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Unformatted text preview: Slide #1 ECE 4001 L9 2008 Lecture 9 Statistical Models of Manufacturing Variation Process Capability Slide #2 ECE 4001 L9 2008 Define a Process Capability Index USL = Upper specification limit LSL = Lower specification limit Standard deviation of process Design Margin USL LSL Process Variation 6 = = = LSL3 USL 3 P P Define a process capability index: design margin C natural variation of process USL LSL C 6 = = ( ) P For USL LSL 6 C 1  = = P When C 1 , the process is said to be "capable", i.e., capable of meeting the desired specifications. Slide #3 ECE 4001 L9 2008 Process Is Not Capable Of Producing Parts Which Meet The Specifications LSL3 USL 3 P When C 1 , the process is said to be "incapable", i.e., incapable of meeting the desired specifications. < Slide #4 ECE 4001 L9 2008 Process Is Capable Of Producing Parts Which Meet The Specifications LSL3 USL 3 P When C 1 , the process is said to be "capable", i.e., capable of meeting the desired specifications. A B P Distance A Design Margin C Distance B Process Variation = = Slide #5 ECE 4001 L9 2008 NonSymmetrical Tolerance Limits P( ) y y LSL USL m A B C D Slide #6 ECE 4001 L9 2008 Introduce Process Capability Terms P( ) y y LSL USL m A B C D ( ) USL upper specification limit LSL lower specification limit average specification limit 0.5 USL LSL mean of population distribution Allowable process spread USL LSL Distance A Upper side spread from m = = = = + = = = mean USL Distance B Lower side spread from mean LSL Distance C Skew of distribution from mean Distance D m = = = = = = Slide #7 ECE 4001 L9 2008 Introduce Process Capability Terms P( ) y y LSL USL m A B C D ( ) USL upper specification limit LSL lower specification limit average specification limit 0.5 USL LSL mean of population distribution Allowable process spread USL LSL Distance A Upper side spread from m = = = = + = = = mean USL Distance B Lower side spread from mean LSL Distance C Skew of distribution from mean Distance D m = = = = = = Slide #8 ECE 4001 L9 2008 Introduce Process Capability Terms P( ) y y LSL USL m A B C D ( ) USL upper specification limit LSL lower specification limit average specification limit 0.5 USL LSL mean of population distribution Allowable process spread USL LSL Distance A Upper side spread from m = = = = + = = = mean USL Distance B Lower side spread from mean LSL Distance C Skew of distribution from mean Distance D m = = = = = = Slide #9 ECE 4001 L9 2008 Introduce Process Capability Terms P( ) y y LSL USL m A B C D ( ) USL upper specification limit LSL lower specification limit average specification limit 0.5 USL LSL mean of population distribution Allowable process spread USL LSL Distance A Upper side spread from m = = = = + = = = mean USL Distance B Lower side spread from mean LSL Distance C Skew of distribution from mean Distance D m = = = = = = Slide #10...
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This note was uploaded on 06/09/2009 for the course ECE 4001 taught by Professor Frazier during the Fall '09 term at Georgia Institute of Technology.
 Fall '09
 FRAZIER

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