How Does Rubber Injection Moulding Work?

How Does Rubber Injection Moulding Work?

Originally a process intended for plastic moulding, rubber injection moulding was developed during the rise of the plastics industry in the 1960s. It is a complex manufacturing process that can be incredibly helpful in the development of new products. But how does it work? What is it used for, and are there similar methods that would be worth exploring? Let’s explore!

What is the Rubber Injection Moulding Process?

Rubber injection moulding is the process of injecting raw, uncured rubber through a hopper, into a metal mould. Pressure is applied, producing a chemical reaction in the rubber, known as vulcanisation or ‘curing’, which causes the cross-linking of polymer particles within the rubber. This means that the rubber develops the sturdy yet flexible qualities that are commonly associated with the material, allowing us to use it in different products where these qualities are needed.

The types of rubber used for this process include natural rubber, nitrile, silicone, hydrogenated nitrile butadiene and urethane.

The Results and What Comes Next

Now that you know how the rubber injection moulding process works, you may be wondering what you might do with the resulting product. Rubber injection moulding is used in the manufacturing process of thousands of different rubber products, with this particular method of rubber moulding a great way to meet high-volume orders. Rubber mould producers are increasingly adjusting to meet the expanding demand for hoses, rubber isolators, O-rings, tubing, rubber seals and grommets, amongst other popular rubber products.

Other Common Types of Rubber Moulding

As well as rubber injection moulding, there are two other common types of rubber moulding processes: compression moulding and transfer moulding. Like injection moulding, the combination of heat and pressure causes a curing process and manipulates the properties of the rubber.

Compression moulding is the original process of moulding rubber, which was developed back in the 1850s. This moulding method requires you to apply clamping pressure from a press, which allows you to mould the rubber through a heated mould too, into a mould that comes in two halves. The benefits of this particular method of rubber moulding are its simplicity and low cost.

Meanwhile, transfer moulding combines techniques used within both injection and compression moulding. Transfer moulding uses a mould that comes in two halves, which is similar to compression moulding, except that there is an open-ended cavity where the rubber is placed, which is known as “the well”. A plunger is pushed into the well, applying pressure which enables the rubber to flow into the mould. As with the other two processes, the curing process begins once the moulds are filled.

How Does Rubber Injection Moulding Work Differently?

Rubber injection moulding is slightly different to the other methods, in that the heated rubber compound is injected into a single closed mould with high pressure applied, whereas compression moulding uses two halves of a mould. Meanwhile, transfer moulding combines both techniques, but uses two mould halves, just like compression moulding.

Compared to injection moulding, both compression and transfer moulding have their pros and cons. On the one hand, transfer moulding is a simpler process than injection moulding, but on the other, it also has the highest chance of material wastage out of the three methods and the moulds can be costly. As for compression rubber moulding, it has a great ability to process tougher, stiff materials and has low wastage levels. However, its slower processing times and difficulty to maintain consistency in the finished products make it a bit more challenging to work with.

While the setup costs for rubber injection moulding may be more expensive than the alternative methods, the reliability of the method through its fast production time and minimal material wastage make it worthwhile.

Find Out More About Compression and Transfer Moulding

Now that you know how rubber injection moulding works, you can see how it can be used to create durable rubber products and how it functions compared to other rubber moulding techniques.

If you’re looking for bespoke rubber manufacturing, Checkmate are here to help. Whether this is through the conception of an idea you have or to manufacture your desired product, we would love to talk to you about what we do and how it could work for you. You can contact us here.