Specialty Silicone Products makes offsets, or alternatives, to CHO-SEAL materials from Parker Chomerics. For example, SSP2486-70 is our 70-durometer (Shore A) silver-aluminum fluorosilcone that can be used instead of CHO-SEAL 1298. Like many of our EMI elastomers, SSP2486-70 is part of the M83528 Qualified Product List (QPL) from the Defense Logistics Agency (DLA).
Recently, a defense contractor asked us to price sheets of this EMI fluorosilicone material. The specifying engineer wanted a cost-effective alternative to CHO-SEAL 1298, but that wasn’t the only requirement. The project required rectangular EMI gaskets on a tight timetable, so we explained that the fastest and most cost-efficient approach was for SSP to supply the finished parts.
Materials Manufacturer and Gasket Fabricator
SSP is both a materials manufacturer and gasket fabricator, so we make our own tooling in-house. That includes molds that resemble a picture frame with an empty area in the middle. For rectangular EMI gaskets like our defense contractor needed, molding uses less material than cutting. That’s because the cut material in the middle of a frame gasket is a form of material waste.
The engineer who contacted us was pleased that we had a frame mold already in stock. SSP makes standard EMI gaskets with M83528 part numbers, but we also provide custom EMI gaskets with faster turnaround times than the competition. Because this was a military project, SSP’s ability to securely handle export-controlled and controlled unclassified information (CUI) was also essential.
After determining that SSP had the right capabilities, the engineer asked about some other EMI elastomers that we offer. We shared pricing and potential delivery dates for several materials along with shielding effectiveness and compression/deflection data. This information is readily available on our website, but we’re happy to help you find what you need.
Technical Assistance for Added Value
In addition to helping the engineer select an EMI elastomer and manufacturing method, SSP answered questions about housing materials and hole placement for fasteners. Unlike some large companies that restrict access to their engineering teams, SSP put the defense contractor directly in touch with Taylor Smith, our Product Engineer.
Taylor shared the results of his calculations along with some general recommendations. For example, don’t place stiff fasteners more than 2” apart. With sheet metal, .075” apart is recommended. SSP also shared best practices for fastener spacing on the corners. For example, if the spacing on a frame length is 2”, then the spacing at the corners should be 1”.
With corners, it’s also important to space fasteners evenly from each other on both the X and Y axes. Plus, all holes should be located farther from the edge of the gasket than the gasket’s thickness. Finally, flanges should be bent outward so that screws and bolts won’t penetrate the shielded compartment. To prevent leakage, the EMI gasket must fit snugly around the threads of the bolts.
Ask SSP for CHO-SEAL Offsets
SSP’s ability to provide this type of assistance is part of what makes us different. Along with making our own materials and tooling, SSP prides itself on lower minimum order quantities (MOQs) and faster lead times. If you’re looking for an offset to CHO-SEAL 1298 or another Parker Chomerics material, contact us.
