Dark spots appear not only at the opening of the Chair […]
Dark spots appear not only at the opening of the Chair Mould, but also often after the sharp corners of the article are formed. For example, the sharp corner surface of an item is usually very smooth, but very gray and rough behind it. This is also due to the excessive flow rate and injection speed that cause the cooling surface layer to be replaced by internal fluid displacement.
It is recommended to use the gradual injection again and gradually increase the injection speed. The best way is to let the melt start to increase speed after passing the sharp edge.
In areas far from the gate, sharp changes in product angle can also cause such defects. Therefore, a smoother fillet transition is used in these areas when designing the product.
For injection molded articles, the difference in gloss is most pronounced on the surface of the textured article. Even if the mold surface is very uniform, irregular gloss may appear on the product. In other words, the surface effect of the chair mould on some parts of the product does not reproduce well.
As the distance from the melt leaves the gate, the injection pressure of the melt gradually decreases. If the end of the product gate cannot be filled, the pressure at that point is minimal, so the texture of the surface of the chair mould cannot be properly reproduced on the surface of the product. Therefore, the area of ??greatest pressure in the chamber (half of the fluid path leaving the gate) is the area with the least difference in gloss.
To change this, you can increase the melt and chair mould temperature or increase the pressure, while increasing the pressure holding time can also reduce the occurrence of gloss differences.