Introduction To Manufacturing Systems by Ed Red

ME 482 - Manufacturing SystemsME 482 - Manufacturing Systems

Introduction To

Manufacturing Systemsby

Ed Red

Introduction To

Manufacturing Systemsby

Ed Red


What we will coverWhat we will cover

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Fundamental metal forming and removal technologiesFundamental metal forming and removal technologies

Flexible manufacturing systemsFlexible manufacturing systems

Electronics manufacturing (1/3rd of all manufacturing)Electronics manufacturing (1/3rd of all manufacturing)Electronics production machines and processesElectronics production machines and processes

Process Models- Force- Power- Wear- Production rate- Etc.


Fundamentals of Metal FormingFundamentals of Metal Forming

• Metal forming is plastic deformation of metals into Metal forming is plastic deformation of metals into desired shapes desired shapes

• Deformation stresses may be tensile or compressive Deformation stresses may be tensile or compressive (usually compressive) (usually compressive)

• Metals must exhibit certain properties to be formed efficientlyMetals must exhibit certain properties to be formed efficiently

• Friction is an important factor in metal formingFriction is an important factor in metal forming

• Strain rate and temperature are important factors in Strain rate and temperature are important factors in metal forming metal forming


Material Behavior in Metal FormingMaterial Behavior in Metal Forming

Engineering Stress and Strain (used by engineering designers):

Engineering stress e = F/Ao

Engineering strain e = (L - Lo)/Lo

Hooke's Law (elastic region): e = E e



Stress - strain diagrams (tensile and compression):

e

e

Elastic region

Plastic region

0.2% offset

Ultimate strengthUltimate strength

Yield strengthYield strength



Common parameter values:Common parameter values: Al Al SteelSteel

EE psipsi 10 x 1010 x 1066 30 x 1030 x 1066

MPaMPa 70 x 1070 x 1033 210 x 10210 x 1033

Yield strengthYield strength psipsi 40004000 60,00060,000MPaMPa 2828 400400

Ultimate strengthUltimate strength psipsi 10,00010,000 90,00090,000MPaMPa 7070 600600


Elastic region

Plastic region

Material Behavior in Metal FormingMaterial Behavior in Metal FormingTrue Stress and Strain (used by manufacturing engineers):

True stress = F/A

True strain = dL/L = ln(L/Lo)

Start of necking



Why do engineering designers base their design on Why do engineering designers base their design on

engineering stress/strain, but manufacturing engineers engineering stress/strain, but manufacturing engineers

use true stress-strain?use true stress-strain?



Strain hardening - Resistance to increasing strain. Stress-strain can be related in the plastic region by the form

= K n

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.



Material Strength coeff, K Strain hardening exp, npsi MPa

Aluminum 30,000 210 0.18Steel 125,000 850 0.15


Material Behavior ExampleMaterial Behavior Example

The following data are collected during a tensile test in which 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 the initial gage length is 5 in. and the cross-sectional area is 0.1 inin22::

Load (lb)Load (lb) 00 40004000 51805180 62006200 65006500 62006200 46004600

Length (in)Length (in) 5.0005.000 5.0095.009 5.255.25 5.605.60 5.885.88 6.126.12 6.406.40

Determine the yield strength Y, modulus of elasticity E, and Determine the yield strength Y, modulus of elasticity E, and tensile strength TS. Also determine the strength coefficient K tensile strength TS. Also determine the strength coefficient K and the hardening exponent n.and the hardening exponent n.


Some relations you need to knowSome relations you need to know

= = ee (1 + e) (1 + e)

= ln (1 + e)= ln (1 + e)

Also note that it is often necessary to use a constant volume Also note that it is often necessary to use a constant volume relationship for modeling process phenomena. In the case of a relationship for modeling process phenomena. In the case of a tensile test, the appropriate equation would betensile test, the appropriate equation would be

AL = AAL = Aoo L Loo


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Introduction To Manufacturing Systems by Ed Red

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