Brief introduction of mold test method and precaut

Introduction to mold testing methods and precautions of plastic injection molding machine

mold testing is an essential part before new mold injection molding or when the machine is replaced with other molds for production. The quality of the test results will directly affect the subsequent production of the factory. Therefore, in the process of mold testing, which is a breakthrough in the automotive interior color industry, we must follow reasonable operating steps and record useful technical parameters in the process of mold testing, so as to facilitate the mass production of products

precautions before mold test

1 Understand the relevant information of the mold:

it is best to obtain the design drawing of the mold, analyze it in detail, and invite the mold technician to participate in the mold trial work

2. First check the mechanical cooperation action on the workbench:

pay attention to whether there are scratches, missing parts and looseness, whether the action of the die to the sliding plate is correct, whether the water channel and gas pipe joints have leaks, and if the opening of the die is limited, it should also be marked on the die. If the above actions can be done before hanging the mold, we can avoid the waste of labor time caused by finding problems during hanging the mold and then disassembling the mold

3. When it is determined that the action of each part of the mold is appropriate, it is necessary to select a suitable mold testing ejector. During the selection, attention should be paid to:

(a) what is the maximum injection volume of the injection molding machine

(b) whether the inner distance of the pull rod is placed in the lower mold

(c) whether the maximum moving stroke of the movable template meets the requirements

(d) whether other relevant mold testing tools and accessories are ready

the next step is to hang the mold after everything is confirmed to be OK, When hanging, pay attention not to remove the hook before locking all 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, carefully check the mechanical action of each part of the mold, such as the action of sliding plate, thimble, tooth retraction 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. During the manual and low-speed mold closing action, pay attention to whether there is any unsmooth action and abnormal sound. In fact, the process of hoisting 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 center can be adjusted by means of test paper

4. Increase the mold temperature:

according to the performance of the raw materials used in the finished products and the size of the mold, select an appropriate mold temperature controller to increase the mold temperature to the temperature required for production. After the mold temperature is increased, the action of each part must be checked again, because the steel may cause mold clamping after thermal expansion, so pay attention to the sliding of each part to avoid strain and vibration

5. If the rule of experimental plan is not implemented in the factory, we suggest that when adjusting the test conditions, only one condition of the current research thinking on overcoming the pest problem of MoSi2 can be adjusted at a time, so as to distinguish the impact of a single condition change on the finished product

6. According to different raw materials, the raw materials used should be properly baked

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

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

9. Internal stress and other problems often affect secondary processing. Secondary processing should be carried out after the mold is tested and the finished product is stable. After the mold is closed slowly, the mold closing pressure should be adjusted and acted several times to check whether there is uneven mold closing pressure, so as to avoid burrs and mold deformation of the finished product

after the above steps are checked, reduce the mold closing speed and mold closing pressure, set the safety lever and jacking travel, and then adjust the normal mold closing and mold closing speed. If the limit switch of the maximum stroke 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 mold opening. This is because the high-speed action stroke is longer than the low-speed one in the whole head shape and measurement stroke of gb/t 5279 ⑴ 985 countersunk head screw during mold installation. On the plastic machine, the mechanical ejector rod must also be adjusted after the full speed mold opening action to avoid the deformation of the ejector plate or stripping plate due to force

please check the following items again before the first mold injection:

(a) whether the feeding stroke is too long or insufficient

(b) whether the pressure is too high or too low

(c) whether the mold filling speed is too fast or too slow

(d) whether the processing cycle is too long or too short

to prevent short shot, fracture, deformation, burr and even damage to the mold of the finished product

if the processing cycle is too short, the thimble will pierce the finished product or the stripping ring will crush the finished product. This kind of situation may make it take you twoorthree hours to take out the finished product. If the processing cycle is too long, the weak part of the mold core may be broken due to the shrinkage of the rubber. Of course, you can't expect all the problems that may occur during the mold trial, but full consideration and timely measures in advance can help you avoid serious and expensive losses

main steps of mold test

in order to avoid unnecessary waste of time and trouble during mass production, it is really necessary to pay patience to adjust and control various processing conditions, find out the best temperature and pressure conditions, and formulate standard mold test procedures, which can be used to establish daily working methods

1. Check whether the plastic materials in the barrel are correct and whether they are baked according to the regulations. (if different raw materials are used in mold trial and production, it is likely that the quality of these products sold through unofficial channels will be mixed, resulting in different results)

2. The material pipe must be cleaned thoroughly to prevent the degraded rubber or impurities from entering the mold, because the degraded rubber and impurities may jam the mold. Check 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 volume to produce a finished product with satisfactory appearance, but do not run burrs. Especially when some mold cavity finished products are not completely solidified, you should think about it before adjusting various control conditions, because a slight change in mold filling rate may cause great mold filling changes

4. Wait patiently until the conditions of the machine and mold stabilize. Even medium-sized machines may have to wait more than 30 minutes. You can use this time to check the possible problems of 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 advance time of the screw should also be extended to compact the finished product

6. Reasonably adjust and reduce the total processing cycle

7. Operate the newly prepared conditions for at least 30 minutes to stabilize, and then continuously produce at least a dozen full mold samples, mark the date and quantity on their containers, and place them separately according to the mold holes, so as to test the stability of their actual operation and derive reasonable control tolerances. (especially valuable for multi hole mold)

8. Measure and record the important dimensions of continuous samples (wait until the samples are cooled to room temperature)

9. Compare the size measured by each mold 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, indicating that the machining conditions are still changing, such as poor temperature control or oil pressure control

(c) whether the change of dimension is within the tolerance range

10. If the size of the finished product does not change much and the processing conditions are normal, it is necessary to observe whether the quality of the finished product of each the first mock examination hole is acceptable and its size can be within the allowable tolerance. Note down the mold hole number measured continuously or higher or lower than the average value, so as to check whether the size of the mold is correct

record the parameters obtained during the mold test

record and analyze the data as the need to modify the mold and production conditions, and as a reference for future mass production

1. Make the processing operation time longer to stabilize the melt temperature and hydraulic oil temperature

2. Adjust the machine conditions according to the size of all finished products. If the shrinkage is too large and the finished products appear to be insufficient, it can also be used as a reference to increase the gate size

3. The size of each mold cavity is too large or too small to be corrected. If the size of mold cavity and door is still correct, then try to change the machine conditions, such as mold filling rate, mold temperature and pressure of each part, and check whether some mold cavities are filled slowly

4. According to the matching condition of the finished products of each mold hole or the displacement of the mold core, it is also allowed to adjust the mold filling rate and mold temperature again, so as to improve its uniformity

5 Check and modify the faults of the ejector, such as the poor oil pump, oil valve, temperature controller, etc., will cause changes in processing conditions. Even the most perfect mold can not play a good work efficiency in the poorly maintained machine. After reviewing all the recorded values, keep a set of samples for checking and comparing whether the corrected samples are improved

properly keep all the records of sample inspection in the process of mold testing, including various pressures in the processing cycle, melt and mold temperature, material pipe temperature, injection action time, screw feeding period, etc. in short, all the data that will help to successfully establish the same processing conditions in the future should be saved, so as to obtain products that meet the quality standards

at present, the mold temperature is often ignored during mold testing in factories, and it is the most difficult to master the mold temperature during short-term mold testing and future mass production, and the incorrect mold temperature is enough to affect the size, brightness, shrinkage, flow lines, shortage of materials and other phenomena of the sample. If you do not use the mold temperature controller to grasp it in future mass production, it may be difficult