Parts washers are the heavy-duty, hardworking machines that have become irreplaceable staples in any automotive or machined part manufacturing process. As manufacturing processes have become more sophisticated, the industries using parts washers includes not only industrial metals and aerospace materials but also more delicate applications such as medical implants and electronic devices.
But what are the Critical Control Points within a parts washer system? What are the elements that get overlooked and result in adhesion failure even though the parts SEEM clean?
The machines tasked with cleaning metal parts have moved from what amounts to large-scale dishwashers to highly advanced ultrasonic aqueous baths and vapor degreasing systems. Ultrasonic parts washers are immersive tanks that pulse the water an industrial component is submerged in using high frequency sound waves to release contaminants from all of the part surfaces. Vapor degreasing systems are also immersive but they use an evaporated solvent to dissolve oils, greases and fluxes from mechanical and electronic parts.
Image to right: Ultrasonic parts washer photo courtesy of Crest Ultrasonics
These high-precision cleaners are able to uniformly wash objects with complex geometries but still require verification to keep them on track. Because clean isn’t clean if the surface isn’t chemically clean. The difference lies in the level to which contaminants that are too miniscule to be seen with human eyes are removed. Manufacturers often don’t pay attention to this fact. If a part isn’t chemically clean it doesn’t stand a chance when it comes time to paint, coat, seal or bond.
Some of the Critical Control Points -- that when fully understood, provide the confidence to know the application will stick -- involved in a parts washing system are:
- Immediately before the part enters the tank or bath (how dirty is it actually at this point? What’s the number that tells you?)
- Before and after a corrosion inhibitor is applied
- After the solvent in a vapor degrease system drips off the surface
- After the determined processing time when using low-, medium- and high-flashpoint solvents
- After any kind of rinse and dry cycle
In order to ensure that a surface has been truly cleaned the cleanliness needs to be quantitatively understood at each Critical Control Point. Common cleanliness test methods, like Dyne ink and water break tests, have an extremely limited scope, leave the tests results up to the whims of the person conducting the test and give you no indication of how close to failure you might be. They are not quantitative or consistent but are, in fact, destructive. They often create the NEED for scrape. Scrape gets built into the system and the parts washers are unable to do their job.
When you can verify how clean a surface actually is, you can ensure the effectiveness and long life of parts washers.
Here are some ways that optimizing any kind of parts washer system by knowing what is going on at each Critical Control Point will upgrade your whole process:
- Verify readiness for sealing applications such as FIPG
- Optimize components of parts washers: part placements, solvents, duration
- Quantify washer performance
- Guarantee uniform cleanliness
- Identify when the water is spent
- Detect the presence of oils—both water-soluble and hydrophobic
- Ensure chemical cleanliness prior to laser welding
- Compare and choose different washer systems
- Evaluate detergent effectiveness
BTG Labs specializes in verifying these cleaning and preparation systems. There are ultrasonic parts washer manufacturers that use our technology to prove the reliability of their systems. Reach out to us using the form below and schedule your free process walk to identify the Critical Control Points in your adhesion process and get the most out of your parts washer.