When it comes to making a custom parts washing basket, it is important to have just the right coating for your basket. The right coating can mean the difference between a perfect basket that will protect the materials within through thousands of washes and a cage that wears out or actually causes damage.
For many wire form baskets, plastic-based coatings such as Halar and Teflon are popular choices. Both of these coating materials are classified as fluoropolymers, a category of highly durable plastics that are widely used for a variety of purposes (such as non-stick cookware). However, which one of these materials is the best for your material handling baskets?
To answer this question, our engineers offered their expertise and knowledge about these two coatings and their characteristics.
Characteristics of Teflon
Teflon is a trademark coating from the DuPont Corporation. As such, only those companies that are licensed by DuPont as Teflon Licensed Industrial Applicators (LIAs) are permitted to use the Teflon brand name.
What most people might not know is that the brand name of Teflon covers four distinct types of fluoropolymers:
- FEP—fluorinated ethylene propylene
- ETFE—ethylene-tetrafluoroethylene (sometimes call Tefzel)
The first two forms of Teflon, PTFE and FEP, are typically used for non-stick applications. However, these two coatings can only be layered .5 to 5 mils (thousandths of an inch) thick. Not only that, but these coatings are somewhat porous, so they are not appropriate for objects that will be totally immersed. They do, however, have a fairly high tolerance for heat; PTFE can be used on objects that will be exposed to temperatures of up to 500 °F and FEP possesses a maximum temperature tolerance of 400 °F.
ETFE, or Tefzel, can be applied more thickly than PTFE or FEP, being anywhere from 5 to 60 mils (0.06”) thick. How thickly this coating can be applied is dependent on the thermal mass of the part being coated. Generally speaking, the higher the thermal mass of the object being coated, the thicker this coating can be applied. This coating is also significantly less expensive than the other Teflon coatings, but only has a maximum use temperature of 300 °F.
PFA is one of the most expensive of the Teflon coatings, but it also has some significant advantages. It has a maximum temperature tolerance of 500 °F and superior chemical resistance compared to Tefzel. The thickness at which PFA can be applied is anywhere between 1 and 30 mils (0.03”), which is dependent on the thermal mass of the object being coated. However, this coating is not only pricier than ETFE, it is more difficult and costly to apply.
Among the types of Teflon, PFA and ETFE are preferred for applications where a high chemical resistance is a must. Both of these coatings are often used in washing baskets that will be submerged in liquids for extended periods of time. Overall, PFA does possess a higher resistance to chemicals than ETFE, and has a higher temperature resistance as well, so it is preferred for use in high-temperature washing processes that involve frequent exposure to liquids.
Characteristics of Halar
Halar, or ECTFE, is a copolymer of ethylene and chlorotrifluoroethylene that is sold by a Belgian chemical company named Solvay Solexis.
In general, Halar is comparable to Tefzel in many ways:
- It can be applied in thicknesses of 5 to 60 mils, dependent on the thermal mass of the object being coated.
- It is considerably less costly than PTFE, FEP, and PFA.
- Has a maximum use temperature of 300 °F.
- Very chemical-resistant, though not quite as much as PTFE, FEP, and PFA.
However, there is a key difference between Halar and the Teflon coatings: Halar is softer.
A common use for Halar is as a coating for circuit boards, thanks to its permeation resistance, surface smoothness, and flame resistance. It is also used for electroplating equipment and other applications that require incredibly pure environments.
Picking out a specific fluoropolymer coating for your wire forms is difficult to do based on broad general information, however. The specific plastic that you will want to use will vary depending on a number of factors, such as the temperatures that your wire frame will be exposed to, your abrasion resistance needs, the specific chemicals that the coating will be exposed to, and whether or not total immersion will occur, among other variables.
Because of the sheer number of variables that could exist in your washing process, it is important to look at each application individually, preferably after consulting an engineer who is knowledgeable in the different uses of each type of coating. Contact Marlin Steel today to learn more.