Marlin Steel specializes in creating custom stainless steel wire baskets for clients in a variety of industries. Many of Marlin’s clients rely on the Marlin team’s expertise in handling the design needs of a stainless steel basket for various manufacturing applications.
Frequently, these clients have questions about the basket designs, materials, and functions that are included in their design. In one recent job, one client had a few specific questions about different coatings for their stainless steel basket after they were sent a few sample coating swatches:
Question 1: Will ECTFE, ETFE, and PFA Adhere Better Than Plastisol on Larger Stainless Steel Surfaces?
At the time Marlin was working with the client, they were using a plastisol coating for their wire baskets, and Marlin’s design engineers thought that some other coating types might better suit the client’s needs. After testing the samples, the client found that the ECTFE, ETFE, and PFA coatings all adhered to their substrates better than their current plastisol coating.
The client wanted to know if this enhanced toughness would apply to a larger basket as well, since the size of the sample pieces was small. The short answer was “yes.”
Each of these three coatings incorporate a chemical primer that improves the adhesion of the coating to the substrate material. To provide an even stronger bond, Marlin’s engineers will grit blast the substrate to help promote mechanical interlocking of the coating and the substrate.
Most plastisol coatings don’t have a primer, and are applied to a “mill finish” surface. This results in a weaker bond, and thus easier separation of the coating from the substrate.
While the adhesion of these coatings to stainless steel will be slightly weaker than it would be to carbon steel, there isn’t any peel strength data available. This is because all three coatings have very good release properties and the pull wire tends to break free of the coating before the coating’s adhesion to the steel fails.
Question 2: What is the Estimated Lifespan of the Coatings with an Estimated 2 Minute Wash 100x a Day, Six Days a Week?
In the case of this client’s wash process, with a short, 2-minute wash 100x a day, six days a week, it was determined that the coatings would fail from mechanical wear before it fell to any chemical degradation.
Specifically, the ECTFE and ETFE coatings have a hardness of about 75 Shore D, which will let them hold up to mechanical force better than the PFA coating (60 Shore D hardness). This durability will allow these coatings to withstand years of use in the client’s wash process, even with hundreds of washes a day.
Question 3: Is Recoating Possible Once the Coating Begins to Flake?
In the event that a coating begins to flake, such as from the aforementioned mechanical wear, it is possible to recoat the basket to add a new layer of coating material. This preserves the integrity of the basket, and helps reduce costs.
For ECTFE and ETFE, the basket needs to be heated to 750 degrees Fahrenheit and then grit blasted to ensure the best possible quality recoat. For the PFA, the temperature needs to be brought up to 950 degrees Fahrenheit and then grit blasted.
While stainless steel shouldn’t be affected by the stripping process, chemical damage (such as at perforation sites in the coating) can show through the new coating. Carbon steel, on the other hand, may suffer some damage from the stripping process.
There are many different kinds of coatings, and many different factors that can affect coating performance. If you have a question about coatings for custom wire baskets, leave a comment in the section below, or talk to a mechanical engineer today!