Problems to be paid attention to in new mould test
Problems to be paid attention to in new mould test
Before the injection molding of new mold or when the machine changes other mold for production, mold testing is an essential part. The result of die test will directly affect the follow-up production of the factory. Therefore, it is necessary to follow the reasonable operation steps and record the useful technical parameters in the process of mold test in order to facilitate the mass production of products.
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.
First, check the mechanical cooperation action on the platform:
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 mark the mold opening if there is any limit. 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.
After determining the proper action of each part of the mold, it is necessary to select a suitable injection molding machine to test the mold, and attention shall be paid to:
What is the maximum injection volume of injection molding machine
Whether the inner distance of the pull rod is placed on the lower die
Whether the maximum travel distance of the activity template meets the requirements
Whether other tools and accessories for mold test are complete
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.
In fact, the process of lifting the mold is relatively simple. The main thing that needs to be careful is that it is difficult to calibrate the center of the mold gate and nozzle. Usually, the test paper can be used to calibrate the center.
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 in 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.
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.
According to different raw materials, bake the raw materials properly.
As far as possible, the same raw materials shall be used for trial production and future mass production. Do not test the mold completely with secondary materials. If there is color demand, color test can be arranged together. 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 carried out. 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.
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 methods.
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).
The cleaning of the material pipe shall be thorough to prevent the poor release rubber or miscellaneous materials from being injected into the mold, because the poor release rubber and miscellaneous materials may block the mold. Check whether the temperature of the material pipe and the temperature of the mold are suitable for the raw materials.
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 finished products have not fully 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.
Wait patiently until the conditions of the machine and the mold are stable, even for medium-sized machines, it may take more than 30 minutes. You can use this time to see what might happen to the finished product.
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. When the mould is heated, the advance time of the screw also needs to be lengthened to compact the finished product.
Reasonable adjustment to reduce the total processing cycle.
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 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.
Measure and record the important dimensions of the continuous sample (it should be measured when the sample is cooled to room temperature).
Make a comparison of the measured dimensions of each model of sample, and pay attention to:
A. Whether the product size is stable.
B、 Whether there is a trend of increase or decrease in some dimensions to show that machining conditions are still changing, such as poor temperature control or oil pressure control.
C. Whether the dimension changes within the tolerance range.
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 mold cavity can be accepted, and its dimensions can be within tolerance. Note down the serial or large or less than average die number to check whether the die size is correct. Record the parameters obtained in the process of mold test, record and analyze the data as the need to modify the mold and production conditions, and as the reference for future mass production.
Problems to be noticed during mold test:
Make the working time longer, to stabilize the temperature of glue and hydraulic oil.
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 for injection, it can also be used for reference to increase the gate size.
If the size of each die cavity is too large or too small, it shall be corrected. If the size of the die cavity and the door is still correct, then the machine conditions, such as the filling rate, the temperature of the die and the pressure of each part, shall be tested and modified, and the filling speed of some die cavities shall be checked.
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
Check and modify the faults of the injection machine, such as the poor oil pump, oil valve, temperature controller, etc., will cause the change of processing conditions, even if the perfect mold can not play a good role in maintaining the poor machine efficiency. After reviewing all the recorded values, a set of samples shall be kept for checking and comparing whether the corrected samples are improved.
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.
