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These Injection Mold Failure, Can Be So Excluded ...
Sep 28, 2017

Gap off the material difficult: in the injection process, the gates glued in the gate sets, easy to prolapse. When the mold is opened, the product is cracked. In addition, the operator must use the tip of the copper rod from the nozzle to knock out, so that after the release can be stripped, seriously affecting the production efficiency. The main reason for this failure is the gate cone hole finish is poor, the hole in the circumferential direction of the knife marks. There is a material too soft, the use of a period of time after the tip of the small hole deformation or damage, as well as the nozzle spherical curvature is too small, resulting in the production of rivets here. The taper hole of the pouring sleeve is difficult to be processed, and the standard parts should be used as far as possible. For self-processing, the special reamer should be made or purchased.

Guide column damage: guide column in the injection mold in the main guiding role in order to ensure that the core and cavity molding surface in any case do not touch each other, can not lead the column as a force or positioning pieces. In the following cases, the injection will move, the mold will produce a huge lateral bias force: (1) plastic wall thickness requirements are not uniform, the flow rate through the thick wall, where the larger Of the pressure; (2) plastic side of the asymmetry, such as stepped shaped surface of the mold, the opposite side of the back pressure is not equal.

Moving, fixed-mode shift: large-scale mold, due to the different feed rate, as well as in the mold when the mold by the weight of the impact, resulting in moving, fixed-mode shift. In these cases, the lateral bias force at the time of injection will be applied to the guide post. When the mold is opened, the surface of the guide post is raised and damaged, and the guide post is bent or cut, and even can not be opened. In order to solve the above problems, in the mold parting surface to add high-intensity positioning keys on each side, the most simple and effective is the use of cylindrical keys. The verticality of the guide pin and the parting surface is critical.

Dynamic mold bending: injection mold at injection, the cavity of molten plastic produced a huge anti-pressure, generally in the 600 ~ 1000 kg / cm 2. Mold manufacturers sometimes do not attach importance to this problem, often change the original design size, or the use of low-strength steel plate instead of the template, with the top of the top of the mold, due to both sides of the seat span, resulting in injection mold bending. Therefore, the use of high-quality steel, must have enough thickness, must not use A3 and other low-strength steel, if necessary, should be set in the dynamic template below the support column or support block to reduce the template thickness and improve the carrying capacity.

Poor cooling or waterway leakage: the cooling effect of injection molds directly affect the quality of products and production efficiency, such as poor cooling, shrinkage of products, or shrinkage uneven appearance and other defects. On the other hand the whole model or local overheating, so that the mold can not be normal and stop production, serious so that the mandrel and other activities such as thermal expansion and damage. The design and processing of the cooling system depends on the shape of the product. Do not save the system because of the complicated structure of the mold or the difficulty of processing. In particular, the medium and large mold must fully consider the cooling problem.

Stretch tension mechanism: the hook, buckle and the like fixed-length tensioning mechanism is generally used for fixed-mode core or some secondary mold release mold, because of these institutions in the mold on both sides of the set in pairs, Its action requirements must be synchronized, that is, mold at the same time buckle, open to a certain position at the same time decoupling.

The length of the guide groove is too small: some mold due to the template area limit, the guide groove length is too small, the slider in the core after the action is exposed to the outside of the channel, so in the core after the end of the mold and mold reset the initial stage are likely to cause the slider tilt , Especially in the mold, the slider reset is not smooth, so that the slider damage, or even bending broken. According to experience, the slider to complete the core action, stay in the chute length should not be less than 2/3 of the full length of the guide groove.