In some instances, a spring is required to operate in challenging environments where it will benefit from some form of surface protection or coating. Two coatings provided by SCS are Polytetrafluoroethylene (PTFE) and Parylene coating. Although similar, the decision on which one to use as protection will come down to the long term needs and functionality of the end application. Below we have outlined the key characteristics of both.
PTFE Coating
Distinguished by its slippery surface, high melting point, and resistance to attack by almost all chemicals, PTFE is an incredibly versatile material due to its stable and durable characteristics. While it’s perhaps best-known to consumers as the coating on non-stick cookware, it is also fabricated into industrial products, including bearings, pipe liners, and parts for valves and pumps.
Key characteristics of PTFE:
- Chemically resistant and chemically inert.
- Excellent electrical properties such as high insulation resistance, low dielectric constant, extremely low dielectric constant (2.0).
- Resistance against light, UV, weathering damage and general wear and tear.
- Low friction material reducing the amount of torque lost.
- High thermal stability without obvious degradation below 440 °C
- Materials coated in PTFE can be continuously used below 260°C.
Commonly used on the following applications:
- Industrial: bearings, pipe liners, valves, pumps and sealing components.
- Aerospace: cable insulation, surface protection, bearings and harnesses.
- Medical: catheters, guidewires and implants.
Parylene Coating
A thin film coating technology used to improve the capabilities of leading-edge technologies, Parylene is a crystalline polymer which results in generally high mechanical strength. Applied as vapor, the coating layer perfectly conforms to complex shapes and provides complete and even coverage. It has a relatively high tensile and yield strength.
Key characteristics of Parylene:
- Powerful insulator.
- Provides protection from moisture, corrosion, salt spray, solvents and airborne contaminants.
- An adhesion layer when applied between a device and a top coating.
- FDA approved material that meets USP Class VI and ISO 10993 biocompatibility.
- Low coefficient of friction, comparable to PTFE.
Commonly used on the following applications:
- Industrial: oil rigs, machinery, seals, gaskets, power systems and circuit boards.
- Aerospace: flight control systems, cockpit instrumentation, displays and imaging equipment.
- Medical: drug eluting stents, catheters, implants, and electrosurgical instruments.
