Injection Moulding Process: How Do They Do It?

Injection Moulding Process… What is it?You’ve heard about fabricating plastics and no doubt you’ve seen plastics of all shapes and kinds. You’ve experienced the toughness and softness of almost all types of plastics.You understand that there are benefits of having plastic products around and you know about the negative impacts of plastic materials due to human negligence.So how are plastic products made? Plastics are either malleable or flexible like take away food containers, or rigid enough to be someone’s chair.The process of moulding these plastic materials is actually called Plastic Injection Moulding.

Injection Moulding Process Explained

Injection Moulding Process ExplainedPlastic Injection Moulding is the common method of producing parts out of plastic material.Examples include toys, chairs, consumer electronic cases, disposable cutleries, and also, Lego parts.With this process, we can mass-produce any high quality plastic material with accuracy in just a short period of time. 

The First Injection Moulding Machine

First Plastic Injection Moulding MachineInjection moulding was actually invented to solve a problem for billiards.Billiard balls were composed of ivory that was being harvested from the tusks of African Elephants in the 19th century.This devastated the Elephant population, so a billiards manufacturer offered a $10,000 prize for a replacement for ivory.John W. Hyatt was the one who developed one of the first plastics celluloid to create billiard balls.Hyatt patented an apparatus for moulding products from celluloid. And his apparatus was the birth of plastic injection moulding. 

Injection Moulding Process is Not that Simple

injection moulding process is not simpleIn principle, injection moulding is simple:Melt plastic, inject it into a mould, let it cool, and then out pops the plastic product.But in reality, injection moulding is an intricate and complex process.The Injection Moulding machine is composed of three parts:The injection unit, the mould, and the clamp. 

STEP 1: Injection Moulding Process–Plastic Granules

Step 1All injection mould objects start with plastic granules or pellets, which are a few millimetres in diameter. They can be mixed with a small amount of pigment called colourant, or with up to 15% recycled material, and fed into the injection moulding machine.These plastic pellets in the hopper will feed into the barrel of the injection unit. 

STEP 2: Reciprocating Screw and Heater Bands

Injection Moulding Process Reciprocating Screw and Heating BandsInside the barrel, a screw transports the granules forward. The reciprocating screw is the most important contribution that revolutionised the plastics industry in the 20th century.Heater bands wrapped around the barrel warm up the plastic pellets. As the pellets were moved forward by the screw, they gradually melt, and they’re entirely molten by the time they reach the front of the barrel. 

STEP 3: Inject into a Mould

Injection Moulding Process Inject into a MouldOnce enough molten plastic is in front of the screw, it rams forward like the plunger of a syringe.In a matter of seconds, the screw injects the molten plastic into the empty part of the mould called the cavity image. The plastic solidifies in under a minute. 

STEP 4: Injection Moulding Process–Eject Finished Plastic Product

Injection Moulding Process - Eject Finished ProductThe mould opens and the plastic part is ejected. The mould then closes, and the process repeats.So that’s how the plastic injection moulding process works.Do you have something in mind that could use some help from plastic injection moulding machines?Contact B&C Plastics today!

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