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Chapter 1

Introduction to Hybrid Machining Technology

Dr. J. Ramkumar1 and Vyom Sharma2

1Professor and 2Research Student

Department of Mechanical Engineering

Micromanufacturing Lab, I.I.T. KanpurMicromanufacturing Lab, I.I.T. Kanpur

Organization of the presentation

1. Overview of Machining Technology

(Introduction to Machining Processes, Advances, and New Challenges)

2. Classification of Hybrid Machining Processes

(Concept and Definition)

3. Major Elements of Hybrid Machining Technology

(Hybrid Machine Tools, Hybrid Tooling, Hybrid Machining Processes, Metrology System,

Work Handling System, Process Monitoring Technique)

4. Benefits of Hybrid Machining Technology

5. Challenges and Opportunities

6. Conclusions and Future Research

2 Micromanufacturing Lab, I.I.T. Kanpur


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Machining operations can be classified into two groups [1]:

(1) Mechanical Machining (2) Non traditional Machining

Mechanical Machining

Turning

Grinding Milling

Other

operations

Micromanufacturing Lab, I.I.T. Kanpur


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Non traditional Machining

Mechanical

Energy

Processes

Ex. USM

WJC

Electrochemical

Processes

Ex. ECM

Thermal Energy

Processes

Ex. EDM

LBM

EBM

Chemical

Machining

Processes

Ex. CHM

PCM



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Biomedical Micro fluidics

Advances and New Challenges in Machining Processes

Ultra precision machining processes are able to achieve a very high accuracy

from 10 nm to 100 nm and material removal rate above 10-4 mm3/sec .

Highly accurate 3D complex parts are made via variety of separate high

precision machining processes. It therefore results in a long process chain and

lead time.

Multifunctional machines/machining centers are developed by key machine

builders like Mazak, DMG Mori, and Okuma to solve this problem. Such

centers helps in drastically reducing the machining time.



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Micro fluidics

Advances and New Challenges in Machining Processes

Generate NC code

Workpiece Setup

Turning Process

Unload, Wait, Transit and setup

Milling Process

Unload, Wait, Transit and setup

Grinding Process

Unload

Traditional Machining Processes

Generate NC code

Workpiece Setup

Turning + Milling + Grinding Process

Unload

Multifunctional Machining Process

Combining traditional mechanical machining processes with non traditional machining

processes can help utilize the advantages of one process and compensate for shortcomings of

the other process. This results in the hybrid machining technology.Micromanufacturing Lab, I.I.T. Kanpur


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Definition: Hybrid machining technology is the integration of traditional and

non-traditional machining processes on the same machine platform with the

objective to obtain “1+1=3” effect.

Hybrid Machining Processes are classified into 3 groups.

Assisted

Hybrid

Machining

Combined

Hybrid

Machining

Controlled

application

of process

mechanisms



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Assisted Hybrid Machining: The major machining process is superimposed

with inputs from one or several types of energy such as ultrasonic vibration,

laser, fluid, magnetic field etc. to improve the constituent machining process

[2][3].

Examples: Laser assisted

Vibration assisted

Fluid assisted

Magnetic field assisted

Abrasive assisted

External electric field assisted

Heat assisted

Media assisted

(Cryogenic fluid, gas, carbon nanotube) Figure: Laser assisted turning



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Combined Hybrid Machining: All the constituent machining processes

simultaneously contribute to the material removal and affect the machining

zone. Such processes have a great potential to produce complex parts with

enhanced material removal rate, surface integrity and dimensional accuracy in a

relatively short processing time [4][5][6].

Examples: Electrochemical discharge

Laser-electrochemical

Electrochemical grinding

Electric discharge grinding

EDM-ER fluid assisted polishing

Mechano-electrochemical

Figure: Electrochemical Spark Machining



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Controlled application of process mechanisms: Material removal process

mechanisms of two different processes are simultaneously combined and

controlled to achieve desired results [7].

Examples: Hybrid abrasive water jet and milling process

Grind hardening process

Electrochemical-Electric discharge

milling process

Figure: Electrochemical-Electric discharge milling process



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Hybrid Platform

Hybrid Machine Tool

Hybrid Tooling

On-Machine metrology

system

Work handling system

Hybrid

Machining

Process

Process

Modelling



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(A) Hybrid Machine Tool: It can be defined as a power driven machine used

for producing a variety of shapes and sizes in metals or other solid materials by

removing away redundant work materials through different hybrid machining

processes [8] .

Such machine tools are categorized into three groups.

