Why Your Gaskets Aren’t Holding Up
It starts small: A device shows signs of interference. Moisture creeps into an enclosure that’s supposed to be sealed. The issue compounds, and suddenly, your carefully engineered system isn’t performing as it should. You replace the EMI gasket, but you’re back where you started within weeks. What went wrong?
The problem often lies in a detail that’s easy to overlook but impossible to ignore: compression set. This single property of your gasket material determines whether your seal stays effective or collapses under pressure—literally. Let’s explore how compression set impacts performance, why it fails in demanding applications, and what you can do to fix it for good.
What is Compression Set and Why it Matters
Compression set measures how well a gasket material recovers after being compressed. It’s expressed as a percentage: the lower the percentage, the better the material is at bouncing back to its original shape. For example:
- Low compression set (15-19%):The gasket maintains its shape and seal over time.
- High compression set (>40%):The gasket flattens permanently, leading to gaps in the seal.
When compression set is high, the gasket fails to maintain consistent contact with the surfaces it seals. This is catastrophic for applications requiring electromagnetic shielding and environmental protection.
The Pain Point: Why High Compression Set Leads to Repeated Failures
Think about what happens when a gasket permanently flattens.
- Gaps Form:Even small inconsistencies in compression allow EMI to penetrate or environmental contaminants to seep in.
- Uneven Shielding:Flattened areas lose their shielding capability, introducing unpredictable system noise or interference.
- Assembly Nightmares:Replacing failed gaskets mid-project delays timelines and increases labor costs.
This isn’t just frustrating—it’s expensive. Teams often blame the installation process or environmental conditions, but the real culprit is often a gasket with a high compression set that is poorly matched to the application.
Common Scenarios Where Compression Set Fails
- Temperature Extremes:Gaskets exposed to cycling temperatures (e.g., outdoor enclosures or industrial equipment) are particularly prone to flattening. At high temperatures, materials soften and compress further. Without a low compression set, the gasket won’t rebound when the temperature drops.
- Frequent Access Enclosures:Devices requiring regular maintenance or inspection need gaskets that can recover from repeated compression. A high compression set means the gasket will fail after a few cycles, forcing costly replacements.
- Irregular Sealing Surfaces:Uneven or complex surfaces (e.g., corners, curves) put uneven pressure on gaskets. Materials with a high compression set can’t compensate for these stresses, leading to localized failures.
How to Choose a Low Compression Set Gasket That Performs
Understanding how material choice impacts performance is the key to solving compression set problems. Here’s what to look for:
- Compression Set Percentage:Aim for gaskets with a compression set below 20%. Jemic’s EMI gaskets, for instance, maintain a compression set of 15%-19% under standard conditions, ensuring long-term reliability.
- Material Composition:Closed-cell foam cores and fabric-over-foam designs are excellent for maintaining shape and sealing capability, even under high compression forces.
- Testing for Your Application:Insist on test data for both shielding effectiveness and environmental durability. Compression set testing should simulate real-world conditions like temperature cycling and repeated compression.
- Custom Solutions:For complex applications, pre-assembled gaskets (like Jemic’s “picture frame” designs) ensure uniform compression and reduce weak points caused by misaligned edges.
Compression Set is the Core of Gasket Performance
Regarding EMI shielding, it’s easy to focus on specs like attenuation or conductivity. But without addressing compression set, even the best shielding materials will fail. Understanding how compression set affects long-term performance—and choosing gaskets designed to minimize it—can save you time, money, and headaches.
Ready to fix your compression set problem for good? Contact us to find a gasket solution tailored to your application, and let’s eliminate failure from your designs.