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Reducing Defect Rates in Quality Management: Strategies and Calculations

This document outlines critical insights from quality management recitations, focusing on the primary contributors to defects, including excess flash, missing caps, and flow lines. It discusses strategies to reduce excess flash through equipment maintenance and emphasizes the importance of monitoring cap placement. The document also provides detailed calculations for determining scrap and rework rates, as well as the definitions and importance of Cp and Cpk in assessing process capabilities.

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Reducing Defect Rates in Quality Management: Strategies and Calculations

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  1. IE 405QUALITY MANAGEMENT RECITATION 6

  2. Rec 6 Q1

  3. The highest contributors of defects is excess flash, missing cap and flow lines. Excess flash also has the highest defect rate in the individual c chart. • Excess flash can be reduced by maintaining the machinery or equipment, in order to reduce the flash rate. • An important parameter missing cap, can be avoided by warning the worker(s) who are responsible for putting on the cap. It is simpler and easier to maintain the caps on the bottles than is to reduce the other defects.

  4. Rec 6 Q2 • USL=12.55mm • LSL=12.45mm • Derive Z value from • 12.45-12.50/0.02= -2.50 • a) Scrap rate of 0.0062 or 0.62% • Rework rate (due to symmetry) is 0.62% also.

  5. b) Area= The value is with respect to LSL not USL.Because the z=-3.59 value is calculated with respect to scrap not rework. • -3.59= 12.45- m/0.02 • m=12.52mm c) Rework 12.55-12.52/0.02= 1.50 1- 0.9332= 6.68%

  6. Rec6 Q3

  7. Q3 X Chart

  8. R chart

  9. Rec 6 Q3 • Cp measures POTENTIAL CAPABILITY • Why? • Does not take into account where the process mean is located relative to the specifications • Cpk measures ACTUAL CAPABILITY • It takes process centering into account

  10. Specifications: • LSL:-50 • USL: 50 with respect to formula • From chart derive Rbar/d2= 3.035 Cp=100/3.02*6= 5.50 • 1/5.50 = 0.1818 Covers 18% of the specification band.

  11. Cpk= min(Cpu, Cpl) • Cpu= (50-10.375/3*3.03)=4.359 • Cpl= (10.375- (-50)/3*3.03)=6.64 • Min (4.359, 6.64)= Cpk • Choose 4.359 • Since Cp>Cpk process is out of center

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