Frequently Asked Questions — ACM O-Rings
What is ACM polyacrylate rubber?
ACM (Acrylic Rubber) is a polyacrylate elastomer developed specifically for resistance to hot engine lubricants. Its ester or epoxy side chains give it excellent stability in hot oil environments where standard NBR hardens and cracks over time. ACM bridges the gap between NBR and HNBR for hot oil sealing applications.
What temperature range can ACM o-rings handle?
Standard ACM o-rings operate from −25 °C to +175 °C in hot mineral oil. Cold-resistant ACM grades extend the lower limit to −40 °C. The upper limit makes ACM suitable for automotive powertrain positions that exceed NBR's +120 °C but do not justify the cost of HNBR.
What chemicals is ACM resistant to?
ACM has excellent resistance to hot mineral oils, automatic transmission fluid (ATF), motor oils, gear oils, and ozone. It is not suitable for hot water, steam, glycol coolants, aromatic solvents, or concentrated acids — applications where EPDM or FKM would be the correct choice.
What are typical applications for ACM o-rings?
ACM o-rings are used in automotive automatic transmissions, power steering systems, differential and gearbox seals, and turbocharger oil seals — wherever long-term contact with hot ATF or gear oil above 120 °C is expected. ACM is the standard choice for OEM transmission sealing in the automotive industry.