Knowledge Center
Practical engineering guides on squeeze, gland fill, stretch, extrusion, material choice and failure analysis.
Featured guides
How to Measure an O-Ring
Measure O-ring inner diameter, outer diameter and cross-section correctly, convert between them, and match your measurements to AS568 or ISO 3601 standard sizes.
Read guide GuideWhat is gland fill?
Why an O-ring groove must never be completely filled, how thermal expansion and media swell consume free volume, and how to check gland fill across tolerances.
Read guide GuideWhat is O-ring squeeze?
How compression creates and maintains a seal, typical squeeze ranges for static and dynamic O-ring applications, and how to calculate it across tolerances.
Read guideAll guides
O-ring extrusion failure
How pressure pushes an O-ring into the clearance gap, the three drivers of extrusion risk, and how to prevent nibbling with hardness, gap control and back-up rings.
Read guideStatic seal vs dynamic seal
Why relative motion changes almost every O-ring design limit: squeeze, surface finish, lubrication and clearance requirements for static versus dynamic service.
Read guideMore topics in preparation
How to calculate O-ring groove dimensions
Turning cord size and target squeeze into a groove.
O-ring stretch limits
How much inner-diameter stretch is safe.
FKM vs NBR
Choosing between fluoroelastomer and nitrile.
FKM vs FFKM
When perfluoroelastomer is worth it.
EPDM chemical compatibility
Where EPDM excels and where it fails.
How to select O-ring hardness
Balancing squeeze, extrusion and friction.
O-ring surface finish requirements
Groove and bore finish for reliable sealing.
O-ring compression set
Why seals lose recovery over time.