temperature applications with global resources and

local support in more than 30 countries.

CORE TECHNOLOGYCORE TECHNOLOGYCORE TECHNOLOGYCONFERENCE & EXHIBITION ON

20-21 (Thu-Fri) April 2017 | Hotel Sun-n-Sand, Pune, India

FOUNDRY AND FORGE TRAINING CENTREA Division of ARKEY TECHNICAL TRAINING & RESEARCH INSTITUTE (TRUST)

‘

For RegistrationPlease Contact

Tel.: +91 20 2565 1717, 2567 0808 Mobile: +91 97647 11315 E‐mail: fftc@arkeycell.com, mail@arkeycell.com

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Nitrogen Degassing Machine

Density Index Unit

MAGMA Engineering India

10th User Group Meeting 2016

17th – 18th NOVEMBER | www.MAGMAugm.in

MAGMA Engineering Asia Pacific Pte. Ltd. - Branch of India has had the privilege of having numerous

delegates and profound intellects at their 10th User Group Meeting 2016 held at “The Park Hotel” in

Hyderabad, Telangana INDIA on 17th & 18th of November 2016.

Both the days were exclusive to the MAGMA users from across India. This spectacular event had the

honoured presence of Mr. Mathias Bodenburg from MAGMA GmbH, Germany and Dr. WangQian Zhao, the

new General Manager for MAGMA Asia Pacific region which brought the exclusivity with enlightening charm

to the event. Mr. Gerard Vong, Senior Manager - Applications, MAGMA Singapore and Mr. Irawan Hariyanto,

Ferrous Application Manager, MAGMA Singapore have also graced the event with their presence and shared

their expertise & knowledge with the crowd. Many esteemed organizations have marked their presence at

this phenomenal event and around 12 of them even had the privilege of proudly showcasing their ‘Success

Stories’ on how their world of castings has evolved into a complete new perspective after incorporating

MAGMA5 into their company’s reign of casting processes.

Event Overview:

17th & 18th November were the days which marked their way into the history of MAGMA, when the 10th

MAGMA INDIA UGM started at the Grand Ball Room at The Park Hotel with around 100 participants

respectively on both day 1 & 2 attending the event who took time out of their busy schedules in marking

their presence at the event. Of the many presentations received from MAGMA’s clientele who came forward

to showcase their expertise in using MAGMA, the best 12 from both Ferrous & Non-ferrous processes were

chosen to be the ones which will be highlighted during the event. Many companies like Godrej, Shiram

Pistons & Rings, Ace Designers, Brakes India, TVS Sundaram Clayton, Federal Mogul India, Minda

Corporation, Endurance Technologies, Koso India, Nelcast, Auto Tech Industries and Malnad Alloy Castings

had the privilege of enlightening the crowd with their exquisite case studies of MAGMA implementation &

success in their respective companies. MAGMA Team as well had presented wonderful trends from the

Ferrous & Non-Ferrous fields in the virtual world of simulation and everyone also had the advantage of

having a preview to the research & development happening within MAGMA. The crowd was overwhelmed to

see the updates to come in the next version v5.4 of their Casting Process Optimisation Software – MAGMA5.

The Park Hotel

# 22 · Raj Bhavan Road · Somajiguda

Hyderabad · Telangana · India · 500082

ABSTRACT

Heat Treatment is an often applied process to realize improved mechanical properties in structural aluminium alloy cast parts, especially for applications in the automotive industry. In many cases a T6/T7 heat treatment, which includes solution treatment, quenching and aging, is the preferred option. For large, thin-walled structural die cast parts, the support during heat treatment has a distinct influence on the deformation during the heat treatment process. The deformation is mainly formed during the solution treatment step, where the part is heated to above 460 °C for several hours for metallurgical reasons. The deformation is caused by gravity forces which lead to creep in the material. As the parts usually only have a few supporting contact areas, the final part distortion can be very sensitive to the design and lay-out of the support frame. In addition distortions developing during the casting process as well as during all heat treatment process stages must be considered to achieve that the final part meets the dimensional specifications. Up to now only the experience of the expert as well as extensive experimentation based on trial and error are the state-of-the art approaches to find an "optimized" frame design for any new part. This may be time consuming and costly.

