NON TRADITIONALMACHINING TECHNIQUES

INTRODUCTION TO NON TRADITIONAL MACHINIING TECHNIQUES

ByMr. Vaddi ThulasikanthAssistant Professor

Manufacturing processes can be broadly divided into two groups 1.Primary manufacturing processesThis provide basic shape and size to the material as per designer‘s requirement.Eg.Casting, forming,  powder metallurgy 2.Secondary manufacturing processes. This  provide the final shape and size with tighter control on dimension and surface characteristics etc.

Material removal processes are mainly the secondary manufacturing processes

Material removal processes are divided into mainly two groups.1.Conventional Machining ProcessesThese processes mostly remove material in the form of chips by applying forces on the work material with a wedge shaped cutting tool that is harder than the work material Eg. turning, boring, milling, shaping, broaching, slotting, grinding etc. 2.Non-Traditional Manufacturing ProcessesIt is defined as a group of processes that remove excess material by various techniques involving mechanical, thermal, electrical or chemical energy or combinations of these energies but do not use a sharp cutting tools as it needs to be used for traditional manufacturing processes. Eg. AJM, EDM,ECM, LBM, EBM etc.

Needs for Non Traditional Machining•Extremely hard and brittle materials are difficult to machine by traditional machining processes.

• When the work piece is too flexible or slender to support the cutting or grinding forces.

• When the shape of the part is too complex.

• Intricate shaped blind hole – e.g. square hole of 15 mm x15 mm with a depth of 30 mm .

• Deep hole with small hole diameter – e.g. φ 1.5 mm hole with l/d = 20 .• Machining of composites.

•Mechanical - erosion of work material by a high Velocity stream of abrasives or fluid (or both) is the typical form of mechanical action•Electrical - electrochemical energy to remove material (reverse of electroplating)•Thermal –thermal energy usually applied to small portion of work surface, causing that portion to be removed by fusion and/or vaporization•Chemical –chemical etchants selectively remove material from portions of work part, while other portions are protected by a mask

Sources or Energy of Metal Removal

PROCESS SELECTION

1.Physical Parameters2.Shapes to be machined3.Process Capability or Machining Parameters4.Economic Consideration

1.Physical Parameters

2. Shapes to be machine

Material applications of various machining methods

Material applications of various machining methods

The various machining characteristics and process capabilities that are governing Non-Traditional Manufacturing Techniques are

(i)Metal removal rate

(ii) Tolerance maintained

(iii) Surface finish obtained

(iv) Depth of surface damage

(v) Power required for machining

3. Machining characteristics/Process Capabilities

Comparison of process capabilities of different Non-Traditional Machining

4.Economic ConsiderationThe economics of the various processes are analysed on the basis of following 

factors

(i) Capital cost (ii) Tooling cost

(iii) Consumed power cost (iv) Metal removal rate efficiency

(v) Tool wear.

COMPARISION OF TRADITIONAL AND NON-TRADITIONAL MACHINING TECHNIQUES

S.No TRADITIONAL MACHINING NON TRADITIONAL MACHINING1 Macroscopic size chip formation Microscopic size chip formation

2There may be a physical tool present eg.Cutting tool

There may not be a physical tool present except in ECM

3

Cuttting tool is harder than work piece at room temperature and machining condition

There may not be a physical tool present except in ECM

4

Matertial removal takes place due to cutting action. It falls in mechanical energy domain.

They fall in different energy domain. Mechanical, thermal and chemical

5 Direct contact of tool and work No direct contact of tool and work6 Lower accuracty and surface fininsh Higher accuracty and surface fininsh

7Tool life is less due to high surface contact and wear Tool life is more.

8Higher waste of material due to high wear

Lower waste of material due to low wear

9 Lower capital cost Higher capital cost10 Easy set up of equipment Complex set up of equipment

Limitations1.More Expensive

2.MRR is slow

3.AJM, PAM and EBM are not commercially economical process

Advantages1.Increases Productivity

2.Reduces number of rejected components

3.Close tolerance is possible

4.Tool material need not be harder than work piece.

5.Machined surface do not have residual stresses.

6.Hard materials can be machined easily

REVIEW QUESTIONS

1.Broadly classify the Manufacturing processes.2.Classify the Material removing processes.3.List the need for Non-Traditional Machining techniques.4. What are the basic factors upon which the unconventional manufacturing processes are classified?5.Why are the unconventional manufacturing processes not completely taking over the conventional manufacturing processes ?6.What are the machining characteristics governing Non-Traditional Machining? Write the inference of comparison of processes with respect to above.7. Distinguish between conventional and unconventional manufacturing processes

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