No best answer

1. Barrel temperature, mold temperature
The temperature of the screw barrel is set according to the properties of different plastic materials. The set temperature of the barrel is generally 10°C-30°C higher than the melting point of the plastic. It must be noted that the materials provided by different manufacturers have different melting points and allowable residence time in the barrel due to different synthesis methods or types of additives added.
The mold temperature is generally cooled by circulating water when setting, but when producing products with high precision dimensions or high surface quality requirements, a mold temperature machine that can be accurately controlled should be used according to the process requirements.
2. Injection pressure holding time, cooling time
Injection time, pressure holding time and cooling time must be set according to product thickness, mold temperature, material properties, etc. The injection time is generally set to be slightly longer than the time for the screw to complete the movement of the injection stroke. Excessive injection time will not only produce negative effects such as mechanical wear and increase energy consumption, but also prolong the molding cycle. The pressure holding time is set according to the thickness of the product, and the pressure holding time is not necessary for thin-walled products during molding;
When setting the holding pressure time, as long as there is no obvious depression on the surface of the product, it can also be determined by the weighing method. Gradually extend the holding pressure time until the time when the product quality no longer changes to determine the best holding pressure time. The cooling time also needs to be determined according to the product thickness, mold temperature, and material properties. Generally, the cooling time of amorphous polymers is longer than that of crystalline polymers.
3. Injection pressure and speed
The injection pressure setting should follow the principle of low rather than high, as long as it can provide enough power to reach the required injection speed, so that the melt can fill the cavity smoothly, too high pressure will easily cause internal stress in the product; When molding products with high dimensional accuracy, in order to prevent excessive product shrinkage, high-pressure injection can be used to reduce the shrinkage of the product after demolding.

The injection speed will affect the appearance quality of the product. The setting should be set according to the geometric structure of the mold, the exhaust condition, etc. Generally, the injection speed should be increased as much as possible to reduce the filling time under the premise of ensuring a good appearance.
In injection molding, when the melt flows in the mold, the mold wall will form a solidified layer, thereby reducing the thickness of the flowable channel. Generally, depending on the mold structure and injection speed, the mold wall will have a solidified layer of about 0.2mm. Therefore, a faster injection speed is usually used in molding.
3. Injection stroke, multi-level injection parameters
In molding, the injection stroke must first be determined. Theoretically, the injection stroke can be calculated as follows:
S1=4(CVp+Va)/ρDs2
In the formula: injection stroke Vp-product volume ρ-resin density C-number of cavities Va-gate volume Ds-screw diameter
In actual production, if the total weight of "product + gate" is known, the following formula can be used to calculate the injection stroke S1=(M/Mmax)·Smax+(5~10)mm
In the formula, S1: injection stroke, mm M—total weight of “product + gate”, g Mmax—maximum injection volume of injection molding machine, g/Smax—maximum injection stroke of injection molding machine.
4. Other process parameters
In injection molding, in addition to the setting of several main parameters such as molding temperature, pressure, speed, time, and multi-stage injection switching position, there are many other process parameters, such as back pressure, screw speed, screw back-cable anti-flow It can't ignore the setting of delay and other various action parameter settings.