Marlin’s engineers are often asked about the use of different coatings in ultrasonic cleaning processes. One question that often gets asked is “should I use Teflon® coating for my ultrasonic cleaning container?”
To this question, Marlin’s engineers usually reply, “what formulation of Teflon® do you mean?” The Teflon® brand name comprises four different fluoropolymers owned by the Chemours company, each with different performance characteristics:
- Polytetrafluoroethylene (PTFE)
- Fluorinated Ethylene Propylene (FEP)
- Perfluoroalkoxy (PFA)
- Ethylene-tetrafluoroethylene (ETFE, or Tefzel®)
Characteristics of Teflon®
The strengths most Teflon® coatings have in common are that they’re very resistant to chemical corrosion and have a high melting point compared to most other polymers.
FEP has a maximum service temperature of 400°F, while PFA and PTFE have a maximum use temperature of 500°F. However, prolonged exposure to such high temperatures is rarely an issue in ultrasonic parts washing.
These three formulations of Teflon® also have fairly high tensile strengths (at or above 3,000 psi in all three cases). This strength can be beneficial for helping the coating survive the rigors of the ultrasonic cleaning process as well as prolonged, repeated contact with heavy parts.
Can Teflon® Be Useful for Ultrasonic Cleaning Containers?
One other characteristic common to all three of these coatings is that their application process usually leaves a thin, porous coating of material.
Unfortunately, this makes them less than ideal for immersion applications—such as ultrasonic parts cleaning. At least, when the goal is to protect the material underneath the coating, that is.
As a means of protecting plain steel from chemical corrosion, a porous Teflon® coating just doesn’t cut it. However, it could be paired with stainless steel materials and be useful for protecting parts from getting scratched by contact with bare metal containers.
Also, there’s one member of the Teflon® family of coatings that we haven’t looked at yet: Tefzel®.
What Makes Tefzel® Useful for Ultrasonic Parts Cleaning Containers?
Among the Chemours Teflon® family of coatings, Tefzel® ETFE is a bit of an outlier. At a recommended operating temperature of 311°F, ETFE has the lowest temperature tolerance of the four Teflon® fluoropolymers. However, in most ultrasonic cleaning processes, this is a relative non-issue.
Where ETFE excels compared to the other Teflon®-brand fluoropolymers is in its tensile strength and coating thickness. Generally speaking, ETFE can take between 5,800 and 6,700 psi of pressure; the highest tensile strength of any of this family of polymers.
Also, where other Teflon® coatings are applied in a thin, porous layer, Tefzel® ETFE is applied in much thicker, nonporous layers. This allows an ETFE coating to completely protect an ultrasonic cleaning container used in a complete immersion application.
This thick coating is also great for protecting held parts from getting abraded by contact with the cleaning container. However, this extra-thick coating may require a bit more open space in the basket design to prevent webbing that could gum up the container’s openings.
So, in some cases, Teflon® can be a good choice for coating an ultrasonic cleaning container. However, before settling on any coating material, it’s important to know as much about the manufacturing process and the parts being handled as possible—which is why Marlin Steel’s engineers use a custom order questionnaire to learn about these details before designing a custom container for any application.
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