419Chapter seventeen: Control
• Check out machine capability
• Examine operator methods and instruction
17.9.4 Recurring cycles
• X chart causes
• Physical environment (temperature and humidity)
• Tired operator
• Regular rotation of machine or operator
• R chart causes
• Scheduled maintenance
• Tired operator
• Tool wear
• Corrective action
• If environment is controllable, adjust it.
• Service equipment
• Rotate operators
• Evaluate machine maintenance
17.9.5 Points near or outside limits
• X chart causes
• Over control
• Large systematic differences in material quality
• Large systematic differences in test methods or equipment
• R chart causes
• Mixture of material of distinctly different quality
• Corrective action
• Check control li ...