Edge trim seal materials include EPDM, neoprene, silicone, PVC and TPE. Each of these elastomers has its advantages, but what’s the right compound for your application? If you specify a trim seal material that’s wrong for your environment, the seal could fail in the field. For example, trim seals that won’t withstand sunlight may crack if installed on outdoor equipment or enclosures.
Let’s consider your choices and compare the different edge trim seal materials. Remember, too, that a trim seal can be fabricated from ether sponge rubber or solid rubber in a range of durometers, or hardness. Softer rubber provides greater compression while harder rubber offers greater impact resistance. If necessary, you can choose trim seal materials that are reinforced with metal wire.
EPDM Rubber Edge Trim
EPDM rubber edge trim resists moisture and withstands temperature extremes. It maintains its flexibility at low temperatures, provides a relatively high degree of electrical insulation, and exhibits superior UV resistance. EPDM edge trim also resists water and steam while providing good resistance to alkalis, acids, and oxygenated solvents.
Fire-rated EPDM edge trim is required for mass transit applications such as buses, subways, and trains. There isn’t just one standard for flame, smoke, and toxicity (FST), however, so engineers need to choose compounds with care. Fire-resistant trim seals are also used in electronic enclosures. Often, these industrial rubber products need to meet UL 94 flame ratings.
Neoprene Rubber Edge Trim
Neoprene rubber edge trim provides resistance to oils, greases, and other petroleum-based products. In addition to physical toughness, this trim seal material offers resistance to ozone, water, weather, and a wide range of indoor and outdoor temperatures. Unlike EPDM rubber, however, neoprene edge trim provides only limited flexibility at low temperatures.
With neoprene and other elastomers, edge trim seal materials come in both commodity and specialty grades. Commodity rubber costs less but may not meet the specific standard that your application requires. Specialty rubber costs more, so it’s important to ensure that you really need it. Otherwise, you could over-engineer your edge trims and incur unnecessary expenses.
PVC Edge Trim vs. TPE Edge Trim
PVC edge trim is strong, lightweight, and abrasion-resistance. Yet polyvinyl chloride (PVC) may crack in the cold and fade in the sunlight. TPE edge trim combines the processing strengths of thermoplastics with the flexibility of thermoset rubbers. Thermoplastic elastomers (TPEs) are less likely to break in the cold but generally cost more than other rubber materials.
TPE’s advantages include flexibility, shock absorption, and weather resistance. Its disadvantages include relatively poor recovery when exposed to heat and compression. Choose TPE edge trim for applications that require recyclable materials, or that need fully non-metal parts. If you need TPE with added impact resistance, TPE edge trim is available with a solid interior plastic core instead of a steel wire.
Silicone Rubber Edge Trim
Silicone rubber edge trim is used in applications that require low toxicity, low chemical reactivity, and thermal stability over a wide temperature range. Silicones can be specially-formulated to impart particular properties and are available in FDA approved silicone sponge. Typically, silicone edge trims are used in food and beverage processing, medical, pharmaceutical, and other sanitary or hygienic applications.
Choose the Right Edge Trim Seal Material
Elasto Proxy keeps hundreds of standard rubber profiles in stock and can custom-fabricate edge trim to meet your specific requirements. We also offer design assistance and help with compound selection. Value-added services like kitting and custom packaging are also part of what make us different from other gasket fabricators. To learn more about us and how we can help you, contact Elasto Proxy.