Acme Corporation makes printed circuit boards for the computer industry. A major part of its process is a copper plating line. Acme is trying to determine the best method for managing issues causing downtimes on this production line.You are Acme’s Quality Assurance Manager. The Quality Engineer has been collecting count data on a check sheet of causes of downtime for the copper plating line. From the check sheet, the engineer has provided you with the following Pareto chart:
You know from the test reports your Quality Technicians prepare each day that copper thickness is one of the major causes of defects in your printed circuit boards.Copper thickness is directly affected by the copper concentration of the solvent used on the line.There is a concentration requirement for the solvent included in the technical specifications for circuit boards.You get your copper solvent from a supplier in Indiana.You have not used this supplier in the past, and you have very little information about the supplier’s process for manufacturing the solvent.
Because this is a relatively new production line, you do not yet have a formal sampling plan or any real-time process monitoring in place.You have a sufficient budget for your QA department, but by no means do you have unlimited funds.You are trying to decide whether to implement Statistical Process Control or Acceptance Sampling or both. You only have resources available to do SPC on one factor, if you do it at all.
With all this in mind, answer the following questions:
1) Would it be prudent to implement Statistical Process Control to monitor variability affecting the downtime of this line? If your answer is ‘yes,’ discuss what considerations support implementing SPC here.
2) Which factor from the Pareto Analysis do you want to monitor using SPC control charts, and why did you choose this particular factor?
3) Is the factor you chose represented by variables data or attribute data? How do you know?
4) Do you want to do acceptance sampling of the circuit boards coming off this line? If so, what factors lead you to believe acceptance sampling is proper here?
5) Assume you decide some acceptance sampling is warranted. Discuss the characteristics you will want to be sure to include in your acceptance sampling plan.