How does injection moulding work?

When it comes to the fabrication of plastic, plastic injection moulding is one of the most cost-effective and popular choices.

This method has a long history and has evolved to become an efficient solution for producing a wide range of plastic products in a huge number of industries. But how does injection moulding work?

The history of injection moulding

Plastic injection moulding goes back to the 1860s and the game of billiards. American inventor John Wesley Hyatt patented a process that produced a product called celluloid, which acted as a superior replacement for ivory in billiard balls.

Like most inventors, Hyatt didn’t stop there. Four years later, in 1872, he and his brother Isaiah became the first to inject that same hot celluloid into a mould, forming the basis of the same injection moulding system we use today.

The brothers then patented their injection moulding machine, a precursor to the machines we use at our cutting edge plastic injection moulding factory in Birmingham. This basic injection moulding system was essentially a needle which injected plastic through a heated cylinder into a mould.

Using their plastic injection moulding machine, the Hyatt brothers’ creation evolved beyond billiard balls, and began to produce everything from buttons to hair combs.

The evolution of plastic injection moulding

Plastic injection moulding remained mostly unchanged until the 1940s. The process evolved due to the demands of the Second World War for products which could be inexpensively mass-produced.

The creation of the screw injection moulding machine quickly revolutionised the process and supported the war effort against the Axis powers. The basic process the Hyatts created was improved upon to allow for a range of benefits to the final product including the use of better plastics, pre-mixing and the addition of colour to standard materials.

The Hendry screw injection moulding machine, invented in 1946, became the first to resemble the machines we use today, allowing far more control over the process. Alongside the creation of the first fully synthetic polymer, Bakelite, which allowed for more uniform production, these advancements made injection moulding efficient and available to all.

James Hendry later went on to develop gas-assisted injection moulding, which meant more complex, hollow articles cooled far more quickly, boosting design flexibility and the strength of manufactured parts. The improved production time and reduction in cost, weight and waste meant plastic production soon overtook steel production, and by 1990, aluminium moulds were being widely used for injection moulding.

Today, James Hendry’s screw injection machine design makes up the majority of all injection machines in service.

Modern-day injection moulding

Today we use the cutting edge descendants of the original injection moulding machines, though the principle remains the same.

The process begins with the design and production of a unique mould, built to customer specifications via our comprehensive design process.

Our designers and industrial engineers use CAD design and decades of experience to produce a suitable, premium mould for each customer. Moulds can be created with attention to minute details, allowing for the creation of tiny but super-strong components.

Granulated plastic is fed into a heated barrel and melted into a liquid. There is a near endless range of polymer types to choose from, with each bringing different benefits to the final product.

This molten liquid polymer is then guided through a nozzle or screw via a plunger system and fills the mould. The plastic cools in just a few seconds, set in the shape of the final component. The process can then be repeated numerous times with the same mould.

The ability to create high strength, premium quality components is what makes injection moulding a firm favourite for many over alternative processes such as 3D printing and extrusion. Injection moulding is ideal for creating a range of components including caps, plugs and seals, as well as plastic covers and protectors in numerous sectors including the automotive, medical and Fast Moving Consumer Goods industries.

To discuss your product requirements or to find out what Cameron-Price can do for you, please fill out our contact form.