Mistake-proofing systems: 7 keys to successful implementation

Mistake proofing is a powerful tool for creating more stable processes by reducing defects. Processes with high defect rates are very problematic for the lean producer: such processes are not conducive to a lean value stream because they require overproduction to ensure that demand is met. This article will teach you how to implement an effective mistake-proofing system and outline seven keys to implementing such a system.

Key No. 1: Create a team and always include those people that work on process in question. Organizations still have the tendency to turn to “technical experts” working in isolation to implement poke-yoke systems. Involving operators in a team setting will dramatically increase the likelihood of success. A kaizen blitz event is one very effective team activity for implementing mistake proofing.

Key No. 2: Use value stream mapping to determine where process stability must improve. (If you are not familiar with value stream mapping, go back and read our series of articles on the subject.) This will allow you to focus on areas that will impact continuous flow.

Key No. 3: Use process mapping within the area selected. If you are implementing mistake proofing as a part of a kaizen blitz event, then this step should be done as a matter of course. However, if you are not using this methodology, you still need to map the current state process in detail. This will clearly identify each process step.

Key No. 4: Use a simple problem-solving methodology like a fishbone diagram to determine root causes of problems within the process. This will identify those specific steps in the process that need mistake proofing.

Key No. 5: Use the simplest technology that will work when implementing a poke-yoke. Many times, low-tech solutions like guide pins and limit switches will work effectively. However, there are times when more complicated systems are necessary.

Key No. 6: Use control systems instead of warning systems wherever practical because control systems are not operator-dependent. (Control systems stop equipment when an irregularity happens, while a warning system signals the operator to take action).

Key No. 7: Have a standard form for every poke-yoke that indicates the:

• Problem being addressed
• Emergency alarm that will sound
• Action to be taken in an emergency
• Method and frequency of confirming it is operating correctly
• Method to perform a quality check in case of breakdown

Mistake-proofing systems are critical to the success of a lean organization simply because process stability is so critical. Using the above seven keys will improve the likelihood of implementing a successful mistake proofing program.

About the author:

Darren Dolcemascolo is an internationally recognized lecturer, author and consultant. As senior partner and co-founder of EMS Consulting Group, he specializes in productivity and quality improvement through lean manufacturing. Dolcemascolo has written the book Improving the Extended Value Stream: Lean for the Entire Supply Chain, published by Productivity Press in 2006. He has also been published in several manufacturing publications and has spoken at such venues as the Lean Management Solutions Conference, Outsourcing World Summit, Biophex, APICS and ASQ. He has a bachelor of science degree in Industrial Engineering from Columbia University and an MBA with graduate honors from San Diego State University.