1. Manufacturing Systems
Introduction To
Manufacturing Systems by
Ed Red

2. What we will cover Process Models - Force - Power - Wear
Electronics manufacturing (1/3rd of all manufacturing)
Electronics production machines and processes
Process Models
- Force
- Power
- Wear
- Production rate
- Etc. L Do Df p
Fundamental metal forming and removal technologies
Flexible manufacturing systems

3. Fundamentals of Metal Forming
Metal forming is plastic deformation of metals into desired shapes
Deformation stresses may be tensile or compressive (usually compressive)
Metals must exhibit certain properties to be formed efficiently
Friction is an important factor in metal forming
Strain rate and temperature are important factors in metal forming

4. Material Behavior in Metal Forming
Engineering Stress and Strain (used by engineering designers):
Engineering stress se = F/Ao
Engineering strain e = (L - Lo)/Lo
Hooke's Law (elastic region): se = E e

5. Material Behavior in Metal Forming
Stress - strain diagrams (tensile and compression):
Ultimate strength se
Plastic region
Yield strength
Elastic region e
0.2% offset

6. Material Behavior in Metal Forming
Common parameter values: Al Steel
E psi 10 x x 106
MPa 70 x x 103
Yield strength psi ,000
MPa
Ultimate strength psi 10, ,000
MPa

7. Material Behavior in Metal Forming
True Stress and Strain (used by manufacturing engineers):
True stress s = F/A
True strain e = dL/L = ln(L/Lo) s
Start of necking
Plastic region
Elastic region e

8. Material Behavior in Metal Forming
Why do engineering designers base their design on engineering stress/strain, but manufacturing engineers use true stress-strain?

9. Material Behavior in Metal Forming
Strain hardening - Resistance to increasing strain. Stress-strain can be related in the plastic region by the form
s = K en
where K is the strength coefficient and n is the hardening exponent. A log-log diagram will show the linear behavior expected for a curve of this form.
Note: The greater the n, the greater the strain hardening effect. Necking for many ductile materials begins approximately when the true strain reaches a value equal to n.

10. Material Behavior in Metal Forming
Material Strength coeff, K Strain hardening exp, n
psi MPa
Aluminum 30,
Steel 125,

11. Material Behavior Example
The following data are collected during a tensile test in which the initial gage length is 5 in. and the cross-sectional area is 0.1 in2:
Load (lb)
Length (in)
Determine the yield strength Y, modulus of elasticity E, and tensile strength TS. Also determine the strength coefficient K and the hardening exponent n.

12. Some relations you need to know
s = se (1 + e)
e = ln (1 + e)
Also note that it is often necessary to use a constant volume relationship for modeling process phenomena. In the case of a tensile test, the appropriate equation would be
AL = Ao Lo

13. What have you learned?