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Plastic mold mainstream design principle

Update:04 Apr 2019
Summary:

The main principles of mainstream design are as follows […]

The main principles of mainstream design are as follows:

1. The shorter the length L of the main channel, the better, especially the main channel of the point gate pouring system, or the plastic with poor fluidity, the mainstream road should be as short as possible. The shorter the main flow path, the lighter the mold exhaust load, and the less the flow material, shortening the molding cycle and reducing the energy (temperature and pressure) loss of the melt.

2. In order to facilitate demolding, the mainstream channels are mostly conical in design. The main course taper of the two-plate mold is 2°~4°, and the main course taper of the three-plate mold can be 5°~10°. The roughness Ra is 0.8~1.6um, the taper must be appropriate, the speed is reduced, the turbulence is generated, the air is easily mixed into the air, and the pores are generated. If the taper is too small, the flow rate will increase, which will make the injection difficult and at the same time It is difficult to demould the mainstream road.

3. In order to ensure the injection molding, the main channel and the nozzle of the injection molding machine do not overflow and affect the demoulding, the design should pay attention to: the diameter D2 of the main channel small end is larger than the diameter D1 of the nozzle nozzle by 0.5~1mm, in general Next, D2=3.2~4.5mm; the diameter of the big end should be 10%~20% larger than the diameter of the largest split runner. Generally, rounded corners (R=1~3mm) are arranged at the big end of the sprue sleeve to facilitate melt flow.

4. If the main channel passes through multiple templates at the same time, be sure to pay attention to the taper of the holes on each template and the size of the holes.

5. The main channel should avoid the block structure as much as possible to prevent the plastic from entering the joint and making the plastic products difficult to demould.