Intro to Metal Working Processes (Ch. 5, 6, 8, 9)

the three major categories of metal working

• deformation(forming)

• material removal

• casting

independent variables affecting bulk deformation

• starting material

• starting geometry

• tool or die geometry

• lubrication

• instantaneous material behavior (in that moment)

  • starting temperature

  • speed

• amount of deformation required

dependent variables affecting bulk deformation

• foce

• final material properties

• exit temperature

• surface finish and precision

• nature of flow material

options for choosing lubricant

• type (liquid or solid)

  • amount

uses for lubrication

• coolant

• thermal barrier (preventing surface of material from changing while working it)

• a release/parting agent

• corrosion inhibitor

advantages of cold working for BD

1. no heating required

2. better surface finish

3. superior dimension control

4. better reproducibility and interchangeability of parts

5. strengths, fatigue, and wear properties increase

6. anisotropy (if desired)

7. less contamination

8. avoids thermal stresses

disadvantages of cold working for BD

1. higher forces required to deform material (might mean energy inc.)

2. need heavier, more powerful, equipment

3. material has less ductility

4. surface must be clean and scale free

5. may need intermediate annealing

6. anisotropy*

   1. may leave undesirable residual stress (more likely to corrode)

affects efficiency in BD - most important consideration

tool or die geometry

friction

certain amount(s) of _____ is required for some manufacturing processes, i.e. rolling vs extrusion

“independent variable”

the variable we can change

“dependent variable”

the outcome, based on input