Mold Design / Mold Flow Analysis

Among the irregular shapes, it is the most difficult to predict the flow balance and filling uniformity. In the product design stage, in order not to destroy the aesthetics and structural functions of the product design, how can the flow balance and filling pressure be done before the mold is opened? In the early stage, by discussing the position of the gate that can be entered, the high cost of mold repair after subsequent mold opening can be avoided.

The flow balance of multi-point pouring is confirmed by computer analysis. In the multi-point pouring product, how to achieve the uniform flow of each pouring point can only be determined by experience in the past. When the mold flow was introduced in the initial stage, It is also possible to determine the position and size of the gate at each point, avoiding repeated modification of the size, position and size after the mold is opened. In multi-point pouring, the most worrying problem is warpage, sometimes less or sometimes more. The gate will cause a larger amount of deformation, especially for long-strip products. Under the initial mold flow verification, the optimal opening mode can be achieved, reducing the development time.

The most worrying and most likely thing for long strip products is the warping and deformation. In the past, if the deformation problem was encountered, the expected allowable value could only be achieved through subsequent correction. For correction, we can use the method of reverse deformation to develop product molds with reverse deformation. Through post-shrinkage deformation, the original reverse deformation product gradually shrinks to the product size we want, and can quickly achieve the accuracy required by customers.

For products that are poured at two or more points, the priority is the issue of the welding line. During the product use process, the wdlding line is often the most vulnerable position. Whether it can meet the user's service cycle and strength requirements, or whether it is in appearance. , whether the aesthetic problem of the welding line can be avoided as much as possible, and the position of the bonding can be accurately marked in the initial development stage to ensure the strength requirements and appearance guarantee of the product in its life cycle.

The most difficult to predict is the upward arch or concave of the lid type product. After adding the cooling water channel in the mold flow analysis, and setting the injection conditions together, the deformation status can be easily judged. For mold-type products, the cooling distribution of the mold cannot achieve a balance between inside and outside, and there is often a phenomenon of internal shrinkage, which causes a big restriction on the adjustment of the machine. What’s more, it is necessary to do follow-up corrective actions after taking out from the mold. In the follow-up correction, due to the uncontrollable external environment, there are often problems of over-correction or insufficient correction. Therefore, how to use scientific development methods to maintain product quality stability within the controllable range of all parties Sex is a big focus.

Among the large-area products, especially large-scale products are evaluated, if it is possible to find a suitable pouring point, the key is to choose the wrong pouring point. Moreover, in production, higher injection pressure and higher holding pressure will be encountered, and there will be problems in the opening of the mold or difficulty in ejecting the product, resulting in waste of energy, and the mold often needs maintenance before production. It is more difficult to use experience to evaluate the problem, and finding the appropriate pouring position can balance the pressure of the entire injection process, especially in the case of uneven meat thickness. In the process of initial development, scientific review and evaluation can reduce Repeated corrections and adjustments in the trial mode greatly reduce the development schedule and the probability of problems.

During injection molding, how to deal with post-shrinkage and post-deformation can be evaluated and judged from the internal stress of injection. In the stages of injection, extrusion and pressure retention, whether there are appropriate pressure retention and pressure relief settings can ensure the product The post-shrinkage and post-deformation are the smallest. How to reduce the residual stress in the product is an important stage in the injection molding process. The low residual stress distribution can ensure that the same product has a longer life cycle in use. , If the residual stress is too high, the product is prone to unexplained cracking or cracking, and there will be greater deformation. By simulating the actual production conditions, it can be more ensured that the product is in use and more in line with customer expectations. life cycle.

One of the key points in the injection process is balanced injection. During the analysis, it is easy to determine what pressure and speed should be used to achieve the optimal injection conditions during actual molding, because excessive injection speed will cause the shear effect of the plastic. The branched material has an upper limit of its shear rate. If the upper limit of the material is exceeded, the essence of the material will be degraded. The plastic is a polymer material, and it is a material formed by many molecular bonds. The shear effect is too large. It will cause the material to have poor solution and thermal degradation, and the strength of the material itself will be greatly reduced, and this phenomenon cannot be selected by appearance in many cases. How to make the material in this new opening during the mold development process The mold of the mold exerts the maximum strength, which is what a developer needs to expect, to avoid the strength structure of the product not meeting expectations, and more costs need to be made to ensure the strength of the product.