Cpk

Process Capability for Deep Hole Drilling: Using Cp and Cpk to Measure Your Process A customer walked into my shop five years ago and asked for capability data on a hydraulic spool bore. I had been drilling deep holes for fifteen years and could hold 18 mm +/- 0.02 mm in my sleep, but I had never calculated a Cp or Cpk in my life. I fumbled through that first report with a spreadsheet and a statistics textbook open on my phone. The numbers that came back surprised me – and they changed how I set up every job from that point forward. ...