Technical>Shields & seals material
Shields & seals material
● Shields material
HCH bearings employ carbon steel as standard, and the option of AISI-300 stainless steel is available when needed.

● Seals material
HCH bearings use a variety of sealing materials to meet the requirements of high temperature operation and compatibility with greases. Buna Nitrile is the standard material used, while fluorocarbon, silicone, and teflon seals are commonly specified for high temperatures.

Type ASTM D1418 Designation Temperature Range Hardness (Shore A) Features Limitation
Nitrile (Buna) NBR (-40~250F) 40~90 Low compression set, high ten- sile strength, and high abrasion resistance.
Excellent resistance to petro- leum-based oils and fuels.
Not recommended for very high temperature.
Not recommended for exposure to sunlight and chemicals as acid, ether and esters.
Silicone MQ/PMQ/ VMQ/PVMP (-94~400F) 25~80 High temperature and dry heat resistance.
High resistance to aging effects of both suglight and ozone attach.
Low abrasion and tear resistance.
High friction characteristics.
Nitrile (Hydrogenated) HNBR/NEM (-30~330F) 50~90 The hydrogenation of Nirtrile, heat resistance, tensile strength. Enhanced physical strength and chemical resistance. Not recommended for very low temperature.
Not recommended for exposure to sunlight and chemicals as acid, ether and esters.
Fluororubber FKM/FPM (-20~400F) 50~95 Combining high temperature re- sistance with outstanding chemi- cal resistance.
Highly resistance to petroleum products,acids and silicone fluids.
Not recommended for situations requiring low temperature flexibility.
Polyacrylate ACM Rubber (0~350F) 40~90 Excellent resistance to hot oil, sunlight and ozone degradation. Also features an enhanced abil- ity to resist flex cracking. Water resistance is lower. Not recommended for very low temperature.

Safety precautions for fluoro rubber is very stable and harmless in normal operating conditions up to +200 . However, if exposed to extreme temperatures above 300 , e.g. fire or the flame of a cutting torch, fluoro rubber seals give off hazardous fumes. These fumes can be harmful if inhaled, as well as to the eyes. In addition, should not be in contact with the skin either.

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