Shielding technology is essential to protect electronics from electromagnetic interference. Many application-specific factors contribute to the impact that electromagnetic interference will have on a device, so it’s important to consider which shielding option is best for your specific case.
Shielding gaskets can be made from a wide range of materials to be shaped and sized to fit nearly any application. One of the more common gasket types is a conductive elastomer gasket. Two of the key manufacturing processes to produce elastomeric EMI gaskets are splicing and molding.
These two techniques offer different manufacturing and application advantages. Some applications can best be served by the use of both techniques for different areas of shielding within a device.
While splicing uses an adhesive or vulcanizing process to bond two conductive elastomer gaskets together, molding involves placing uncured conductive elastomers into a custom-designed mold, allowing the elastomers to form into a unique, consistent product. Both techniques have their advantages and disadvantages.
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The splicing process begins when conductive elastomer gaskets are created in long strips that need to be manipulated in order to form a proper O-ring. To create that O-ring, the elastomer gaskets are cut to the desired length and then fused together with a strong, proprietary adhesive glue at the ends. This process of cutting and fusing elastomer gaskets is called splicing.
Advantages of Splicing
The manufacturing process by which the shielding material is extruded is rapid and efficient. Materials can even be spliced in bulk. Similarly, these extrusion profiles can be designed to match the dimension requirements for almost any application. A hollow cross-section profile enables the manufacturing of parts that can succeed in low compression force enclosures.
The efficiencies within this process including low tooling cost for high production volumes, make it one of the most cost-effective EMI shield manufacturing techniques used today. Complex cross-sections can be designed using FEA (Finite Elemental Analysis) to meet the required closure force EMI Shielding and environmental sealing requirements.
Disadvantages of Splicing
While extruded gaskets can be designed with complex cross-sections, for complex gasket patterns, Form-In-Place (FIP) gaskets or molded gaskets are often the better.
Some have found that O-rings do not retain their shape as well as if they were to have been molded. Part of this might be due to the lack of complexity that the splicing process is able to achieve due to its loop-like way of operating.
The molded O-rings can be crafted to fit near any desired shape or size. The splicing process is also known for its low tolerance range. Typically, splicing will not hold tight tolerances. Of course, there are tight regulations for how small gaskets should be when spliced.
To mold a gasket, uncured elastomers are compressed into a pre-designed mold. Once the material takes the form of the mold, the gasket is complete. This allows for very precise size and shape and warrants unparalleled consistency throughout the manufacturing process.
Advantages of Molding
Once a mold is created, it makes for a resilient, durable gasket time and time again. A molded gasket allows for complex designs including joints, cross-sections, and more. Molded gaskets can retain their shape under extreme force and hold tolerances within thousandths of an inch. The nature of the molding process eliminates some of the manual labor present in the splicing process, making it even more cost-effective in some instances.
Disadvantages of Molding
The molding process requires a mold for each gasket pattern and design so it does not offer the flexibility and speed for design change offered by other techniques. The molding process can be less efficient when each new gasket design requires a new mold. Unlike splicing, the molding method is not conducive to creating hollow gaskets.
Vulcanizing is a commonly-known bonding technique used for splicing where heat, pressure and a splice are used to fuse the ends of a gasket together. At KraFAB, our expert manufacturers perform vulcanizations daily. This process is a dependable, cost-efficient way to join profiles of countless types of materials in a variety of different shapes and sizes.
Typically, this tactic is used when there is a space for the free-flowing passage of air to the gasket. All things considered, the vulcanizing technique should be used for low-volume applications as opposed to high-volume production rates.
Splicing vs. Vulcanizing O-Rings
Spliced and vulcanized O-rings have different purposes that should be taken into consideration well before the gasket manufacturing process. First, ask yourself whether or not the project at hand is a dynamic application or not.
If there are moving parts near the O-ring, a vulcanized O-ring likely isn’t the best fit. If the application is not dynamic, a vulcanizing ring might be a good solution. The vulcanized O-ring is suitable for a wide range of industries and applications, so long as there is a lid that needs to be sealed.
Molding and splicing are both industry-leading techniques for manufacturing durable EMI shielding gaskets of various shapes and sizes.
The best EMI gasket manufacturing process, material selection, and gasket design depend on variables including your need for rapid design change, closure force, operating environment, shielding attenuation needed at specific frequencies, and quantity required.