Hot-dip plating, referred to as hot-dip plating, is a method of immersing the metal material to be plated in other liquid metals or alloys with a lower melting point for coating. The basic feature of this method is that an alloy layer is formed between the base metal and the coating metal. Therefore, the hot dip coating is composed of alloy metal and plated metal. The metal materials to be plated are generally steel, cast iron and stainless steel. The low melting point metals used for hot dipping include zinc, aluminum, tin and their alloys.
Investment casting takes the final product as a copy, presses the paraffin material into a precise and smooth wax mold, coats multiple layers of refractory material on the wax mold, and forms a mold shell after the slurry is dried and hardened, and then solidifies in the mold shell. The wax mold is melted to make it flow out, then the shell is roasted to make it firm and dry, and finally the molten liquid metal is poured into the shell. After the liquid metal cools and solidifies in the shell, it becomes a precise and smooth casting. This casting process can produce sophisticated and complex metal parts or exquisite handicrafts that are close to the final shape of the product and can be used directly without or with little processing. Therefore, it is a near-net shape metal liquid forming process. Compared with the sand casting method, it has the following characteristics:
Foreign heat treatment manufacturers attach great importance to cooling during heat treatment. According to the technical and technological requirements of the product, slow cooling, oil quenching, and one-time gas quenching can be performed. Rapid atmosphere circulation cooling uses high-pressure gas injected into the cooling chamber, and the change of flow rate and flow is controlled by the computer to achieve the cooling rate within a specific time, so as to achieve the required cooling curve in the heat treatment process and ensure the heat treatment quality of the parts. The quenching gases that used to be cooled by gas quenching method include nitrogen, helium, etc., but now they are strongly sprayed with air to cool the workpiece at an extremely fast speed. After quenching, there is only a very thin oxide film on the surface, which is gray-white, and the color of the parts is still beautiful. , and save a lot of nitrogen and inert gas, so that the cost of heat treatment is further reduced.
Induction heat treatment has many advantages such as fast heating speed, energy saving, no oxidation and decarbonization, no environmental pollution and high production efficiency. These advantages are widely recognized by heat treatment workers, so they have developed rapidly in the past ten years. Of course, this actual demand also greatly promotes the development and technical improvement of domestic induction heat treatment equipment. Take "China FAW" in Changchun as an example, the company has nearly 100 induction heat treatment equipment, of which 50 have been newly added or updated in the past ten years, almost all of which are thyristor intermediate frequency equipment and IGBT super audio equipment. At present, the weight of induction heat-treated parts of "FAW" medium-sized trucks reaches 291.3kg, accounting for 52% of all heat-treated parts.