Process Capability study measures the performance and capability of a process in meeting customer specifications. The Process Capability Index (Cpk) uses both process variability and customer specifications to determine process capability. The larger the index, the less likely it is that a product will be outside customer specifications.
Using R and ShinyApps I’ve created an open-access Process Capability Calculator to help in calculating the Cpk of a process. The Calculator receives the following input variables of the Cpk formula:
- USL: upper specification limit (as specified by customer)
- LSL: lower specification limit (as specified by customer)
- mu: mean (average) value of the measurements as produced by the process
- stdDev: process standard deviation of the measurements
The Calculator produces the following output:
- Process Capability Plot. A normal distribution curve showing process variation compared to USL and LSL.
- The Process Capability Index (Cpk)
- Percentage Defective. A percentage of out-of-specs items your process is producing
- Defect Per Million Opportunity (DPMO). The number of defects the process is probable to produce out of a million defect opportunities.
- Process Sigma Level. A measure of the defect rate of the process based on the DPMO estimate.
- Results Interpretation and Recommendations to improve the process based on input and output values.
Try the application here, and view the ui.R and server.R files in my GitHub here
Watch this video navigating the Process Capability Calculator with ShinyApps.