The work shows how heat treatment support frames can be optimized by virtual experimentation using an integrated simulation approach. A unified creep material model is applied to model the distortion of an industrial thin-walled aluminium structural die cast part. The changing part deformation during the entire casting and heat treatment process as well as the effects of different supporting frame concepts on the distortion will be discussed. The predicted part deformation is compared for different supporting frame designs and is quantitatively assessed using a virtual 6-point (Reference Point System) measurement device.

KEYWORDS

Stress simulation, minimizing distortions, gravity, aluminium, structural part, solution treatment, precipitation hardening, creep, virtual experi-mentation, optimization

INTRODUCTION

Heat treatment of cast aluminum parts often follows the T6/T7 procedure were the parts are heated to a temperature level close to the solidus temperature for solution treatment, followed by a rapid cooling where the part is quenched to the ambient temperature to maintain the obtained microstructure. The quenching step is followed by a reheating to approx. 40% of the solidus temperature for artificial aging before cooling down to room temperature again, Fig. 1. This treatment of the cast parts is governed by the interest of optimizing the microstructure and mechanical properties of the final part to improve performance during service.

The most widely used aluminum casting alloys are based on different contents of Si, Cu and Mg. For the hypoeutectic alloys, the microstructure consists of a primary -Al phase and Al-Si eutectic. The additional components Mg and Cu are either contained in the -Al in solid solution or precipitated as intermetallic phases e.g. Mg2Si or Al2Cu. The content of Mg and Cu in solid solution is temperature dependent according to the phase diagram, [1]. This temperature dependency is exploited during solution treatment to form a super-saturated solution of Mg and Cu, which is maintained during quenching to allow a controlled precipitation of intermetallic phases during artificial aging.

Fig. 1: Left: Process view showing the thermal history of the casting and heat treatment processes. Right: The phase diagram indicating the path for generating the super-saturated solid solution.

10February 2017

Design Optimization of Heat Treatment Support Frames for Aluminum Alloy

Structural Cast Parts Using Virtual Experimentation 1 1Heinz-Jürgen Gaspers , Jesper Thorborg

1MAGMA Gießereitechnologie GmbH, Aachen, Germany E-Mail: HJ.Gaspers@magmasoft.de

11February 2017

However, the heat treatment process can also have a major influence on the development of distortions and

stresses in the part due to the elevated temperature level during solution treatment and possible thermal gradients

during the quenching step. For bulk parts, such as cylinder heads etc., the deformation during the solution

treatment step can be more or less neglected, while the gravity forces on thin-walled structural parts can have a

significant influence on the overall deformation during heat treatment.

For thin-walled structural parts a moderate air quenching is sufficient to obtain a satisfying microstructure inside the

material. Since this type of cooling leads to small thermal gradients, structural parts do typically not build up large

plastic deformation during the quenching step. At higher temperature levels however, the strength of the aluminum

part decreases during the solution treatment step, allowing gravity forces to deform the parts due to creep, [2].

Depending on the handling and supports during the high temperature treatment thin-walled structural parts can be

distorted considerably, [3].

During the final artificial aging step, the temperature level is only increased to allow the precipitation hardening to

take place. This temperature level can lead to moderate stress relaxation due to creep but typically not to additional

deformations. Thermo-mechanical modeling of the casting and heat treatment process is a challenge even without

considering the evolution of the material data. The main concern is to model the response of the material at different

temperature levels, on different time scales and sometimes with different strain rates, which is governed by different

deformation mechanisms. To have a reasonable compromise between the stability in the results when doing

calculations in different process steps and agreement between simulations and performed creep and tensile tests,

a unified creep formulation is used as the fundamental constitutive law, [4], in this work. The model is based on

Norton's power law and includes by that, strain rate sensitivity and the possibility to describe creep at elevated

temperature, [5] and [6].

1. OPTIMIZING THE SUPPORT FRAME DURING SOLUTION TREATMENT

The example presented in this paper is a thin-walled structural part, in the following called "connecting part LTR", of

the Audi TT vehicle. Fig. 2 shows the part and its position in the Audi TT space frame. The part is connecting the

back seat area and the side wall in the main frame. Detailed simulations, experiments and measurements of

deformations and changing material properties during and after heat treatment of this part were done in a research

project named "ProGRess", [7], with partners MAGMA GmbH, Trimet and Audi AG. The main objectives of

"ProGRess" were investigations concerning the possibilities to save energy during the casting processes, and the

heat treatment process, while at the same time to maintain quality and mechanical properties. Therefore variations

of temperatures and holding times of the solution treatment step were performed. Following the experiments of the

project additional virtual DOE experiments have been done by MAGMA and are presented in this paper.

