Low gloss (LowGloss) means that the surface is dark and dull, and the transparency of the transparent product is low, which causes many reasons for poor gloss. Other injection defects are also causes of poor gloss.
Since the surface of the plastic part is the reproduction of the cavity surface of the mold, if there are surface defects such as scratches, corrosion, micropores, etc. on the surface of the mold, it will be reproduced on the surface of the plastic part to produce poor gloss. If the surface of the cavity is oily, moisture, too much or improperly used, the surface of the plastic part will be dark.
Therefore, the cavity surface of the mold should have a good finish, preferably polished or chrome-plated. The surface of the cavity must be kept clean to remove oil and water stains in a timely manner. The selection and dosage of the release agent should be appropriate.
The mold temperature also has a great influence on the surface quality of the plastic parts. Generally, different types of plastics have different surface gloss under different mold temperature conditions, and the mold temperature is too high or too low, which may lead to poor gloss. If the mold temperature is too low, the melt will solidify immediately after contact with the mold cavity, which will reduce the reproducibility of the mold cavity surface.
In order to increase the gloss, the mold temperature can be appropriately increased. It is preferable to use a method of introducing warm water into the mold cooling circuit to transfer heat in the cavity to avoid prolonging the molding cycle. This method can also reduce residual stress during molding. . In general, in addition to polystyrene, ABS, AS, the mold temperature can be controlled above 100 degrees. However, it should be noted that if the mold temperature is too high, the surface of the plastic part will be dark.
In addition, the draft is too small, the thickness of the section is abrupt, the ribs are too thick, and the gate and runner cross sections are too small or abruptly changed. The shearing effect of the casting system is too large, the molten material flows in a turbulent state, and the mold is poorly discharged. Mold failure can affect the surface quality of the plastic parts, resulting in poor surface gloss.