Dinosaur Blue Box Injection Moulding Parts Hand Models Kits Set

Injection Moulding Parts Process Method:

The process cycle for Injection Moulding Parts are very short, typically between 2 seconds and 2 minutes, and consists of the following four stages:

1. Clamping - Prior to the injection of the material into the mould, the two halves of the mould must first be securely closed by the clamping unit. Each half of the mould is attached to the injection moulding machine and one half is allowed to slide. The hydraulically powered clamping unit pushes the mould halves together and exerts sufficient force to keep the mould securely closed while the material is injected. The time required to close and clamp the mould is dependent upon the machine - larger machines (those with greater clamping forces) will require more time. This time can be estimated from the dry cycle time of the machine.

2. Injection - The Injection Moulding Parts’ raw plastic material, usually in the form of pellets, is fed into the injection moulding machine, and advanced towards the mould by the injection unit. During this process, the material is melted by heat and pressure. The molten plastic is then injected into the mould very quickly and the buildup of pressure packs and holds the material. The amount of material that is injected is referred to as the shot. The injection time is difficult to calculate accurately due to the complex and changing flow of the molten plastic into the mould. However, the injection time can be estimated by the shot volume, injection pressure, and injection power.

3. Cooling - The Injection Moulding Parts’ molten plastic that is inside the mould begins to cool as soon as it makes contact with the interior mould surfaces. As the plastic cools, it will solidify into the shape of the desired part. However, during cooling some shrinkage of the part may occur. The packing of material in the injection stage allows additional material to flow into the mould and reduce the amount of visible shrinkage. The mould can not be opened until the required cooling time has elapsed. The cooling time can be estimated from several thermodynamic properties of the plastic and the maximum wall thickness of the part.

4. Ejection - After sufficient time has passed, the cooled part may be ejected from the mould by the ejection system, which is attached to the rear half of the mould. When the mould is opened, a mechanism is used to push the part out of the mould. Force must be applied to eject the part because during cooling the part shrinks and adheres to the mould. In order to facilitate the ejection of the part, a mould release agent can be sprayed onto the surfaces of the mould cavity prior to injection of the material. The time that is required to open the mould and eject the part can be estimated from the dry cycle time of the machine and should include time for the part to fall free of the mould. Once the part is ejected, the mould can be clamped shut for the next shot to be injected.