Five Key Factors in Injection Molding Process

Five Key Factors in Injection Molding Process

The five main factors in the injection molding process are: temperature, speed, pressure, time, and position.

1. Temperature

Temperature can be divided into three types: oil temperature, material temperature, and mold temperature.

• Oil temperature: The oil temperature rises due to the frictional heat generated during the continuous operation of the hydraulic press. It is adjusted by cooling water. When starting the machine, it is necessary to confirm that the oil temperature is approximately 45 degrees Celsius. Too high or too low oil temperature will affect the pressure transmission effect.

• Material temperature: This is the molding temperature of the raw material. The temperature setting of the barrel is based on the material and the shape of the product.

• Mold temperature： This temperature has a great impact on the quality of the product, and should be set according to the material performance.

2. Speed

Speed refers to the speed setting of opening and closing the mold, the speed setting of the ejector pin, and the injection speed.

• Opening and closing mold speed: The general setting is slow-fast-slow. This setting mainly protects the mold and the machine. The fast part can improve the molding cycle of the product.

• Ejector pin speed: The parameter setting of the ejector pin is based on the structure of the mold and the product. If the product has flash or whitening after being ejected, it is recommended to slow down the speed and then quickly demold it, which can shorten the molding cycle.

• Injection speed: The injection speed is set according to the size of the product. For thin-walled products, use fast speed, and for thick-walled products, use slow speed. The specific setting should also be based on the material properties, from slow to fast. 

3. Pressure

Pressure refers to injection pressure, holding pressure, low-pressure protection pressure, and clamping force.

• Injection pressure: It is set from low to high according to the size and wall thickness of the product to achieve the appropriate parameters.

• Holding pressure: It mainly ensures the product's molding and stabilizes the dimensions. It is set according to the product's structure.

• Low-pressure protection pressure: It mainly protects the mold and minimizes mold damage.

• Clamping force: It refers to the force required for the mold to close under high pressure. Some robots can adjust the clamping force, and some robots cannot manually adjust the clamping force.

4. Time

Time refers to injection time, low-pressure protection time, cooling time, and holding time.

• Injection time: This time is longer than the actual time, which can play a protective role in injection. When setting, the set value is about 0.2 seconds larger than the actual value. Consider whether the pressure, speed, and temperature match during setting.

• Low-pressure protection time: In the manual state, first set the time to 2 seconds, and then add it to about 0.02 seconds according to the actual time.

• Cooling time: This time is set according to the size and thickness of the product. However, the plasticizing time should not be greater than the cooling time, which can achieve product setting.

• Holding time: After injection molding is completed, in order to ensure the product's dimensions, the time to cool the gate before the melt backflow under the holding pressure can be set according to the size of the gate.

5. Position

Position refers to the opening and closing mold position, the ejector pin position, and the plasticizing position.

• Opening and closing mold position: It is set according to the opening and closing mold speed. The key is to set the starting position of low-pressure protection. The low-pressure starting position should be the middle finger position that can best protect the mold without affecting the cycle. Because the position where the moving mold contacts the fixed mold during slow mold closing.

• Ejector pin position: This position can meet the complete demolding of the product. First, it is a process from short to long. Note that when the middle mold is used, the return position must be set to 0, otherwise the mold will be damaged.

• Plasticizing position: It is calculated according to the size of the product and the size of the screw to calculate the measurement of a material and set the corresponding position.