(1) Improper feed adjustment, lack of material or multiple materials.
Inadequate feeding measurement or feeding control system operation, injection molding machine or mold or operating conditions lead to abnormal injection cycle, pre-plastic back pressure is too small or the material density of the barrel can be caused by lack of material, for large particles, Plastics with large void volume and crystallinity, and plastics with higher specific viscosities should be adjusted with higher material content. When the material temperature is high, the amount of material should be adjusted.
When the cylinder end stores excessive material, the injection screw consumes extra injection pressure to compress and push the excess material in the cylinder. This greatly reduces the effective injection pressure of the plastic that enters the cavity. Products are difficult to fill.
(2) The injection pressure is too low, the injection time is short, and the plunger or screw retracts too early.
Molten plastics have high viscosity at low working temperatures and poor fluidity, and should be injected with greater pressure and speed. For example, in the manufacture of ABS colored parts, the high temperature resistance of the colorant limits the heating temperature of the barrel, which is compensated by the higher injection pressure and the longer injection time than usual.
(3) The injection speed is slow.
The injection speed is of great significance for some products with complex shapes, large thickness variations, long flow processes, and high viscosity plastics such as toughened ABS. When using high pressure can not be full of products, should be considered high-speed injection to overcome dissatisfaction with the problem.
(4) The material temperature is too low.
The temperature at the front of the barrel is low, and the melt entering the cavity causes the viscosity to rise prematurely to the point where it is difficult to flow due to the cooling effect of the mold, hindering filling of the distal end; the temperature at the rear of the barrel is low, and the viscosity is high. Difficulties in flow hinder the forward movement of the screw. As a result, it appears that the pressure indicated by the pressure gauge is sufficient and actually the melt enters the cavity at low pressure and low speed;
The low nozzle temperature may cause the nozzle to lose contact with the cold mold in contact with the mold for a long time when the material is fixed, or the nozzle heating coil may cause insufficient heating or poor contact to cause the material temperature to be low, which may block the feeding channel of the mold; if the mold does not have the cold material Wells, with self-locking nozzles, using post-feeding procedures, the nozzles are able to maintain the necessary temperature; just when the nozzle is too cold, sometimes the flame gun can be used for external heating to accelerate the nozzle temperature.