The director of the injection department of PTJ Plastic Mould Co., Ltd. came to explain to us how to do a good trial of plastic molds.
Before the injection molding of a new mold or when the machine is replaced with other molds, the trial mold is an indispensable part.The quality of the test results directly affects whether the follow-up production of the factory is smooth.Therefore, reasonable operation steps must be followed and the useful technical parameters recorded in the trial mold process in order to facilitate the mass production of the product.
1. Precautions before mold trial
(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 coordination action on the workbench: pay attention to whether there are scratches, missing parts and looseness, whether the mold slide is correct, whether there is leakage in the water channel and air pipe joints, and if the mold opening is restricted The words should also be marked on the mold.If the above actions can be done before hanging the mold, it can avoid the waste of man-hours caused by the removal of the mold when the problem is found when the mold is hanging.
(3) When it is determined that the various parts of the mold are suitable for action, it is necessary to select a suitable test mold injection machine. When selecting, pay attention to:
①What is the maximum injection volume of the injection molding machine?
②Whether the inner distance of the tie rod can be put down the mold;
③Whether the maximum moving stroke of the movable template meets the requirements;
④Whether other relevant 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, be careful not to remove the hook before locking all the 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 actions of each part of the mold, such as the movement of the sliding plate, thimble, withdrawal structure, and limit switch.And pay attention to whether the injection 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 mold clamping action, pay attention to see and listen for any unsmooth movements and abnormal noises.The process of hoisting the mold is actually relatively simple. The main points that need careful attention are that it is difficult to align 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 properties of the raw materials used in the finished product and the size of the mold, select an appropriate mold temperature control machine to increase the temperature of the mold to the temperature required for production.After the mold temperature rises, the movement of each part must be checked again, because the steel may cause a mold jam phenomenon after thermal expansion, so pay attention to the sliding of each part to avoid strain and vibration.
(5) If the experiment plan rule is not implemented in the factory, it is recommended to adjust only one condition at a time when adjusting the test conditions, so as to distinguish the impact of a single condition change on the finished product.
(6) According to the different raw materials, do a moderate baking of the original used.
(7) Try to use the same raw materials as much as possible for mass production in the future.
(8) Do not try the mold completely with the inferior material. If there is a color requirement, you can arrange the color test together.
(9) Problems such as internal stress often affect the secondary processing. After the mold is tested, the finished product should be stabilized and then the secondary processing mold should be performed. After the slow closing, the closing pressure should be adjusted, and the action should be performed several times to check if there is any Uneven clamping pressure to avoid burrs and mold deformation in the finished product.
After checking the above steps, lower the mold closing speed and pressure, and set the safety hook and ejection stroke, and then adjust the normal mold closing and closing speed.
If the maximum stroke limit switch 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 the high-speed stroke is longer than the low-speed stroke in the entire mold opening stroke during mold loading.On the plastic machine, the mechanical ejection must also be adjusted after the full-speed mold opening action to prevent the ejector plate or the peeling plate from being deformed by force.
Please check the following items before making the first mold injection:
①Whether the feeding stroke is too long or insufficient;
②Whether the pressure is too high or too low;
③Whether the filling speed is too fast or too slow;
④Whether the processing cycle is too long or too short.In order to prevent the finished product from short shot, fracture, deformation, burrs and even damage to the mold.
If the processing cycle is too short, the thimble will penetrate the finished product or squeeze the finished product by peeling the ring.This type of situation may cost people two or three hours to take out the finished product.If the processing cycle is too long, the weak parts of the mold core may be broken due to the shrinkage of the rubber.Of course, it is impossible to predict all the problems that may occur during the mold trial process, but serious losses can be avoided by taking full consideration in advance.
2. The main steps of tryout
(1) Check whether the plastic raw materials in the barrel are correct, and whether they are baked in accordance with the regulations (if different raw materials are used for trial and production, different results may be obtained).
(2) The material pipe must be cleaned thoroughly to prevent inferior rubber or miscellaneous materials from being injected into the mold, because inferior rubber and miscellaneous materials may jam the mold.Check whether the temperature of the material tube and the temperature of the mold are suitable for processing the raw materials.
(3) Adjust the pressure and injection volume to produce a satisfactory appearance, but do not run off the burrs, especially when some mold cavity products are not completely solidified, you should think about it before adjusting various control conditions, because A slight change in the mold filling rate may cause a large change in the mold filling.
(4) Wait patiently until the conditions of the machine and mold stabilize, even if the medium-sized machine may have to wait for more than 30 minutes.You can use this time to view possible problems with the finished product.
(5) The advancing time of the screw should 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 impaired, and the advancing time of the screw should be appropriately extended when the mold is heated in order to compact the finished product.
(6) Reasonably reduce the total processing cycle.
(7) Run the newly adjusted conditions for at least 30 minutes to be stable, and then produce at least a dozen full mold samples continuously, mark the date and quantity on the container, and place them according to the mold cavity to test the stability and operation of the mold. Derive reasonable control tolerances (especially valuable for multi-cavity molds).
(8) Measure and record the important dimensions of continuous samples (we should wait for the samples to cool to room temperature before measuring).
(9) Compare the measured size of each mold sample, and pay attention to:
①Whether the product size is stable;
②Whether some dimensions have a tendency to increase or decrease, indicating that the machining conditions are still changing, such as poor temperature control or oil pressure control;
③Whether the size change 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 cavity is acceptable and whether its size can be within the allowable tolerance.Note down the number of cavities that are continuous or larger or smaller than the average to check whether the size of the mold is correct.
Well, have you learned the methods that Director Feng explained to us?At present, the products processed by molds with rapid industrial development in our country have become common materials in our real life, and they are also indispensable materials in our lives. The mold industry is a basic industry in the national economy, and specifically involves machinery, automobiles, light industry, electronics, Various industries, such as chemical industry, metallurgy, building materials, etc., have a wide range of applications.Our company is a professional manufacturer specializing in plastic mold injection processing, two-color plastic molds, single-color plastic molds, mold precision injection molding and other manufacturing fields.The factory can realize the one-stop service of plastic mold opening, injection molding, spraying, silk screen printing, hot stamping, and assembly. You don’t need to go to each factory. It saves you worry and effort, and implements one-to-one order tracking service, on time Report the production progress for you, and it is also convenient for you to monitor the product processing process at any time to ensure punctual delivery.
Link to this article：how to do a good job of plastic mold trial