Fig. 2: Structural part of Audi TT

Fig. 3, left shows the performed experiments of solution treatment with temperatures and times based on the

"reference" solution treatment with 485 °C for 2 hours. Fig. 3, right shows the measured mechanical properties and

energies used for the different variants of solution treatment.

Fig. 3: Left: Solution treatment experiments with different temperatures and holding times. Right: Mechanical

properties and energy usage for the different variants.

Fig. 5 shows the "connecting part LTR" in the support frame "No.1" which was designed to model the contact areas

that were detected in the experiments. The contact areas were marked by Indian ink and are visible in the

photograph of the part in Fig. 4.

Fig. 4: Cast part "connecting part" with marked contact areas (black ink markings)

In Fig. 5, the displacement results (gravity vector points in y-direction) of the solution treatment simulation in support

frame No.1 show a clear deformation of the part. The outer left edge of the part is deformed downward due to gravity

forces. The distortion of the part is shown with a distortion factor of 20. The geometry of the part at the beginning of

the solution treatment is shown in transparent grey.

12February 2017

13February 2017

Fig. 5: Support frame No.1. Gravity vector points in y-direction. The result shows the deformation in y-direction at

the end of the solution treatment.

A first DOE (Design of Experiments) of the solution treatment step for the "connecting part LTR" is performed with

the support frame "No.1" for the different solution treatment temperatures and times according to the ones shown in

Fig. 3. The objective is to show how the deformation of the part depends on the different temperature levels and

holding times.

The result of this DOE investigation is represented in the diagram of Fig. 6. On the x-axis the holding time of the

solution treatment is plotted, and the y-axis shows the maximum difference of deformation in the part compared to

the reference geometry. The green colored dots show the simulation results for the (reference) solution treatment

temperature of 485 °C, red dots show the results for 535 °C and the blue ones show the results for 465 °C.

Fig. 6: DOE: Maximum Deformation of the part during heat treatment for different solution treatment temperatures

and times, using Support Frame No.1

The diagram clarifies that for the same holding time (e.g. 2 hours) the solution treatment with the highest

temperature shows the highest deformations of the treated part. At the same time the diagram illustrates the clear

tendency towards higher deformations for longer treatment times for the same temperature levels. The lines of

different colored dots in the diagram show that the values on the y-axis increase analogous to the x-values. These

observations correspond to the results presented in the final report of the ProGRes report, [7]. Hence, not only

energy savings but also lower deformations can be the advantage of changing the solution treatment parameters to

14February 2017

lower temperatures and/or shorter treatment times. Of course, as mentioned before, it has to be ensured that by

changing these process parameters the desired microstructure and mechanical properties are still reached,

because the super-saturated solution of Mg and Cu at the end of the solution treatment is a requirement for the

subsequent aging process. Virtual experiments to optimize the mechanical properties are described in the section

"Precipitation hardening during artificial aging".

The possibility to optimize a support frame for a given part, in this case the Audi TT "connecting part LTR", is shown

as the next DOE. The objective is to minimize the deformation of the part for different layouts of the supporting

frame, while keeping solution treatment parameters fixed at 2 hours and 485 °C. Therefore different combinations

of the front supporting beams, see pictures in Fig. 7, are defined as a start sequence and these combinations are

automatically changed by the program MAGMA5 Rel. 5.3 after starting the DOE.

Fig. 7: Changing support frames for first DOE sequence, objective: minimize deformation.

Fig. 8: Optimizing the support frame by changing the supporting areas (contact areas)

The results of these DOE simulations are shown in Fig. 8. For the first frame (support frame No.1) in the top left

corner of Fig. 8 a displacement of 3.2 mm in direction of the gravity vector (y-direction) is evaluated in the left front

area of the cast geometry. Using an additional support in the front left corner of the geometry the deformations

already show significant reductions as can be seen in the plot in the upper right corner of Fig. 8. The next variation is

done by taking away one of the former front support beams. This variation has only minor effect on the deformations

of the part (plot in lower left corner of Fig. 8). Moving the front left support further left and to the back of the geometry

seems to lead to the best result of the performed variations with the lowest displacements in gravity (y-) direction, as

the plot in the lower right corner of Fig. 8 shows.

