Hello
I have been tasked with preparing a work instruction for 'next steps' when it is determined there is an issue with the results from conducting a capability study.
I have investigated this but there seems to be no indicators of what to do next
Can anyone help
Thanks to all
You really need to go back to the basics that should be addressed before doing a capability study.
1. Review the data. Is it "in control" on an SPC chart? If it is not "in control", deal with the trends / out of control points. Get the process stable and in control. By the way, a capability number on an "out of control" process is meaningless.
2. If the data are in control, check to see if there is a "gap" in the data just outside the spec limits. A lot of times, if the data are "close enough" operators will round the number off so it meets spec.
3. If the data are stable and predictable, and the histogram of the long term data is reasonable, now you need to start analyzing why the process isn't meeting specification.
3a. Is the specification correct? Is it "unreasonable"? Can the / Should the spec be changed?
3b. Look at lower level (leading) data that leads to the final spec data. For example, annealing temperature may have an effect on strength of the metal. What detailed data are available about the process that may correlate to the overall result.
3c. At an extreme, there is the Shainin Red X process where you compare a "good" part to a "bad" part and try to tell what led to the difference.
3d. Oh, and then there is the step most people forget - go to the "Gemba" (work location). Observe the work be done. TALK TO THE WORKERS!