1. Manufacturing Processes
Rolling and Forging
Manufacturing Processes

2. Outline Temperature Rolling Forging Flat Rolling
Shape Rolling Operations
Thread Rolling
Seamless Tubing and Pipe
Rolling Nonmetallic Materials
Forging
Open-Die Forging
Closed-Die Forging
Roll Forging
Heading
Rotary Swaging
Forging Machines
Dies
Economics

3. Rolling and Forging Rolling
The thickness of a slab of a slab or plate is reduced by cylindrical rolls which rotate to pull the material between them and compress it
Forging
A workpiece is compressed between opposing dies so that the material is forced into the die shape

4. Temperature in Metal Forming
Cold working (room temperature or slightly higher)
Warm working (30% - 50% of the melting temperature)
Hot working (50% - 75% of the melting temperature)
Isothermal forming
Tools are preheated to prevent surface cooling during forming

5. Structure/Property Modification

6. Cold Working Advantages No heating required Better surface finish
Better dimensional accuracy
Parts are interchangeable
Better strength, fatigue and wear properties
Directional properties can be imparted
Minimal contamination problems

7. Cold Working Disadvantages Higher forces required
More powerful equipment required
Less ductility is available
Surfaces must be clean
Intermediate anneals may be needed to restore ductility
Directional properties may be detrimental
May produce undesirable residual stresses

8. Typical Rolled Products

9. Typical Rolled Products

10. Rolling Process

11. Rolling Process

12. Rolling Process

13. Rolling Process

14. Rolling Process

15. Example of a Hot Rolling Line

16. Rolling Defects

17. Shape Rolling
Uses a series of specially shaped rolls to form a beam with a specific cross section (such as an I-beam)

18. Ring Rolling
Uses rolls to form a thick, small-diameter ring into a thin, larger-diameter ring

19. Ring Rolling

20. Thread Rolling
Uses moving dies with grooves to form threads on cylindrical parts

21. Thread Rolling

22. Material Property Changes

23. Roll Piercing
Uses compressive stresses on a cylindrical part to cause tensile forces at the interior, creating a hole to form a thick-walled tube

24. Example of a Tube Rolling Mill

25. Rolling Nonmetallic Materials
Paper
Plastic sheets
Rubber products
Reinforced fabric
Calendering
Passes material through a series of gaps between rolls to form a thin sheet

26. Calendering

27. Example of a calendered rubber sheet with two layers
Calendering
Example of a calendered rubber sheet with two layers
Courtesy Cooper Tire

28. Calendering of Rubber

29. Coated Products

30. Coating on both sides of reinforcing material
Reinforced Materials
Coating on both sides of reinforcing material
coating material
spools
comb
reinforcing material
coating material
windup

31. Example of a polyester-reinforced rubber sheet with fibers exposed
Reinforced Materials
Example of a polyester-reinforced rubber sheet with fibers exposed
Courtesy Cooper Tire

32. Example of a steel-belted rubber sheet with the belt exposed
Reinforced Materials
Example of a steel-belted rubber sheet with the belt exposed
Courtesy Cooper Tire

33. Calender Control Systems

34. Calendering Thickness Sensors
Emitter
X rays or beta radiation (electrons)
some radiation is blocked, depending on thickness
Detector

35. Milling
Squeezes material between rolls to mix or preheat it for further processes

36. Forging
Forging
A deformation process in which the material is compressed between dies, using impact or gradual pressure to form the part

37. Forging

38. Example of a Forging Machine

39. Example of a Forging Machine

40. Working Temperature Hot Forging
Material is above its recrystallization temperature
Cold Forging
Increased strength from strain hardening

41. Forging
Billet
A piece of material with a square or circular cross section; usually produced by a deformation process such as rolling or extrusion

42. Open Die Forging
Compresses the work between flat or nearly flat dies

43. Open Die Forging

44. Open Die Forging

45. Open Die Forging Advantages
Simple, inexpensive dies; wide range of sizes; good strength
Limitations
Simple shapes only; difficult to hold close tolerances; machining necessary; low production rate; poor utilization of material; high skill required

46. Closed Die Forging
Also called impression-die forging; compresses the material into the shape of the die cavity

47. Closed Die Forging

48. Closed Die Forging Advantages
Good utilization of material; better properties than open die forging; good dimensional accuracy; high production rate; good reproducibility
Limitations
High die cost for small quantities; machining often necessary

49. Roll Forging
Uses grooved rolls to reduce thickness and increase length of round or flat bars

50. Roll Forging

51. Roll Forging

52. Roll Forging

53. Coining
Uses dies to press fine detail into both sides of the workpiece

54. Upsetting/Heading
Decreases the length and increases the diameter of the workpiece; often used to form heads on nails, bolts, etc.

55. Orbital Forging
Uses a die that moves in various directions to compress the workpiece

56. Swaging
Uses hammering dies to decrease the diameter of the part

57. Swaging

58. Forging Dies and Die Inserts
Separate inserts may be used for forging complex shapes; this may be less expensive than a complex single-piece die

59. Forging Defects

60. Forging Machines

61. Forging Machines

62. Example of a Forging Machine

63. Economics

64. Summary
Rolling and forging shape parts by deforming the material into the desired shape