Up to this point the minimization of deformations has only been based on the evolution of deformations during the

heat treatment process. But in a real casting process the minor percentage of all cast parts will have exactly the

intended form of the reference (CAD) geometry. In most cases the outcome of the casting process will differ more or

less from this targeted geometry. In these cases an additional deformation during heat treatment, if, of course,

going in the right direction, can even be helpful and bring the part back into tolerances. And working with complex 3-

D parts even experienced experts can only guess which could be the best approach.

Fig. 9 shows the simulation results of the deformed "connection part LTR" after the casting process. The geometry

of the (pre-deformed) part after the casting simulation is already positioned onto the support frame No.1 (supporting

frame No.1 is shown in the upper right-hand corner of Fig. 7) and again the solution treatment is simulated as

described above. The earlier simulations did not take into account deformations caused by the casting process and

were performed with the CAD geometry.

15February 2017

Fig. 9: Deformed part after casting simulation is positioned onto heat treatment support frame No.1. Contours show deformation after casting.

Fig. 10: Deformations of the cast part (pre-deformed after casting) after solution treatment when supported on frame No.1. Contours only show deformation due to heat treatment.

16February 2017

Fig. 11: 6-point Reference Point System used in "ProGRess"

Today the trend in industry is to evaluate deformations with the help of virtual measurements. The parts to be

measured are scanned with optical laser systems, which in a best-case scenario cover the whole geometry of the

measured part. Evaluations are typically done as 'Best Fit' or in most cases 6-point, also known as Reference Point

System, measurement. The results are usually given as contour plots of the deviation values of the deformed

geometry from the reference geometry (target geometry) in normal direction. To compare the deformation results

after the heat treatment on support frame No.1 for both geometries (pre-deformed geometry due to casting and

CAD geometry) the 6-point measurement is used. The results of these measurements can be seen in Fig. 12 and

Fig. 13.

A comparison of the deformation of the cast part, Fig. 12, after heat treatment with the deformation of the CAD

geometry, Fig. 13, after heat treatment indicates that deformations due to the casting process cannot be neglected.

Alternatively the deformed part (after casting) is positioned onto a "grid support frame" as shown in Fig. 14. The idea

of support frames like this is to have extensive supporting areas where the part can deform back onto its desired

(CAD-reference) form. These frames show advantages for the casting processes where widely spread

deformations or very low deformations are generated by the casting process. Disadvantages of these extensive

supporting frames can be the higher production costs of the frames and the ineffectiveness due to widely distributed

loads (less concentrated loads can mean lower deformation in favoured directions) for well-known deformations

after the casting process.

Fig. 12: Deviation of the cast part from the reference

(target geometry) after heat treatment in support

frame No.1 (6-point measurement positioning)

Fig. 13: Deviation of the CAD-geometry part from the

reference (target geometry) after heat treatment in

support frame No.1 (6-point measurement

positioning)

The contours in Fig. 14 show the deformation due to solution treatment. Fig. 15 shows the contact areas of the (pre-

deformed after casting) part to the grid support frame. It illustrates that even precisely constructed support frames

do not always give the support as planned, if planning is started from CAD-geometry.

In Fig. 16 the deviation of the (pre-deformed after casting) part is given in 6-point measurement positioning. Again

there is difference to the result in Fig. 12, which shows the deviations after heat treatment on the support frame No.1

for the same initial geometry.

Fig. 14: Deformation of the cast part (pre-deformed after casting) after solution treatment simulation on "grid support frame" (contours only show deformation due to heat treatment), low deformations

Fig. 15: Contact areas of the cast part to the grid support frame

The Jawaharlal Nehru National Solar Mission was launched in January 2010, set target of

deploying 20,000 MW of grid connected solar power by 2022.

In June 2015, the target has been stepped up to 1,00,000 MW by 2022

To Be Continued in Next Issue : Part II & the references of the full article in next issue.

Fig. 16: Deviation of the cast part (pre-deformed after casting) from the reference (target geometry) after heat treatment on grid support frame (6-point measurement positioning)

17February 2017

18February 2017

Statistical Techniques for Industry

Pramod Gajare , Consultant.

