Materials For Seals in Pneumatic Roofbolters

I. Rubber Seals
1. Nitrile Rubber (NBR)
Applicable Scenarios: Normal temperature (-20℃~80℃), light load conditions, good water resistance, low cost.
Limitations: Prone to aging at high temperatures, general oil resistance (only suitable for oil-free or low-oil environments).
2. Fluororubber (FKM)
Advantages: Excellent oil resistance (swelling rate <5%), temperature range -30℃~200℃, suitable for oil-containing media.
Disadvantages: Poor elasticity, high cost.
3. Hydrogenated Nitrile Rubber (HNBR)
Features: Strong corrosion resistance (acidic environment with pH<5), temperature resistance -40℃~150℃.
4. Polyurethane (PU)
Performance: Abrasion resistance is 3 times that of nitrile rubber, oil resistance is 5 times higher, but it is prone to embrittlement at low temperatures.
II. Engineering Plastics
1. Polytetrafluoroethylene (PTFE)
Characteristics: Extremely low friction coefficient (approximately 0.04), temperature resistance -273℃~300℃, corrosion resistance, but high cost.
2. Perfluoroelastomer (FFKM)
Application: Ultra-high temperature (120℃~200℃) environment, compression set <10%.
III. Composite Materials
Teflon + Nitrile combination sealing ring: Combines low friction and oil resistance, suitable for hydraulic and pneumatic systems.
Selection Suggestions
Conventional conditions: Prioritize nitrile rubber or polyurethane.
High temperature/oily environment: Fluororubber or perfluoroelastomer.
Acidic media: Hydrogenated nitrile rubber.