Common Causes of O-ring Failure
O-ring failure can be traced back to design, installation, production quality and material choice. Choosing the proper materials, size, compression and surface finish will make a big different in machine performance and longevity. Design related failures are particularly common, and can be avoided with certain considerations:Know the depth – O-rings sit in a channel known as a gland. Knowing the gland depth allows a machine designer to calculate compression and choose an O-ring that will avoid extrusion and tearing.
Leave space – O-rings should not fill the entire gland, but leave space for O-ring swelling and possible thermal expansion of the seal.
Avoid stretching – Stretching the O-ring past five percent of the centerline diameter should be avoided, as it can flatten the O-ring cross section. If the O-ring must be stretched past the five percent mark, the gland depth should be reduced to retain the necessary compression.
Proper installation – As with any component, proper installation is important to successful operation. In the case of O-rings, installers should use the correct lubricant, keep both the O-ring and gland clean, and install the O-ring without stretching or pulling on the device with a screwdriver or other tools. The surface finish should also be inspected before installation, and an O-ring with scratches, nicks or imperfections should not be used.
Choose a reputable supplier – Sourcing O-rings from a reputable supplier or manufacturer can help avoid potential production-related quality concerns. Poorly made O-rings might fail sooner than expected due to low quality materials.
