Mistake Proofing

Published December 2015

Iíve written previously about how important mistake proofing is in order to meet todayís customer expected levels for quality in our products and services. As a quick review, mistake proofing recognizes that humans arenít perfect; we all make mistakes. But through creative design of products, services and processes, those mistakes donít have to turn into product/service defects at the customer. This month I want to delve deeper into how to implement mistake proofing within your organization.

First of all, it makes sense to understand the defects which are already escaping to your customers. Hopefully, a system is in place to capture customer complaint data. Use that data to identify a high frequency defect.

Once a defect has been selected, use the experts who actually produce the product or service to identify the human error that causes the defect. More often than not, they will know.

At this point, we typically call the troops together and announce, ďBe careful so you donít forget to ÖĒ But, this approach is only effective when the root cause of the error is lack of knowledge, not human fallibility. And so the defect occurs again and again.

For example, the fact that I know Iím supposed to turn off the coffee maker each morning doesnít mean that I will do it 100 percent of the time. A warning message on the machine would be of little use. Instead, the coffee maker is designed to automatically turn off if a certain temperature is exceeded, a more effective mistake proof.

With mistake proofing, once the human error has been identified, the fun and creative work begins. In order of preference, we want to identify an entirely effective means for

  • Preventing the specific human error from happening in the first place (Level 1 mistake proof)
  • Immediately detecting the human error if it does occur (Level 2)
  • Effectively identifying the defect if it occurs (Level 3)

Letís assume we have a call center and workers occasionally forget to complete a required date field on an electronic form. Or perhaps they occasionally mistype and enter an invalid date.

A Level 1 mistake proof might involve improving the form so that workers click on the actual date on a calendar within the field rather than typing the date info. A Level 2 mistake proof might turn the field red immediately and not allow the worker to exit it until a valid date has been entered. A Level 3 mistake proof might inform the worker that the date field contains invalid data when they go to submit the completed form.

Frequently, effective mistake proofs can be implemented at minimal cost. Like identifying the actual error that caused the defect, using the creativity of the folks who actually produce the product or deliver the service to brainstorm and select the mistake proof is highly recommended.

Years ago, a supervisor friend was frustrated by recurring reports of units failing prematurely because an extra washer was included. The washers were about the size and thickness of a large soup can except perfectly flat and smooth. My friend took an example of a failed unit to a team meeting, split the group into two teams and challenged them to independently identify the human error which resulted in two plates being assembled and a means to prevent the error.

Both teams agreed that the error was caused by assemblers mistakenly grabbing two washers instead of one. This was exacerbated by the fact that the washers were thin, flat and tended to stick together due to the oil coating used to prevent rust.

One of the teams came up with a slick idea for a washer dispenser similar to the coin dispensers that car hops used years ago. The washers were loaded into a tube constructed of PVC with a slot at the bottom wide enough to accommodate only a single washer. A few hours and ten bucks later, the idea was being piloted. The team later switched from PVC to steel for the dispenser as they learned that continual use caused the critical slot width to grow.

Communicating customer feedback and involving workers in eliminating defects provides double benefits of telling workers that their ideas are valued while also greatly increasing the idea pool. Thatís a winning combination.

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