- Set-up the Barrel Temperature
It should be noted here that the initial barrel temperature setting must be based on the recommendations of the material supplier. This is because the same material from different manufacturers and different brands may have considerable differences, and the material supplier often has a deep research and understanding of their own materials. Users can make basic settings based on their recommendations, and then fine-tune them appropriately according to specific production conditions.
In addition, the actual temperature of the melt needs to be measured with a detector. Because the barrel temperature we set is often due to the environment, the type of the temperature sensor and the depth of the location, etc., it cannot guarantee 100% consistency with the melt temperature. Sometimes due to the presence of oil stains or other reasons, the actual temperature of the melt and the setting temperature of the barrel are very different (previously, we have had examples where the temperature difference between the two was as high as 30 ° C).
- Set-up the Mould Temperature
When setting up mold temperature, we should take recommendation of mold steel supplier who might suggest us some advise.
It should be noted that the mold temperature we refer to is the temperature of the cavity surface, not the temperature displayed on the mold temperature controller. Many times, due to the environment and improper power selection of the mold temperature controller, the temperature displayed on the mold temperature controller is not consistent with the temperature on the surface of the mold cavity.
Therefore, the temperature of the cavity surface must be measured and recorded before the formal test. At the same time, different positions in the mold cavity should be measured to see if the temperature at each point is balanced, and the corresponding results should be recorded to provide reference data for subsequent mold optimization.
- Set-up the Injection Machine Temperature
We set up injection machine temperature according to experience, those parameters such as the amount of plasticization, the limiting value of injection pressure, the injection speed, the cooling time, and the rotation speed of the screw are initially set and appropriately optimized.
- Perform fill tests to find transition points
The switching point refers to the switching point from the injection phase to the holding pressure phase. It can be the screw position, filling time, and filling pressure. This is one of the most important and basic parameters in the injection molding process. In the actual filling test, the following points need to be followed:
- The holding pressure and holding time during the test are usually set to zero;
- The product is generally filled to 90% ~ 98%, depending on the wall thickness and the structural design of the mold;
- Since the injection speed affects the position of the pressure point, the pressure point must be reconfirmed every time the injection speed is changed.
Through the filling test, the user can see the flow path of the material in the mold cavity, so as to determine where the mold is likely to trap air, or where the exhaust gas needs to be improved.
- Finding out the Limit of Injection Pressure
In this process, attention should be paid to the relationship between injection pressure and injection speed. For hydraulic systems, pressure and speed are interrelated. Therefore, these two parameters cannot be set at the same time so that they meet the required conditions at the same time.
The injection pressure set on the screen is the limit value of the actual injection pressure, so the limit value of the injection pressure should be set to always be greater than the actual injection pressure. If the injection pressure limit is too low, so that the actual injection pressure approaches or exceeds the limit of the injection pressure, then the actual injection speed will automatically decrease due to the power limitation, which will affect the injection time and molding cycle.
- Finding out the optimized injection speed
The injection speed referred to here is an injection speed at which both the filling time is as short as possible and the filling pressure is as small as possible. In this process, you need to pay attention to the following points:
- The surface defects of most products, especially those near the gate, are caused by the injection speed;
- Multi-stage injection is only used when one injection cannot meet the process requirements, especially in the trial mode;
- When the mold is intact, the transfer pressure point is set correctly, and the injection speed is sufficient, the speed of injection speed is not directly related to the generation of flash.
- Finding out the holding Pressure Time
The holding pressure time is the condensation time of the gate. Generally, the condensation time of the gate can be determined by weighing to obtain different holding times, and the optimal holding time is the time when the product’s mold weight reaches the maximum.