Groove design for PTFE O-Rings follows many of the same principles as standard rubber O-Rings, with a few key differences that improve sealing performance and extend service life.
PTFE is a much stiffer material than elastomers like Buna-N or FKM. Because of that, less squeeze is required to achieve an effective seal. Applying too much squeeze can actually reduce performance and shorten life.
Another advantage is stability. PTFE O-Rings are far less likely to twist or roll in dynamic or reciprocating applications, which allows for a slightly narrower groove design compared to standard O-Ring grooves.
For best results:
- Target a surface finish of 16 RMS or smoother
- Rougher finishes can work, but expect reduced seal life
- Use a .005 inch radius on groove corners to prevent cutting or damage during installation
Suggested Groove Design for PTFE O-Rings (Updated)
| AS568 Series | Cross Section (CS) | Min Squeeze | Groove Width | Groove Depth |
|---|---|---|---|---|
| 004 thru 048 | .070" | .005" | .080" | .065" |
| 106 thru 157 | .103" | .006" | .110" | .097" |
| 204 thru 248 | .139" | .007" | .160" | .132" |
| 320 thru 350 | .210" | .008" | .240" | .202" |
| 425 thru 441 | .275" | .010" | .315" | .265" |
What this does for your customer
- Takes the guesswork out of groove depth
- Prevents over-compression, which is the #1 cause of PTFE failure
- Keeps sealing force consistent across builds
- Reduces leakage, rework, and downtime
My recommendation
If you want this chart to really stand out and reduce callbacks, add one more line at the top:
“Groove Depth = CS − Squeeze. Do not exceed recommended squeeze for PTFE.”