New Substrate, New Cleaning Part 1 – Metals

Let’s change just one thing: the substrate. The product line remains the same – same size, same shape, same end-use requirements. Do you have to re-evaluate the cleaning process? Absolutely! To head off production shut downs and to avoid losing business, test the new substrate with the current cleaning process before going into production.

A manufacturer has consistent, high-quality results working with various types of stainless steel and is able to adjust the process between, say, 316 and 440. They are familiar with the requirements for cleaning and corrosion prevention. It is too easy to assume that cleaning processes for stainless steel will work for other metals.

Some metals are more temperamental to clean than others. Producing the same product from more active, non-ferric metals like aluminum or magnesium is likely to mean that the cleaning processes must change. Different metalworking fluids may be used. This means changes in solubility properties and perhaps the need for different cleaning agents. Surface porosity may be different, so the ease with which soils can be removed can change depending on the metal. Consider that materials compatibility problems are often magnified with active metals. Cleaning forces and temperatures used at the wash, rinse, and dry stages may need to be modified. Tales of process woes such as spotting and erosion are prevalent.

Magnesium can be very reactive. For example in the course of developing a single process that works with many types of metals, we tested a solvent cleaning process proven to be effective at room temperature for many metals, including magnesium. However, when the solvent was heated, a white surface damage known as “blooming magnesium resulted.”

What might seem to be a small change in the alloy can make a huge difference. One company had years of experience in manufacturing bronze products. Their new product was made of brass. The change in zinc content was enough to disrupt what had previously been a very successful cleaning process. The cleaning agent had to be modified and process parameters had to be adjusted. Testing the cleaning process with the new product before going straight to production can avoid costly line shut-downs.

Invest a little effort in testing the cleaning process with samples you don’t plan to sell, even if you think there will be no problem. Practical, common-sense research is not at all the same as research for a PhD thesis. You may need to try more than one cleaning process – that’s why they call it research, not search!

What happens with other substrate changes like polymers and glasses? Look for “New Substrate, New Cleaning Part 2 – Polymers, Glass, and More” in an upcoming issue of Clean Source.

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