Injection mold is an indispensable part of injection molding. Now Dongguan Kaiyu Plastic Mould Co., Ltd. begins to introduce to you: the number of cavities, gate location, hot runner, design principles of assembly drawings and material selection of injection molds. Today we will continue to introduce the design of plastic injection mold exhaust system.
In addition to the original air in the cavity, the gas in the cavity also contains low molecular volatile gases produced by the heating or curing of the injection molding material. It is necessary to consider the sequential discharge of these gases. Generally speaking, it is difficult to pre-estimate the exact position of the air lock for a mold with a complex structure. Therefore, it is usually necessary to determine its position by try-out, and then open the exhaust slot. The vent slot usually opens at the point where the cavity Z fills.
The exhaust method is to use the gap between the mold parts to open the exhaust groove to exhaust.
Injection molding requires exhaust, and injection molding requires exhaust. For deep cavity shell injection molding parts, after injection molding, the gas in the cavity is blown away, and during the demolding process, a vacuum is formed between the appearance of the plastic part and the appearance of the core, which is difficult to demold. Injection molded parts can easily be deformed or damaged if demolded forcibly. Therefore, it is necessary to introduce air, that is, between the injection molded part and the core, so that the plastic injection molded part can be demolded smoothly. At the same time, several shallow grooves are machined on the parting surface to facilitate exhaust.
1. The template of cavity and core needs to use tapered positioning block or precision positioning block, the guide is installed on the four sides or around the mold.
2. Flat pads or round pads should be used on the contact surface between the A-plate of the mold base and the reset rod to avoid damage to the A-plate.
3. The perforated part of the guide rail should be inclined more than 2 degrees to avoid burrs and burrs, and the perforated part should not be a thin blade structure.
4. In order to prevent dents from injection molded products, the width of the reinforcing rib should be less than 50% of the wall thickness of the appearance surface (ideal value<40%).>
5. The wall thickness of the product should be average, and at least sudden changes should be considered to avoid dents.
6. If the injection molded parts are electroplated parts, the movable mold also needs to be polished. Polishing requirements are second only to mirror polishing requirements to reduce the generation of cold material during forming.
7. Ribs and grooves in poorly ventilated cavities and cores must be embedded to avoid dissatisfaction and burn marks.
8. Inserts, inserts, etc. should be positioned and fixed firmly, and the disc should have anti-rotation measures. Copper and iron sheets are not allowed under the inserts. If the pads are taller, the soldered portion should make a large surface contact and be ground flat.
CN
