1. Rolling and Forging of Metals Group 8 ME 260 Fall 2005 10/10/05
Kurt Sorenson
Derek Benavidez
Colin Evans
Steven Best

2. Introduction Flat Rolling- Processes and Practices
Rolling- Processes and Mills
Die Forging- Open, Impression, and Closed
Forging Operations
Forgeability of Metals and Defects
Die Design, Die Materials, Lubrication, and Manufacturing Methods
Forging Machines, and Economics

3. Forging and Die Forging

4. Shapes

5. Definitions
Plastic Deformation- When forces are applied to a material causing it to take on a new shape. Basis for all forming processes
Forging- A forming method which shapes a metal part through controlled plastic deformation.
Die- An impression or an opposite machined copy of an existing shape or complex structure (generally a ceramic or highly treated metal) used to repeatedly mimic the desired product shape in a press.

6. Hot and Cold Rolling Mills
A) Four High Rolling Mill
B) Two-High Mill
C) Three-High Mill
D) Cluster Mill

7. Flat Rolling Processes

8. Cold Rolling
Normally produces better surface finishes than hot rolling.
Machines can keep tighter tolerances.
Has superior mechanical properties to hot rolling due to the strain hardening which occurs during the rolling process.

9. Hot Rolling
The first hot-rolling operation is called the bloom or slab ( usually rectangular cross section).
Further processed into I-beams, railroad rails.
Commonly the surfaces are conditioned prior to being hot rolled (normally by acid etching or rough grinding).

10. Flat Hot Rolling Practice
The process of hot rolling is very effective for dramatically reducing the grain size in metals, thus improving the strength, and ductility.
Occasionally a phenomenon occurs called stretcher strains, though this can be corrected by subjecting the metal to a final light pass of 0.5” to 1.5% called temper rolling or skin pass.

11. Rolling Geometric Considerations
A) Bending of straight cylindrical rolls due to roll forces.
B) Bending of rolls ground with a camber offset, producing a strip of the desired uniform thickness.

12. Defects in Rolled Plates and Sheets
Many defects can occur during the rolling process, and can be brought on by many different factors (rust, scratches, gouges, pits, and cracks).
These defects can be caused by impurities and or impurities in the original cast material or various conditions related to the preparation of the original material.
A) Wavy Edges- result of Roll Bending ( middle is thicker that the edges).
B) Zipper Cracks- result of improper rolling temperature.
C) Edge Cracks- result of poor material ductility.
D) Alligatoring- a very complex phenomenon usually a result of non-uniform bulk deformation or defects in the original casting material.

13. Hot 2-High for Making Machetes
Rolling Mills
Hot or cold rolling can be done on same equipment
Automated mills:
close-tolerance, high quality, fast production, low cost
Hot 2-High for Making Machetes

14. Rolling Mills Two-high rolling mills for initial hot rolling
Four-high mills: small diameter rolls reduce power requirements and spreading but need support from larger rolls
2 High Temper Pass Mill

15. Tandem Rolling: series of thinner gages

16. Roll Materials Strength and resistance to wear
Cast iron, cast steel, forged steel (stronger, stiffer, tougher)
Tungsten carbides for small-diameter rolls
Cold rolls not suitable for hot rolling
Ultra Precision
Narrower Mill

17. Lubricants for Hot and Cold Rolling
Hot Rolling:
Ferrous alloys do not require lubricants
Non-ferrous are hot rolled with compounded oils, emulsions, and fatty acids
Cold Rolling:
Use of water-soluble oils or low viscosity lubricants (mineral oils, emulsions, paraffin, and fatty oils)

18. Rolling Processes Shape rolling: I-beams, railroad rails
Roll forging: tapered shafts, table knives, springs, hand tools
Shape Rolling
Roll Forging

19. Rolling Processes
Skew Rolling: used for ball bearings. Round wire or rod rolled between skewed rollers with grooves.
Ring Rolling: thick ring expanded into large-diameter thinner one

