Sand cutting sand cutting adaptability is very wide, small pieces, large pieces, simple pieces, complex pieces, single pieces, large quantities can be used. Sand mold is more refractory than metal mold, so materials with higher melting points such as copper alloys and ferrous metals are also used in this process. Sand cutting mold, general wood production, commonly known as wood mold. In order to improve the dimensional accuracy is higher, but also often use a longer life of aluminum alloy mold or resin mold. Although the price has increased, but still much cheaper than the metal cutting mold, in the small batch and large production, the price advantage is particularly prominent. When metal type cutting is used for metal type cutting, the following factors must be comprehensively considered: long manufacturing cycle, high cost, not suitable for single-piece and small-batch production; It is not suitable for cutting complex shapes (especially inner cavities), thin-walled and large castings (metal molds are limited by the size of mold materials and the capabilities of cavity processing equipment and cutting equipment, so metal molds are not suitable for the production of particularly large castings) molds are more expensive than sand molds, cheaper than die casting. Gravity cutting is widely used in the production of various non-ferrous castings, but metal cutting also has the disadvantages of low metal utilization, difficult pouring of thin-walled complex castings, and low relative pressure cutting of casting tissue density. High-pressure cutting because the metal liquid in the process of filling the cavity under high pressure and high speed, inevitably the air in the cavity is trapped inside the casting, forming subcutaneous pores, so aluminum alloy die castings should not be heat treated, zinc alloy die castings should not be surface spray plastic (but can be painted). Otherwise, the internal pores of the casting will be thermally expanded when heated as described above, resulting in deformation or bubbling of the casting. The machining allowance of die castings should also be smaller, generally about 0.5mm, which can reduce the weight of the casting, reduce the amount of cutting to reduce the cost, and avoid penetrating the surface dense layer, exposing subcutaneous pores, causing the workpiece to be scrapped. Due to the internal looseness of die-casting parts, poor plasticity and toughness, it is not suitable for manufacturing parts to withstand impact loads. The wall thickness of the casting is uniform, and it is advisable to use 3~4mm thin-walled castings, and the maximum wall thickness should be less than 6~8mm to prevent defects such as shrinkage cavity. Avoid machining to prevent internal holes from being exposed. Low-pressure cutting molten metal filling under pressure can improve the fluidity of molten metal, and the castings have good formability, which is conducive to the formation of castings with clear contours and smooth surfaces, and is more favorable for the formation of large thin-walled castings. The casting crystallizes and solidifies under pressure and can be fully replenished, so the casting has compact structure and high mechanical properties. The yield of the molten metal process is improved, in general, there is no need for risers, so that the yield of metal liquid is greatly improved, and the yield is generally up to 90%. Good working conditions, high production efficiency, easy to achieve mechanization and automation, but also the outstanding advantages of low-pressure cutting. Low pressure cutting has a wide range of applications for alloy grades and can basically be used for cutting various alloys. Not only for cutting non-ferrous alloys, but also for cast iron and cast steel. Especially for non-ferrous alloys that are easy to oxidize, it shows its superior performance, that is, it can effectively prevent the molten metal from oxidizing slag during the pouring process. Low-pressure cutting has no special requirements for mold materials.