First, the molding materials do not meet the requirements of use.

Raw materials do not meet the requirements of use, which will lead to poor surface gloss of plastic parts.The causes and treatment methods are as follows: the content of water or other volatile substances in the molding material is too high, and the volatile components of the molding are condensed between the mold cavity wall and the molten material during the molding, which leads to the poor gloss on the surface of the plastic parts. The raw materials should be pre dried. Discoloration of raw materials or coloring agents leads to poor gloss. High temperature resistant raw materials and coloring agents should be selected.

Poor flowability of raw materials causes poor gloss on the surface of plastic parts. We should replace the resin with better fluidity, increase the amount of lubricant and improve the processing temperature. The raw materials are mixed with different materials or insoluble materials. New materials should be replaced. The grain size of the raw material is not uniform. It is necessary to screen out the material with too much difference in particle size.

Crystalline resin causes poor gloss due to uneven cooling. The mould should be properly controlled and the processing temperature should be properly controlled. For the thick wall plastic parts, if the cooling is insufficient, the surface of the plastic parts will be hairy and the gloss is dark. The solution is to remove the plastic parts from the mold and immediately put them into the cold pressing die immersed in cold water. The proportion of recycled materials in raw materials is too high to affect the even plasticization of the melt. Its dosage should be reduced.

Two. The molding conditions are not properly controlled.

If the injection speed of the vertical injection molding machine is too fast or too slow, the injection pressure is too low, the pressure holding time is too short, the pressure of the supercharger is not enough, the cushion is too large, the nozzle is too small or the temperature is too low, the dispersion performance of the filler of the fiber reinforced plastic is too poor, the filler is exposed or the aluminum foil like filler has no direction distribution, the barrel temperature is too low and the melt plastic is plastic. Poor surface and insufficient supply will lead to poor gloss on the surface of plastic parts.

In this regard, the specific circumstances should be adjusted.If the dark area is produced near the gate or in the variable section, it can be eliminated by reducing the injection rate, changing the gate position, expanding the area of the gate and increasing the arc transition at the variable section. If there is a thin layer of milky white on the surface of the plastic part, the injection speed of the vertical injection molding machine can be reduced properly. If the poor dispersion of filler results in poor surface luster, it is better to replace the resin with better fluidity or to replace the screw with stronger mixing capacity.

Three, mold problems.

Because the surface of the plastic part is the reappearance of the mold cavity surface, if the vertical injection molding machine has the surface defects such as the scar, corrosion, and micropores, it will be reflected to the surface of the plastic parts to produce a bad gloss.

If the surface of the cavity has oily dirt and moisture, the amount of releasing agent is too much or the improper selection will also make the surface of the plastic part dark.

Therefore, the surface of mold cavity of vertical injection molding machine should have better finish, preferably polishing or chrome plating. The surface of the cavity must be kept clean, and timely remove oil and water stains. The variety and dosage of demoulding agent should be appropriate.

The mold temperature has a great influence on the surface quality of the plastic parts. Usually, the surface luster of different kinds of plastics varies greatly under different mold temperature conditions, and the high or low mold temperature will lead to the bad luster. If the mold temperature is too low, the instant solidification of the melt after contacting with the mold cavity will make the mold cavity surface reproducibility decrease.

In order to increase the luster, the mold temperature of the vertical injection molding machine can be properly improved. It is better to pass the warm water in the mold cooling loop to make the heat transfer in the cavity, so as not to prolong the molding cycle. This method can also reduce the residual stress in the molding.

?Under normal circumstances, in addition to ABS, polystyrene, AS, die temperature control in 100 degrees above. It should be noted that if the mold temperature is too high, it will lead to the plastic surface dark.

In addition, the mold failure of the casting system will affect the surface quality of the plastic parts, and the surface luster will be bad.