Email: pramodgajare2013@gmail.com

Learning Objectives

Method for calculating process control limits for

mean and range charts.

Steps for design of the control chart for mean and

range.

Introduction

In previous chapter we had seen that control chart is

like a traffic signal. Its operation is based on evidence

from process samples taken at random intervals. A

green light indication is given when only random or

common causes are present and hence the process

should be allowed to run without adjustment. Any

possibility of trouble is indicated by yellow light. The

red light is an indication for presence of assignable or

special causes; and the process has wandered.

For the traffic signal the limits for glowing a particular

light (Green, yellow or red) are predefined. This

definition is based on the previously collected data

about the condition of the traffic at that particular

junction. Similarly the limits for warning and action are

defined based on the previously collected data for the

particular process.

Warning and Action limits for the Mean Chart

Figure 11.1: Principle of mean control chart.

For ease of understanding, the principle of mean

control chart is repeated here. From Figure 11.1, we

can understand following;

The Upper Warning line is at

The Lower Warning line is at

The Upper Action line is at

The Upper Action line is at

The Process mean or Grand mean is at

These calculations for control limits can be simplified.

In statistical process control for variables, the sample

size is definite (normally less than 10). Due to this it is

possible to use alternative measure of spread of the

process. We can replace Sigma (σ) by the mean

range of samples ( ) For correct estimation of the

standard deviation we need to make use of Hartley's

constant (d or d ).n 2

The individual range of each sample (R) is calculated i

and the average range ( ) obtained from the individual

sample ranges using following equation

…eq. : 11.1

Where,

k = the number of sample sizes n.

Then,

…eq.: 11.2

Where,

d or d = Hartley's constant n 2

Now we will insert value of σ in the formula for Action

11. Process control using variables: Part 2

limit, as follows;

Hence,

Similarly we have,

Since 3, 2, d and n are all constants for the same n

sample size, these can be replaced by just one

constant.

Hence we get,

Also we get

Now, the control limits have become;

Statisticians had calculated the values of constants d , n

A2, and 2/3 A2 for samples sizes from n=2 to 12.

Figure 11.2 shows the values of constants used in

control charts for mean. As seen earlier for bigger

sample size i.e. n greater than 12, the range looses

effectiveness rapidly since it ignores all the

information in the samples between the highest and

lowest value.

Figure 11.2: Constants used in control charts for

mean.

Warning and Action limits for the Range Chart

The distribution of samples ranges is positively

skewed distribution, as shown in Figure 11.3. Hence

the control limits on the range chart are asymmetrical.

Figure 11.3: Distribution of sample ranges.

Figure 11.4: Constants used in control charts for

range.1 1Figure 11.4 shows four constants D .001, D .025,

1 1D .975 and D .999. These can be used to calculate the

control limits for range chart. Thus we have the control

limits for range charts as follows;

19February 2017

Steps for designing control chart for mean and

range

With the knowledge gained so far, one can design

control charts for means and ranges without any

hurdle. For making this activity simple, the steps are

listed below.

Select the random samples of size n, (less than 12 but

greater than or equal to 4). The total number of

individual results has to be between 50 and 100. (For

sample size n = 4 and 100 individual results, there will

be 25 subgroups)

Measure the variable (diameter, length etc) for each

individual item and record the results.

Calculate the sample mean (X bar) and sample range

(R) for each sample.

Calculate the Process Mean (X double bar) i.e.

average of sample means, and Mean Range (R bar)

i.e. average of sample ranges.

Plot the mean and range chart and check for possible

calculation errors.

Look up for the values of constants d , A2, and 2/3 A2; n

and calculate the action and warning limits for the

mean chart.

1 1Look up for the values of constants D .001, D .025, 1 1D .975 and D .999; and calculate the action and

warning limits for the range chart.

Draw the action lines and warning lines on the mean

and range chart.

Examine the chart again. Can you tell, whether the

process is in statistical control?

Control Charts used in automotive industry.

The Control Charts used in automotive industry have

different approach for the control limits. We will

discuss that in due course of time.

What we learned?

Control limits for Mean Chart are derived from the

Process Mean (X double bar).

Control limits for Range Chart are derived from the

Mean range (R bar).

The constants (d , A2, and 2/3 A2) are used to n

calculate the action and warning limits for the

Mean Chart.

