Injection molding knowledge points

- Mar 09, 2019-

01. Shooting nozzle

The melt usually flows from the nozzle into the nozzle, but with some molds, the nozzle is part of the mold because it extends to the bottom of the mold. There are two main types of nozzles: open shot nozzles and closed nozzles. In injection molding, open nozzles should be used more because they are less expensive and less likely to stay.

If the injection molding machine is equipped with a depressurizing device, this nozzle can be used even with a lower viscosity melt. Sometimes it is necessary to use a closed nozzle, which acts as a stop valve and blocks the plastic shade in the shot cylinder. Make sure the nozzle is properly inserted into the nozzle sleeve. The top hole is slightly smaller than the nozzle sleeve, which makes the nozzle easier to remove from the mold. The hole of the mouthpiece sleeve is 1mm larger than the mouth of the nozzle, that is, the radius of the nozzle is 0.5mm thinner than the radius of the nozzle sleeve.

02. Filter and combined nozzle

The impurities of the plastic can be removed by a filter of the extensible nozzle, ie the melt and the plastic flow through a channel which is separated into narrow spaces by the insert. These narrow and gaps remove impurities and improve the mixing of plastics. Therefore extending it, a fixed mixer can be used to achieve a better mixing effect. These devices can be installed between the shooting tank and the nozzle to separate and remix the melt, mostly to allow the melt to flow through the stainless steel channel.

03. Exhaust

Some plastics need to be vented in the shooting tank during injection molding to allow the gas to escape. In most cases these gases are only air, but they may be melted moisture or monomolecular gases. If these gases are not released, the gas will be compressed by the melt and brought into the mold, which will expand and form bubbles in the product. To remove the gas before it reaches the nozzle or mold, reduce or reduce the diameter of the screw root to decompress the melt in the shot cylinder.

Here, the gas can be discharged from holes or holes in the shooting tank. Then the screw root diameter injection molding personnel must master the 18 knowledge points! Large, and the melt of the volatiles is suitable for the nozzle. The injection molding machine equipped with this facility is called a vented injection molding machine. Above the vented injection molding machine, there should be a good ventilator for the removal of potentially harmful gases.

Injection molding knowledge points