English
русский
The main reasons for air trapping of plastic injecton mold
During the injection molding process, the front end of the slight ribs may be air trapped and plastic burnt, and also cause the molded part may become black and carbonized.
The mechanism of air trapped scorching is that when the air in the mold cavity is extruded by the molten plastic flowing into the cavity, the air will heat due to being compressed if it is in a sealing state without an outlet, and then it leads to combustion and burns.
Since the air is a kind of gas, it can be compressed, but it generates heat when compressed, it is like when we use a pump to inflate our bike tires, the pump gets hot.
The compression of the residual air in the cavity usually occurs in a short time of about 0.1 to 0.5 seconds, because it is compressed under a high pressure of 200 to 500 kgf per square centimeter, it is easy to heat up to the ignition point of the plastic (as shown in picture 1).
Therefore, for some slight ribs, pillars and other product features in the gas injection mold, it is necessary to make venting slot to let the gas in the mold which can be discharged to the outside of the cavity.
Slider designing tips 1
Aug 3, 20221. After the slider core pulls out, the length of staying in the guide pin slot should not be less than 2/3 of the total length of the slider, for special cases, the slider slot can be partially...view
Slider angle designing tips
Dec 4, 20231. Normally, all the insertion slopes of the slider are not allowed to be less than 3° to prevent excessive self-locking force and scratched; 2. The angle of the locking surface must be bigger than...view
What is the side parting and core pulling mechanisms with their function?
May 31, 2022When there are holes, cavities or cores on the inside or outside of the injection-molded plastic parts that are different from the opening and closing directions of the mold, the plastic parts cannot...view
Banana gate of plastic injection mold runner system design
Feb 7, 2022In order to get the best injection quality, the gate type must be selected carefully, the coommon gate tyeps are: direct gate, side gate, pin-point gate, sub gate,valve gate of hot runner etc. Among...view
Controling method of plastic injection mold temperature
Feb 15, 2022Except for heat radiation and heat convection from the mold, most of the heat bring into the mold by the plastic needs to be taken out of the mold by the circulating heat transfer medium by heat...view
The design requirements of slider wear plate
Jan 2, 20241. The wear plate of slider requires hardening treatment, with a hardness of 45-48HRC; 2. The friction surface of the wear plate is required to be 1.0mm higher than the slider surface (see picture-1);...view