Keep the wall thickness as thin as possible according to the application. The thinner the wall thickness, the shorter the cooling time phase of the injection molding cycle. As the wall becomes thinner, the cost of the molding machine and the material cost of the parts are also reduced. In determining the wall thickness of a particular part it is ensured that the part strength is still within the quality limit and that the forming machine has the ability to make thinner parts. Clicking the link below will display a case study to reduce the wall thickness.
The design of the cooling channels in the mold plays an important role in minimizing the cycle duration. Make sure there are many large channels near the molding surface. However, please be careful not to compromise the strength of the mold. If the cooling channel is made too large on the molding surface, if it is too close to the molding surface, it contributes to the deflection of the mold, causing not only cracks in the mold cavity but also part quality problems. Cracked cavities are usually a great chaos in productivity level because exchange inserts are required.
Another mold design characteristic to be considered is the ejector system. The ejector system must be robust enough to quickly damage parts from the mold. Generally, the thinner the part, the less extruded surface area, the more difficult to discharge. This is one reason why thin wall molding is difficult. For details on thin wall molding, please click the link:
Molding Machine Suitability
A suitable molding machine must be able to achieve the correct filling time limit to make acceptable parts. If the filling time is too short or too long, a rejected part is generated. Accurate filling time uses specific injection pressure and injection speed.
For details of molding machine selection, please click the following link:
Process Technician’s Ability
Injection molding is a complicated process because there are many parameters in the machine controller, and when changed it affect cycle time. For example, it is possible to shorten the cycle duration by increasing the injection speed, increasing the platen speed, increasing the injection speed, reducing the mold opening stroke, shortening the holding time, and shortening the cooling time. Unless a systematic approach is taken, it is difficult to make the best combination of process parameters. The training of scientific molding principles of process engineers is a great merit.
Some material suppliers claim to manufacture the same resin grade to reduce cycle time. They have a special formulation which means that parts are discharged faster than usual. If a substitute for such a resin is not available, please consider additives such as Nanosil. Clicking on this link will display information about Nanosil’s experiment which reduced cycle time by 13%.
Product designers specify polishing of a specific grade based on cosmetic purposes. Grinding grade is often high mirror polishing, causing many molding difficulties and increasing cycle time. Since there are various grades for the mirror finish, please execute only the minimum requirement according to the application.
Please let me know if you have any idea about ways to reduce cycle time.