Elastomers are synthetic polymers that can bend and stretch in numerous ways and then return to their original shape. Because elastomeric products are so ubiquitous, it is tempting to believe that all elastomers serve the same purpose - but think again. Here, APM Hexseal offers a handy guide of the different types of elastomers that it uses, as well as some of their most common applications.
Commonly used as insulation and for injection moulding products such as vehicle tires, rubber bands, and pencil erasers, elastomer production is actually one of the most dynamic fields in manufacturing. More than 20 different types of elastomers exist to serve unique functions in both process equipment and finished products.
Different elastomer formulations affect a parts physical properties, functions, and service life. Therefore, it is important to test a few different elastomers, when assembling a product, to determine the best one for your needs.
Silicone
Although it is used extensively for outdoor applications, silicone appears in a wide range of industries and industrial processes as well. Silicone elastomers hold up well against ozone, salt spray, soap, weather, fungus, dust, most acids, as well as lubricating oil.
This elastomer also performs well across the widest range of temperatures of all elastomer options while remaining extremely flexible. Its low compression requirements ensure that it has many different uses, and the FDA recommends its use in the food and beverage industry. Silicone is the most common elastomer used at APM Hexseal, used in the fabrication of its boots, Seeloc washers, Seelnuts, as well as its O-rings.
However, silicone does not perform well when exposed to petroleum or related products. It also tears and abrades easily, making it unsuitable for applications that expose it to sharp objects or coarse surfaces. These properties can also cause silicone to create a lot of friction and it is permeable to gases as well. APM recommends using other elastomers when products are intended to operate in environments where exposure to ketones or highly concentrated acids is likely.
FluoroSilicone
Aerospace manufacturers value FluoroSilicone for its ability to hold up against ozone, petroleum, soap, and chemical exposure, making it an excellent choice for applications where there is exposure to oil and fuel. It also performs well at temperature extremes, so it is geographically universal. However, FluoroSilicone has limited physical strength, low abrasion resistance, and high friction characteristics.
APM does not recommend it for applications that involve exposure to brake fluids, hydrazine, or ketones. APM uses FluoroSilicone as an alternative to silicone in many of its products including O-rings, Seelnuts, Seeloc washers, and boots.
Neoprene
Neoprene has relatively low compression requirements, and industries as varied as construction, medical, sporting goods, and marine manufacturing prize it for its high resilience and physical toughness. Furthermore, neoprene can withstand a wide range of elements, such as hydrogen and natural gas, ammonium salts, mineral oils, silicone oils and greases, petroleum oil, Ozone, soap, Freon®, as well as oxygen and oxygen aging.
Finally, Neoprene is relatively inexpensive to produce, allowing manufacturers to construct economically competitive products with this material without sacrificing performance. Neoprene can resist moderate levels of chemical exposure, but it does not perform well in applications that expose it to strong oxidizing acids, chlorinated/aromatic/nitro hydrocarbons, ketones, or esters. The FDA approves of Neoprene’s use in many food and beverage processing applications.
Buna-N (Nitrile) Viton® (Fluorocarbon)
Nitrile holds up against threats from water, soap, hydraulic fluid, silicone greases, alcohol and petroleum. Oil drillers and automotive manufacturers use Buna-N in a wide variety of applications, valuing it for its resistance to petroleum-based oils and fuels, low compression set, high abrasion resistance, and high-tensile strength.
Nitrile does not hold up well against environmental factors like weather and temperature extremes. It also performs poorly in environments that involve high amounts of ozone, polar solvents, chemicals, or flames, as well as those with ambient chlorinated hydrocarbon and aromatic hydrocarbons. Buna-N is yet another alternative to silicone in APM’s range of boots, Seeloc washers, Seelnuts, and O-rings.
Viton (fluorocarbon)
Viton fluorocarbon is an elastomer that can handle the highest temperatures and the most hostile conditions. It boasts high resistance to chemicals, oils, weather, water, ozone, and fuels. Viton’s extremely high chemical resistance also stands out among other elastomers, making it particularly useful for manufacturing O-rings. The base polymer and compounding ingredients in the final products improve the elastomer’s performance.
Many industries use fluorocarbons, from aerospace/aviation manufacturing to chemical processing, and it is also the top choice for oil/gas exploration and refining. Fluorocarbon does not perform well with ketones, nitro hydrocarbons, amines, hot hydrofluoric/ chlorosulfonic acids, or low-molecular weight esters and ethers. It also loses flexibility when exposed to low temperatures.
EPDM
Widely used in industries such as HVAC installation, industrial manufacturing, roofing, and automotive assembly, ethylene propylene diene terpolymer (EPDM) provides excellent resistance to ozone, oxidants, and weather conditions. It can also stand up to soap, aging, and steam as well as temperature extremes, and it comes with excellent insulating capabilities.
In addition to its resistance to acids and solvents, EPDM can also withstand a wide range of weather conditions, making it a good choice for use in outdoor equipment. EPDM does not perform well against oils or in food-related applications. It also does not work well when exposed to hydrocarbon fluids.
Despite their numerous differences, all elastomers bring advantages to the injection moulding field. Injection moulding forces rubber compounds through runners into a mould by using high pressure, and elastomers’ unique properties allow them to perform very well in this environment. Elastomers are also a great choice for products made via compression molding.
This process handles high-viscosity compounds. It processes compounds into a pre-form, and then compresses the pre-form into a mould and cures it. Elastomers protect against a host of hostile environments, including extreme temperatures, oils and chemicals, food and beverage, road salt, air, dirt/dust/sand, water, as well as extreme weather.
With all the options available for elastomers, finding the right one is crucial. APM Hexseal uses its in-depth knowledge of elastomers to create the most optimal self-sealing boots, fasteners, and hardware for every application. To learn more about how it can help choose the best material, ask the experts at APM Hexseal.
Having spent a decade in the fastener industry experiencing every facet – from steel mills, fastener manufacturers, wholesalers, distributors, as well as machinery builders and plating + coating companies, Claire has developed an in-depth knowledge of all things fasteners.
Alongside visiting numerous companies, exhibitions and conferences around the world, Claire has also interviewed high profile figures – focusing on key topics impacting the sector and making sure readers stay up to date with the latest developments within the industry.
