How to improve the success rate of mold test​

How to improve the success rate of mold test

Precautions before mold test
1. Understand the relevant information of the mold:
It is better to get the design drawing of the mould, analyze it in detail, and invite the mould technician to participate in the mould test.
2. Check the mechanical cooperation action on the workbench first:
Pay attention to whether there are scratches, missing parts, looseness and other phenomena, whether the mold moves towards the sliding plate truly, whether there is leakage at the water channel and air pipe joint, and if there is any limit on the opening of the mold, it shall also be indicated on the mold. If the above actions can be done before die hanging, problems can be avoided during die hanging, and then the waste of working hours occurred during die dismantling can be avoided.
3. After determining the proper action of each part of the mold, it is necessary to select a suitable testing injection machine, and attention shall be paid to the selection
Injection Capacity
Width of guide rod
Maximum start
parts
Whether it is complete or not. After everything is confirmed to be OK, the next step is to hang the mold. During hanging, pay attention not to take off the hook before locking all clamping formworks and opening the mold, so as to avoid the mold falling due to the loosening or fracture of clamping formworks.
After the mold is installed, carefully check the mechanical action of each part of the mold, such as the action of sliding plate, thimble, tooth withdrawal structure and limit switch. And pay attention to whether the injection nozzle is aligned with the feed inlet. The next step is to pay attention to the mold closing action. At this time, the mold closing pressure should be reduced. In the manual and low-speed mold closing action, pay attention to see and hear whether there are any non smooth actions and abnormal sounds.
4. Increase mold temperature:
According to the properties of the raw materials used in the finished product and the size of the mold, select the appropriate mold temperature control machine to raise the temperature of the mold to the temperature required for production. After the mold temperature is increased, the action of each part shall be inspected again. Because the steel may cause clamping phenomenon after thermal expansion, it is necessary to pay attention to the sliding of each part to avoid the occurrence of strain and vibration.
5. If there is no experimental planning rule in the factory, we suggest that only one condition can be adjusted 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 different raw materials, bake the raw materials properly.
7. Try to use the same raw materials as the mass production in the future.
8. Do not test the mold completely with secondary materials. If there is color demand, color test can be arranged together.
9. Internal stress and other problems often affect the secondary processing. After the mold is tested and the finished product is stable, the secondary processing mold should be used. After the mold is closed slowly, the mold closing pressure should be adjusted and operated several times to check whether there is any mold closing pressure inequality, so as to avoid rough edge and mold deformation of the finished product.
After the above steps are checked, the mold closing speed and pressure shall be reduced, and the safety buckle and top travel schedule shall be set, then the normal mold closing speed and mold closing speed shall be adjusted. If the limit switch of the maximum stroke is involved, the die opening stroke shall be adjusted a little shorter, and the high-speed die opening action shall be cut off before the maximum stroke of the die opening.
This is due to the fact that the high-speed action stroke is longer than that of the low-speed one during the whole opening stroke during the mold installation. The mechanical ejector rod on the plastic machine must also be adjusted after the full speed opening action to avoid deformation of the ejector plate or stripping plate due to stress.
Before the first mock exam is launched, please check the following items again:
Whether the feeding stroke is too long or insufficient.
Whether the pressure is too high or too low.
Whether the filling speed is too fast or too slow.
Whether the processing cycle is too long or too short.
To prevent short shot, fracture, deformation, burr or even damage to the mold.
If the processing cycle is too short, the thimble will break through the finished product or peel the ring and crush the finished product. This kind of situation may take you two or three hours to get the finished product out.
If the processing cycle is too long, the thin and weak part of die core may be broken due to the shrink of rubber.
Of course, you can't expect all the problems that may occur in the mold testing process, but full consideration and timely measures in advance will help you avoid serious and expensive losses.
Main steps of mold test
In order to avoid unnecessary waste of time and trouble in mass production, it is necessary to be patient to adjust and control various processing conditions, Find out the best temperature and pressure conditions, and formulate standard mold testing procedures, which can be used to establish daily working methods.
1. Check whether the plastic material in the barrel is correct, and whether it is baked according to the regulations (different results may be obtained if different materials are used for mold test and production).
2. The cleaning of the material pipe shall be thorough to prevent the poor release rubber or impurities from entering the mold, because the poor release rubber and impurities may block the mold. Test whether the temperature of the material pipe and the temperature of the mold are suitable for the raw materials.
3. Adjust the pressure and injection quantity to produce the finished products with satisfactory appearance, but do not run the burr, especially when some die cavity products are not completely solidified, before adjusting various control conditions, you should think about it, because a slight change in the filling rate may cause a very large filling change.
4. Wait patiently until the conditions of the machine and the mold are stable, that is, the medium-sized machine may have to wait more than 30 minutes. You can use this time to see what might happen to the finished product.
5. The advance time of the screw shall not be shorter than the solidification time of the gate plastic, otherwise the weight of the finished product will be reduced and the performance of the finished product will be damaged. And when the mold is heated, the screw forward time also needs to be lengthened to compact the finished product.
6. Reasonably adjust and reduce the total processing cycle.
7. Run the newly transferred condition for at least 30 minutes to be stable, and then continuously produce a dozen of full mold samples, mark the date and quantity on the container, and place them respectively according to the mold cavity, so as to test the stability of its actual operation and derive reasonable control tolerance. It is especially valuable for multi hole mold.
8.8. Measure and record the important dimensions of the continuous sample (measure again when the sample is cooled to room temperature).
9. Make a comparison of the measured dimensions of each model of sample, and pay attention to:
Whether the size is stable.
Whether there is a trend of increase or decrease in some dimensions indicating that machining conditions are still changing, such as poor temperature control or oil pressure control.
Whether the dimension changes within the tolerance range.
10. if the first mock exam is not very variable and the conditions for processing are normal, it is necessary to observe whether the quality of the finished products of each mould cavity can be accepted, and the dimensions can be tolerable. Note down the serial or large or less than average die number to check whether the die size is correct.
Record and analyze the data to modify the mold and production conditions, and provide reference for future mass production.
1. Make the processing run longer to stabilize the melt temperature and hydraulic oil temperature.
2. Adjust the machine conditions according to the too large or too small size of all finished products. If the shrinkage is too large and the finished products appear to be insufficient in injection, it can also be used as reference to increase the gate size.
3. If the hole size is too large or too small, it shall be corrected. If the hole size and door size are still correct, then the machine conditions, such as filling rate, mold temperature and pressure of each part, shall be tested and modified, and check whether some holes are filled slowly.
4. According to the matching condition or die core displacement of each die cavity finished product, it is also allowed to adjust the filling rate and die temperature again, so as to improve its uniformity.
5. Check and modify the faults of the injection machine, such as the poor oil pump, oil valve, temperature controller, etc., which will cause the change of processing conditions. Even the perfect mold can not play a good role in the maintenance of the poor machine.
After reviewing all the recorded values, a set of samples shall be kept for checking and comparing whether the corrected samples are improved.
4、 Important matters
Properly keep all the records of sample inspection in the process of mold test, including various pressures in the processing cycle, melt glue and mold temperature, material pipe temperature, injection action time, screw feeding period, etc., in short, keep all the data that will help to establish the same processing conditions in the future, so as to obtain the products meeting the quality standards.
At present, the mold temperature is often ignored in the factory's mold test, but it is the most difficult to master the mold temperature in the short-term mold test and future mass production, and the incorrect mold temperature is enough to affect the size, luminosity, shrinkage, flow pattern and material shortage of the sample. If the mold temperature controller is not used to grasp the future mass production, it may be difficult.