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zh Advantages and Disadvantages of V - Process Castin
2025-01-22 16:59:29 hits：0
The V - process casting has incomparable advantages over traditional sand casting, which are specifically manifested in the following seven aspects:
- Molding and Mould Features: It is easy to draw the pattern during molding. There are fewer molds and no wear, and the metal molds have a long service life. Wooden materials can be used for the molds.
- High - Precision Castings: The castings have high dimensional accuracy and clear outlines. The roughness value of iron castings can reach Ra18 - 25μm. The cast iron counterweight of a forklift is a typical representative of V - process casting products. The forklift counterweight produced by Hefei Foundry and Forging Plant of Anhui Heli Forklift Group won the first - prize of castings at the 4th Beijing International Foundry Industry Exhibition in 2002. Almost all the counterweights and balance blocks required for forklifts and other construction vehicles in the world are produced by V - process casting.
- Improved Molten Metal Fluidity: Both the heat - preservation effect of the dry sand in the V - process and the vacuum suction can improve the fluidity of the molten metal. Tests show that compared with green - sand casting, the fluidity of the molten metal in V - process casting can be increased by 27%. Therefore, V - process casting can produce not only thick - walled castings but also thin - walled castings. For example, Nanjing Toto Co., Ltd. introduced a new Dong Foundry production line from Japan to produce high - end cast iron bathtubs. The largest bathtub has dimensions of 1829mm×1067mm×650mm, weighs 180kg, and has a wall thickness of 7mm, as shown in Figure 2. The cast iron string frame of a piano produced by Tianjin Young Chang Piano Casting Co., Ltd. in Figure 3 is also a typical thin - walled product of V - process casting.
- Higher Metal Utilization Rate: Compared with traditional green - sand molds, the V - process sand molds have little or no mold wall movement, and their hardness can reach 90 - 95. Due to the long heat - preservation time of the dry sand, the volume of the riser can be reduced by 5% - 15%. Therefore, V - process casting can improve the utilization rate of the molten metal (about 25% for ductile iron castings and about 20% for steel castings). V - process casting is suitable for producing both ductile iron castings and steel castings. Figure 4 shows a ductile iron rear axle produced by V - process casting. Figure 5 shows the steel side frame of a railway locomotive produced by V - process casting by Tianrui Group Foundry Co., Ltd. in China.
- Suitability for Aluminum Alloy Castings: The V - process sand mold is in a vacuum state, contains no moisture, and has good heat - preservation performance, which is very suitable for producing small - batch aluminum alloy castings with few or no internal cavities. Japan once used a large - scale V - process molding machine and an extra - large sand box (7000mm×4000mm×1000/800mm) to produce an aluminum - cast yacht hull (see Figure 6). Several foundries in Ukraine, the Netherlands, the United States, etc. use the V - process to produce small aluminum castings for the medical, electronic, and communication industries. The surface quality of their castings can be comparable to that of aluminum castings produced by metal molds. Figure 7 shows an aluminum - cast part produced by Harmony Casting in the United States using the V - process. The thickness of the large plane is 4.7mm, and the local thickness is as thin as 2.3mm.
- Low Investment and Energy Consumption: V - process casting requires less investment, has a relatively simple sand - treatment system, and consumes less energy during operation.
- Environment - Friendly and Labor - Saving: Compared with other sand - casting methods, V - process casting is environment - friendly. The noise at the production site is low, the shot - blasting and cleaning volume of castings is reduced by more than 50%, and the labor force is reduced by more than 35%. During pouring, the smoke generated by the film, coating, and resin sand cores is sucked away by the vacuum system, and after dry - wet filtration, it is exhausted into the air, causing less air pollution. V - process casting produces less solid waste, and the regeneration rate of dry sand is as high as 95%, which meets the high requirements of energy conservation and emission reduction.
Although the V - process casting has distinct advantages, its disadvantages are also prominent:
1.Limited by the stretching performance of the film, V - process casting is not suitable for producing castings with complex shapes.
2. The core - making technology in the V - process is not yet mature. Resin sand cores or water - glass sand cores are required to cast castings with complex internal cavities.
3. The vacuum system needs to be connected to the sand mold at all times.
4. V - process casting is not suitable for producing small - sized castings, and it is difficult to improve the production efficiency.
5. Casting defects such as porosity and slag inclusions are likely to occur in V - process steel casting, especially in low - carbon steel parts, there is a relatively serious carburization problem.
