Rotary shaft seals are generally used to seal rotating machine elements. They can be manufactured using several kinds of standard and special elastomers. However, selection of the right elastomer must be depended on several parameters, including operating temperature and operating medium, among others.
This blog attempts to provide an overview of commonly used elastomers in the manufacturing of high pressure rotary shaft seals.
High Pressure Rotary Shaft Seal Manufacturing – Types of Elastomers Used
- NBR – Acrylonitrile-Butadiene Rubber: The material is largely chosen due to its exceptional resistance to mineral oil-based lubricants and greases. Also, it possesses excellent abrasion resistance, ensuring unfailing performance for years. The drawback of this material is that it cannot resist fuels with a high aromatic content and non-inflammable hydraulic fluids.
- FPM – Fluoro Rubber – The material is known for its good resistance to high pressure and temperature. In addition, it can withstand harsh chemicals, ageing, and ozone. Although, the material can resist mineral oils and greases, aromatic and chlorinated hydrocarbons, FPM cannot withstand polar solvents and low-molecular organic acids.
- PTFE – Polytetrafluorethylene – It is the commonly used elastomer for high pressure rotary shaft seals due to its outstanding resistance to wide temperature range, ozone, weather and ageing.
In addition to these standard elastomers, several special elastomers are available to manufacture rotary shaft seals. These include:
- HNBR – Hydrogenated Acrylonitrile-Butadiene Rubber – The material is widely chosen for high temperature applications. It possesses exceptional mechanical properties, good resistance to wear, and outstanding resistance to ozone.
- VMQ – Silicon Rubber – This specialized elastomer is widely chosen for rotary shaft seals that are meant for food processing and medical industry applications. The material is ideal for use in a temperature ranging from -50°C to +200°C. VMQ possesses excellent resistance to ageing, transmission oils, animal and vegetable oils and fats.
- EPDM – Ethylene-Propylene-Diene Rubber – The material exhibits good resistance to natron and potassium hydroxide solutions, several polar solvents and harsh chemicals.
Apart from these, manufacturers utilize ACM – acrylate rubber, and NBR graphite / NBR MoS2 to fabricate high pressure rotary shaft seals.
The aforementioned elastomers are mixed with the following materials to produce the finished material.
- Filler material
- Softeners
- Processing aids
- Vulcanization agents
- Accelerators
- Additives
High pressure rotary shaft seals are designed for demanding applications, experiencing high levels of stress, impact, and abuse. Since they are ought to perform in stressful industrial environments, they must be manufactured utilizing the best of raw material. All the aforementioned elastomers are known for their exceptional mechanical and physical properties.
