Defining SPM acceptance criteria

A rate needs a basis. Parts per hour at a steady state is different from parts per shift including changeovers, breaks and the occasional jam — sometimes by a wide margin.

State which you mean, over what period, and whether planned stoppages count. Most rate disputes are definitional rather than technical.

A machine can only be held to features it actually produces. Incoming variation in the blank, or a characteristic created by a prior operation, is not the machine's to guarantee.

List the characteristics the machine controls, the tolerance on each, and the measurement method. Agreeing how something is measured prevents two correct measurements disagreeing.

• How many consecutive parts constitute the demonstration
• Whether the run must be uninterrupted, and what counts as an interruption
• How many parts are measured, and to what sampling plan
• Whether the run is repeated on a different shift or by a different operator

A machine demonstrating rate and quality on hand-picked blanks, with the supplier's engineer operating it, is not the same as the same machine on your material with your operator.

Specify the material, who operates it, and where the demonstration happens — at the builder's works, at yours, or both. Two-stage acceptance is common and reasonable.

• How long the builder has to correct a shortfall, and how many attempts
• Whether partial acceptance is possible if rate is met but quality is marginal
• How payment relates to acceptance stages
• What happens if a criterion turns out to be unachievable for a reason outside the builder's control

• Documentation: drawings, parts lists, electrical schematics, operating and maintenance instructions
• Spares supplied, and the recommended holding list with lead times
• Training for operators and for maintenance, and how many people
• Support arrangements after acceptance, and for how long