When I graduated from university and moved into my own place, the only house I could afford was right near a manufacturing plant. At first, I thought living in the industrial part of the city would be a nightmare, but it actually turned out to be fascinating. I quickly developed an interest in industrial equipment and supplies, and spent many evenings walking around the factories to get a better look at what was going on inside. Since then, I've moved to a quiet part of the city, but my interest in industry never waned. Since I don't have the luxury of being able to visit the industrial district anymore, I thought I'd do the next best thing--start a blog about it!
O-ring seals are small but essential components in most fluid power applications. Faulty installation of these seals can cause leakages and catastrophic system failures. Therefore, proper design, careful material selection and professional installation are vital.
O-rings may fail because of various reasons. Continue reading this guide for some invaluable insights on four common failures, their causes and some solutions for these essential seals.
Abrasion
You can notice abrasion on the sliding contact faces of the O-ring seal exhibiting grazed surfaces. This problem is commonly experienced in dynamic applications, where repeated contact between the housing and the seal causes excessive friction. Inadequate lubrication of the metal housing can aggravate the risk too.
Solution — Always provide enough lubrication to the sealing system. Consider using sealants that have enhanced abrasion resistance. Additionally, work with an expert for the right advice on an appropriate surface finish. You can also minimise ingress of contaminants by using scraper rings.
Out-gassing
Visually, your O-rings may show no evident signs of change, but shrinking may be witnessed in extreme conditions. Out-gassing happens when the elastomer formulation elements are volatilised under vacuum conditions. The out-gassed ingredients can cause severe contamination in semiconductor applications during wafer processing. Such particles also affect vacuum performance in industrial applications.
Solution — Materials designed from pure polymers can help reduce out-gassing. Additionally, consider using seal materials with the right temperature ratings as per your application. This way, you'll manage to keep out-gassing levels low.
Chemical Attack
Another common cause of O-ring failure is chemical attacks. When chemicals react with specific elastomers, it causes cross-link density. Consequently, this results in the production of brittle and hard substances. There can also be chain scission, which results in reduced strength.
Solution — Selecting a proper elastomer material is crucial in ensuring compatibility between the application media and the seal. Increased temperatures and stressed seals also heighten the chemical attacks. Therefore, it's recommended to choose the right sealant according to your system's specifications, which has high chemical and temperature resistance.
UV Degradation
Another common cause of O-ring failure is exposure to ultraviolet rays. Generally, UV light has shorter wavelengths and high energy, which can produce an extremely destructive effect on the seals. This light can also react with the exposed molecular surface of the elastomer, causing cracking and polymer chain cleavage. Consequently, this causes premature collapse and leakage from the seals.
Solution — Consider using fluorinated or black materials for your seals that have excellent resistance to UV light.
Conclusion
These are the four common causes of O-ring failures, their causes and solutions. However, there are other possible causes not discussed here, including thermal extrusion, spiral failure, installation damage, and plasma degradation, etc. Consider researching more about them to have a better understanding of your O-rings and how to identify and fix any problems immediately.
For more information, contact an O-ring supplier