Do you have a silverware drawer that separates your spoons, forks, and knives? If so, you have a poka yoke! Does your clothes dryer stop spinning when you open the door? Does your car not shift out of park unless the key is in and turned on, or your foot is on the brake? Does your lawn mower stop running when you let go of the handle? Have you ever driven under a clearance sign or hanging pipe when entering a drive-through or parking garage with a low ceiling? They’re all poka yokes.
Poka Yoke (pronounced POH-kah YOH-kay) is a Japanese term that means “mistake-proofing”. This Lean term was first applied by Shigeo Shingo in the 1960s to industrial processes designed to prevent human errors. A poka yoke is any mechanism that helps avoid (yokeru) mistakes (poka).
In Lean Manufacturing, like at Cadet, its purpose is to eliminate product defects by correcting, drawing attention to, or preventing, potential defects or safety hazards before they occur. In our case, either the operator is alerted when a mistake is about to be made, or the poka yoke device actually prevents the mistake from being made.
At Cadet, poka yoke has even become part of our product design. Fixtures are used and parts are designed to only fit one way, preventing them from being installed incorrectly. Some argue that errors are inevitable in any manufacturing process, but we believe that if appropriate poka yokes are implemented, then mistakes can be caught quickly and prevented from resulting in the first place. We believe that if we can prevent defects at the source, the cost of mistakes within our company, and to our customers, is greatly reduced.
So look around you and ask yourself, do you poka yoke?