Why Are High-Performance Vulcanized O-Rings A Preferred Choice?

by Jack Scarlett Blogger

EMI rings are common in the medical, aerospace, automotive, and medical industries because they reliably protect against Electromagnetic Interference (EMI) and radio-frequency interference (RFI). Moreover, they guarantee electrical conductivity and environmental sealing.

To meet the necessary performance requirements, high-performance vulcanized custom O-rings are recommended over molded O-rings. They’re also a sound economic decision. Statistics prove that vulcanized O-rings provide just as much protection against electromagnetic interference (EMI) and radio frequency interference (RFI) as the molded variety. Additionally, electrically conductive EMI/RFI O-rings are considered just as effective in the role of environmental sealing.

The Use of EMI-based Bonding Agents In The Vulcanization Process

The custom O-ring requires an EMI bonding agent whose characteristics match the extruded cord. This will eliminate EMI penetration or leakage. Custom rubber rings use a silicone-based adhesive that contains EMI filler in their bonding process. Using a non-silicone glue without EMI filler is not recommended as it can lead to leakage, resulting in a weaker seal.

Pricing And Molded EMI-Shielded O-Rings

The compounds used for EMI and RFI O-rings are expensive. On top of that, the molding process leads to waste in the form of uncured compound. This waste cost is factored into the total amount of the O-ring, driving the customer’s price up. Custom rubber rings do away with this needless expense. And because the extruded cord has already moved through inventory and can be vulcanized on immediately, the entire manufacturing process is made more efficient.

Another problem with using non-silicone glues like acrylics is that they dry much harder than an EMI silicone core. The resulting “hard spot” in the finished gasket can lead to breakage because the glue can’t match the temperature range of the EMI’s cord material.

The Solution

To remedy this, it’s essential to use a bonding agent that displays characteristics identical to the extruded cord. A reputable custom O-ring manufacturer knows this, which is why custom O-rings are bonded with adhesives that are silicone-based. The adhesives also contain EMI filler to stop anything from entering or leaving the seal.

When To Choose Custom Rubber Rings

The prime incentive for using a custom O-ring is when a military specification requires it. Customized O-rings can also be used when an EMI ring is too small and therefore can’t be vulcanized, necessitating remolding. In this instance, both the cross-section and surface area of the tool dictate the minimum size of ring that can be vulcanized. O-rings can also be used in environments that are static and non-pressurized.