Hybrid

Machine

Tools

Sequential

Assisted

Combined



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(i) Sequential

Sequential Hybrid Machines

These machines are build under the philosophy of

integrating sequential machining processes in one

machine platform, where machining processes take

place one after the other. All the machining process

occur in one coordinated system, there is no need to

transfer the workpiece from one machine to another.

Ex. Hybrid μ-EDM Machine DT-110 Micromanufacturing Lab, I.I.T. Kanpur


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(ii) Assisted

Assisted Hybrid Machines

These machines are used to implement hybrid

machining process. Ultrasonic hybrid machine is the

most popular and commercially successful machine

tool. It is particularly useful for machining hard-to-

machine materials. For example, in turning operation,

conventional tool post is replaced by a ultrasonic tool

post [9].

Ex. Assisted Turning Hybrid Machine Tool

Ultrasonic Vibrating Tool PostMicromanufacturing Lab, I.I.T. Kanpur


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(iii) Combined

Combined Hybrid Machines

These machines combine material removal mechanisms

of two different machining processes under one

platform to perform simultaneous machining. Such

hybrid machines are used for achieving combined

material removal rate higher than rates of individual

machining process.

Ex. Mechano-Electrochemical Milling (MECM, developed by

KU Leuven University)Micromanufacturing Lab, I.I.T. Kanpur


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(B) Hybrid Tooling: The Hybrid tooling combines two or more established

processing modules into one tooling device in order to achieve desirable

material removal effect. Some examples are as follows:

Hybrid

Tooling

Laser

Assisted

Turning

Tool

Holder

Laser

Micro-Jet

Tooling

Ultrasonic

Assisted

Turning

Tool

Holder

Ultrasonic

Assisted

Milling-

Grinding

Tool

Holder



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Laser Assisted Turning Tool Holder [2] Laser Micro-Jet Tooling [3]



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Ultrasonic Assisted Turning Tool Holder [10]Ultrasonic Assisted Milling-Grinding Tool Holder [10]



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(C) On-Machine Metrology System: On machine monitoring (OMM) is very

important in hybrid machining processes as it can avoid time-consuming

realignment operations and possible damage during the transportation between

machine tool and measurement platform. It can therefore further enhance

machining accuracy and efficiency [11].

Two major tasks for OMM are:

(i) Dimensional Metrology.

(ii) Surface Metrology.

In the above mentioned two tasks, both contact metrology and non-contact

metrology play key roles.



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(i) Contact Metrology

Parallel Kinematics Probe: Uses linearly movable styli and flat probe tips. It

uses incremental sensors to measure the displacement of each stylus. The lines

of measurement of the probes are typically arranged orthogonal to each other

and perpendicular to the sphere surface. The three measurement line passes

approximately through the center of the sphere. This probe demonstrates

repeatability of less than 0.5 μm and an error range of less than 2 μm

throughout the large measurement range of the probe [1].



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(ii) Non-Contact Metrology

Optical methods of metrology are the fastest and most reliable methods of

OMM applications. Optical techniques can operate effectively over scales

ranging from few nanometers to few meters meaning that there is a high level

of applicability across many types of manufacturing.

Due to working volume constrictions and cost implications, a single-point

optical method, namely dispersed reference interferometry is used in online

monitoring for hybrid machines [1].

Example: NanoCam from 4D TechnologyMicromanufacturing Lab, I.I.T. Kanpur


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(C) Work Handling System

Hybrid Machining requires automated handling of the workpiece. Use of

robotic handling systems have become a commonplace in recent years. These

standard workpiece handling robots are fully automated and usually have tech-

in functions for different workpieces which provide great flexibility for

different operations.

As in hybrid machines, multiple processes are integrated on one machine

platform, the workpiece handling system needs to be within and as a part of the

hybrid machine [1].


4. Benefits of Hybrid Machining Technology [1][12][13]

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1. Hybrid Machining makes it possible to machine hard-to-machine materials

that may not be possible by conventional approach. For instance, diamond

turning tools will experience severe thermochemical tool wear when

machining ferrous metals. Applying ultrasonic assisted diamond turning, an

optical quality surface (Ra < 5nm) can be achieved on hardened steel for

mould manufacturing.

2. Improving the existing process capabilities in terms of improved surface

finish, surface integrity, tool life etc. For example, compared with

conventional diamond grinding, a 30 % improvement of machined surface

finish has been achieved along with a defect free subsurface in dry LAM of

Si3N4 and Al2O3 .

3. Reducing machining time and production cost. As hybrid machining takes

place on the same machine bed, there is no need to transfer and reposition

the workpiece at different times. The setup time is therefore reduced.


