Don’t Just Collect SPC Data: Interrogate Them!
Listen to what your data are trying to tell you about process and product quality.
There’s been a crime. You saw the perpetrator! Okay, well, maybe not a crime, per se—but data from production line 3 are showing something is out of spec. Money has been lost. Quality has suffered. And that’s criminal.
What to do? Well, to get to the bottom of the crime, you’ve got to interrogate the data.
What does that mean? You know that your organization collects tons of quality management data points every minute, every hour, every day. Your operators can see the statistical process control (SPC) data that are important to them on a real-time control chart, pinpoint the issues they are having, and act accordingly—fix the issue or submit a corrective action to fix it. That’s the front line of data consumption, out on the shop floor.
But you haven’t really asked the big questions yet. You haven’t dug in there and forced the data to spit out the salient points of information you really need to keep all your manufacturing processes running as smoothly as possible.
To dig deeper, you have to put those data under the bright spotlight, sweat them, ask them a thousand questions, and listen closely to the answers.
What part were you pressing on the night of the 14th? What were the other machines in your plant doing at the time of the incident in question? What shift did it happen on? What raw material were you using?
What is Data Interrogation?
Data interrogation is quality geek heaven. It’s beyond what the operator on the shop floor sees and reacts to. It’s about stepping back to obtain the broader view of your operation—seeing the entire scope of what all your production machines are doing, but in a context that enables you to maximize product quality and minimize downtime and overall costs.
When we interrogate the data, we’re looking at a lot of data—a week’s worth, a month, or a quarter—across several or even all your production lines. We summarize data by placing them all in one big, centralized bucket. What’s in there that you didn’t know before? Having those data centralized and standardized all in one place gives you the opportunity to ask new questions—and learn something new about your operations.
The exciting stuff (if you’re one of those aforementioned quality geeks) is what we find out. You might discover that all the machines that run the Acme-supplied raw materials are running heavy compared to target, but line 3 is running light. Line 1 has the least variability, regardless of supplier, while line 8 generates the most variation and is running multiple different products.
Because all the data are in one bucket, we can see them all and ask any question we want. And we can dig deeper, if we want to. We can assess how a single mold performs on different production lines; review performance differences between mold cavities; and see how performance differs line-to-line or from weekday to weekend days.
And because we interrogate frequently, we can see that during week 3 of every month, the parts run a little heavier than the other weeks. We’re able to spot trends, see potential issues develop before our eyes, and anticipate problems before they even occur. We’re finding out who the perp was hanging out with before the alleged incident, what led to the crime, and how we might prevent it from happening in the future.
How Often Should You Analyze Quality Data?
Well, that’s entirely up to you. Weekly? Monthly? Quarterly? Whatever works for you and your organization. And the frequency may change according to your specific situation.
But the important thing is to regularly and consistently step back, roll up lots of SPC data, toss them into a single bucket, and interrogate them.
Is Interrogating SPC Data Worth Your Time?
If you want to save money and run at optimum efficiency, you can’t afford not to interrogate your data. The most successful organizations regularly interrogate large amounts of data.
If your company mantra is, “our quality is no worse than our competitors’,” then you may not be motivated to take this step. However, if you want to see big improvements in quality across your organization while enhancing your bottom line, you need to interrogate data on a regular schedule.
When you interrogate your quality data, you have detailed information available to you that you just didn’t have before—much more than the operator sees in a control chart.
That perp in the chair under the bright light has information that can save your organization money. And he knows how your operation can be more profitable and competitive. That’s where you find real value. That’s the result of interrogating data.
We invite you to visit our website to learn more about how the data you already collect can help you solve your biggest challenges.