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Design - Coggle Diagram
Design
Process Capability
Cpk
x double bar - LSL / 3 sigma and USL - x double bar / 3 sigma
Take the lower of the two
PCI
USL - LSL / 6 sigma
Larger CP the better (1.33) or more
Drawbacks
Can't identify process centrality
Must know spec limits
Overcome Drawbacks
Redesign
Alternate
Remove defects
Relax requirements
Control Limits
Tolerances
Variability
3 Critical Metrics
Critical to Quality
Use estimation of defects
Defects Per Unit
no. defects / no. defects sampled
Defects Per Opportunity
no. defects / no. defects opportunities
Defects Per Million Opportunity (DPMO)
DPO x 10 6 (power)
Id process parameters
Critical to Cost
Critical to Schedule
Cycle Time
Time used to produce product
Financial flow metric
Information flow metric
Process Cycle Efficiency
Map process
Value-added
Non-value added
Process value added time / Process total time
Process lead time
no. items completed / per hour
Can't take new orders until others produced
Takt Time
max acceptable time to meet customer demands
speed of production to meet customer demands
Ta (net available time / Demand
Benefits
ID bottlenecks
ID stations that need rework or repair
ID non valued added task
Greater understanding of value added activities
Drawbacks
If tasks are not leveled can bulk up process
Customer demand my reduct Take time
Stations may have to be added
if a station breaks, stop process
Overall Equip Effectiveness
Rolled Throughput Yield (RTY)
Compute yield of each process
Multiply Yield1 x Yield2 x ....YieldX
Normalized Yield
N Square Root of 1 - DPMO / 1 million (repeated)