4. Benefits of Hybrid Machining Technology [1][12][13]

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4. Gaining significant benefits of interactions of different process energies. For

example ECDM combines electrochemical and electric discharge process

energies.


5. Challenges and Opportunities [1]

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There are two types of challenges in Hybrid Machining Processes:

(a) Scientific Challenges (b) Technical Challenges

(a) Scientific Challenges:

1. Machining mechanism of Hybrid Machining:

Understanding fundamental material removal and surface generation

mechanisms is very important to improve the machining accuracy and

efficiency.

2. Multi-scale and Multi-physics modelling:

Hybrid machining is a complicated machining process. The working zone is

usually under the actions involving mechanical, electrical, thermal or chemical

energies.



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3. Online metrology for surface integrity

One of the benefits of Hybrid machining is to improve surface integrity.

However, currently there is no method to realize on line measurement of

surface integrity. It therefore, needs a new reliable measurement approach.

(b) Technical Challenges

1. Hybrid machining system integration:

The integration of a number of machining systems into one compact machine

platform proposes a big technical challenge in terms of kinematic design and

dynamic design.

2. Hybrid system control:

The material removal in hybrid machining is through not only mechanical

motion but also other electrical or thermal processes. Controlling the complex

system, therefore, becomes another technical challenge for implementation.



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3. Online metrology:

Implementing the surface sensor in a real production floor will need to

overcome influences from environmental vibrations, thermal deformations,

humidity, and obstacles from cutting chips, fluids, etc.


6. Conclusions and Future Research

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Hybrid machining technology offers great potentials in obtaining high quality

products with great efficiency productivities, accuracy, and energy efficiency.

The future research and development focus for hybrid machining technology is

envisage in the following aspects [14]:

1. Development of specific multi-axis hybrid machine tools.

2. Opportunities for improving process monitoring techniques.

3. Development of on-machine tool fabrication and metrology techniques.

4. Establishment of noble processes.

5. Cost effectiveness study.

6. Industrial implementation.Micromanufacturing Lab, I.I.T. Kanpur

References

[1] Sundaram M.M. (2014) Hybrid Machining Process. In: Nee A. (eds) Handbook of Manufacturing Engineering

and Technology. Springer, London

[2] De Silva AKM et al (2011) Thermal effects in laser assisted jet electrochemical machining. CIRP Ann Manuf

Technol 60(1):243–246.

[3] Kim S et al (2010) Hybrid micromachining using a nanosecond pulsed laser and micro EDM. J Micromech

Microeng 20:015037

[4] Jain VK, Choudhury SK, Ramesh KM (2002) On the machining of alumina and glass. Int J Mach Tool Manuf

42(11):1269–1276

[5] Jui SK, Kamaraj AB, Sundaram MM (2013) Fabrication of high aspect ratio micro holes in glass by micro

electrochemical discharge machining. Submitted to NAMRI/SME, vol 41

[6] Kasashima N, Kurita T (2012) Laser and electrochemical complex machining of micro-stent with on-machine

three-dimensional measurement. Opt Lasers Eng 50(3):354–358

[7] Aspinwall DK et al (2001) Hybrid high speed machining (HSM): system design and experimental results for

grinding/HSM and EDM/HSM. Ann CIRP 50(1):145–148

References

[8] Kurita T, Watanabe S, Hattori M (2001) Development of hybrid micro machine tool. In: Proceedings of the second

international symposium on environmentally conscious design and inverse manufacturing, Kraków, Poland, pp 797–

802

[9] Brehl DE, Dow TA (2008) Review of vibration-assisted machining. Precis Eng 32(3):153–172

[10] Curodeau A et al (2008) Ultrasonic abrasive μ-machining with thermoplastic tooling. Int J Mach Tool Manuf

48(14):1553–1561

[11] Schuh G, Kreysa J, Orilski S (2009) Roadmap “Hybride Produktion”–Wie 1+ 1= 3-Effekte in der Produktion

maximiert werden können. ZWF – Zeitschrift für wirtschaftlichen Fabrikbetrieb 104(5):385–391

[12] Lim H, Kumar AS, Rahman M (2002) Improvement of form accuracy in hybrid machining of microstructures. J

Electron Mater 31(10):1032–1038

[13] Pa PS (2009) Super finishing with ultrasonic and magnetic assistance in electrochemical micro-machining.

Electrochim Acta 54(25):6022–6027

[14] Sommer C (2000) Non-traditional machining handbook. Advance Pub, Houston, 432


Thank You

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