Precautions Before Mold Trial

1. Understand the relevant information of the injection mold

It is best to obtain the design drawing of the injection mold, analyze it in detail, and invite mold technicians to participate in the trial work.

2. First check the mechanical coordination action of injection mold on the workbench

Pay attention to whether there are scratches, missing parts, looseness, etc., whether the mold slide is correct, whether there is leakage in the water channel and air pipe joints, and if there are restrictions on the mold opening, it should also be marked on the mold. If the above actions can be done before hanging the mold, the waste of man-hours caused by the removal of the mold after the problem is found when the mold is hanging can be avoided.

3. When it is determined that the various parts of the mold are suitable for action, it is necessary to select a suitable trial mold injection machine, and pay attention to:

①What is the maximum injection volume of the injection molding machine?

②Whether the inner distance of the tie rod can be put down the mold;

③Whether the maximum moving itinerary of the movable template meets the requirements;

④Whether other relevant tools and accessories for mold trial are ready.

After everything is confirmed that there is no problem, the next step is to hang the mold. When hanging, be careful not to remove the hook before locking all the clamping templates and opening the mold, so as to prevent the clamping template from loosening or breaking and causing the mold to fall. After the mold is installed, you should carefully check the mechanical actions of each part of the injection molding mold, such as the movement of the sliding plate, thimble, withdrawal structure, and limit switch. And pay attention to whether the injection nozzle and the feed port are aligned. The next step is to pay attention to the mold clamping action. At this time, the mold closing pressure should be lowered. In the manual and low-speed mold clamping action, pay attention to see and listen for any unsmooth movements and abnormal noises. The process of hoisting the mold is actually relatively simple. The main points that need careful attention are that it is difficult to align the center of the mold gate and nozzle. Usually, the center can be adjusted by means of test paper.

4. Increase mold temperature:

According to the properties of the raw materials used in the finished product and the size of the mold, an appropriate mold temperature control machine is selected to increase the temperature of the injection mold to the temperature required for production. After the mold temperature rises, you need to check the movements of each part again, because the steel may cause a jam phenomenon after thermal expansion, so you must pay attention to the sliding of each part to avoid strain and vibration.

5. If the experiment plan rule is not implemented in the factory, it is recommended to adjust only one condition at a time when adjusting the injection mold test conditions, in order to distinguish the impact of a single condition change on the finished product.

6. According to the different raw materials, do a moderate baking of the original used.

7. Try to use the same raw materials as much as possible for mass production in the future.

8. Do not try the mold completely with inferior materials. If there is a color requirement, you can arrange the color test together.

9. Problems such as internal stress often affect the secondary processing. The finished product should be stabilized after the trial mold. After the secondary processing injection mold is closed at a slow speed, adjust the mold closing pressure and perform several actions to check whether it is closed. Unequal mold pressure to avoid burrs and mold deformation in the finished product.

After checking the above steps, lower the mold closing speed and pressure, and set the safety hook and ejection stroke, and then adjust the normal mold closing and closing speed. If the maximum stroke limit switch is involved, the mold opening stroke should be adjusted slightly shorter, and the high-speed mold opening action should be cut off before the maximum stroke of the mold opening. This is because the high-speed stroke is longer than the low-speed stroke in the entire mold opening stroke during mold loading. On the plastic machine, the mechanical ejection must also be adjusted after the full-speed mold opening action to prevent the ejector plate or the peeling plate from being deformed by force.

Please check the following items again before making the first mold injection: ① Whether the feeding stroke is too long or insufficient; ② Whether the pressure is too high or too low; ③ Whether the filling speed is too fast or too slow; ④ Whether the processing cycle is too long or too short. In order to prevent the finished product from short shot, fracture, deformation, burrs and even damage to the mold.

If the processing cycle is too short, the thimble will penetrate the finished product or squeeze the finished product by peeling the ring. This type of situation may cost people two or three hours to take out the finished product. If the processing cycle is too long, the weak parts of the mold core may be broken due to the shrinkage of the rubber. Of course, it is impossible to predict all the problems that may occur in the trial mold process, but full consideration in advance can avoid serious losses.