Non-forming factors in vertical injection molding machine operation

Vertical injection molding machine work problems, generally is the work of the process problem, the following four points are the four major factors of the operation is not forming.

(1) the injection pressure is too low, the injection time is short, the plunger or screw back too early. Molten plastic in the low operating temperature viscosity is high, poor activity, should be at greater pressure and speed injection. For example, when making ABS colorful parts, the high temperature resistance of the colorant limits the heating temperature of the barrel, which requires higher than the general injection pressure and extended injection time to compensate.

(2) slow injection speed. Inserting speed has a very prominent meaning on some disorderly shapes, large thickness changes, long process of finished products, as well as plastic with greater viscosity, such as endurance ABS, etc. Elected with high pressure is not filled with finished products, should be able to consider the selection of high-speed injection ability to overcome the shortcomings of dissatisfaction.

(3) the feed temperature is too low. The temperature of the front end of the barrel is low, and the viscosity of the molten material entering the mold cavity rises prematurely to the point that it is difficult to move because of the cooling effect of the mold, which impedes the filling of the mold at the far end. The low temperature in the back section of the barrel and the plastic with large viscosity are difficult to move, which hinders the forward movement of the screw. The result appears to be that the pressure shown by the pressure gauge is satisfied, but in fact the molten material enters the cavity at low pressure and low speed. When the nozzle temperature is low, it may be that the nozzle loses heat when it touches the cold mold for a long time. Perhaps the lack of heating or bad touch of the nozzle heating ring results in low material temperature, which may block the feeding channel of the mold. If the mold does not have a cold material well, the self-locking nozzle is used, and the feeding procedure is selected after the nozzle can adhere to the necessary temperature. When the nozzle is too cold at the beginning of the machine, sometimes the flame gun can be used to do external heating to accelerate the temperature rise of the nozzle.

(4) improper conditioning, lack of material or more material. Banning of measurement or control of feeding system operation is not normal, and the limit of the injection mould or operating conditions in an injection cycle disorders, plastic small back pressure or barrel inside small grain density could form a lack of material, aggregate on large particles and a lot of space and the crystalline volume change large plastic such as polyethylene, polypropylene, nylon plastic such as ABS and high viscosity should be adjusted higher feed rate, feed temperature on the high side should be adjustable for big shoes. When the end of the barrel is too much material, the screw should spend more rated injection pressure to compress and promote the excessive material storage in the barrel, which greatly reduces the useful injection pressure of the plastic into the mold cavity and makes the finished product difficult to fill.