


The first material that we are going to look at is Nitrile Buna- N 70 or NBR for short.
Leather is probably the oldest of the lip materials still in common use, but the move towards mass production methods has seen a massive increase in the development of synthetic rubbers which lend themselves to accurate and repeatable injection and compression moulding. Nitrile (NBR) is still by far the most common elastomer for “normal” use, whilst Viton® (FKM/FPM) is rapidly replacing Polyacrylate (ACM) and Silicone (VMQ) for high-temperature applications. Viton® also has high resistance to abrasion and chemical attack making it a preferred elastomer. Recent developments in the use of PTFE for Rotary shaft seals has caused widespread interest particularly for high-speed shaft rotation or poor lubrication applications.
<Seal selection example>
Based on the above flowcharts, the oil seal type that meets the requirements shown in Table 3 would be the type code MHSA or HMSA shown in Table 4.
A more comprehensive study of aeration by Dinzburg8 showed that even a minimal level of aeration of an aggressive European SF oil led to protection of a VDF/HFP/TFE compound, but to severe deterioration of an HNBR compound. He notes that aeration increases the severity of aging in oil for silicone and acrylic elastomers, while decreasing the severity for FKM elastomers.
In fact, modern and outstanding engine concepts require new and outstanding properties and solutions for dynamic seals, which continuously can withstand the high loads.
Different Types of Oil Seals