How to establish an error-proofing process according to IATF 16949

What is an error?

Errors are inadvertent, unintentional, accidental mistakes made by people because of the human sensitivity designed into our products, which result in those “once in a while” defects that we always find difficult to control. Inadvertent errors are not only possible, but inevitable, and they happen regularly.

Have you ever locked the keys inside your car, or run out of gas, or forgotten to turn off the coffee pot? Mistakes, or errors, are part of our everyday lives. It is hard to avoid them, and even harder to explain why they happened. If you are required to write your name 1500 times, are you 100% sure that you won’t make any mistakes?

Being an ever-present part of our lives, it is hard to avoid errors in the workplace as well. Examples of work-related errors are:

• missing parts – forgetting to assemble a part: screws, labels, orifice tubes …
• misassembled parts – incorrect assembly: loose parts, upside down, not aligned, e.g., brackets (backwards), seals (not aligned), screws (loose), labels (upside down) …
• incorrect processing – disposing of a part rejected during testing in the wrong pile
• incorrect parts – retrieving and assembling the wrong part from a model mix selection: seals, labels, brackets, cases …
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And, of course, these examples are related to the production process mainly, but you probably can think of something related to your area of work. Depending on the type of error, the stakes can be high. Work-related errors can lead to work-related injuries, loss of money, wasted time, loss of jobs or deals, and even injury or death of consumers, so it is no wonder that this is an important part of a standard that focuses on quality in the automotive industry.

What does the standard require?

Requirements for error-proofing processes are part of the continual improvement requirements, and an entire sub clause (10.2.4) is dedicated to them. The standard requires an organization to establish a documented process to determine the use of appropriate error-proofing methodology. However, the methodology for error-proofing should be documented in the process risk analysis, such as PFMEA (Process Failure Mode Effect Analysis), and the test frequency should be documented in the control plan (to learn more about the control plan, see: How to Develop a Control Plan According to IATF 16949).

The process must include testing of the error-proofing devices for failure or simulated failure, and the error-proofing device failures should have a reaction plan. And finally, of course, records of this process should be maintained.

How do we error-proof?

Error-proofing is the activity of awareness, detection, and prevention of errors that could adversely affect our customers (defects) and our people (injuries), and result in WASTE!

Awareness: Having the forethought that a mistake can be made, communicating the potential, and planning the design of the product or process to detect or prevent it.

Detection: Allowing the mistake to happen, but providing some means of detecting it and alerting someone so that we fix it before sending it to our customer.

Prevention: Not allowing the possibility for the mistake to occur in the first place.

There are two main techniques for error-proofing:

• Design For Manufacturability (DFM) – This is a technique that results in designs that cannot be incorrectly manufactured or assembled. This technique can also be used to “simplify” the design, and therefore reduce its cost.
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• “Poka-Yoke” System – Devices or inspection techniques are put in place that assure that setup is done correctly; i.e., 100% good parts are produced from the first piece onward.
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Regardless of the technique you decide to apply (and you will probably decide to apply them both), the error -proofing process has some common steps that ensure success:

1. Identify – The organization needs to identify error-proofing opportunities through PFMEA, quality data, PR/R, warranty data, brainstorming (questions to ask, freeform …), etc.
2. Analyze – The organization needs to prioritize the error-proofing opportunities, determine the level of error-proofing required, brainstorm, and select the error-proofing mechanisms.
3. Plan – The organization needs to determine process mechanisms for error-proofing, define actions plans, and create the Error-Proofing Control Plan.
4. Implement – The organization needs to implement various activities to put the error-proofing process into practice, such as installation, validation, check sheet/log, and operator instructions.
5. Evaluate – Finally, the organization needs to evaluate the effects of the actions taken, and if the number of errors has not decreased as expected, an additional set of actions should be taken.