Checks and Double Checks

Roman Tuero
Oct 07, 2019

Quality as a Metric

It doesn’t help to be faster than your competition if your product quality is inferior. It is also important to recognize that there’s more to quality than just saying it is important. Quality is a metric and a measurement, and the goal should be getting parts-per-million (PPM) quality.

Efficient and Effective Quality Checks

FlowVision pioneered this practice with a tool we call Checks and Double Checks. The fact that so many employees touch your product is one of the many benefits of flowing product down a line. If only one person works on a product from start to finish, then no one else gets a chance to check the quality unless you introduce a quality inspection station at the end of the process. Using this method can be wasteful (one person’s job is focused exclusively on quality and not production) and often times happens at a stage where error-finding requires significant rework and time delays to fix.

Setting Standards

When setting up a line, every calculated operation needs to have standard work. What that means is that while there’s more than one way to do most types of work, there needs to be one, agreed upon, correct way to do that work, and that way needs to be how the work is performed every time. Without standard work, it’s nearly impossible to implement consistent and standard quality since the employees cannot predict which work content steps should have already been completed.

Getting to PPM

Once the standard work is agreed upon, a specific sequence must be followed to introduce the standard quality checks. When a product flows into an operation, the first thing we do is what we call a Double Check – we “double check” the work that was done in the previous upstream operation. Next, we do the standard work required for that operation. And finally, we “Check” our own work that we just performed. This process gives us PPM quality. When you double check the work that was performed in the previous operation, there’s a 1/100 chance that you’ll have a workmanship defect. When you do your work, there’s another 1/100 chance of a defect. And lastly, when you check your own work, there’s still yet another 1/100 chance that there will be a defect. Checks and Double Checks is a simple tool to introduce that has profound benefits.

Understanding the Savings

While there certainly is a cost to implementing Checks and Double Checks, typically it is nominal. This is especially true when compared to the cost of rework when catching quality issues at the end of the line. We also find savings in the fact that, because the quality check process is built into the building process, we no longer need to have a person solely focused on checking quality at the end of the line. If you instead apply the Checks and Double Checks at the process level, once you catch a defect, it is corrected right at the point of occurrence.