In order to improving product quality and production efficiency, the technicians of the adjustment machine must be familiar with the injection process parameters and machine adjustment procedures, and use them fully to improve the defects of plastic products. The following are the main parameters of the Plastic injection molding adjustment and the common defects and improvement measures of the plastic products. . (The adjustment machine mentioned in the injection molding process refers to a series of adjustment schemes that continuously adjust the various parameters of the injection molding machine and other auxiliary parameters according to a specific mold and raw materials until a qualified plastic part is produced, which is called the Plastic injection molding adjustment.
The main parameters of the Plastic injection molding adjustment are as follows:
1 Comprehensive parameters
1.1 Die size: width × height × thickness
1.2 Maximum injection volume: It is the maximum volume that can be injected by the injection molding machine. The weight is generally expressed in grams (g) or ounces (oz) (1oz=28.4g). Due to the different specific gravity of various rubber materials, they are generally Taking PS (the specific gravity is about 1) as a reference, the beer is converted when used as other rubber materials. The total beer weight (including the nozzle) of the beer rubber parts must be less than (or equal to) 80% of the maximum injection volume, and it cannot Less than 15% of the maximum injection volume, otherwise it will affect the injection efficiency.
1.3 Clamping force: It is the maximum separating force that the mold can withstand after the mold is closed. Generally, the beer machine has a rated clamping force. If it is adjusted too large, it will easily deform the machine or mold.
The clamping force is roughly proportional to the projected area of the part. The rough calculation method is as follows: clamping force (tons) = projected area of cavity (cm²) × material pressure coefficient ÷ 90% of the rated clamping force attached: material Pressure coefficient parameter table
Name PS PE PP ABS plastic nylon Saigang fiberglass other engineering plastics KP (t / cm²) 0.32 0.32 0.32 0.39 0.68 0.64 ~ 0.72 0.64 ~ 0.72 0.64 ~ 0.8 Example: A two molded product, wherein: the projection plane product 10 = ×17=170cm², nozzle projection surface=0.8×14=11.2cm², the average pressure coefficient of ABS material is 0.39, so: clamping force=170+11.2=181.2×0.39=70.67 tons, 70.67÷90% = 78.5 tons. If it is said that the model calculated according to the projection surface of the product, although the clamping force of 80 tons is sufficient, consider whether the gross weight of the product exceeds the maximum glue capacity of the model (the maximum glue capacity of the 80-ton model is 142g), and If the clamping force is greater than (or equal to) 85 tons, the relationship between the mold capacity size and product characteristics should also be considered. Whether to use a model of 80 tons (5A) or more; the product characteristics requirements are relatively strict, and the size of the machine mold cannot be installed. Therefore, it is generally necessary to use models of more than 120 tons (7A).
2 Temperature parameters
The temperature limits involved in the injection molding process are as follows: -baking material drying temperature -barrel temperature -mold temperature
2.1 Baking material drying temperature
When beer is made, it is necessary to dry the moisture content of the raw materials to a certain percentage or less, which is called baking, because the high moisture content of the raw materials will cause sparkling and peeling.