3 principles and 6 points for attention in 2shot mold design

 The first principle: determine the viscosity of the combination of hard glue and soft glue. In addition, it should be noted that the melting point of hard glue is higher than that of soft glue. Don’t melt the hard glue when forming soft glue, otherwise it will not work.


1. The first shot: Hard glue: PA66+ The second shot: Soft glue: TPE The combination is OK.


2. The first shot: Hard glue: PC/ABS+ The second shot: Soft glue: PC The combination is OK.


3. First shot: Hard glue: PP+ Second shot: Soft glue: TPU Combination will not work, because PP material and TPU material are incompatible.


The second principle: Make sure that the second shot of soft glue and the first shot of hard glue cannot fall off after molding.


1. When the first shot of hard glue is used to seal the second shot of soft glue, try to use a flat surface to seal the glue.


2. If the side or inclined roof is sealed, try to steal 0.1~0.15MM of the hard rubber seal, and use the mold steel position to seal the glue.

The third principle: design in combination with the company's existing two-color machine.


1. The normal type of two-color machine is that the double barrels are side by side.


2. Abnormal two-color machine, two barrels produce a 90-degree pattern, usually customized or rebuilt.


3. If the insert is put into injection molding, use the vertical injection molding machine normally. First note:


The shrinkage rate of hard rubber and soft rubber is uniformly scaled according to the shrinkage rate of hard rubber.


Second note:


It takes four minutes for the mold guide pillars and related positioning mechanisms, and the distance must be uniform, because the male mold side is exactly the same when the mold is designed, and it needs to be rotated 180 degrees during molding.

Third note:


For the first injection molding hard glue point, you must use a three-plate mold to point the glue, or use a hot runner, because the male mold side is exactly the same, and the product needs to be ejected.


The fourth note:


1. The waterway on the male mold side should be designed inside the mold as much as possible, because the male mold side needs to be rotated 180 degrees. If the waterway is on the outside, the waterway will be as loose as possible during the rotation of the mold, causing water leakage.


2. If the male template is one-piece, the waterway is designed on the open side, and the waterway is fixed on the turning circle of the injection molding machine.

Fifth note:


When molding the hard rubber for the first shot, when it is necessary to form the second soft rubber, the mold steel position on the soft rubber side needs to be sealed with the hard rubber. In the case of the soft rubber, the mold steel position needs to be oversized by 0.1~0.2 MM, after the T0 mold trial, if you find that the hard rubber is crushed, you can make minor adjustments.


The sixth note:


1. Full 3D inspection.


2. Rotate the rear mold 180 degrees, and then conduct a full inspection to see if there is interference.


3. Create the same part of the water pipe of the rear mold, and then perform a 180-degree back and forth, and rotate it for inspection.

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