Additive Manufactured parts used in Plastic Injection Moulding Machine
ASSAB Engineered Products
An ASSAB engineered product is a steel part manufactured by ASSAB that is either completely finished or mostly finished, and can be used immediately by the customer in a tool, machine, or assembly without requiring significant additional finishing steps.
ASSAB efficiently utilises Additive Manufacturing to produce ASSAB engineered products that can be used in the plastic injection moulding process.
1) Sprue bush, hot runner gate inserts, and tunnel/cashew gate inserts
The function of a sprue is to assist in the transfer of molten plastic from the nozzle of a plastic injection machine to the mould cavity. This is made possible by connecting the sprue to the machine’s nozzle using a sprue bush, which enables a smooth and seamless flow of molten plastic into the mould cavity without any leakage, even at high temperatures. ASSAB supplies customised sprue bush with conformal cooling design to achieve an effective flow of molten plastic.
The hot runner system is a set of channels or passages that distribute the molten plastic material to the mould cavities. It is composed of hot runner inserts for maintaining the plastic material’s temperature and viscosity. A hot runner system increases the temperature in the gate area of the mould, and if the gate area is not sufficiently cooled, it can cause defects and surface quality problems, which can be costly to remedy by altering the cycle or increased rejects. ASSAB incorporates conformal designs for these inserts to tackle these problems.
The flow of molten plastic in a plastic injection moulding process is regulated by tunnel gates and cashew gates, which also dictate the position of plastic entry into the mould cavity. Careful design of gates is necessary to ensure that the molten plastic flows smoothly and fills the mould cavity evenly, with no air pockets or voids. ASSAB provides customised gate inserts to achieve the required shape and size of the gate that optimise the flow of molten plastic for better results.
2) Venting inserts
Venting is crucial in achieving quality parts during the injection moulding process. When air is trapped inside the mould during the process, it needs a way to escape, or else it will compress and become trapped in the cavity. If the trapped air comes in contact with high temperature and melt pressure, it may ignite the oxygen resulting in burnings, gloss marks, and stress cracks in the finished plastic part, which is commonly known as the “diesel effect”. Moreover, poor venting combined with the diesel effect can cause the mould to wear on the mould parting lines and result in excess plastic on the injected part, known as flash. Reducing the injection speed can allow more time for the air to escape through the vents, but this may lead to other issues such as short shots where the plastic starts to harden before the mould is completely full, resulting in incomplete parts due to the increased melt viscosity at lower temperatures. ASSAB can help you solve these issues using Additive Manufacturing.
Please click >> ASSAB Engineered Products for High Pressure Die Casting