How to choose between silicone, rubber and fluorine rubber (FKM)? Comparison of temperature and oil resistance and chemical resistance

Clarify first: what are you trying to solve, "what is resistant"?

Make the working conditions clear before selecting the material:

  • Maximum/minimum temperature, hot/cold cycle or not
  • Exposure: oil, fuel, alcohol, solvents, acids, alkalis, vapors
  • Outdoor or not: UV, ozone, rainwater
  • Whether food/medical contact compliance is required

Visual differences between the three types of materials

1) Silicone (Silicone)

Better at: temperature resistance, weather resistance, soft touch, color appearance

Common applications: consumer electronics waterproofing, home appliance parts, mother and baby silicone, keys, gaskets

Note: Different formulations vary greatly in tear strength and media resistance.

2) General-purpose rubber (e.g. NBR/EPDM, etc., depending on the type)

Better at what they do: certain rubbers are better at resisting oil, abrasion or cost

Common applications: industrial seals, general machinery

Note: The temperature and media resistance of different rubber types varies greatly, so you can't generalize with "rubber".

3) Fluorine rubber FKM (Viton system)

Better at: oil, fuel, chemical resistance and higher temperatures

Common applications: automotive, energy, chemical-related seals

Note: more costly, also has boundary conditions for low temperature elasticity and certain media

Selection recommendations (simple method for engineering decisions)

  1. Media screening first: Is there any oil/fuel/solvent?
  2. Re-screening with temperature: Are the maximum and minimum temperatures outside the material comfort zone?
  3. Look again at the mechanical requirements: Does it need to be abrasion, extrusion and tear resistant?
  4. Final Look at Compliance and Appearance: food/medical contact, color, odor

This is the recommended way to write requirements when communicating with procurement/engineering

  • Medium: e.g., "prolonged exposure to oil", "intermittent alcohol wiping".
  • Temperature: e.g. "-20°C to 120°C, hot/cold cycle 2 times per day".
  • Service life: e.g. "3 years without leakage" or "500 assemblies without breakage".
  • Inspection: size, hardness, compression permanent deformation, resistance to medium immersion, etc.

Common Misconceptions

  • Just say "high temperature resistant", not medium and time
  • Only material change without changing the groove and fitment
  • Samples passed, but mass production without small batch validation
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