1 1 1 1 The constants D .001, D .025, D .975 and D .999

are used to calculate the action and warning limits

for the Range Chart.

Acknowledgments :

I would like to acknowledge My Guru Mr. S B Deo, who

taught me 'Statistical Process Control'.

20February 2017

Mr. Vivek Bhide, Managing Director-TSL Consulting Pvt. Ltd.

COFFEE TALK ON : Stress ManagementThrough Meditation

4th January 2017 (Wednesday)

Mr. R. V. Apshankar Welcoming Mr. Vivek Bhide Audience At Coffee Talk

21February 2017

Metallography of Aluminium Alloys : Through Questions - Answers

Prof. S. K. Paknikar , Consultant.

Email: skpaknikar@gmail.com

Q. 1. Aluminium-Silicon Equilibrium Diagram which

reaction is most important?

(A) Perieutectic (B) Eutectoid

(C) Eutectic (D) Monoeutectic.

Q. 2. Which gas solubility is very harmful to achieve sound

castings?

(A) Nitrogen (B) Hydrogen

(C) Chlorine (D) Oxygen.

Q. 3. How effectiveness of modification is confirmed from

Microstructure.

(A) More eutectic (B) Flakes of Silicon

(C) Nodularity (D) Fineness.

Q. 4. Which element from following makes Al- alloys

Precipitation hardenable?.

(A) Zinc (B) Titanium

(C) Silicon (D) Copper.

Q. 5. The microstructure of hyper eutectic Aluminium-

Silicon is as under.

(A) Alpha + Silicon (B) 100 % Eutectic

(C) Only alpha (D) 100 % Si.

Q. 6. For solution treatment the alloy is heated to a

temperature ------

(A) Eutectic (B) Alpha region

(C) Below Eutectic (D) Alpha +Silicon.

Q. 7. The aging treatment is given after solution treatment

depends on -----

(A) Salvoes line (B) Temperature

(C) Soaking Time (D) Hardness.

Q. 8. The strength of Aluminium Alloys can be improved by

alloying with-

(A) Iron (B) Silicon Carbide

(C) Magnesium (D) Strontium.

Answers In Next Issue...

Answers In Next Issue...

EXCERPTS FROM INTERVIEW OF PROF. K. S. S. MURTHY (ADVISORY BOARD MEMBER GDC TECH)

TAKEN IN JANUARY 2017 BY MR. R. T. KULKARNI, VICE CHAIRMAN, GDC TECH FORUM

Education : B.E (Mech) - University of Mysore, M.E (Foundry Engg.) - Indian Institute of Science, Ph.D -do-

NRC Post-Doctorate Fellow of Canmet Centre, Ottawa, Canada

Experience :

Retired as Professor of Mechanical Engineering. Member of the faculty of the Institute in Dec - 1959 - July 31, 1997; and was engaged in teaching and research in metal casting and metal joining

Has been involved in teaching, research and industrial consultancy relating to ferrous and non-ferrous foundry practices, gravity and pressure die casting of aluminium and zinc base alloys, welding and other metal joining techniques, metal working - hot and cold, forging, selection of materials, failure analysis and several

other metallurgical problems for several decades. Also offered/offering technical advice on production processes, selection of plant and machinery, preparation of project reports etc., relating to new projects/modernization/revival of sick units.

Guided a number of Master of Science (Engg.) and Doctoral Research Programmes relating to these areas including welding; Published over 250 papers in leading International and National technical Journals. Also presented a number of technical papers in several important International and National Conferences.

Actively engaged in advising various Ministries in Government of India and was responsible for initiating several nationally important projects such as Aluminium Mission Plan, Technology Roadmap for Indian Aluminium Industries, Litebus project etc.

He has established National Facility for Semi Solid Forming, an advanced casting research facility at Indian Institute of Science.

Other affiliations (past/current)

Consultant to various industries in the country

Worked as Hon.General Secretary, Aluminium Association of India, the apex body of Indian Aluminium Industry

Member - Participant, Meetings of World Aluminium Association Leaders, periodically organised by The International Aluminium Institute, UK.

Secretary, National Steering Committee, International Conference on Aluminium INCAL-91 and INCAL-98, INCAL- 2003, INCAL 2007, INCAL 2011.

Fellow of the Institute of Indian Foundrymen.

Director on the board of GWASF.