1. ME 330 Manufacturing Processes CUTTING PROCESSES

2. Overview of processes
Cutting processes

3. Principle of the process
Structure and configuration
Process modeling
Defects
Design For Manufacturing (DFM)
Process variation
Module 4a

4. Major cutting processes
Bulk
Mechanical processes
Machining and grinding (will be covered in later classes)
Shearing, blanking, and punching (sheet metalworking operations)
Ultrasonic machining (USM)
Water jet cutting (WJC or hydrojet)
Abrasive water jet cutting (AWJC or abrasive hydrojet)
For sheet and plate
Shearing by power shears or squaring shears and blanking and punching by presses
Make choice on process depending on what the product requires (i.e. precision) and what the cost and timeframe allow

5. Definition of sheets and plates
Sheets: thickness is 1/64” (0.04 mm) to 1/4” (6 mm).
Plates: thickness is greater than: 1/4” (6mm)
We are going to cover…
First a few definitions: (WRITE ON BOARD)
- Typical sheet sizes are 1/64” (0.04mm) to 1/4” (6mm)
Typical plate sizes are > 1/4” (6mm)
Reason why we are making parts from sheets and plates…

6. Principle of the process
Structure and configuration
Process modeling
Defects
Design For Manufacturing (DFM)
Process variation
Module 4a

7. Principle of cutting for sheets and plates:
There is a shear stress induced on the surface of the cross section area of plates or sheets. The shearing stress causes the fracture of two parts.
Module 4a

8. Principle of the process
Structure/Configuration of the operation
Process modeling
Defects
Design For Manufacturing (DFM)
Process variation
Module 4a

9. Shearing, Blanking, and Punching
Three principal configurations in press working that cut sheet metal:
Shearing
Blanking
Punching
Different configurations of the manufacturing system or machine to generate shear stress, and they share the same principle of cutting.

10. Shearing Operation
(a) Side view of the operation; (b) front view of the operation, equipped with inclined upper cutting blade

11. Blanking and Punching
Blanking (a) - sheet metal cutting to separate piece (called a blank) from surrounding stock
Punching (b) - similar to blanking except cut piece is scrap, called a slug
Punch and

12. Shearing, Blanking, and Punching
Generic configurations: punch, die, work piece

13. Shearing
Generic configurations: punch, die, work piece

14. Punch and Die in blanking and punching
Components of a punch and die for a punch operation
Components of a punch and die for a blanking operation
Punch
Die

15. Cost of tooling is concern
The cost for tooling is even higher than the press machine in itself.
Punch and die may need frequently change due to wear, which is a part of the reasons for the high cost of tooling.

16. Non-traditional Cutting Processes
Cutting force is not generated by solid state force such as solid punch and solid die.

17. Non-traditional Processes: why
Newly developed metals and non‑metals with special properties that make them difficult or impossible to cut or machine by the solid force approach.
Complex part geometries that cannot readily be accomplished by conventional cutting and machining.
Avoid surface damage that often accompanies with the conventional machining and cutting.

18. Principle of the process
Structure and configuration
Process modeling
Defects
Design For Manufacturing (DFM)
Process variation
Module 4a

19. Major cutting processes
Mechanical processes
Machining and grinding (will be covered in later classes)
Shearing, blanking, and punching (sheet metalworking operations)
Ultrasonic machining (USM)
Water jet cutting (WJC or hydrojet)
Abrasive water jet cutting (AWJC or abrasive hydrojet)
Shearing by power shears or squaring shears and blanking and punching by presses
Make choice on process depending on what the product requires (i.e. precision) and what the cost and timeframe allow

20. The punch is a water stream
Water Jet Cutting (WJC) or Hydro-jet Cutting
Uses high pressure, high velocity stream of water directed at work surface for cutting
The punch is a water stream

21. WJC & Applications
Usually automated by CNC or industrial robots to manipulate nozzle along desired trajectory.
Water also acts as a cooling agent.
Can cut complex shaped parts.
Used to cut narrow slits in flat stock such as plastic, textiles, composites, floor tile, carpet, leather, and cardboard.
Not suitable for brittle materials (e.g., glass).
Intensity of water-jet is not enough, as opposed to the solid force, to make a clear-cut. The material tends to spreading around.

