What are the basic principles of mold casting system design


1. Consideration of CavityLayout 1) Try to use a balanc […]

1. Consideration of CavityLayout
1) Try to use a balanced layout;
2) The mold cavity layout and gate opening should be symmetrical to prevent the uneven load of the mold from unbalanced load, and the problem of mold flashing;
3) The cavity layout is as compact as possible to reduce the size of the mold.
2. Flow guidance considerations
1) It can smoothly guide the molten plastic to fill the mold cavity, without eddy current, and can smoothly exhaust;
2) Try to avoid the frontal impact of plastic melt on cores and metal inserts with smaller diameters to prevent core shift or deformation.

3. Consideration of heat loss and pressure drop
1) The smaller the heat loss and pressure drop, the better;
2) The process should be short;
3) The cross-sectional area of ​​the runner should be large enough;
4) Try to avoid bending of the runner and sudden change of flow direction (change the direction at an arc angle);
5) The surface roughness should be low during runner processing;
6) Multi-point pouring can reduce the pressure drop and the required injection pressure, but there will be suture problems.
4. Consideration of flow balance
1) When filling a multi-cavity (Multi-Cavity) mold, the flow channel should be balanced, and try to make the plastic fill each cavity at the same time to ensure the quality consistency of the molded products of each cavity;
2) As far as possible, the runner should adopt a natural-balanced layout (Naturally-BalancedLayout);
3) When natural balance is not possible, use artificial balance to balance the flow channel.
5. Scrap considerations
On the premise of smooth filling without affecting the flow and pressure loss, reduce the flow channel volume (length or cross-sectional area) to reduce the flow channel waste generation and recycling costs.
6. Cold material considerations
Design an appropriate cold slug well (ColdSlugWell) and overflow trough on the runner system to supplement the colder plastic wave front in the initial stage of filling and prevent the cold material from directly entering the mold cavity and affecting the filling quality.
7. Exhaust considerations
The plastic should be smoothly guided to fill the mold cavity and allow the air in the mold cavity to escape smoothly to avoid the problem of scorching of the package.
8. Consideration of the quality of molded products
1) Avoid short shots, burrs, encapsulation, suture lines, flow marks, jets, residual stress, warpage deformation, mold core deviation and other problems;
2) When the runner system has a long process or multiple pouring (MultipleGating), the warpage and deformation of the finished product caused by unbalanced flow, insufficient pressure or uneven shrinkage should be prevented;
3) The appearance of the product is good, it is convenient to remove and trim the gate, and the gate mark (GateMark) does not damage the appearance and application of the plastic part.
9. Consideration of production efficiency
Minimize the post-processing required to shorten the forming cycle and improve production efficiency.
10. Consideration of ejection point
It is necessary to consider the proper ejection position to avoid the deformation of the molded product.
11. Considerations for using plastic
For plastics with higher viscosity or shorter L/t, avoid using too long or too small runners