Tips for testing molds for injection molds as belows:
First, the precautions before the test
1. Understand the relevant information of the mold:It is best to get the design drawings of the mold, analyze it in detail, and get the mold technician to participate in the test work.
2. Check the mechanical coordination action on the workbench:Pay attention to whether there are any scratches, missing parts and looseness, whether the mold-sliding action is correct, whether there is leakage in the water channel and the air pipe joint, and if the opening of the mold is restricted, it should be marked on the mold. If the above actions can be done before the mold is hung, it is possible to avoid the problem of finding the problem when the mold is hanging, and then the waste of work caused by disassembling the mold.
3. When it is determined that all parts of the mold are suitable for action, it is necessary to select a suitable test injection molding machine. When selecting, you should pay attention to:
(1) What is the maximum injection volume of the injection molding machine;
(2) Whether the inner distance of the tie rod is placed under the mold;
(3) Whether the maximum movement schedule of the activity template meets the requirements;
(4) Are other related test tools and accessories ready?
After everything is confirmed to be no problem, the next step is to hang the mold. When hanging, please note that the hook should not be removed before locking all the clamps and opening the mold, so as to prevent the clamp from loosening or breaking so that the mold falls.
After the mold is installed, the mechanical action of each part of the mold should be carefully checked, such as the action of the skateboard, the thimble, the backrest structure and the limit switch, and pay attention to whether the 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 clamping movement, pay attention to whether or not there is any smooth movement and abnormal sound. The process of lifting the mold is actually relatively simple. It is difficult to adjust the center of the mold gate and the nozzle. The test center can usually be used to adjust the center.
4. Increase the mold temperature According to the properties of the raw materials used in the product and the size of the mold, an appropriate mold temperature control machine is used to raise the temperature of the mold to the temperature required for production. After the mold temperature is increased, the movement of each part must be reviewed again, because the steel may cause jamming after thermal expansion, so it is necessary to pay attention to the sliding of each part to avoid the occurrence of strain and chatter.
5. If the experiment plan rule is not implemented in the factory, it is recommended that only one condition can be adjusted at a time when adjusting the test conditions to distinguish the influence of a single condition change on the product.
6. Depending on the raw materials, make a proper baking of the original used.
7. Try the mold and mass production in the future, use the same raw materials as much as possible.
8. Do not try the test by default. If there is any color requirement, you can arrange the test color together.
9. Problems such as internal stress often affect secondary processing. After the test, the product should be stabilized, that is, the mold should be processed twice. After the slow speed is closed, the clamping pressure should be adjusted and acted several times to check whether there is uneven clamping pressure, so as to avoid burrs and mold deformation.
After the above steps are checked, the mold closing speed and the closing pressure are lowered, and the safety buckle and the ejection stroke are set, and then the normal closing mode and the closing speed are adjusted. If the limit switch involving 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 the mold opening. This is because during the mold clamping period, the high-speed operation stroke is longer than the low speed during the entire mold opening stroke. On a plastic machine, the mechanical ejector rod must also be adjusted to act after the full-speed mold opening action to prevent the ejector plate or the peeling plate from being deformed by force.
Before making the first shot, please check the following items:
an examination
(1) Whether the feeding schedule 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.
To prevent short shots, breaks, deformations, burrs and even damage to the mold. If the processing cycle is too short, the thimble will pierce the product or strip the product, which may take two or three hours to remove the product. If the processing cycle is too long, the weak part of the core may be broken due to shrinkage of the rubber. Of course, you can’t predict all the possible problems in the trial process, but taking good care and taking timely measures in advance will help you avoid serious and expensive losses.
Second, the main steps of the test mold
In order to avoid wasting time and trouble during mass production, it is necessary to patience to adjust and control various processing conditions, and to find the best temperature and pressure conditions, and to develop a standard test procedure, which is beneficial for establishing daily routines. Working method.
1. Check if the plastic in the barrel is correct and whether it is baked according to the regulations (if different materials are used for the test and production, it is likely to produce different results).
2. The cleaning of the material pipe should be thorough to prevent the inferior compound or miscellaneous material from being injected into the mold. Because the inferior compound and miscellaneous materials may jam the mold. Check if the temperature of the tube and the temperature of the mold are suitable for the raw materials for processing.
3. Adjust the pressure and the amount of injection to produce a product with satisfactory appearance. However, it is not possible to run the burrs, especially when some cavity products have not yet fully solidified. Think about it before adjusting various control conditions. Because the filling rate is slightly changed, it may cause a large filling change.
4. Be patient and wait until the conditions of the machine and the mold are stable, that is, the medium-sized machine may have to wait for more than 30 minutes. This time can be used to see what can happen to the product.
5. The advancement time of the screw should not be shorter than the time when the gate plastic solidifies. Otherwise, the weight of the product will decrease and the performance of the product will be impaired. And when the mold is heated, the screw advance time also needs to be lengthened to compact the product.
6. Reasonable adjustment to reduce the total processing cycle.
7. Run the newly transferred conditions for at least 30 minutes, and then stabilize, and then at least continuously produce a dozen full-mode samples, mark the date and quantity on the holder, and place them separately according to the cavity to test the stability of the operation. Sexuality and the introduction of reasonable control tolerances (especially valuable for multi-cavity molds).
8. Measure and record the continuous size of the continuous sample (should be re-sampled when the sample is cooled to room temperature).
9. Compare the dimensions of each model sample and note that:
(1) Whether the size of the product is stable;
(2) Whether some sizes have an increasing or decreasing trend, and the machine processing conditions are still changing, such as poor temperature control or oil pressure control;
(3) Whether the change in size is within the tolerance range.
10. If the product size does not change and the processing conditions are normal, it is necessary to observe whether the quality of each cavity product is acceptable and its dimensions can be within the tolerances. Make a note of the number of holes that are continuous or large or smaller than the average to check if the size of the mold is correct.
Third, record the parameters obtained during the trial process
Record and analyze the data as a need to modify the mold and production conditions, and as a reference for future mass production.
1. Make the processing run time longer to stabilize the melt temperature and hydraulic oil temperature.
2. According to the size of all products is too large or too small to adjust the machine conditions, if the shrinkage rate is too large and the product appears to be insufficient, it can also be used to increase the gate size.
3. The size of each cavity is too large or too small to be corrected. If the cavity and gate size are correct, then the machine conditions should be changed, such as filling rate, mold temperature and pressure of each part, and some Whether the cavity is filled slowly.
4. According to the matching situation of each cavity product or the displacement of the core, it may be individually corrected. It may be possible to test the filling rate and the mold temperature again in order to improve the uniformity.
5. Check and modify the fault of the injection machine. For example, the poor performance of the oil pump, oil valve, temperature controller, etc. will cause the processing conditions to change. Even the perfect mold can not work well in the poorly maintained machine.
After reviewing all of the recorded values, a set of samples is retained to proofread whether the corrected samples have improved. Properly keep records of all sample inspections during the test process, including various pressures during the processing cycle, melt and mold temperatures, tube temperature, injection action time, screw feed period, etc. In short, all future contributions should be saved. It is possible to successfully establish data on the same processing conditions in order to obtain products that meet the quality standards.
At present, the mold temperature is often neglected during factory test, and the mold temperature is the most difficult to master in short-term test and future mass production. The incorrect mold temperature is enough to affect the sample size, luminosity, shrinkage, flow pattern and material loss. Such phenomena, if not controlled by the mold temperature controller, may cause difficulties in mass production in the future.
Post time: Aug-15-2019