The Ultimate Guide to Rubber Extrusions

Rubber is everywhere, from car tyres to furniture tips. It’s such a common material that rubber’s purposefulness in everyday life becomes negligible for many. Whether it’s derived from trees or petroleum byproducts, the world will always find some use for rubber.

The rubber industry has several ways of processing rubber, such as calendaring, latex dipping, moulding, and the most common: extrusion. Simple and mass-producible, extrusion produces rubber products for various uses, from door and window seals to utility gaskets.

Their widespread applications make them an in-demand product. Learn more about rubber extrusions, their manufacturing process, and their applications.

What is rubber extrusion?

The term ‘rubber extrusion’ refers to both the process and the product. Extrusion, simply put, is the process of forcing the rubber through an elongated die. Manufacturers custom-shape and use different dies to produce extrusions for numerous applications. For instance, a window seal has a different die to that of a utility gasket.

Our array of rubber extrusions comes in three shapes: E-shape, P-shape, and U-shape. E- and P-shape extrusions are moulded from ethylene propylene diene monomer (EPDM) rubber, a kind of synthetic rubber sought for its durability, UV stabilisation as well as cold and heat resistance. Meanwhile, U-shape extrusions are made from natural rubber, which is also durable but has low resistance to heat. With the exception of some of our U-Shapes also being made from the EPDM material.

Despite some differences in their innate properties, there’s always a good reason to buy rubber extrusions for each type. We’ll learn these in detail a little later.

What is the process of rubber extrusion?

The rubber extrusion process begins as a lump of unvulcanised rubber. While the material’s elasticity and durability can be attributed to vulcanisation or adding chemical agents to form molecular bonds, unvulcanised rubber has neither of these properties.

The compound is then fed into the extruder, a tube with a large screw inside and external heaters to form the desired consistency. The extruder then pushes the substance through a die where it conforms to the die’s shape as it passes through. Sometimes, multiple extruders blend different types of rubber, creating a more resilient material to push through the die.

Once it comes out of the die, the rubber undergoes vulcanisation, which involves applying heat and binding agents. The temperatures used in this process are hotter than those in the extrusion, around 140 to 160o C. The agents, usually sulphur or sulphur-based compounds, are responsible for forming the crosslinked polymer chains which give rubber its elasticity.

After vulcanisation, the rubber is ready for cutting and other necessary processes depending on the nature of the end product. For example, door and window seals appear as a continuous loop, so the rubber needs to be cut and spliced.

What are the benefits of rubber extrusions?

The biggest advantage of rubber extrusions is their seamless appearance. Even as some rubber is cut and spliced, the processes used to do so (hot and cold splicing) are designed to make rubber products hold under immense stresses and harsh conditions. Because of this, you don’t need to cut and splice the rubber yourself, maintaining the rubber’s integrity.

Additionally, the simplicity of rubber extrusion manufacturing results in favourable cost-effectiveness. The machinery required isn’t as complicated or resource exhaustive as other processes like moulding, helping keep the cost of extrusions in the market low. Although not viable for processing very soft rubber, extrusion is still a good choice for most types of rubber.

Where are rubber extrusions used?

Various types of rubber extrusions are used across industries. It’s a highly evident fact when you observe your surroundings. Here are some examples:

• E-shape: This extrusion consists of an enclosure dangling from an extended flap, all in the shape of a small letter E. The enclosure serves as a buffer mounted on the edges of boats and trolleys or as a sheath for delicate wiring.

• P-shape: This extrusion appears as a letter P but with a more bulbous head. It sees widespread use in construction, namely as door and window seals. Proper sealing is instrumental for a house or office building to save on energy costs.

• U-shape: This extrusion is as true to its name as the other two, though it can appear with a rounded or flat base. It’s often inserted along the edges of glass or metal sheets to prevent chipping and cutting someone unaware.

The market is also rife with other shapes and forms of rubber extrusions. Each of them gets the job done in their respective applications, whether sealing doors and windows or ensuring a car’s engine works as intended.

Rubber extrusions are cost-effective for their durability and versatility, making them sought after in many industries. You’ll rarely find a shortage of types of extrusions in the market, let alone in their supply, thanks to the ease of manufacturing.