Effect of Mold Temperature on Gloss
Mold temperature has a significant impact on the gloss of plastic products. In general, the higher the mold temperature, the higher the surface gloss of the plastic product. This is because:
The higher the mold temperature, the better the flowability of the plastic melt, and the easier it is to fill the mold cavity, reduce bubbles and flash, and thus obtain a smooth and flat surface.
The higher the mold temperature, the more orderly the arrangement of molecules in the plastic melt, and the higher the degree of crystallization, resulting in a smoother surface.
Specifically, the effect of mold temperature on gloss is mainly reflected in the following aspects:
If the mold temperature is too low, it will cause poor flowability of the plastic melt, difficulty in filling the mold cavity, and easily produce bubbles and flash, thereby reducing the surface gloss.
If the mold temperature is too high, it will cause the plastic melt to decompose and produce volatile substances, affecting the surface gloss.
If the mold temperature is too high, it will cause the plastic melt to solidify too early, leaving no time for sufficient exhaust, and affecting the surface gloss.
Therefore, in the injection molding process, the mold temperature should be reasonably selected according to the properties of the plastic and the requirements of the product. Generally speaking, for plastics with high crystallinity, the mold temperature should be higher; for plastics with low crystallinity, the mold temperature should be lower.
Here are the recommended mold temperatures for some common plastics:
PS: 180-230℃
PE: 160-220℃
PP: 180-240℃
ABS: 190-250℃
PC: 220-280℃
POM: 200-260℃
PBT: 220-280℃
PET: 250-300℃
In addition to mold temperature, factors affecting the gloss of plastic products include:
Properties of the plastic: The higher the crystallinity, the higher the gloss.
Additives: Some additives, such as lubricants and flame retardants, can reduce the surface gloss of plastic products.
Processing technology: Injection pressure, injection speed, cooling time, and other factors will also affect the surface gloss of plastic products.
