Influencing factors of injection molding machine not forming

- 2021-07-12-

The influencing factors of injection molding machine not forming are as follows:

The injection speed is slow. The injection speed has a very prominent meaning for some products with messy shapes, large thickness changes, long processes, and high viscosity plastics such as resistant ABS. When the high pressure is not enough to fill the finished product, high-speed injection should be considered to solve the shortcomings of dissatisfaction.

Improper feed conditioning, lack of material or excess material. The feeding machine quantity is prohibited or the feeding control system is not operating normally, the injection cycle is abnormal due to the restriction of the injection molding machine or the mold or the operating conditions, the pre-plastic back pressure is too small, or the density of the material in the barrel is small. The amount of pellets with a lot of open space and plastics with large changes in the specific volume of crystallinity, such as polyethylene, polypropylene, nylon, etc., as well as plastics with higher viscosity, such as ABS, should be adjusted to a higher volume. When the temperature of the material is high, the volume should be adjusted. When there is too much material at the end of the barrel, the screw will consume more injection pressure to compress and push the excess stock of the barrel during injection, which greatly reduces the effective injection pressure of the plastic entering the mold cavity and makes the finished product Hard to overflow.

The injection pressure is too low, and the plunger or screw returns too early during the injection period. Molten plastic has higher viscosity and poor mobility at lower operating temperatures, and injections should be made at higher pressure and speed. For example, when making ABS colorful parts, the high temperature resistance of the colorant limits the heating temperature of the barrel. It is necessary to compensate for higher injection pressure and extended injection time.

The material temperature is too low. The temperature in the front of the barrel of the injection molding machine is low, and the viscosity of the melt entering the cavity rises prematurely to the point where it is difficult to move due to the cooling effect of the mold, which hinders the filling of the distal end; the temperature at the rear of the barrel is low, and the viscosity The large plastic movement is difficult, which prevents the screw from moving forward. The result is that the pressure displayed by the pressure gauge is satisfied. In fact, the melt enters the cavity at low pressure and low speed, which may block the injection channel of the mold; the nozzle is too cold when it is just turned on. Sometimes a flame gun can be used for external heating to speed up the temperature of the nozzle.