Change is inevitable. Frequently change is good. It’s progress. But changes, even good changes, don’t always get communicated down the supply chain. Unknown, unexpected changes can cause problems for critical cleaning and surface prep. Here are some practical ideas to recognize change, to avoid detrimental changes, to troubleshoot quickly, and to respond to unforeseen change.
Cleaning problems seem to occur at the most inopportune moment. Consider the case of the gooey pie crust. When Barbara was about 4 years old, her Aunt Vera taught her to make pie crust. It was simple – flour, a little water, and an iconic veggie shortening introduced in the early 1900s. If you followed the recipe –the ingredients and process, you ended up with pie dough that was easy to roll out, baked to a golden brown, and tasted great. It was sort of like play dough that turned into dessert.
Until that fateful, very large dinner party, half a century later.
Barb made about 6x the usual recipe. What resulted was a mess that was both gooey and crumbly. It would not roll out – it just fell apart. After repeated attempts including frantic attempts at minor modification, she threw a large glob of dough across the room, where it landed on a kitchen cabinet and sagged down to the floor. She later discovered that the shortening formulation, including the type of oils used, had been changed in response to regulatory requirements to eliminate trans fats. Barbara does not recall seeing an announcement at the time (the shortening manufacturers were said to have announced the change); there were no apparent changes to the label. The supplier claimed no change in performance. She would dispute that claim! After a nutrition break and a refreshing beverage, she implemented a new recipe.
Our dinner guests were pleased with the product. No one required NADCAP inspection or process revalidation. Because there were no complaints or catastrophic product failure, the FDA, the FAA, the military, and assorted lawyers did not become involved. In manufacturing, emergency changes to cleaning processes are more problematic and complex. If you are involved in critical cleaning or high-volume cleaning, we suggest any notification regarding a change in any chemical or blend be looked at carefully, even if the vendor claims that the new product is substantially the same as the old one.
Metalworking materials
Metalworking materials are essential to manufacturing. We use the term very loosely to include various lubricants, coolants, maskants, polishing and buffing agents, liquids, solids, emulsions – anything that is used to make metals look the way we want them to or have the desired configuration. They may be biobased, natural products derived from animals or plants; tallow, for example. They may contain synthesized chemicals. Many are complex, proprietary blends. We suspect there are more choices in metalworking fluids than there are in shortening.
Metalworking materials, even well-established ones, can change. Key ingredients may become unavailable due to economic and/or regulatory pressure. The supplier may not consider changes in ingredients to be significant, particularly if the behavior is equivalent during the process (the equivalent of having the pie dough roll out and bake successfully). Therefore, a change in formulation may not be noted on the label; customers might not be informed. However, decreased cleanability of the residue after machining or metalworking could happen. If the new chemicals are not hazardous to workers, it is unlikely that they would be listed on the SDS. However, a chemical that is non-hazardous to workers might still change the physical and functional characteristics of the product, by leaving undesirable residue or by undesirable interaction with the substrate.
You think it’s not there, but is it actually there?
What’s a key ingredient in a formulation? Do suppliers always know everything that is in a formulation? Not always! Manufacturers have used t-butyl acetate (TBAC) and parachlorobenzotrifluoride (PCBTF) in surface prep because they are not regulated as VOCs. They may also be used in other process materials. The chemicals have been considered environmentally preferred solvents. They are popular in areas of poor air quality, where regulations limit or ban the use of other, effective cleaning solvents. However, these solvents are no longer favored; and the changes may impact cleaning processes and formulated products. Recently, in response to reports from California’s OEHHA (Office of Environmental Health Hazard Assessment), the South Coast Air Quality Management District (SCAQMD) voted to phase out the use of both chemicals. A veteran formulations expert, who was present at the SCAQMD hearing, said that there was very little concern on the part of formulators – they did not perceive the loss of the solvents to be a problem, and amended Rule 1171 was adopted relatively easily. The formulations expert explained that the impact of new regulations could take a while to become apparent. What happens in California is likely to happen elsewhere in the U.S. Providers of metalworking materials may decide to reformulate with “safer” solvents (or solvents that are not under regulatory scrutiny). The formulations expert commented that the solvent you thought you weren’t using, may actually be present, because it is part of a “sub-formulation.” For example, his client was convinced that TBAC was not used in their formulations, until it showed up as part of an ingredient (a sub-formulation) that is then further formulated into the final product.
