Rolling and Forging

1. Rolling and Forging Manufacturing Processes

2. Outline Temperature Rolling 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. Calendering

28. Calendering of Rubber

29. Coated Products

30. Reinforced Materials

31. Reinforced Materials

32. Reinforced Materials

33. Calender Control Systems

34. Calendering Thickness Sensors

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