TECHNICAL FEATURES OF DOUBLE COLOR INJECTION MOLDING

The double color injection molding machine consists of two pre-plasticization and injection systems, wherein slight fluctuation of temperature, pressure and quantity of the injected fused materials will influence the color and pattern of products. To ensure uniform appearance of the same batch of products, the technical parameters such as temperature, pressure as well as quantity of injection of the two systems must be under strict control and be kept invariable during production.

The blended color injection molding machine is long and complicated in structure and has turning corners therein, above all, pressure losses of the fused materials are immense, which requires large injection pressure to ensure smooth filling in the molds.

To ensure sound fluidity of the fused materials as well as smooth filling in the molds, temperature of the materials should be properly set higher.

The high temperature of fused materials and their long stop time in the running channel may result in thermal decomposition. Therefore, raw materials for double color injection and molding should be taken from thermal plastic materials steady in thermal stability and low in viscosity.

During double color injection, fused materials of two different colors can be either taken from the same plastics or from different ones. When the latter alternative is adopted, plastics with sound viscosity and compatibility under fusing temperature.During double color injection, fused materials of two different colors are blended in the molds. Therefore, the welding mark and internal stress of double-color products should be taken into full account during the formulation of technical parameters. High material and mold temperature as well as high injection rate are beneficial for reducing welding mark and internal stress.