The idea and setting method of filling speed of injection molding

Due to the influence of injection mold structure, product size, molding machine selection, resin flow difficulty degree and many other factors, it is difficult to determine the measurement value and filling speed from the beginning. Damage to injection moulds due to overfilling must be avoided.

First, the idea of filling speed of injection molding

Basically, the velocity of the flow front in the injection mold cavity changes according to the flow cross-sectional area. First fill at 1 gear speed, observe the shape of the product at the same time, change the speed at 1-5 gear to find the best effect.

Bad case of filling speed

1. Appearance defects (jet marks, flow marks, gas marks, welding lines, gas burns, etc.)

2. Poor function and shape (warping and deformation due to increased residual stress)

3. Uneven weight, instability, etc.

Two. Injection molding filling speed setting method

The first injection molding at 1 gear speed, in order not to cause excessive stuffing measurement value, VP switch position, from the underinjection state to start injection molding.

After that, gradually increase the filling amount while changing VP switch.

The standard filling amount at the filling speed is usually about 85 ~ 95% of the cavity.

At this time, when the appearance is bad due to the gate location or injection mold structure, the filling speed is set to multiple levels, and the speed is adjusted while confirming the position of each screw and the passing position in the injection mold.

Three. Injection molding experience

Depending on the structure of the injection mold, it is best to gradually increase the filling amount, although it may occur that the mold cannot be removed once it is shot short. It's ideal to be able to fill at 1st gear without any defects, but it's basically hard to do. By carefully identifying the relationship between the flow front, screw position and the defect, the conditions that can effectively eliminate the defect can be found.

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