Lean manufacturing companies will have quality built in their processes as much as possible. By building quality into your process, you prevent unnecessary rework and scrap. This means that your machines are capable of detecting abnormalities (jidoka) and your fixtures have mistake proofing to avoid mis-assembly (poka yoke).

Detecting Abnormalities with Machines (Jidoka)

When considering quality built in, the main aspect that should come to mind is “automation with a human touch” or jidoka. This is one of the main pillars of lean manufacturing.

Automatization (jidoka) refers to a machine’s ability to judge good or bad conditions. When an abnormal condition is detected, the machine will stop and trigger an alarm. This should cause someone to remove parts and reset the machine. If not, there is a possibility that the suspect parts could continue through the process.

The original concept was born when Toyota developed a loom that would stop if a thread was broken. This eliminates the need for a person to stand there and monitor each machine. Hence the term, “automation with a human touch”.

Mistake Proofing (Poka-yoke)

In a lean manufacturing environment, the concept of JIT does not allow you to do things a second time. That is why having quality built in to your process is so important. The ideas required to be successful do not always have to be highly sophisticated or expensive.

Profile fixtures with presence sensors are a good example of poka-yoke. It should allow you only to put in the components that fit and will alarm if the machine is cycled without all the components present. A swipe for height detection to verify if staking has been performed. Interlock this to the next operation and you will virtually guarantee good quality parts.

No matter what the idea, the more mistake proofing in the process, the better off you will be. This prevents costly rework, scrap and potentially missed shipments.