Cold runner and hot runner

The difference between cold runner and hot runner

1.Save material costs: The waste generated by the cold runner channel and gate is very large, especially the larger the part volume is, the more waste there is due to the long channel. Some of these wastes can be recycled, while others cannot. Even if they can be recycled, the comprehensive performance of the material is greatly reduced, and recycling equipment is required.

2.Improve production efficiency: The molding cycle of injection molded parts = - injection time + holding time + cooling time + ejection time + trimming time. The longest of these is the cooling time. In plastic molds, the thicker the wall of the product, the longer the cooling time. Since the cold runner needs to feed multiple mold cavities or more pouring points at the same time, the wall thickness of the product in the cold runner is usually greater than the thickness of the injection molded product itself. Because there is a cooling time difference between the cold runner melt and the injection molded product, the cooling time will be shortened if the cold runner is eliminated. The difference in injection time is also an aspect of using hot runners instead of cold runners. The difference in injection time is attributed to the extra time required to fill the cold runner. This is because the cold runner mold increases the injection molding machine's opening/closing stroke, and the increase in stroke is to ensure the safe ejection of the cold runner. Products molded with hot runners are more suitable for automatic removal of products. Since there is no interference from cold runners on product removal, the time for secondary manual operations in injection molding, such as separation of products from runners, product trimming and packaging, can be greatly shortened or completely eliminated. Thus, the production capacity per unit time is improved, that is, the production efficiency is improved.

3.Improve the quality of parts: The use of hot runners can effectively improve the surface quality and mechanical properties of products, greatly improve the warping deformation of thin-walled parts, and ensure the consistent quality of injection molded parts in multi-cavity molds.

In particular, the needle valve nozzle has a more obvious effect on improving the appearance quality of injection molded products. Its main advantages are: no gate residue is left on the product. The ability to use a larger diameter gate can speed up cavity filling, further reduce injection pressure, and reduce product deformation. It can prevent wire drawing and drooling when opening the mold: when the screw of the injection molding machine retreats, it can prevent the material from being sucked back from the cavity.

Most of our small and medium-sized plastic parts such as Car Front and Rear Lights, Electronic Thermometer, Health Massage Products for Home, etc. generally use cold runners. For some Electronic appliances and instruments, if customers require higher quality or want to speed up production efficiency, we will use hot runners to make molds. Whether to use hot runners or cold runners, we will give customers the best suggestions based on customer requirements and product structure requirements. Let customers choose for themselves