The field of metal forming, the choice of casting process directly affects product quality, production costs, and production efficiency. Among them, gravity casting and high-pressure casting are two widely used processes, but many customers often find themselves in a dilemma when faced with these two technologies. This article will delve into the process principles, advantages and disadvantages, and applicable fields of the two, helping you quickly find a suitable casting solution.
1、 Process principle: Core differences between two casting methods
The principle of gravity casting is relatively direct. It relies on the gravity of the molten metal itself to naturally fill the cavity of the metal mold, and then cool and solidify inside the mold to form. The entire process does not require additional pressure, and the flow of the molten metal is mainly guided by gravity and the mold cavity structure, resulting in a relatively gentle molding rhythm.High pressure casting is completely different. It injects molten metal into steel molds at high speed through high pressure (usually 10-150MPa), and uses strong pressure to force the molten metal to quickly fill the mold cavity, completing solidification under pressure. The characteristic of “high pressure and high speed” allows the molten metal to form in a very short time, which is the core difference between it and gravity casting.
2、 Key indicator comparison: advantages and disadvantages are clear at a glance
Cost differenceMold cost: Gravity casting molds have a relatively simple structure and are mostly made of cast iron, with a cost typically ranging from 50000 to 200000 yuan; High pressure casting molds need to withstand high pressure and often use high-strength alloy steel with high processing accuracy requirements. The cost can reach 300000 to 2 million yuan.
2. Production efficiencyThe production cycle of gravity casting is relatively slow, and the single piece production cycle is usually 15-60 seconds; High pressure casting is suitable for efficient mass production, especially for automated production lines, due to its fast filling speed of metal liquid (up to 10-50 meters/second) and shorter cycle time.
3. Product accuracy and surface quality• Dimensional accuracy: Gravity casting accuracy is generally between CT6-CT8 levels (tolerance range of about 0.1-0.3mm); High pressure casting results in a tighter fit between the molten metal and the mold due to pressure, with an accuracy of up to CT4-CT6 levels (tolerance range of approximately 0.05-0.1mm).Surface quality: The surface roughness of gravity casting is usually Ra 6.3 μ m, and there may be slight shrinkage marks; High pressure casting has a smoother surface with a roughness of up to Ra 1.6 μ m, and requires less post-processing.
- 4. Material propertiesGravity casting of molten metal has a slow cooling rate, more uniform crystallization, high density, and superior mechanical properties (such as strength and toughness), making it suitable for parts that need to withstand loads; High pressure casting, due to its fast cooling rate, is prone to the formation of gas pores in the molten metal, resulting in slightly lower material strength, and generally cannot undergo heat treatment (otherwise the pores will expand and cause deformation).
3、 Applicable fields: On demand selection is key
Typical scenarios of gravity castingSmall and medium-sized production with an annual output of less than 50000 pieces, such as customized mechanical parts.Structural components that require heat treatment strengthening, such as engine cylinder heads and hydraulic valve bodies.Areas with fast product iteration and frequent mold replacement can reduce the risk of initial investment.Advantages of High Pressure Casting in Various FieldsUltra thin wall components (such as shells with a thickness of 1-3mm) and complex shaped parts, such as phone frames and laptop casings.Large scale production scenarios with an annual output of over 100000 pieces, such as automotive gearbox housings and motor end caps.High requirements for dimensional accuracy and surface quality, requiring a reduction in post-processing products.
4、 Industry application examples
In the automotive industry, integrated die-casting parts for car bodies are produced using high-pressure casting, which greatly reduces the cost of car body assembly due to efficient mass production and the ability to form complex structures; For parts such as diesel engine cylinder heads that require high temperature and pressure, gravity casting is often used to ensure sufficient strength and sealing.In the field of industrial equipment, hydraulic pump housings need to withstand the impact of high-pressure hydraulic oil and rely on high-density gravity casting; The motor end cover is more suitable for high-pressure casting due to its large batch size and moderate precision requirements.In the field of new energy, in order to balance sealing and mass production efficiency, energy storage battery enclosures are often produced using vacuum die-casting (an improved type of high-pressure casting); The heat dissipation substrate of photovoltaic inverters requires good thermal conductivity and structural strength, and gravity casting is a better choice.
5、 Summary
Gravity casting and high-pressure casting are not “who is better”, but “who is more suitable”. When making a selection, factors such as production scale, cost budget, product structure, and performance requirements should be comprehensively considered: small and medium-sized batches, load-bearing parts, and heat treatment required. Gravity casting should be given priority; Large quantities, high precision, complex thin-walled parts, high-pressure casting has more advantages. Only by making reasonable choices based on actual needs can we achieve a balance between cost and efficiency while ensuring quality.
Yongkang Zhonghuan has a production capacity of 5000 tons of aluminum alloy parts and over 300 production and testing equipment. From mold customization to casting and processing, we provide one-on-one customization services. We offer the highest quality aluminum casting products and services to customers around the world. Our service industries include automobiles, engineering machinery, ships and oceans, new energy, compressors, etc
Post time: Aug-26-2025