Both handle heat. Both resist oil. But when it comes to sealing performance, longevity, and chemical resistance—how do fluoroelastomer and polyacrylate really compare?
Fluoroelastomer (FKM) offers better overall performance than polyacrylate rubber (ACM) in high-temperature, chemical, and fuel-exposed environments, but it also comes at a higher cost.
I’ve helped customers choose between these two in everything from gearbox seals to engine gaskets. The right choice depends on your priorities: performance or price.
What is polyacrylate rubber (ACM)?
Polyacrylate rubber is a synthetic elastomer known for good oil resistance and heat stability, especially in automotive environments.
ACM is widely used in transmission seals, oil pan gaskets, and automotive hoses where exposure to hot oil is present, but chemical exposure is moderate.
✅ Core Features of ACM
| Property | Typical Performance |
|---|---|
| Temperature resistance1 | –20°C to +150°C |
| Oil resistance | Good (engine oils, ATF) |
| Oxygen/ozone resistance | Good |
| Chemical resistance2 | Limited (not for fuels or acids) |
| Cost3 | Lower than FKM |
We supply ACM seals for budget-sensitive applications like gear pump covers and oil filters, where moderate heat and oil exposure are expected but cost control is critical.
What is fluoroelastomer (FKM)?
Fluoroelastomer, often known by the brand Viton®, is a premium rubber that offers superior resistance to heat, fuel, chemicals, and environmental exposure.
FKM is used in demanding applications such as crankshaft seals, aerospace O-rings, chemical pump gaskets, and high-temperature rotary seals.
✅ Core Features of FKM
| Property | Typical Performance |
|---|---|
| Temperature resistance | –20°C to +230°C (some up to 300°C) |
| Oil and fuel resistance | Excellent |
| Chemical resistance | Excellent (acids, solvents, fuels) |
| Compression set4 | Low—ideal for long-term sealing |
| Cost | Higher than ACM |
I recommend FKM when equipment runs hot, handles aggressive fluids, or is expected to last longer without maintenance.
FKM vs ACM: Head-to-head comparison
If you’re debating which rubber to use in seals or gaskets, this chart makes it simple:
🧪 Performance Comparison
| Property | Polyacrylate (ACM) | Fluoroelastomer (FKM) |
|---|---|---|
| Max temperature | +150°C | +230°C (up to 300°C) |
| Oil resistance5 | Good | Excellent |
| Fuel resistance | Poor | Excellent |
| Ozone/weather resistance | Good | Excellent |
| Chemical resistance | Limited | Excellent |
| Compression set (sealing) | Moderate | Low (very good retention) |
| Dynamic motion durability6 | Moderate | High |
| Cost | Lower | Higher |
So: if you’re sealing hot oil in a gearbox at moderate speed, ACM may be fine. But if fuel, high pressure, or chemical exposure enters the equation—FKM wins every time.
When should you choose ACM instead of FKM?
ACM has a clear advantage in cost-sensitive automotive and industrial applications—especially when conditions are controlled and performance demands are moderate.
Choose ACM for low-pressure, oil-resistant seals in environments up to 150°C, where fuel exposure is not present.
📌 Ideal Use Cases for ACM
- Automotive transmission seals7
- Power steering hoses8
- Oil pan gaskets9
- Light-duty rotary oil seals
One client producing compact gear pumps for forklifts uses ACM for their standard line—but switches to FKM for the export models used in desert environments.
When is FKM clearly the better choice?
If failure isn’t an option—or if chemicals, fuel, or extreme heat are involved—FKM is the right pick.
Choose fluoroelastomer when dealing with fuel, chemicals, high temperature, or long-life expectations.
📌 Ideal Use Cases for FKM
- Crankshaft and camshaft oil seals10
- Fuel injector O-rings11
- Chemical-resistant pump gaskets12
- Turbocharger and high-heat seals
We often upgrade clients to FKM when they deal with biodiesel or ethanol blends. ACM can’t handle those fuels long term—FKM seals last much longer.
Conclusion
Fluoroelastomer beats polyacrylate in almost every technical category—but at a higher price. Choose based on application severity and performance priorities.
Need help picking between FKM and ACM for your next sealing project?
Contact Julong Rubber or Request a Quote for price comparisons and technical guidance.
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Understanding temperature resistance is crucial for selecting materials that can withstand extreme conditions. Explore this link for detailed insights. ↩
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Chemical resistance is vital for ensuring material longevity in harsh environments. Discover more about suitable materials here. ↩
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Cost analysis helps in making informed decisions for material selection. Learn more about the cost differences and benefits here. ↩
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Low compression set indicates better long-term sealing performance. Learn more about its significance in sealing applications. ↩
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Understanding oil resistance in elastomers is crucial for selecting the right material for applications involving oils. Explore this link for detailed insights. ↩
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Dynamic motion durability impacts the performance of elastomers in moving applications. Learn more about the factors influencing this durability. ↩
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Explore this link to understand how automotive transmission seals enhance vehicle performance and reliability. ↩
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Learn about the critical role of power steering hoses in vehicle steering systems and their maintenance. ↩
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Discover the importance of oil pan gaskets in preventing leaks and ensuring engine efficiency. ↩
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Explore this link to understand the materials that enhance the performance and longevity of crankshaft and camshaft oil seals. ↩
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Learn about the critical role of fuel injector O-rings in engine performance and maintenance. ↩
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Discover the top materials for chemical-resistant pump gaskets to ensure durability and efficiency in your applications. ↩
