Five major elements of plastic injection molding process
1. Temperature:
A. Temperature: For hydraulic presses, it is the heat energy generated by the friction of hydraulic oil movement due to the continuous operation of the machine. It is controlled by cooling water. When starting the machine, it is necessary to confirm that the oil temperature is around 45°C. If the oil temperature is too high or too low, it will affect the transmission of pressure.
B. Material temperature: that is, the barrel temperature. This temperature should be set according to the shape and function of the material and product. If there is a file, set it according to the file.
C. Mold temperature: This temperature is also an important parameter. Its high or low has a great impact on the performance of the product. Therefore, when setting it, the function and structure of the product must be considered, and the material and cycle must also be considered.
2. Speed:
A. The speed setting of opening and closing the mold is generally based on the principle of slow-fast-slow. This setting mainly considers the machine, mold, and cycle.
B. Ejection setting: It can be set according to the structure of the product. For complex structures, it is best to use slow ejection and then fast demolding to shorten the cycle.
C. Shooting speed: set according to the size and structure of the product. If the structure is complex and the wall is thin, it can be fast. If the structure is simple and the wall is thick, it can be slow. It should also be set from slow to fast according to the performance of the material.
3. Pressure:
A. Injection pressure: set from low to high according to the size of the product and the thickness of the wall. Other factors should be considered during debugging.
B. Holding pressure: The holding pressure is mainly to ensure the finalization and stable size of the product. Its setting should also be set according to the structure and shape of the product.
C. Low pressure protection pressure: This pressure mainly protects the mold and minimizes the damage to the mold.
D. Clamping force: refers to the force required for the mold to close the mold and generate high pressure. Some machines can adjust the clamping force, while others cannot.
4. Time:
A. Injection time: This time setting must be longer than the actual time, and it can also play a role in injection protection. The setting value is about 0.2 seconds larger than the actual value during the injection timing. When setting, the coordination with pressure, speed and temperature should be considered.
B. Low-pressure protection time: In manual mode, first set the time to 2 seconds, and then add about 0.02 seconds according to the actual time.
C. Cooling time: This time is generally set according to the size and thickness of the product, but the melting time should not be longer than the cooling time, so that the product can be fully formed.
D. Holding time: This time is the time to cool the gate before the melt flows back under the holding pressure to ensure the size of the product after the injection is completed. It can be set according to the size of the gate.
5. Position:
A. The opening and closing mold position can be set according to the corresponding opening and closing mold speed. The key is to set the starting position of the low-pressure protection, that is, the starting position of the low pressure should be the point that is most likely to protect the mold without affecting the cycle. The end position should be the position where the front and rear molds of the mold are in contact when the mold is closed at a slow speed.
B. Ejection position: This position can meet the complete demolding of the product. First, set it from small to large. Note that the return position must be set to "0" when installing the mold, otherwise it is easy to damage the mold.
C. Melt position: Calculate the material amount according to the product size and screw size, and then set the corresponding position.
D. The V-P position (i.e. V-P switching point) should be found from large to small using the Short-Short method.
