Mold quality is not a simple topic, it includes the following aspects:
(1) Product quality: the stability and conformity of the product size, the smoothness of the surface of the product, the utilization rate of the product materials, etc.;
(2) Service life: the number of work cycles or the number of parts produced by the mold under the conditions of ensuring the quality of the product;
(3) Maintenance and maintenance of the mold: whether it is the most convenient to use, easy to demould, and the production auxiliary time is as short as possible;
(4) Maintenance costs, maintenance periodicity, etc.
The basic way to improve the quality of the mold:
(1) First of all, the design of the parts should be fair, and the best structural scheme should be selected as much as possible. The designer of the parts should consider that the technical requirements of the parts and their structure must conform to the craftability and feasibility of the mold manufacturing.
(2) The design of the mold is the most important step to improve the quality of the mold. Many factors need to be considered, including the selection of the mold material, the usability and safety of the mold structure, the processability of the mold parts and the convenience of mold maintenance. At the beginning of the design, you should try your best to think about it.
1 The selection of mold materials must meet the customer's requirements for product quality, but also the cost of the material and its strength during the set period. Of course, according to the type of mold, the working mode, the processing speed, and the main failure form. Other factors to choose materials. For example, the main failure mode of the blanking die is the edge wear, and the material with high surface hardness and good wear resistance should be selected. The stamping die is mainly subjected to periodic load, which is easy to cause surface fatigue crack, which causes the surface layer to peel off. A material with good surface toughness; a material with a particularly low friction coefficient should be selected for the drawing die; a material with strong heat fatigue should be selected for the die-casting mold due to cyclic thermal stress; for injection molding, when the plastic part is aBS, PP, PC For such materials, the mold material can be pre-hardened and tempered steel. When the plastic parts are high-gloss and transparent materials, the corrosion-resistant stainless steel can be selected. When the batch size is large, the quenched and tempered steel can be selected. In addition, it is necessary to consider the use of mold materials with less affinity for the parts, in order to prevent the sticking mold from aggravating the wear of the mold parts, thereby affecting the quality of the mold.
2 When designing the mold structure, it should be as compact as possible and easy to operate. It must also ensure sufficient strength and rigidity of the mold parts. When the mold structure is promised, the corners of each surface of the mold parts should be designed as rounded transitions to avoid stress concentration. For concave molds, cavities and partial punches and cores, a combination or inlay structure can be used to eliminate stress concentration, and elongated punches or cores should be properly protected in construction; for cold dies, Configure devices to prevent blockage of parts or waste (eg, pop-up pins, compressed air, etc.). At the same time, it is also necessary to consider how to reduce the impact on the quality of the mold caused by the wear of the sliding fittings and the frequent impacting parts in long-term use.
3 In the design, it is necessary to reduce the range of disassembly and assembly when repairing a certain component, especially when replacing consumable parts, and reduce the scope of disassembly and assembly as much as possible.
(3) The manufacturing process of the mold is also an important part of ensuring the quality of the mold. The processing method and processing precision in the mold manufacturing process also affect the service life of the mold. The accuracy of each component directly affects the overall assembly of the mold. In addition to the influence of the accuracy of the equipment itself, it is necessary to improve the machining accuracy of the mold parts by improving the machining method of the parts and improving the technical level of the fitter in the mold grinding process. If the overall assembly effect of the mold does not meet the requirements, the probability of the mold moving in an abnormal state will be improved in the trial mold, which will have a great influence on the overall quality of the mold. Therefore, in order to ensure that the mold has good original precision - the original mold quality, in the manufacturing process, we must first select high-precision processing methods, such as EDM, wire cutting, CNC machining, etc., and should pay attention to the accuracy inspection of the mold. Including the machining precision, assembly precision of the mold parts and the accuracy of the mold inspection through the acceptance of the test mode acceptance work, it is also necessary to select the high-precision measuring instrument when inspecting. For the mold parts with complex surface and surface structure, if ordinary straight The ruler and the vernier card cannot achieve accurate measurement data. In this case, a precision measuring device such as a three-coordinate measuring instrument is needed to ensure the correctness of the measured data.
(4) Surface strengthening of the main forming parts of the mold to improve the surface wear resistance of the mold parts, thereby better improving the quality of the mold. For surface strengthening, different strengthening methods should be used according to the molds for different purposes. For example, the punching die can be made by electric spark strengthening, hard alloy surfacing, etc., in order to improve the wear resistance and compressive strength of the surface of the mold parts; the hot-working die steel parts such as die-casting molds and plastic molds can be nitrided (hard nitrogen). Treatment) to improve the wear resistance, heat fatigue and abrasion resistance of the parts; the drawing die and bending die can be treated by sulfurizing to reduce the friction coefficient and improve the wear resistance of the material; carbonitriding (Soft nitriding) can be applied to the surface strengthening treatment of various types of molds. In addition, a kind of FCVa vacuum-plated diamond film technology developed in recent years can form a protective film on the surface of the part that is very strong and very smooth and evenly bonded to the substrate. This technology is especially suitable for mold surface protection. Processing is also an obvious method to improve the quality of the mold. Of course, if the part is a trial product or the production batch is quite small, it is not necessary to perform surface strengthening treatment of the mold part.
(5) The correct use and maintenance of the mold is also a major factor in improving the quality of the mold. For example, the installation and debugging mode of the mold should be appropriate. In the case of hot runners, the power supply wiring should be correct, and the cooling water circuit should meet the design requirements. The parameters of the injection molding machine, die casting machine and press in the production of the mold should be consistent with the design requirements. and many more. When the mold is used correctly, the mold needs to be regularly maintained. The guide post, guide sleeve and other parts with relative movement of the mold should be filled with lubricating oil. For each of the forging mold, plastic mold and die-casting mold, A lubricant or mold release agent should be applied to the surface of the molded part before molding. Planned protective maintenance of the mold and data processing during maintenance can prevent problems that may arise in the production of the mold, and improve the efficiency of maintenance work.
In short, in order to improve the quality of the mold, we must first consider the impact on the quality of the mold in each link, and secondly through the cooperation of various parts. The quality of the mold is the true embodiment of the mold company's own strength.
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