The problems that should be paid attention to in the design of die-casting molds have been detailed in the mold design manual, but the maximum speed should not exceed 100m/s when determining the injection speed. The speed is too high, causing corrosion of the mold and increased deposits on the cavity and core; however, too low a defect in the casting. Therefore, for magnesium, aluminum, zinc, the corresponding minimum injection speed is 27, 18, 12m / s, the maximum injection speed of cast aluminum should not exceed 53m / s, the average injection speed is 43m / s.

Thicker stencils cannot be layered to ensure their thickness during processing. Because the thickness of the steel plate is 1 times and the amount of bending deformation is reduced by 85%, the laminate can only act as a superposition. The bending deformation of the two plates of the same thickness as the veneer is four times that of the veneer. In addition, when processing the cooling water channel, special attention should be paid to ensuring the concentricity in the two-sided processing. If the corners of the head are not concentric with each other, the corners of the joint will crack during use. The surface of the cooling system should be smooth, preferably without machining marks.

EDM is more and more widely used in mold cavity machining, but the surface of the cavity after processing has a hardened layer. This is due to the carburizing and quenching of the mold surface during processing. The thickness of the hardened layer is determined by the current intensity and frequency during processing, deeper during roughing, and shallower during finishing. Regardless of the depth, the mold surface has great stress. If the hardened layer is not removed or the stress is removed, cracks, pitting and cracking will occur on the surface of the mold during use. To eliminate the hardened layer or to remove stress, it is possible to use: 1 to remove the hardened layer with oil stone or grinding; 2 to lower the stress below the tempering temperature without lowering the hardness, which can greatly reduce the surface stress of the cavity.

The casting process should be strictly controlled during the use of the mold. Within the scope of the process, minimize the casting temperature of the aluminum liquid, the injection speed, and increase the preheating temperature of the mold. The preheating temperature of the aluminum die-casting mold is increased from 100 to 130 ° C to 180 to 200 ° C, and the mold life can be greatly improved.

Welding repair is a common method in mold repair. Before welding, the model of the welded steel should be mastered, and the surface defects should be eliminated by machining or grinding. The welding surface must be clean and dried. The electrode used should be consistent with the die steel composition and must be clean and dried. The mold is preheated together with the electrode (H13 is 450 ° C), and after the surface and the core temperature are the same, the welding is repaired under the protective gas. During the welding process, when the temperature is lower than 260 ° C, it is necessary to reheat. After welding, when the mold is cooled to the hand, it can be touched, heated to 475 ° C, and kept at 25 mm / h. Finally, it is completely cooled in the still air, and then the cavity is trimmed and finished. Heating and tempering after welding of the mold is an important part of the welding repair, that is, eliminating the welding stress and tempering the thin layer under the welded layer which is heated and quenched during welding.

After the mold has been used for a period of time, there are deposits on the cavity and core due to the high injection speed and long-term use. These deposits are formed by combining a release agent, a coolant impurity, and a small amount of die-cast metal at high temperature and pressure.