Discovering the source of the contamination that you thought you didn’t have but actually do have may require detective work. One of our clients had problems with their lead frames. Laboratory analysis indicated sulfur contamination. Sulfur contamination is undesirable because it can result in corrosion of the final electronic assembly, even with conformal coating. Everyone swore up and down that the sulfur was an analytical artifact, that it could not possibly be present. In response, we conducted a micro archeological expedition. By working back about eight steps through the supply chain, we found the source of the sulfur. Knowing “whodunnit” allowed the client to fix the problem.
Applying and Removing Maskants
Maskants are materials that are used to temporarily coat surfaces to prevent exposure of that surface to subsequent process actions. Examples are masking tape prior to painting and coatings to keep water or corrosive chemicals away from a critical area. Maskants may contain organic (carbon based) and inorganic chemicals. They may be applied as a tape or as a thick suspension. The key word is temporary. Just as soils have a useful function but then need to be removed; maskants can be considered a soil. How they are applied and the environment they are exposed to (temperature, time, force, other process fluids) influences how well they can be removed.
Knowing what the maskant is and using one that can be easily removed is not necessarily enough. A client was faced with adherent residue from a maskant that interfered with subsequent coating. The product information indicated that any residue should be readily removed with a stream of water. We tried water blast – no go. We tried ultrasonics – nope. We tried aggressive solvents – zippo! Nothing touched it. The parts were masked by an external group, then shipped; communicating with the techs who actually did the masking was not an option. We found the source of the problem by interfacing with the technical person at the company that formulated the maskant. The directions called for painting on a small amount of maskant. He observed that some people think if a little maskant is good, more is better, and too much is just right. More is not necessarily better. The maskant contains aluminum. Because aluminum is readily oxidized; exposure to air and heat could result in a residue that was nearly impossible to remove. He also observed that people have been known to add extra “stuff” to the maskant in attempts to make it better; or they might use a diluent that is different from the one that was recommended.
Shocking! More is not always better. And people don’t always follow directions. When Aunt Shirley, Aunt Vera’s sister, was taking “Home Ec” in middle school; she figured that if 1 teaspoon of baking soda made the coffee cake rise, imagine what a cup would do. Reportedly, the cake exploded while baking. If the problem is detected rapidly, as with Aunt Shirley’s coffee cake, the issue sort of self-corrects.
In the case of the maskant, the problem was not detected until days to weeks later; and the people applying the maskant did not know there would be a problem. Of course, they could RTFM (Read the Fabulous Manual). But they didn’t. In the case of the maskant, while clear directions were provided with the maskant in the form of written instructions, it is not clear that the directions were communicated to those doing the actual masking. Communicating directions is a universal problem, one that impacts manufacturing, repair, heavy industry, and precision or safety critical applications like medical device manufacturing. Avoiding unexpected problems may involve not just following directions but making sure that the directions are clear, accurate, and communicated to those who need to follow them.
Controlling the unknown
In critical cleaning, surface prep, contamination control, contamination detection, and residue removal, determining significant changes can build a great reputation or destroy your business. While we don’t have the answers to preventing all unexpected changes or to dealing with them when they occur, there are some steps you can take.
Unexpected, unknown process problems are exacerbated with supply chains that are geographically diverse, where communication is limited, and where secrecy is part of the culture. Just as it makes good economic sense to purchase quality cleaning equipment, it makes good sense to populate your supply chain with high-quality shops and to set up mechanisms to promote transparency.
What if you detect a potential problem? In some instances, you are contractually required to report significant, defined changes to the customer. Ultimately, managing change involves an agreement between you and your customer, you and your suppliers, and your own understanding of critical/precision cleaning.
How does one detect changes? Even with excellent manufacturing practices, chemical and process changes happen; tracking down those changes can be tricky and time-consuming.
There could be a small change, not enough to trigger revalidation, the product moves to the next supplier who makes another small change, again not enough to trigger revalidation. This can be thought of as analogous to compound interest in that small undesirable changes can have a multiplier effect.
A company can install all manner of inspection equipment. It can be very helpful, given the number of variables in cleaning agents and cleaning processes; problems can slip past automated inspection. We maintain that ongoing observation, usually visual observation, by well-educated employees is essential. Employee education and encouraging employee feedback are essential. Classic “employee training” along with a command and control mentality often means ignoring unexpected changes until it is too late. Employees have to be very comfortable communicating their observations. There must be a company culture that encourages communication. This communication has to occur within the company and among all companies involved in production.
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