How to improve the quality of zinc alloy die casting

The most basic equipment in the production of zinc alloy die casting is the zinc alloy die casting machine. It is the condition to provide energy and select the best process parameters in the production of zinc alloy die casting. It is the guarantee foundation to achieve the characteristics of high-pressure and high-speed die casting and obtain excellent zinc alloy die casting. In order to ensure the quality of zinc alloy castings, avoid the occurrence of casting defects, save energy consumption, improve labor productivity and economic benefits, it is necessary to select the model of die casting machine reasonably. Of course, correct operation and maintenance to ensure the good performance of the die casting machine is a very important measure in the die casting production. According to the weight of the casting (including runner, material handle and overflow slot), choosing the appropriate die casting machine model and the die casting machine with excellent performance is the reliable guarantee to obtain the high quality zinc alloy die casting.

In order to improve the surface quality of zinc alloy die casting and to facilitate electroplating, painting or removal of small burrs on the parting surface of the die casting die, emery can be used for grinding. The particle size of emery is determined by the surface condition of the casting, generally 150 ~ 300, and the rotation speed is 1800 ~ 2400m.min-1. The emery polishing should not be excessive. During die casting, because the solution is quenched on the surface of die casting die, a layer of compact cold hard structure (generally 50-300 μ m) is formed on the surface of die casting die, but the inner part of it is easy to produce shrinkage defects. Therefore, do not grind off this good cold hard layer when grinding. If too much is removed, defects such as pitting and bubbles will appear during electroplating or painting.

In addition, if the zinc alloy die-casting is pressed too tightly on the polishing wheel during polishing, it will overheat, and the internal air expansion will make the surface produce fine spots. Try to avoid using the diamond wheel which is excessively worn and very low cut. The polishing wheel for finishing (oily polishing wheel) can be interwoven polishing wheel, and the abrasives can be plate-shaped diatomite or rod-shaped iron oxide polishing paste, which can be slightly ground at the speed of 2000-2700 m.min-1. Zinc alloy die castings should not be too tight, otherwise the abrasives will be bonded with the products, resulting in incomplete or excessive degreasing later, resulting in poor electroplating.