• 2023-05-09
• 228
• 5 Comments

Precautions before mold trial

After the completion of mold design and processing, it is necessary to verify whether the mold design and manufacturing are qualified and whether the products produced meet the requirements. If there are defects and deficiencies, can they be corrected before mass production? Therefore, die test is a crucial step between die processing and mass production.

(1) Understand the relevant information of the mold: it is best to obtain the mold design drawing, detailed analysis, and invite the mold designer to participate in the mold trial work.

(2) First check the mechanical fit action on the workbench: pay attention to whether there are scratches, missing parts and loosening, whether the mold slide action is correct, whether the water channel and gas pipe joint leak, if there are restrictions on the opening of the mold should also be marked on the mold. If the above actions can be done before hanging the mold, it can avoid the waste of time caused by removing the mold when the problem is found.

(3) When determining the appropriate action of each part of the mold, it is necessary to choose the appropriate die injection machine. Attention should be paid to the selection of:

① What is the maximum injection volume of the injection machine;

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

(3) Whether the maximum moving stroke of the movable template meets the requirements;

④ Other 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, attention should be paid to locking all clamping plates and not taking off the hook before opening the mold, so as to avoid loosening or breaking the clamping plates and causing the mold to fall. After the mold is installed, the mechanical action of each part of the mold should be carefully checked, such as whether the action of skateboard, thimble, tooth withdrawal structure and limit switch is true. And pay attention to the injection nozzle and feed port alignment.

The next step is to pay attention to the mold closing action. At this time, the mold closing pressure should be lowered. In the manual and low speed mold closing action, pay attention to see and listen to whether there is any unsmooth movement and abnormal sound. In fact, the process of hoisting the mold is relatively simple. The main place that needs careful attention is that the center of the mold gate and the nozzle is difficult to adjust. Usually, the center can be adjusted by the way of test paper.

(4) Improve the mold temperature: according to the performance of the raw materials used in the finished product and the size of the mold, the appropriate mold temperature control machine is selected to raise the mold temperature to the temperature required during production. After the increase of die temperature, the action of each part should be checked again, because the steel may cause mold clamping phenomenon after thermal expansion, so it is necessary to pay attention to the sliding of each part, so as to avoid strain and vibration.

(5) If the experimental planning rule is not implemented in the factory, it is suggested to adjust only one condition at a time when adjusting the test conditions, so as to distinguish the impact of single condition change on the finished product.

(6) According to the different raw materials, the raw materials used to do moderate baking.

(7) The same raw materials shall be used as far as possible for mold trial and mass production in the future.

(8) Do not completely test the mold with secondary materials. If there is a color need, you can arrange the color test together.

(9) Internal stress and other problems often affect the secondary processing, should be in the mold test after the stability of the finished product to the secondary processing of the mold, after the slow closing, to adjust the mold pressure, and action several times, to check whether there is a closing pressure inequality, so as to avoid the finished product burr and mold deformation.

After the above steps are checked, the closing speed and closing pressure should be reduced, and the safety buckle and ejection stroke should be fixed, and then the normal closing speed and closing speed should be adjusted.

If a limit switch with a maximum stroke is involved, the die opening stroke should be adjusted slightly shorter, and the high-speed die opening action should be cut off before the maximum die opening stroke. This is because the high speed travel is longer than the low speed during the whole die opening travel. The mechanical ejection on the injection machine must also be adjusted after the full speed opening action, so as to avoid the force of the thimble plate or the stripping plate deformation.

Please check the following items before making the first mold injection:

(1) Whether the feeding stroke is too long or insufficient;

Whether the pressure is too high or too low;

(3) Whether the mold filling speed is too fast or too slow;

Whether the processing cycle is too long or too short. To prevent the finished product from short shot, fracture, deformation, burr and even damage to the mold.

If the processing cycle is too short, the thimble will push through the finished product or strip the ring and squeeze the finished product. It can take two or three hours to get the finished product out. If the processing cycle is too long, the thin part of the mold core may be broken due to the tightening of the rubber material. Of course, it is impossible to predict all the problems that may occur during the mold trial process, but it is possible to avoid serious losses by giving full consideration in advance.