• On-line SPC
  • screening - the output is inspected and if the quality is not acceptable, the substandard items are
    • recycled for re-work
    • sold at reduced price
    • scrapped
  • preventative -attempts to avoid production of defective items by applying process control methods

SPC - the philosophy

"It is good management to reduce the variation of any quality characteristic (say thickness or measure of performance), whether this characteristic be in a state of control or not, and even when few or no defectives are being produced" - Deming

• Zero defects is not sufficient - aim for continuous process improvement
• Technical expertise itself is not good enough and should pay attention to
  • training
  • capital
  • equipment
  • management philosophy and structure that encourages workers to strive for quality products

Ensuring the Success of SPC

• Off-line SPC
  • is the next stage on from on-line SPC
  • should ideally be built into the design an operating procedures of the process
  • aims to reduce or remove the effect of potential causes of process variability