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PRODUCT/PROCESS CAPABILITY STUDIES
Where failure costs, e.g. scrap, rework, returns and credit/warranty costs are
over budget, process improvement will assess present process capability,
identify and correct process variables causing excessive variability and track
the improved process with statistical process control. Stability studies are
conducted to assess and correct any process instability. Product capability studies are run on
the critical product characteristics to establish an initial baseline and
subsequently on component parts of the process when the key process variables
are identified. See
Process Improvement Flowchart
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DESIGNED EXPERIMENTS
Designed experiments using factorial designs, along with regression and
correlation methods are used to identify and quantify the key process variables
and combinations of process variables, i.e. those causing the greatest
components of overall process variability. The entire sequence may involve a
multitude of experiments ranging from screening studies to final validation. See Process
Improvement Flowchart
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KEY VARIABLES STUDIES
Capability studies may be run on individual key variables to determine the
capability of each variable relative to the requirement. The variables may
involve operators or operator training, materials, machines (including machine
settings), measurement systems and environmental variables. The Key Variables
Studies produce recommendations to bring the key variables in conformance with
the requirements or better. See
Process Improvement Flowchart
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STATISTICAL PROCESS CONTROL
A final process capability study is performed on the process to ensure that it
meets or exceeds requirements. Statistical process control is established at
key points in the process to ensure that the process will remain in control or
that out-of-control conditions will be noted and reported. See Process
Improvement Flowchart
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If excessive failure costs are eroding
your firm's profits, contact us for assistance in process improvement. The
first year's savings usually more than pays for the consulting and training
costs.