Electroplated PC/ABS parts are used more and more widely in the home appliance, automotive and IT industries. It is believed that the main factors affecting the plating performance of PC/ABS are material formulation design and electroplating process, however, few people will pay attention to the influence of injection molding process on electroplating performance. Today Xiaobian analyzes the impact of injection molding process on PC/ABS plating performance:
Higher injection temperatures allow for better plating performance while ensuring that the material does not crack.
At lower injection temperatures, the flowability of the PC/ABS material is poor, the molded product has a large internal stress, and the stress is released during the roughening process, resulting in uneven etching on the surface of the product, resulting in poor appearance of the electroplated product. And the situation of poor plating bonding is produced. The higher injection temperature can reduce the internal stress of the injection molding of the product, thereby improving the plating performance of the material. Related studies have shown that compared with the injection temperature of 230 Â° C, when the temperature is increased to 260 Â° C -270 Â° C, the adhesion of the coating is increased by about 50%, and the surface appearance defect rate is also greatly reduced. However, the injection temperature should not be too high. If the cracking temperature of the material is exceeded, the appearance of the surface of the injection molded product will be poor, which will affect the plating performance.
Injection speed and pressure
Lower injection pressure and proper injection speed help to improve the plating performance of PC/ABS.
Excessive injection pressure will lead to excessive extrusion of the internal molecules of the product, resulting in higher internal stress of the product, resulting in uneven product coarsening and poor plating adhesion; appropriately increasing the injection speed, the gate position can be cut Increased, resulting in increased fluid temperature, which in turn will improve the fluidity of the entire material, which is conducive to product filling and reduce the internal stress of the product; but too much shear will lead to cracking of the material, resulting in gas marks, peeling, burrs, etc. .
Holding pressure and pressure maintaining switching point
Excessive holding pressure and late holding pressure switching position are likely to lead to excessive filling of the product and stress concentration at the gate position and high residual stress inside the product. Therefore, it is necessary to set the holding pressure and the holding pressure switching point in combination with the actual product filling state.
The high mold temperature is beneficial to improve the plating performance of the material.
In the low mold temperature state, the material has poor fluidity. During the filling process, due to the extrusion and stretching between the molecules, the molecular chain orientation of the product after cooling is severe, the internal stress of the product is large, and the plating performance is poor. On the contrary, in the high mold temperature state, the material has good fluidity, which is favorable for filling, the molecular chain is in a natural curl state, the internal stress of the product is small, and the plating performance is greatly improved. The actual mold temperature setting needs to be set in combination with the mold water path, heating method and molding cycle requirements. The mold temperature should be increased as much as possible without affecting other performances; while controlling the mold temperature, the mold temperature should be maintained evenly. Uneven mold temperature distribution will result in uneven shrinkage internal stress and thus affect plating performance.
Lower screw speed helps improve the plating performance of the material
The setting of the screw speed is to control the measurement time of the plastic, that is, the time when the plastic enters the material tube to receive the screw mixing and transport to the nozzle. The screw speed also affects the uniformity of plasticizing. The too fast screw speed will cause the material in the screw to shear and the melt temperature will rise sharply, and the faster the screw speed, the worse the mixing effect of the plastic will form the melting glue. The difference in temperature increases, causing differences in filling flow and cooling, which is one of the main reasons for the formation of internal stress in products. Therefore, in general, under the premise of ensuring the melting of the material, the screw rotation speed is set so that the measurement time is slightly shorter than the cooling time.
Jiuzhi Plastics Network Summary
Injection molding temperature, injection speed and pressure, holding pressure, mold temperature, screw speed, etc., all have an effect on the plating performance of PC/ABS. The most direct adverse effect is excessive product internal stress, which affects the uniformity of etching in the plating roughening stage, which in turn affects the plating adhesion of the final product. In short, combined with the product structure, mold state and state of the forming machine, by setting a suitable injection molding process, trying to reduce the internal stress of the material, the plating performance of the PC/ABS material can be significantly improved.
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