Thompson Jr., Lindsay A. (1989, ASQC) GEAE, Cincinnati, OH
In the high volume, automated manufacturing realm, Statistical Process Control (SPC) is well documented. The majority of American Industry falls outside of high volume manufacturing. You can apply SPC in the low volume, labor intensive, job shop by: modifying the technique to suit small sample sizes and/or by identifying common factors in similar operations.
The use of SPC rests upon the understanding that the information contained in even small samples can be used to make decisions. I will discuss methods of extracting maximum information from the data which is presently available and using it to construct control charts. This will enable the "Job Shop" to use control charts based on its generic operations.
The use of SPC also rests upon the selection of a common denominator among similar products. For example, in an injection molding process where several parts are manufactured, perhaps the water-cooling temperature can be monitored as a process performance predictor. Perception of a process can also be altered by the use of Delta Plots, in which the departure from nominal or target is used to control the processes of similar items.
Thus, SPC methods can be creatively applied to the job shop environment. Low volume operations can reap the benefits usually associated with SPC as used by the industrial giants: reduced cost, increased productivity, and improved quality.
Chemical and process industries