Prioritized Reduction Plan & Kaizen




SPC has been widely used in special characteristics especially on dimensional measurements.

But how about attribute data on defects?

Example: Fabric - Product specification (except testing specification) as below:

Fabric width control is within +-1m, mostly meeting 0, not much variances.

Color variation is through grey scale, is anyone using colorimeter or spectrometer to measure?

Defects allowed are 6m/1s - ie. 1 defect in 6 meter.

Currently using U chart to monitor defects ratio on prioritized reduction plan. Is there any other better method?



I used to use a C chart to track defects per unit and type. Then do root cause analysis to correct. Unit defininition may correspond to you spec.
We also used a Macbeth colorimeter to obtain Delta E numeric variances on lightness, darkness, and the hues from the approved color chip standard. This will provide variable SPC data. I suppose you could use it to measure a pass/fail to you color spec., and record that as attribute results, but mostly people want to quantify the results of the color spectrum when measured against the standard.
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