Parts Washing Process to Reduce Scrap Rate for Welding

The parts washing process for safety-critical components is no joke. If a part is not cleaned properly, it will not weld correctly. Witness Inspection took on the task of cleaning airbag diffusers for a Tier-1 supplier. Our customer dictated the parts washing process based on the historical success of similar programs. However, shortly after we launched their cleaning process, we learned that the OEM was having welding issues. Their scrap rate had skyrocketed up to 30% as a result.

As soon as our customer notified us, we assembled our A-Team. Our design engineer, chemical engineer, and process engineer worked with our customer to conduct a full design review. This confirmed that the process was consistent and within control. The parts were meeting the required Dyne Cleanliness Specification, but still not welding correctly. Something else was going on.

A Reimagined Parts Washing Process

After the design review, we ran a series of controlled trials to determine the best process. We needed to understand all the variables that could be impacting the welding process. The goal was to develop a comprehensive process that would significantly reduce their scrap rate during assembly.

First, we defined the cleanliness results and consistency of the process to establish a baseline. Our hypothesis was that foreign coolants or fluids were still on the part and reacting poorly to the welding process. So, we suggested an alternative test to measure non-volatile residue, which can show up after the initial cleaning process. That, in addition to other control variables like times, temperatures, and RI concentration of the parts washing process. The customer received each trial run upon completion to measure the results in production. Through data review and monitoring, a process was developed utilizing our high-volume drum washers to pre-clean the parts, followed by ultrasonic cleaning. The new process actually eliminated a secondary ultrasonic cleaning process which was more time-intensive.

A Holistic Approach to Quality Issues

Since we have a unique blend of in-house equipment and expertise, we were able to run the trials from start to finish, test the parts, and monitor and report results all under one roof. This saved the OEM a whole lot of time, money, and headaches and made our customer look good! Normally, a trial like this would shut down production for several weeks and cost tens of thousands in lost revenue and scrap material. The OEM would have had to manage the transportation of parts between multiple vendors to run parts through specialized equipment at each step. But we saved them from this logistical nightmare–and associated costs.

Some of the equipment we used included vibratory deburring systems, drum washers, ultrasonic cleaners, and de-rust/passivation. By testing different parts washing methods and combinations, we were able to design a process that worked. And we saved our customer tens of thousands of dollars in production downtime and scrap.

Results: Reduced Scrap + Major Cost Savings

The OEM was able to reduce their scrap rate during assembly on a safety-critical component. The reduced scrap saves them well over $100k annually. The cost of downtime can become massive if left unresolved. When our customer asked for our recommendation, we went to work to provide a solution to benefit all parties!

Find out how you can be the Quality Hero.

Contact us today to see what we can do for your high-volume production process.