Last month I began to answer this question by examining some of the 14 Principles of Lean Manufacturing according to Jeffery Liker. Let’s continue that examination.
Liker’s fourth principle is “Level out the workload (Work like the tortoise, not the hare).” Eliminating waste is just one part of making Lean successful. It’s just as important to eliminate the overburden to people and equipment and smooth out the production schedule.
SPC can show you how much variation is present in your production flow rate. As you make improvements in your load leveling, you should see reduced variation around the target level.
Liker’s fifth principle is to “Build a culture of stopping to fix problems, to get quality right the first time.” Up to this point, I have described SPC as a tool that you can use to baseline, monitor, and track improvements as you institute Lean. But ultimately, success in a Lean environment requires using SPC as part of your ongoing manufacturing process.
As you are monitoring product characteristics, SPC will act as an early warning system for when your product output differs significantly from historical levels. And as you learn more about your process, you can move to real-time SPC charts on the process variables that control those outputs. Once you have real-time SPC analysis on the critical process variables controlling the product output, you can catch a problem in the process before it is reflected in your product. Then, by collecting the sources of these problems when they happen, you can generate a Pareto chart of the causes and prioritize activities to eliminate those causes.
Principle seven is to “Use visual controls so no problems are hidden.” Real-time SPC is the best way to display visually what is going on in a process and whether that process is being affected by unexpected sources of variability. When it is, your operators are visually signaled to record and react, ensuring a quick response time and accurate data collection for improvement efforts. Managers can be alerted via email and pager, machines can be shut down and other visual and audio alarms can be deployed.
These are some of the principles that make up a Lean Manufacturing system. As I hope I have shown you, SPC is integral to Lean and integral to improving your processes. SPC gives you some special abilities to turn a microscope on your process looking for opportunities for Lean improvements.
Steven Wachs, Principal Statistician
Integral Concepts, Inc.
Integral Concepts provides consulting services and training in the application of quantitative methods to understand, predict, and optimize product designs, manufacturing operations, and product reliability. www.integral-concepts.com