22. Abrasive Water Jet Cutting (AWJC)
Abrasive particles are added to jet stream for quicker cutting, which increases the intensity of water jet so that the high force can be created.
Suitable to cut metals.
Slower than laser cutting, but produces a cleaner finish.
Note that the water jet cut is tapered.
Draw picture of taper

23. Major cutting processes
Thermal Energy Processes
Ram electric discharge machining (Ram EDM)
Wire electric discharge machining (Wire EDM)
Electron beam machining (EBM)
Laser beam machining (LBM)
Plasma arc cutting (PAC) or plasma arc machining (PAM)
Air carbon arc cutting
Oxyfuel Cutting (OFC) or flame cutting
Shearing by power shears or squaring shears and blanking and punching by presses
Make choice on process depending on what the product requires (i.e. precision) and what the cost and timeframe allow

24. Principle of the process
Structure and configuration
Process modeling
Defects
Design For Manufacturing (DFM)
Process variation
Module 4a

25. Electric Discharge Machining (EDM)

26. EDM Operation One of the most widely used non-traditional processes
Shape of a finished work surface produced by a shape of electrode tool
Can be used only on electrically conducting work materials
Requires dielectric fluid, which creates a path for each discharge as fluid becomes ionized in the gap.
Metal is melted/vaporized by the series of electrical discharges
Can be very precise and produces a very good surface finish

27. Work Materials in EDM Work materials must be electrically conducting
Hardness and strength of work material are not factors in EDM
Material removal rate depends on melting point of work material

28. Principle of the process
Structure and configuration
Process modeling
Defects
Design For Manufacturing (DFM)
Process variation
Module 4a

29. Wire EDM
Special form of EDM uses small diameter wire as electrode to cut a narrow kerf in work

30. Operation of Wire EDM
Work is fed slowly past wire along desired cutting path.
CNC used for motion control.
While cutting, wire is continuously advanced between supply spool and take‑up spool to maintain a constant diameter.
Dielectric fluid is required.
Applied using nozzles directed at tool‑work interface or submerging work part

31. Wire EDM Applications Ideal for stamping die components
Since kerf is so narrow, it is often possible to fabricate punch and die in a single cut
Other tools and parts with intricate outline shapes, such as lathe form tools, extrusion dies, and flat templates

32. Dental part cut from nitinol material by wire EDM
New Wire EDM Capability: Here is a good example of what the rotary axis can do. This nitinol pin is used to hold a dental implant onto a special wrench during implant surgery. The material is very hard and also super elastic making it very difficult to machine conventionally. This tiny part was burned in one setup on the wire EDM to tolerances of +/ ” using the rotary axis in indexing mode.

33. The punch is a light beam
Laser Beam Machining (LBM)
Uses the light energy from a laser to remove material by vaporization and ablation
The punch is a light beam
Laser = Light amplification by stimulated emission of radiation"

34. LBM Applications
Drilling, slitting, slotting, scribing, and marking operations
Drilling small diameter holes ‑ down to mm (0.001 in)
Generally used on thin stock
Work materials: metals with high hardness and strength, soft metals, ceramics, glass and glass epoxy, plastics, rubber, cloth, and wood

35. The punch is a plasma arc
Plasma Arc Cutting (PAC)
Uses plasma stream operating at very high temperatures to cut metal by melting
The punch is a plasma arc

36. Operation of PAC Plasma = a superheated, electrically ionized gas
PAC temperatures: 10,000C to 14,000C (18,000F to 25,000F)
Plasma arc generated between electrode in torch and anode work piece
The plasma flows through water‑cooled nozzle that constricts and directs stream to desired location

37. Applications of PAC
Most applications of PAC involve cutting of flat metal sheets and plates.
Hole piercing and cutting along a defined path.
Comparable to laser cutting, but cuts are usually is more coarse.
Can cut any electrically conductive metal.
Most frequently cut metals: carbon steel, stainless steel, aluminum.

