Injection molding and temperature

Mold temperature is an important variable in the injection molding process. A hot mold surface is the plastic surface, which keeps the plastic surface liquid for a long time, enough to form pressure in the mold cavity. For each kind of plastic and plastic parts, there is a limit of mold surface temperature, beyond which one or more adverse effects may occur.

The higher the mold temperature, the smaller the flow resistance. On many injection molding machines, this naturally means faster flow through the sprue, gate and cavity, because the injection flow control valve used cannot correct this change, and faster filling will lead to higher effective pressure in the sprue and cavity. May cause flash. Since the hot mold will not freeze the plastic entering the overflow edge area before the high pressure is formed, the melt will overflow around the ejector rod and overflow into the gap of the dividing line. This shows the need for good injection rate control, which some modern flow control programmers can do.

Generally speaking, higher mold temperature will reduce the amount of plastic with condensation layer in the mold cavity, making the molten material easier to flow through the mold cavity, so as to increase the weight of parts and improve the surface quality. At the same time, the die temperature will also improve the tensile strength of the parts.

Mold insulation. Many molds, especially thermoplastics, work at relatively high temperatures, such as 80 degrees Celsius or 176 degrees Fahrenheit. If the mold is not insulated, the heat lost to the air and the injection molding machine can easily be as much as the heat lost by the injection cylinder. Therefore, the mold and plate shall be insulated. If possible, the mold surface shall be insulated. If the hot runner mold is considered, the heat exchange between the hot runner part and the cooling injection part should be minimized. This can reduce energy loss and warm-up time.

1、 Mold temperature control

1. Temperature control has an impact on formability, appearance of formed products, physical properties of materials, forming cycle, etc., This is affected by the core temperature. In general, it is ideal to keep the mold core temperature low, which can increase the injection times, but the molding cycle is related to the shape of the molded product (mold core structure) and the type of finished material, and also depends on whether the filling temperature of the mold core needs to be increased.

2. In order to prevent stress from temperature control, this is a problem of formed material, and the requirement is cooling speed. Shortening the cooling time can avoid the stress caused by uneven shrinkage, even if some parts have hardened and some parts have softened. In other words, proper temperature control can improve the performance of cooling stress.

3. For the temperature control of crystallization regulation of injection molding materials, the crystallinity regulation of polythiourethane (nylon), polyacetate, polypropylene and other crystalline materials and the improvement of mechanical properties, a higher mold core temperature is generally required.



About Huizhou Dj Molding Co., Ltd

Dj Mold is a China mold maker of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer, mold manufacturer China– plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Person: James Yuan
Company: Huizhou Dj Molding Company Limited
Add:  LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Tel: 86-752-6682869
Email: [email protected]


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