How to design the runner of precision injection mold?

(1) Main design points of precision injection mold main channel
The sprue of precision injection mold is usually set on the center line of the mold. The diameter of the sprue affects the pressure, flow velocity and filling time of the injection molding.
In order to make the precision injection mold more convenient for processing, the sprue is usually not directly made on the fixed mold, but is used as the gate sleeve. In general, the length of gate sleeve should be as short as possible to avoid excessive pressure loss of plastic melt flow and reduce waste and manufacturing cost.

(2) Key points in design of diversion channel of precision injection mold
The diverter channel of precision injection mold is a channel to smoothly enter the feeding gate in the mold cavity by changing the cross-section and direction of the flow channel from the main channel.
Design points of diversion channel:
① Under the condition of meeting the injection molding process of precision injection mold, the cross-sectional area of shunt channel should be as small as possible
② The distribution principle of flow channel and cavity is compact arrangement and reasonable distance. Axial symmetry or central symmetry should be adopted to balance each flow channel and reduce the total area of molding area as far as possible.
③ In general, the length of the shunt should be as short as possible.
④ In the design of diversion channel, the number of turns should be as few as possible, and the turning point should be smooth without sharp angle
⑤ The internal surface roughness of the shunt channel is generally Ra1.6.

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