1. Manufacturing processes
PART 1
A.POURMIKAEIL

2. Manufacturing processes
PART 1
A.POURMIKAEIL

3. MATERIAL REMOVAL PROCESSES

4. INTRODUCTION OF METAL CUTTING

5. Figure 1:Classification of Material Removal Process
MACHINING
TRADITIONAL MACHINING
TURNING
RELATED
AND
DRILLNG AND RELATED
MILLING
ABRASIVE MACHINING
GRINDING
ABRASIVE
OTHER
NONTRADITIONAL MACHINING
MECHANICAL ENERGY
CHEMICAL
ELECTRO
ENERGY
THERMAL
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Figure 1:Classification of
Material Removal Process

6. Classification description 1
Conventional machining
The most important branch
Use sharp cutting tool
Three principal
Turning
Drilling
Milling
Others machining operation

7. Classification description 2
Abrasive machining
Removed material by hard & abrasive particle
Classified in two group:
Grinding
Other abrasive
Honing
Lapping
Super finishing

8. Classification description 3
Nontraditional processes
Use various energy forms other than sharp cutting tools or abrasive particles to remove materials.
Classified into four group
Mechanical
Electrochemical
Thermal
chemical

9. Machining
Cutting action involves shear deformation of work material to form a chip
As chip is removed, new surface is exposed
Figure 2: (a) A cross‑sectional view of the machining process, (b) tool with negative rake angle; compare with positive rake angle in (a).
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

10. Advantages Variety of work materials
Metals
Plastics
Ceramics (in some technology)
compsites
Variety of part shapes and geometry features.
All regular geometry
by combination several machining operation in sequence, shapes of almost unlimited complexity and variety are produced.

11. Advantages (continued)
Dimensional accuracy
Some technology achieve mm tolerance .
Good surface finishes
Very smooth surface
Less than 0.4 microns
Some abrasive processes better than this

12. Disadvantages Waste of materials Time consumption
Machining is generally performed after other processes.

13. Machining in Manufacturing Sequence
Generally performed after other manufacturing processes, such as casting, forging, and bar drawing
Other processes create the general shape of the starting work part
Machining provides the final shape, dimensions, finish, and special geometric details that other processes cannot create

14. Overview of machining technology
Most important machining operations:
Turning
Drilling
Milling
Other machining operations:
Shaping and planning
Broaching
Sawing

15. Turning
Single point cutting tool removes material from a rotating work piece to form a cylindrical shape
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Figure 3: Three most common machining processes: (a) turning,

16. Drilling
Used to create a round hole, usually by means of a rotating tool (drill bit) with two cutting edges
Figure 4 (b) drilling,
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

17. Milling
Rotating multiple-cutting-edge tool is moved across work to cut a plane or straight surface
Two forms: peripheral milling and face milling
Figure 5: (c) peripheral milling, and (d) face milling
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

18. Cutting tool classification
Single-Point Tools
One dominant cutting edge
Point is usually rounded to form a nose radius
Turning uses single point tools
Multiple Cutting Edge Tools
More than one cutting edge
Motion relative to work achieved by rotating
Drilling and milling use rotating multiple cutting edge tools

19. Cutting tools
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Figure 6: (a) A single‑point tool showing rake face, flank, and tool point; and (b) a helical milling cutter, representative of tools with multiple cutting edges.

20. Cutting Conditions in Machining
Three dimensions of a machining process:
Cutting speed v – primary motion
Feed f – secondary motion
Depth of cut d – penetration of tool below original work surface
For certain operations, material removal rate can be computed as
RMR = v f d
where v = cutting speed; f = feed; d = depth of cut

21. Cutting Conditions for Turning
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Figure 7: Speed, feed, and depth of cut in turning.

22. Roughing vs. Finishing
In production, several roughing cuts are usually taken on the part, followed by one or two finishing cuts
Roughing - removes large amounts of material from starting workpart
Creates shape close to desired geometry, but leaves some material for finish cutting
High feeds and depths, low speeds
Finishing - completes part geometry
Final dimensions, tolerances, and finish
Low feeds and depths, high cutting speeds

23. Machine Tools
A power‑driven machine that performs a machining operation, including grinding
Functions in machining:
Holds workpart
Positions tool relative to work
Provides power at speed, feed, and depth that have been set
The term is also applied to machines that perform metal forming operations

24. Chip Formation
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Figure 8: More realistic view of chip formation, showing shear zone rather than shear plane. Also shown is the secondary shear zone resulting from tool‑chip friction.

25. Four Basic Types of Chip in Machining
Discontinuous chip
Continuous chip
Continuous chip with Built-up Edge (BUE)
Serrated chip

26. Discontinuous Chip Brittle work materials Low cutting speeds
Large feed and depth of cut
High tool‑chip friction
Figure 9: Four types of chip formation in metal cutting: (a) discontinuous
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

27. Continuous Chip Ductile work materials High cutting speeds
Small feeds and depths
Sharp cutting edge
Low tool‑chip friction
Figure 10: (b) continuous
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

28. Continuous with BUE Ductile materials Low‑to‑medium cutting speeds
Tool-chip friction causes portions of chip to adhere to rake face
BUE forms, then breaks off, cyclically
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Figure 11: (c) continuous with built‑up edge

29. Serrated Chip Semicontinuous - saw-tooth appearance
Cyclical chip forms with alternating high shear strain then low shear strain
Associated with difficult-to-machine metals at high cutting speeds
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Figure 12: (d) serrated

30. Forces Acting on Chip Friction force F and Normal force to friction N
Shear force Fs and Normal force to shear Fn
Figure13: Forces in metal cutting: (a) forces acting on the chip in orthogonal cutting
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

31. Cutting Force and Thrust Force
F, N, Fs, and Fn cannot be directly measured
Forces acting on the tool that can be measured:
Cutting force Fc and Thrust force Ft
Figure14: Forces in metal cutting: (b) forces acting on the tool that can be measured
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e

32. Effect of Higher Shear Plane Angle
Higher shear plane angle means smaller shear plane which means lower shear force, cutting forces, power, and temperature
©2007 John Wiley & Sons, Inc. M P Groover, Fundamentals of Modern Manufacturing 3/e
Figure 15: Effect of shear plane angle  : (a) higher  with a resulting lower shear plane area; (b) smaller  with a corresponding larger shear plane area. Note that the rake angle is larger in (a), which tends to increase shear angle according to the Merchant equation

33. Cutting Temperature
Approximately 98% of the energy in machining is converted into heat
This can cause temperatures to be very high at the tool‑chip
The remaining energy (about 2%) is retained as elastic energy in the chip

34. Cutting Temperatures are Important
High cutting temperatures
Reduce tool life
Produce hot chips that pose safety hazards to the machine operator
Can cause inaccuracies in part dimensions due to thermal expansion of work material