Things to be avoided in the casting process of machine tool castings
The machine tool castings are all made of resin sand and lost foam casting. Our company has a complete resin sand production line. The whole production process is non-polluting. The third-level environmental protection can eliminate or reduce the casting defects such as blisters and air and air. Let us understand the production. The following points should be noted in the machine tool castings:
First, use the bottom note package as much as possible. The bottom note metal liquid has small heat loss, large indenter, and high pouring speed. The slag floats on the upper surface of the molten metal, and the molten steel is relatively clean. Due to equipment conditions, some requirements are not high or general small and medium machine tool castings can also be subcontracted.
2. At the initial stage of pouring, especially when the molten metal is in contact with the foam, the static pressure of the molten metal is less than that of polystyrene when the sprue is not filled or just started pouring. When the gas pressure of the product is too high, it is easy to produce a bonfire phenomenon, causing the molten metal to splash. In order to avoid this phenomenon, the method of first fine flow and slow pouring can be adopted at the beginning of pouring. After the pouring system is filled with the molten metal, the pouring speed can be increased as fast as possible, but the pouring cup is filled with metal instead of Spillover is the criterion. At the end of the casting, when the molten metal reaches the top of the pattern or the root of the riser, it should be slightly packed to keep the metal rising smoothly and not to cause the molten metal to rush out of the riser.
Third, the pouring process can not be interrupted. When the lost foam casting is poured, the molten metal must be continuously injected until the mold is completely filled. Otherwise, it is easy to cause a cold partition defect in the entire plane of the casting at the standstill.
The purpose of casting tempering is as follows:
1. Reduce brittleness, eliminate or reduce internal stress, and there is great internal stress and brittleness after quenching steel. If it is not tempered in time, it will cause deformation or even cracking of steel.
2. Stabilize workpiece size
3. Obtaining the mechanical properties required for the workpiece, the workpiece has high hardness and high brittleness after quenching. In order to meet the different performance requirements of various workpieces, the hardness can be adjusted by appropriate tempering to reduce the brittleness and obtain the required toughness. Plasticity.
4. For some alloy steels that are difficult to soften by annealing, high temperature tempering is often used after quenching (or normalizing) to properly aggregate the carbides in the steel and reduce the hardness to facilitate cutting.
DESHENGRUI Machinery is a professional CNC manufacturing and Sheet metal fabrication company, including CNC machining services, CNC Turning service, CNC milling services, CNC drilling services, laser cutting services, stamping services, Die casting service, iron casting service and Steel Forging service.