38. Important: Water Jet, Laser, Plasma
Need to start the cut away from the wanted cut to prevent a rough surface irregularity where the cut starts
Starting cut
Wanted cut

39. Summary of Cutting Processes for Sheets and Plates in terms of Quality & Cost
Wire EDM
Machining
Quality
(In terms of tolerances & surface finish
Water Jet
Laser
Punching/ Blanking
Plasma
Cost

40. Comparison: sheet and plate cutting
Plasma
Laser
Waterjet
We are going to cover…
First a few definitions: (WRITE ON BOARD)
- Typical sheet sizes are 1/64” (0.04mm) to 1/4” (6mm)
Typical plate sizes are > 1/4” (6mm)
Reason why we are making parts from sheets and plates…

41. Comparison: sheet and plate cutting
Main criteria for comparison:
Materials
Cost
Quality
Productivity

42. Comparison: sheet and plate cutting
Processes
Material
Thickness
Quality
Cost
Note
Plasma
All electrically conductive materials
Gauge to 2 in
Poor
Low
Need high power
Laser
A variety of materials
¼ in and thinner
Middle
Problem with reflective materials
Waterjet
A variety of materials, usually soft material
Highest
High
Cost: decided by the speed.

43. Major cutting processes
Electrochemical process:
Electrochemical Machining (ECM)
Shearing by power shears or squaring shears and blanking and punching by presses
Make choice on process depending on what the product requires (i.e. precision) and what the cost and timeframe allow

44. Principle of the process
Structure and configuration
Process modeling
Defects
Design For Manufacturing (DFM)
Process variation
Module 4a

45. Electrochemical Machining (ECM)
Material removal by anodic dissolution, using electrode (tool) in close proximity to work but separated by a rapidly flowing electrolyte
(-)
(+)

46. Electrochemical Machining (ECM)
Material removal by anodic dissolution, using electrode (tool) in close proximity to work but separated by a rapidly flowing electrolyte .

47. Electrochemical Machining (ECM) Processes
Electrical energy used in combination with chemical reactions to remove material
Reverse of electroplating
Work material must be a conductor
Processes:
Electrochemical machining (ECM)
Electrochemical deburring (ECD)
Electrochemical grinding (ECG)

48. ECM Operation
Material is depleted from anode workpiece (positive pole) and transported to a cathode tool (negative pole) in an electrolyte bath
Electrolyte flows rapidly between two poles to carry off depleted material, so it does not plate onto tool
Electrode materials: Cu, brass, or stainless steel
Tool has inverse shape of part
Tool size and shape must allow for the gap

49. Helps drive costs for assembled products down
General benefits to manufacture parts by cutting from sheets and plates:
Fast to manufacture
Parts are low in cost
Helps drive costs for assembled products down
From low to high quantities
Simple to complex parts
Parts can later be formed (bent) to make more complex shapes
We are going to cover…
First a few definitions: (WRITE ON BOARD)
- Typical sheet sizes are 1/64” (0.04mm) to 1/4” (6mm)
Typical plate sizes are > 1/4” (6mm)
Reason why we are making parts from sheets and plates…

50. Summary
Sheet and plate cutting. Sheet and plate can be further processed by bending, forming, and drawing.
Principle of cutting.
Shear stress principle (solid force, water-jet)
Electric or light or plasma energy to thermal energy
Electric-chemical effect
Structure and configuration of each principle.
Mechanical process (blanking/shearing/punching, waterjet), Thermal process (EDM, Laser, Plasma), Chemical (ECM).
Constraints, pros and cons of each cutting process.
We are going to cover…
First a few definitions: (WRITE ON BOARD)
- Typical sheet sizes are 1/64” (0.04mm) to 1/4” (6mm)
Typical plate sizes are > 1/4” (6mm)
Reason why we are making parts from sheets and plates…