Hot runner mold trial 8 steps

Step 1. Set the temperature of the bucket

It should be noted that the initial barrel temperature setting must be based on the recommendation of the material supplier. This is because different manufacturers and brands of the same material may have significant differences, and material suppliers often have their own

Considerable in-depth research and understanding. Users can make basic settings based on their recommendations, and then make appropriate adjustments according to the specific production situation.

In addition, a detector is also required to measure the actual temperature of the melt. Because the barrel temperature we set often cannot guarantee 100% consistency with the melt temperature due to differences in environment, temperature sensor model, and location depth.

Sometimes, due to the presence of oil stains or other reasons, the actual temperature of the melt and the set temperature of the material barrel differ greatly (previously, we had examples where the temperature difference between the two was as high as 30 ℃).

Step 2. Set the temperature of the mold

Similarly, the initial mold temperature setting must also be based on the recommended values provided by the material supplier.

It should be noted that the mold temperature we refer to refers to the surface temperature of the mold cavity, rather than the temperature displayed on the mold temperature controller. Many times, due to environmental factors and improper power selection of the mold temperature controller, the display on the mold temperature controller

The temperature is not consistent with the surface temperature of the mold cavity. Therefore, before the formal trial mold, the temperature of the mold cavity surface must be measured and recorded. At the same time, measurements should also be taken at different positions in the mold cavity to check if the temperature at each point is balanced,

And record the corresponding results to provide reference data for subsequent mold optimization.

Step 3

Based on experience, preliminarily set parameters such as plasticizing amount, injection pressure limit, injection speed, cooling time, and screw speed, and optimize them appropriately.

Step 4. Conduct a filling test to identify the transition points.

The transition point refers to the transition point from the injection stage to the pressure maintaining stage, which can include screw position, filling time, and filling pressure. This is one of the most important and fundamental parameters in the injection molding process. In actual filling tests, the following points need to be followed:

(1) The holding pressure and holding time during the test are usually set to zero;

(2) The product is generally filled to 90%~98%, depending on the wall thickness and the structural design of the mold;

(3) Due to the impact of injection speed on the position of the transfer point, it is necessary to reconfirm the transfer point every time the injection speed is changed.

Through filling experiments, users can see the flow path of the material in the mold cavity, thereby determining where the mold is prone to air trapping or where exhaust needs to be improved.

Step 5. Find the limit value of injection pressure.

During this process, attention should be paid to the relationship between injection pressure and injection speed. For hydraulic systems, pressure and speed are interrelated. Therefore, it is not possible to set both parameters simultaneously to meet the required conditions.

The injection pressure set on the screen is the limit value of the actual injection pressure, therefore, 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, causing the actual injection pressure to approach or exceed the injection pressure

By limiting the value, the actual injection speed will automatically decrease due to power limitations, thereby affecting the injection time and molding cycle.

Step 6. Find the optimized injection speed.

The injection speed referred to here refers to an injection speed that simultaneously minimizes the filling time and minimizes the filling pressure. During this process, the following points need to be noted:

(1) Most surface defects of products, especially those near the gate, are caused by injection speed.

(2) Multi stage injection is only used when one injection cannot meet the process requirements, especially during the mold trial stage.

(3) When the mold is intact, the pressure transfer point is set correctly, and the injection speed is sufficient, the speed of injection is not directly related to the generation of flash.

Step 7. Optimize the holding time.

The holding time is also 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 mold weight reaches its maximum.

Step 8. Optimize other parameters, such as holding pressure and locking force.

Finally, it should be emphasized that the purpose and focus of the trial mold is to optimize the mold and process to meet the requirements of mass production, rather than just testing out good product samples.