Quality - Dealing with Process Uncertainty Proc view ops...

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Manufact. process (4) Process analysis Quality (6) Waiting line (5) Inventory (12) Project (2) Service (5) Capacity (3) Sourcing (7), Logistics (8), lean (9). Aggregate planning (11) Dealing with Process Uncertainty Supply Chain Management Linear program (F) Decision analysis MRP (13) Transformation Process Proc view ops strategy (1) Forecasting (10)
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2 Variability, Six Sigma, and Statistical Process Control
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3 Practical motivation Design specification of steer support Target: 79.950 mm Tolerance level: [79.900 mm, 80.000mm]   What causes variation?
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4 Common Cause Variation (low level) Common Cause Variation (high level) Assignable Cause Variation Two Types of Causes for Variation
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5 Two Kinds of Process Variability Common cause variation (random errors, normal variability) Common or random cause Inherent in the process Not traceable to a single factor Assignable cause variation (systematic errors, abnormal variability) Special or assignable cause A “discoverable” cause E.g., worn tool, new untrained worker, defective raw material An assignable cause for one may be common cause for others.
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6 “In Control” or “Out of Control”? A process is in control if it is operating without assignable cause variation. Otherwise, the process is out of control, and immediate corrective action can be taken and will be fruitful. A manager should 1. Get the process in control 2. Reduce common cause variation 3. Go back to Step 1
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7 Pareto Chart To identify and highlight major symptoms, 80/20 Rule Separate “vital few” and “trivial many”
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8 Time Process Parameter Upper Control Limit (UCL) Lower Control Limit (LCL) Center Line Track process parameter over time - percentage ( p -chart) - mean ( -chart) Distinguish between - common cause variation (within the control limits) - assignable cause variation (outside the control limits) Statistical Process Control: Control Charts
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9 Variable control chart or attribute control chart? Variable control chart (
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This note was uploaded on 05/21/2011 for the course ISOM 111 taught by Professor Hu,inchi during the Spring '10 term at HKUST.

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Quality - Dealing with Process Uncertainty Proc view ops...

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