Elasto Proxy fabricates and distributes silicone bulb trim for sealing, insulation, and edge protection. We can supply you with coils of rubber that you fabricate yourself, or we can provide cut lengths or ready-to-install gaskets. With our supply chain strength, Elasto Proxy sources silicone bulb trim from U.S. and European suppliers so that you can minimize the effects for tariffs.
Keep reading to learn more and contact us for more information or to request a quote.
What is Bulb Trim?
Bulb trim is used with doors that have rounded, or radiused, corners. It consists of a softer rubber bulb and a harder rubber trim, or retainer. The trim section installs over the edge of the door. The bulb fits between the door and the door jam. When the door is closed, the bulb compresses to provide a seal. When the door is opened, the bulb returns to its original dimensions.
Each section of a bulb trim has a different durometer, or hardness, on the Shore A scale. The bulb is softer to support compression, and the trim is harder to provide impact resistance. The bulb needs to be large enough to fill the gap between the door and the door jam, and the trim needs to cover the edge, or flange, completely while remaining in position.
Why Use Silicone?
Silicone bulb trim combines temperature resistance and flexibility with environmental sealing and edge protection. Silicone is a synthetic polymer that can withstand a wide range of temperatures without significant changes in its material properties. It can resist higher temperatures than many other rubbers and remains flexible at low temperatures.
In addition to heat and cold, silicone resists water, ozone, sunlight, and many chemicals. Because it’s chemically inert, silicone won’t react with most substances. This makes it safe for many food contact and medical applications, but special grades may be required to meet industry or regulatory requirements. Silicone costs more than other polymers, but it offers strong advantages.
Product Specifications for Silicone Bulb Trim
Because silicone bulb trims are used with rounded corners, engineers need to specify the minimum edge radius. It’s also important to consider material properties, bulb and trim specifications, standards and approvals, and product colors.
Material Properties
Silicone bulb trim can be made of solid, sponge, or a combination of sponge and solid materials. Silicone sponge can have open cells that allow for the absorption of liquids or closed cells for water resistance. Material specifications include durometer, temperature range, and tensile strength: the maximum stress a material can withstand while being pulled or stretched.
Bulb Specifications
Most silicone bulb trims have a single rounded bulb; however, products with other bulb styles and shapes are available. Examples include teardrop-shaped double bulbs with an extended lip. The location of the bulb can vary, so make sure to account for how your door opens. To choose the right bulb size, find the average jam dimension and add 25% to 50% to support compression.
Trim Specifications
There are two key specifications for the trim section: edge thickness and leg length.
- The edge thickness needs to match the thickness of the door’s edge.
- The leg length needs to be long enough to cover the flange.
The trim section can contain interior tongues for additional gripping or reinforcements for greater impact resistance.
Standards and Approvals
Silicone bulb trim is available with UL 94 flame ratings for electronic enclosures. Engineers can also select products that meets FDA 21 CFR 177.2600 requirements for food contact applications. FDA approved silicone bulb trim is also used with medical and pharmaceutical equipment. For food equipment and potable water systems, silicone bulb trim that meets NSF-51 or NSF-61 may be needed.
Colors
Standard colors for silicone bulb trim include gray, black, red, and white. Often, gray is used for industrial applications while white is used with food processing, pharmaceutical, and medical equipment to convey cleanliness. Pantone color matching is available and is sometimes used for branding purposes. Translucent silicone supports light transmission and is used in LED enclosures.
Applications for Silicone Bulb Trim
Silicone bulb trim provides sealing, insulation and edge protection in demanding industries.
- Medical equipment: Diagnostic machines, sterilizers, ventilators, patient monitors and infusion pumps
- Food and beverage processing: Ovens, blenders, refrigerators, freezers, and filling and capping machines
- Automotive and mobile equipment: Engine compartments, vehicle interiors, and access doors for RVs and emergency vehicles
- Enclosures and industrial machinery: Outdoor electronic cabinets, dust and moisture seals for access covers, and vibration isolation in equipment frames.
Choose Silicone Bulb Trim from Elasto Proxy
Elasto Proxy sells silicone bulb trims that we keep in-stock or special order, but you can also request cut lengths or finished gaskets that speed installation. From reduced material waste to higher quality, the advantages of outsourced gasket fabrication are many – especially when you consider the true costs of in-house fabrication.
Ready to learn more? Talk to our team.
