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3 Steps on How to Control Nonconforming Material

Within quality management systems, establishing a process that effectively controls suspect material is a prerequisite to manufacturing success. In this write-out, we share the best practices and tips to know for implementing a system that works efficiently in your environment – with just three steps to remember. Our success in providing proven quality tactics for transportation sectors spans over 20 years and across continents. Let’s dive in.


Step #1: Review Your Process & Identify Risks


First, you’ll need to review your existing process and identify risk areas. Using quality tools you have at hand is one sound-proof method. Here are our top recommendations when reviewing your process:

  • Use PFMEA and control plan principles to have a clearly defined flow of nonconforming products throughout your facility.
  • Clearly define each step in the process to check suspect parts. From receipt to shipment, identify where risks of failure can occur.
  • Place multiple controls to keep your process from failing.

After determining the risk areas of your process, identify exactly where and how to implement controls.


Step #2: Implement Controls


This is all about looking at the specifics in your process to identify the best locations for controlling parts. Unfortunately, prioritizing easy accessibility for the operator has been neglected across sectors in many cases. As a result, defective parts are usually held in stations until the operator has time to deliver them to approved locations.


To help alleviate the pain points that come with implementing control areas, consider some of our widely used and easy-to-implement tactics:

  • Use colored bins – a traditional and effective method – as simple indicators for depositing suspect parts. Red is used in most environments to signal “not good”.
  • Set up your assembly operation with several cells where components are added to the final product. At each cell, define what kind of suspect parts to look for. Then, establish a way for the operator to set those parts aside for review by the appropriate support staff. The key here is to effectively segregate defect parts from the normal flow of conforming materials.
  • Red bins, in some cases, is enough and can be designated to accommodate the size and volume of suspect materials. In other cases, error-proof!


Also, helpful information about torque: If the station is designed to torque on a nut, it’s likely that the nut could get cross-threaded. While it will achieve torque, it will not rotate the full distance or angle. You may have a great system to monitor torque and angle, plus undo torque automatically. But what do you do to make sure the operator does not retorque a damaged nut?


Suggestions in controlling torque:

  • Set up a chute for the operator to drop the nut for the operation to continue to run. It can have a sensor that looks for parts passing through along with a lockbox at the end for collecting suspect nuts.
  • If the controller does not see the nut, it would prevent the operation from being cycled again. This makes it easier for the operator to follow the process and remove suspect parts without having to call someone to reset the machine to revisit the suspect part.


It’s important to note that this type of operation is not a one size fits all solution especially when your operation involves extremely large parts. For example, if you are welding truck frames together and your main risk is passing a frame to a defective weld, the control can be much more challenging to manage.


Interestingly, we have seen manufacturing players using the control of weld parameters as a mandatory reaction to machine failure.


For controlling fuller frames with torque stations, you may need another way – here are some solutions:

  • Set up a system that requires automatic application on a suspected part with an erasable marker. This way, you can remove the mark at the last stage of your controlled rework process.
  • Use a traceability system to handle more complex processes. For example, see how our globally used system works in this quick but informative video. Your system should be able to identify each part as it goes through the process. When nonconformity is identified, it should then flag the suspect part until conformity is reached. A full traceability system should record information from the start and finish of any operation. This option can cost more money with either developing the IT in-house or paying elsewhere for the service, but it can effectively eliminate human error and may be worth the investment.


Step #3: Maintenance


Finally, be sure to maintain your system after implementation and beyond. We’ve seen it happen, where a control system gets neglected and eventually fails. The ability to identify suspect parts is a responsibility of everyone in the facility, however, the review and disposition of parts should be controlled by a trained and qualified professional:

  • Your dedicated person can be from any of these departments: quality, operations, manufacturing engineering, or product engineering.
  • If choosing an individual outside of the quality department, see your PFMEA and controls identified in your control plan to learn the risks to look out for.


Need to Optimize Costs? Run a Nonconforming Material Control System with Confidence


With the three stages we just mentioned, the risk in nonconforming and wider quality management systems is the “human factor”. The ability to effectively eliminate that risk is your system’s measure of success. To have an effective system, it needs to be simple for people to understand and implement.


If you’re unable to implement a more complex system within your process due to financial constraints, additional points of control and review in the system can still be utilized. Again, in this case, we recommend using the PFMEA and your unique control plan to identify risks and place controls as needed.


If you need help with getting the right knowledge and skills to implement PFMEAs, Control Plans, or Quality Management Systems, please feel free to contact TRIGO. As a trusted global partner in the quality manufacturing world for over +8,000 businesses, our experts also provide globally certified training courses online or on-site.