Process Audit Checklist
I am often asked how would I audit a new process. Invariably, some type of process checklist is desired to identify all of the critical variables. So, without further ado, this month's issue of Quality Concepts describes my process audit checklist.
What is the final product?
The final product can be a part, design, or just knowledge. Sometimes this is not obvious. When an OEM manufacturer produces a prototype, exactly what is the deliverable? The prototype itself, a completed design, or the finished good? Understanding the goal lets companies develop a quality plan to achieve the objectives.
What are the critical to quality elements of the final product?
Nothing is perfect; so what are the tolerances for the features? If a company has not looked at this, then undoubtedly some are going to loose while many will be too tight.
How are the critical to quality elements verified?
Once something has been established as important, how will it be verified? Will inspection be used or is the process well understood? If inspection is used, how was that verified? Ever try to measure a plastic part with a pair of calipers? Let me tell you, there is definitely room for interpretation. This is common to many inspection methods.
Which raw materials have a substantial impact on the process and which are incidental?
Always a difficult question. Often used to deflect process improvement efforts, raw material variability is tricky. Sometimes it has an affect, sometimes it does not. Don't forget to include cleaning agents, lubricants, and in-process containers in your assessment. All of these can affect the product in unpredictable ways.
How robust is the process to variation?
Often the toughest question, this is usually unexplored. Design of experiments and Taguchi designs are perfect for characterizing the process variability. The best processes can handle a maximum of variation and product the best product. Weak processes are delicate and are intolerant of variation. Moving weak processes to strong / robust should be the goal for any quality improvement effort.