The process of Injection moulding is one of the most common and recognisable steps in the plastic manufacturing process. Many of the plastic items we use daily are made from using this process. Here we give a basic overview of the five steps that occur during the injection moulding process.
Step 1: The mould closes
In step 1, the injection mould closes, clamping together the two halves of the injection mould, and the cycle timer begins.
Step 2: Injection
Heated plastic is injected into the mould while the displaced air escapes along the parting line and through the vents in the injection pins. The runner, vent design and gate ensure that the mould is filled correctly.
Step 3: Cooling period
Once the mould has been filled, the part cools down. The piece is given precisely the right amount of cool-down time needed to harden the material used.
Step 4: The resin is plasticised
During the cool-down period, a barrel screw retracts and draws new plastic resin into the barrel. This plastic resin is drawn in from the material hopper. Heather bands maintained the necessary barrel temperature for the type of resin used.
Step 5: Ejection
The mould opens while the ejector rod shifts the ejector pins forward. This step causes the part to fall into a bin located under the mould. The unused sprues and runners can be recycled to be used in future moulds.
Injection moulding allows for the creation of complicated, high-quality three-dimensional parts, created with consistency; perfect for items like packaging, automotive parts and toys. Most injection moulding processes use thermoplastics because they can be melted and cooled down many times, limiting wasted materials The most common thermoplastics used during the injection moulding process include polyethene, polycarbonate, polypropylene and high impact polystyrene. Injection moulding is valuable due to its low labour costs, minimal wastage and high production rates.
Plastic & Chemical Trading together with international partner KraussMaffei Berstorff deliver world-class plastics, injection moulding, and extrusion solutions.