emi shielding gaskets deflashing

Deflashing EMI Shielding Gaskets and EMI O-Rings


Nitrofreeze® provides deflashing services for EMI shielding gaskets and EMI O-rings. These environmental seals and EMI shields are made of electrically conductive silicones, elastomers that are filled with metal or metal-coated particles to provide protection against electromagnetic interference (EMI), a growing problem with electronic devices and electrical equipment

At our Worcester, Massachusetts (USA) facility, Nitrofreeze® can use cryogenic deflashing or dry ice deflashing to efficiently remove flash from your molded parts. These processes won’t change critical part dimensions or affect physical and mechanical properties. They’re also fast and efficient. Keep reading to learn more, or contact us for a quote.

Mold Flash on EMI Gaskets and EMI O-Rings

Flash, or flashing, is excess material on the surface of a part, typically because of leakage between mold surfaces. When manufacturing EMI shielding gaskets and EMI O-rings, compression molding rather than injection molding is used. That’s because compression molding is a better choice for more viscous elastomers like particle-filled silicones. Compression molding doesn’t need to push the rubber through sprues, gates, or runners. Excess material can still form along the mold’s parting lines when the tool is closed.

Compression molders want to ensure that gaskets are free from defects, especially with more expensive materials such as electrically conductive silicones. The metal or metal-coated particles in these elastomeric compounds can be made of nickel-aluminum, nickel-graphite, silver-aluminum, silver-copper, silver-glass, or silver-nickel. Silver, of course, is a precious metal. The base elastomer is either silicone, which continues to be in short supply, or fluorosilicone, which can be significantly more expensive.

If mold flash is excessive, an EMI gasket or EMI O-ring may not seat and seal properly. This can result in the ingress of water or environmental contaminants as well as electromagnetic interference. Any of these problems can affect the performance of the electronic devices and electrical equipment where EMI shielding is used. When EMI shields meet all application requirements, however, they seal out the environment and absorb unwanted signals so that the resulting electrical current is sent to ground.

Better Parts Deflashing for EMI Gasketing

Nitrofreeze® cryogenic deflashing and dry ice deflashing are faster than manual deflashing and provide high-quality results. The first process, cryogenic deflashing, freezes parts and blasts them with polycarbonate media. The non-abrasive polycarbonate media that Nitrofreeze® uses comes in different lengths and diameters to reach part features. Batches of molded EMI gaskets or O-rings are put in a perforated drum inside a computer-programmable machine and then subjected to very low temperatures. The EMI silicone flash becomes embrittled, and the plastic media cleanly removes part flash.

Nitrofreeze® can also use dry ice deflashing, to deflash EMI shielding gaskets and EMI O-rings. Dry ice blasting can be used on individual parts or batches of parts. It can be used on components that are too large to fit inside a cryogenic machine. Most EMI O-rings can be processed with cryogenic deflashing or dry ice deflashing, however, and these processes allow us to save the “recipe” for removing mold flash from future batches of the same part.

Nitrofreeze® Deflashes EMI Shielding Gaskets and O-Rings

What’s the best way to remove flash from compression-molded EMI shielding gaskets and O-rings? Contact the experts at Nitrofreeze® to review your requirements. If your molded part is a viable candidate for any of our deflashing techniques, we can perform sampling to demonstrate our process. The consultation is free of charge. Nitrofreeze® also sells cryogenic machines and dry ice blasters so that molders of EMI gaskets and EMI O-rings can use this equipment in-house.

To learn more, contact us at (508) 459-7447 x105 or email us at info@nitrofreeze.com. Alternatively, you can fill out the form below to start your no-cost deflashing evaluation.