20. Ring Rolling

21. Ring Rolling: different shapes formed by changing shape of rolls

22. Thread Rolling: Process of adding threads to screws and bolts

23. Thread Rolling

24. Rotary Tube Piercing Hot-working operation
To make long, thick-walled seamless pipes and tubing

25. Open-Die Forging Hot forging Uses simple and inexpensive dies
Limited to simple shapes
Flat-Die Forging

26. Open-Die Forging

27. Open-Die: Barreling Minimized by using lubricant
Barreling from thermal effects reduced by using heated dies

28. Open-Die: Cogging
Thickness of a bar is reduced by successive forging steps
Does not require large forces or heavy machinery

29. Impression-Die and Closed-Die Forging
Takes shape of die cavity
Forms a flash
Performing Operations
Fullering- material distribute away
Edging- material gathered into localized area

30. Precision Forging Flashless forging Complex dies
Control of blanks volume and shape
Positioning of blank in cavity

31. Various Forging Operations
Coining
Closed-die forging process
Very high pressure required
No lubricants
Heading
Upset forging
Nails, bolt heads, etc.

32. Various Forging Operations
Piercing
Indenting the surface
Pressure required is approximately that of hardness test
Hubbing

33. Various Forging Operations
Orbital Forging
Forms part incrementally
Disk shaped/Conical parts
Lower forces required
Incremental Forging
Similar to Orbital Forging
Isothermal Forging
Hot-die forging
Good dimensional accuracy
Expensive

34. Various Forging Operations
Rotary Swaging
Radial forging, rotary forging, or swaging
1. Retainer
2. Planetary rollers
3. Hammer
4. Driver
5. Die

35. Various Forging Operations
Tube Swaging
Internal diameter/thickness is reduced
Mandrels
Fits inside piece
Have a specific geometry/pattern style

36. Forgeability of Metals– Forging Defects
Upsetting Test
Solid, cylindrical specimen is upset between flat dies
Greater deformation, greater forgeability
Hot-Twist Test
Specimen twisted until it fails
Different specimens & temps.

37. Forgeability of Metals- Forging Defects
Surface Cracks
Laps
Internal Cracks

38. Die Design Considerations Materials Lubrication Strength and Toughness
Hardenability and Uniformity
Resistance to Shock
Resistance to Wear
Lubrication
Thermal Barrier
Parting Agent

39. Die Failures Improper Die Design Overheating Excessive Wear
Improper Material Selection
Overloading
Bad Alignment
Improper Finishing
Misuse
Improper Setup

40. Forging of Metals What is it? Advantages Disadvantages
Types of Forging

41. What is Forging?
Forging: A forming method which shapes a metal part through controlled plastic deformation.

42. Types of Forging Hammer Forging Drop Forging Press Forging
Upset Forging
Roll Forging

43. Advantages of Forging Hardness and Ductility Grain Flow Tougher Metal
Intricate Shapes
Impurity Uniformity

44. Disadvantages of Forging
High Temperature
Cost
Tolerances
Maintenance

45. Hammer Forging “Open-Die Forging” Oldest Style
Free Fall or Steam Driven
Low Rate and Accuracy

46. Drop Forging Aligned Cavity Dies Horizontal Impact Forging
High Accuracy
High Tensile Strength

47. Press Forging Large Forgings Produced Slow, Steady Pressure
Uniform Deformation
Mechanical or Hydraulic

48. Upset Forging
“Machine Forging”
Common
Hot or Cold

49. Roll Forging
Fast
Widely Used
Long, Tapered or Symmetrical Sections

50. References
Callister, William D. Jr. Materials Science And Engineering An Introduction. New York: John Wiley & Sons, Inc., ©2003.
Kalpakjian, Serope, and Steven R. Schmid. Manufacturing Engineering and Technology. Upper Saddle River: Pearson Education Inc., ©2006.
Lindbeck, John R. Product Design and Manufacturing. Upper Saddle River: Prentice-Hall, ©1995.
AIST Steellinks.com. Association for Iron & Steel Technology. October 4,