June 19, 2012
Make SPC Easy
When it comes to statistical process control (SPC), it's easy to get lost in the weeds and forget what you are really trying to accomplish. The whole point is to make better products for the customer. To do that you have to perform the same exact processes over and over across every production line. Most importantly, it has to be done as safely and efficiently as possible so you don’t waste time or money.
When Walter A. Shewhart developed control charts, the powerful charts and plots were created with paper and pencil. Today SPC can occur in real time. It doesn’t have to be overly complicated when you stop and think about it. Watch the process, collect data, make that data useful, and then make decisions based on that useful information. It’s as simple as that. Perform these tasks and you will be running to target while reducing variation.
Data > Information > Decision
Don't get caught up in what program you are going to deploy. Will it be Lean, Six Sigma, or Lean Six Sigma? Will you use this software program or that one? Should you outsource, or will take it on internally? Traveling around the world and seeing many different companies make lots of different products in lots of different ways has brought me a new appreciation for SPC. It is not how you do it as much as “Are you doing it?” Keep in mind a couple things: Strategy and Execution.
Make sure the measurement devices are accurate, the sampling frequency is correct, and the data entry is fool-proofed. These are great and noble things and should be worth the time. However, the largest and most crucial step that I believe is being most overlooked in SPC today is using the data to make decisions, which is where execution comes in. In the execution phase, product is being made efficiently and decisions are being made based on the data.
You collect data and have databases full of it. You’ve made all of the checks and the auditors are proud. You work extremely hard to collect accurate data. You have tools that automatically collect data from testing centers, computers and other systems. You have all these nice charts where data lives and breathes.
At the end of the day, how did you utilize that data to make decisions to improve processes? How much did you reduce variation? Are you stopping to look at our products to see if they are being made more consistently? Are you identifying the root causes of our variation and instituting control plans to prevent them from returning or are you going to have to revisit this next year? Here are some examples of the things you can focus on:
- Collect data that is relevant for SPC – Don’t collect data just because it is there
- Focus on key characteristics – It’s not reasonable for operators to react to dozens of charts
- Implement a system that highlights exceptions and doesn’t require users to look at every chart – This is especially useful when many characteristics are collected
- Provide clear instructions for operators when an exception occurs
- Review the data in a ‘timely’ fashion – ‘Timely’ may mean different things for an operator, supervisor, manager, director
When you slow down long enough to think about what we are doing and remember what it is you are trying to do, the better our SPC programs will be. Carve out a little time, grab a cup of coffee, think about your current SPC implementation, and ask yourself, “How has my data helped me improve my process?”