Moulding process

Introduction

Injection moulding is the manufacturing process that is used to fabricate plastic parts. However, the products manufactured using this method differs in application, complexity and size. The injection moulding process is executed through the use of injection moulding tooling and machine, raw plastic material and mould. The raw plastic is melted in the moulding machine after which it is injected in the mould to cool and solidify. This process is used to produce thin walled plastic parts that are used in numerous applications such as plastic housing.


To get the most out of injection moulding processes, you ought to understand the tools that are used and the moulding process. The process is short and takes a maximum of 2 minutes. However, if it is not implemented in the right manner, you may not get the best results.

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Moulding process

Clamping clamping units should be used to close the two halves of the mould before injecting the materials in the mould. The two halves are attached to the moulding machine but one half is allowed to slide. If the clamping unit is functioning properly, it should push the two halves together to exert pressure with an aim of keeping the mould closed securely.


Injection the injection unit is used to advance the raw plastic towards the mould. The plastic material is melted through heating and application of pressure. The plastic unit should be injected the molten plastic into the mould as fast as possible before it starts cooling.


Cooling if your injection moulding tooling is effective, the molten plastic should start cooling as soon as it is injected in the mould. It solidifies in the desired shape as it cools. The mould can only be opened once the cooling type elapses. The time it takes for the molten plastic to cool depends on the wall thickness and a number of thermodynamic properties.


Ejection the ejection system is used to eject the cooled part after the cooling time elapses. The ejection system should be attached to the mould's rear half. Force is used to eject the cooled part since it shrinks and adheres to the mould as it cools. Therefore, a mould release agent should be sprayed on the mould's cavity surface.


Injection moulding tooling

The custom tooling used during the moulding process is made from aluminum and steel. A mould contains two components that can be split in half and each half is attached to the moulding machine. The mould cavity and core are mounted to the mould base that is fixed to the platens in the machine. The front part of a mould base comprises of a support plate attached to the mould cavity, locating ring that aligns the mould base with the nozzle and a sprue bushing into which the material flows from the nozzle. For the molten plastic to flow in the mould cavities, several channels are used. Channels known as runners are used to carry molten plastic to the cavities that should be filled. Hot runners are used to heat the channels and allow the materials to melt and get detached from the part. The cooling channels allow flow of water through walls to cool the plastic.