Many common rubber products are manufactured using a technique called rubber extrusion, during which rubber is heated and forced through a die to form a uniform, cross-sectional, continuous shape that can then be cut to the desired length.
Products that are commonly manufactured using a rubber extrusion process include rubber seals, weather strips, tubes, hoses, and gaskets.
Various types of rubber, including natural and synthetic rubbers, can be used in the extrusion process. Each type offers distinct properties and benefits suited to different applications. In this article, we will explore the different types of rubber used in extrusions and learn about their specific uses and the reasons they are chosen for different applications.
What are the different types of rubber used in extrusions?
Rubber extrusions can be manufactured using various types of rubber, from natural rubber to speciality synthetic rubbers. Let’s find out more about the different types of rubber used in extrusions and the products they are used to manufacture.
Natural Rubber
Natural rubber is made from latex, a type of liquid sap found in certain types of trees and plants. Most latex is sourced from the Hevea Brasiliensis tree, also known as the rubber tree. Natural rubber has excellent elasticity, flexibility, and durability; however, it is vulnerable to damage from UV and Ozone and is more expensive than synthetic rubbers. It is primarily used to produce automotive tyres but is sometimes extruded to manufacture seals, hoses, and gaskets.
Synthetic Rubbers
Synthetic rubbers are more commonly used to manufacture rubber products than natural rubber. Over 70% of the material used to manufacture rubber products is synthetic. Most synthetic rubbers are made through a chemical synthesis process using petroleum byproducts.
Styrene-Butadiene Rubber (SBR)
SBR is a cost-effective alternative to natural rubber. It is a general-purpose synthetic rubber manufactured from petroleum byproducts. SBR has excellent abrasion resistance and high tensile strength but poor weather resistance. It can also harden and lose its flexibility with age. It is often used to manufacture low-cost sealing products.
Ethylene Propylene Rubber (EPDM)
EPDM is the most common and widely used synthetic rubber and is the preferred material for manufacturing different types of rubber seals within almost every industry. So, what makes EPDM such a popular extrusion material? EPDM is a highly durable and resistant synthetic rubber. It can withstand exposure to extreme weather and ozone. It also has excellent chemical resistance and electrical insulating properties. EPDM is a low-cost material, so it’s easy to understand its widespread appeal. The only time EPDM is not suitable is for applications where it will be exposed to petroleum-based oils and fuels, which can cause this type of rubber to break down, and in extreme temperatures below or above -40 and 120 degrees celcius. At Seals Direct, many of our extruded rubber products are made from EPDM, including our edge trims, seals, rubber cords, and U channels.
Nitrile Rubber (NBR)
Nitrile Rubber, also known as Buna-N, is made by emulsifying butadiene and acrylonitrile in water and then polymerising the result. Nitrile stands out for its superior resistance to oils, fuels, and other chemicals, making it the perfect material for manufacturing rubber products used in the automotive, engineering, and industrial sectors. NBR is not suited to environments where it will be exposed to ozone or UV radiation, which can cause it to crack and degrade. Although NBR is more expensive than general-purpose synthetic rubbers like silicone and EPDM, its use is justified in applications that demand its superior oil and chemical resistance. For applications that do not require these specific properties, opting for a cheaper general-purpose rubber is a more cost-effective solution.
Silicone Rubber
Silicone is an exceptionally versatile rubber used to manufacture extruded rubber products for a variety of applications. It is produced by heating the chemical element silicon to 1800 degrees Celsius, adding methyl chloride, and distilling. Silicone stands out for its excellent temperature resistance, FDA approval, and non-toxicity properties, which make it a popular choice for the manufacture of extruded rubber products for the food, pharmaceutical, and healthcare industries.
Other synthetic rubbers
Other popular types of synthetic rubber used to manufacture rubber extrusions include neoprene (also known as polychloroprene) and fluoroelastomers (FKM). Neoprene offers excellent protection against ozone and sunlight, making it ideal for outdoor applications, whilst FKM is resistant to high temperatures and chemicals, including oils and fuels, making it popular within the automotive, aerospace, and chemical processing industries.
Rubber Extrusions from Seals Direct
At Seals Direct, we sell a wide range of extruded rubber products, including different types of rubber seals, rubber U channels, rubber P seals, rubber tadpole seals, T-shaped rubber seals, L-shaped rubber seals, and rubber cords.
With over 50 years of experience, we are one of the UK’s leading suppliers of rubber seals and trims. Whether you need one bespoke trim or a high volume of extruded rubber products, our team are here to provide you with a fast, efficient, and flexible service.