In the field of metal processing, forging and casting are two long-standing and vital processing methods. They each have unique advantages and occupy an indispensable position in industrial production. This article discusses the principles, technical characteristics, application scope, material adaptability, performance impact, economic cost, etc. of forging and casting in depth, aiming to provide practitioners in related industries with a comprehensive and profound understanding.
As an indispensable basic material in modern society, the progress of metal processing technology is directly related to the development level of the manufacturing industry. Forging and casting are the two pillars of metal processing. They process metal raw materials into parts with specific shapes, sizes and performances through different methods. There are obvious differences between the two in terms of process principles, process control, product quality and economic costs, and they are suitable for different production needs and market environments.
2.1 Process principle
Forging is a metal processing technology that involves applying external force to plastically deform the metal blank to obtain the desired shape and size. The forging process places the metal blank in the working area of a forging device (such as a hammer or press). The plasticity and fluidity of the metal are enhanced by heating, and then pressure is applied to shape the metal. During the forging process, the metal’s internal grain structure slides, breaks, and rearranges, creating a new microstructure that enhances the metal’s mechanical and physical properties.
2.2 Technical Features
• High precision: During the forging process, the metal billet is deformed under the constraints of the die or tool, so that the shape and size of the part can be precisely controlled to meet the requirements of high precision.
• High strength: The pressure applied during the forging process refines the internal grain structure of the metal, forming a dense microstructure, which enhances the strength and toughness of the part.
• High plasticity: Heating gives the metal good plasticity, which is conducive to making complex shapes during the forging process.
• High adaptability: Forging is suitable for a variety of metal materials, including high-strength steel, aluminum alloy, titanium alloy, etc.
2.3 Scope of application
Forging is widely used in industries such as aerospace, automobile manufacturing, shipbuilding and armaments. It is used to produce key components such as engine parts, transmission systems and structural parts. These parts require high strength, toughness, precision and fatigue resistance, and forging can meet these requirements to ensure the reliability and safety of the product.
3.1 Process principle
Casting involves pouring molten metal into a mold cavity, allowing it to cool and solidify, and then removing the mold to obtain a part with the desired shape and size. During the casting process, the metal material is heated to a molten state, injected into the mold cavity through the pouring system, and gradually cooled and solidified into a casting with a specific shape and performance under the constraint of the mold.
3.2 Technical features
• One-time molding: Casting can produce complex and large parts in one go, reducing processing steps and costs.
• High material utilization: The molten metal thoroughly fills the cavity, minimizing material waste and improving material utilization.
• Wide adaptability: Casting can adapt to various metal materials, including cast iron, cast steel and non-ferrous metals.
• Economic efficiency: The casting equipment is relatively simple, easy to automate, and can be mass-produced, reducing production costs.
3.3 Application scope
Casting is widely used in machinery manufacturing, construction, transportation, energy and other industries to produce various mechanical parts, structural parts, pipelines, etc., and has high requirements for the dimensional accuracy, surface quality and mechanical properties of castings to meet various industrial needs.
4.1 Process comparison
The forging process is to plastically deform the metal billet under the action of external force, which requires high temperature and high pressure, and the mold design and manufacturing precision requirements are high. The casting process is to pour molten metal into the mold cavity and form it after cooling and solidification. The casting process is relatively simple, but it requires high precision in mold manufacturing and pouring system design.
4.2 Comparison of material adaptability
Forging is suitable for metals with high melting points and good plasticity, such as carbon steel, alloy steel, aluminum alloy, etc. The plasticity and fluidity of these metals remain basically unchanged during the forging process. Casting is suitable for a wide range of metal materials, including cast iron, cast steel, non-ferrous metals, etc. The casting properties of different materials are not the same, and process design and adjustment are required according to the characteristics and requirements of specific materials.
4.3 Comparison of product quality
Forged parts usually have high strength and toughness, dense internal structure, and no defects such as pores and inclusions. The precise control of shape and size during the forging process meets the high-precision requirements. In contrast, castings may have problems such as inconsistent internal quality, pores and inclusions, which require post-processing improvements. However, for large or complex-shaped parts, casting still has irreplaceable advantages.
4.4 Comparison of economic costs
Since forging requires customized molds and the output is usually low, the production cost is relatively high. High temperature and high pressure also increase energy consumption and equipment costs. In contrast, casting has lower production costs due to the reusable molds, strong mass production capacity, and economies of scale in equipment investment, raw material consumption, and post-processing.
5.1 Influence of material properties
• Casting: Plastic deformation during forging refines, breaks, and rearranges metal grains, improving the strength, toughness, fatigue life, and corrosion resistance of the metal. It can also eliminate defects such as shrinkage and porosity, thereby improving the overall material quality.
• Angle selection: The cooling and solidification of the molten metal in the mold cavity can cause defects such as pores, shrinkage, and inclusions, which affect the mechanical properties of the casting. Strict control of pouring temperature, speed, mold temperature, and exhaust conditions can minimize these defects.
5.2 Influence of product accuracy
• Casting: Forging achieves high dimensional and shape accuracy by limiting metal deformation within the mold or tool. Heat treatment can further optimize part performance and accuracy.
• Angle selection: The dimensional and shape accuracy of castings is relatively low. Although modern casting technology can produce high-precision castings, there are still errors and deviations in castings due to factors such as metal flow, solidification shrinkage, deformation and mold accuracy. Appropriate pouring system, mold design and post-processing measures can improve the precision and quality of castings.
6.1 Forging Cases
• Aircraft engine blades: require high strength, high toughness, high temperature resistance and corrosion resistance. The forged product blades have a dense and defect-free internal structure, which improves reliability and service life.
• Automobile crankshaft: Under large torque and stress, the forged crankshaft has high strength and high precision and can withstand complex operating conditions.
6.2 Casting Cases
• Machine tool bed: Castings require high rigidity and stability, and can produce large and complex bed with stable internal quality and high dimensional accuracy to meet the requirements of machine tools.
• Water pipes: As an indispensable infrastructure, casting produces pipes of various sizes and materials (such as cast iron and cast steel) with excellent corrosion resistance and mechanical properties, suitable for various environments.
In summary, for the same material forming, the mechanical properties of forgings are generally better than those of castings.
· Due to their different process characteristics, forging and casting have different main application scenarios: forging is suitable for simple structural parts with harsh service conditions and pursuit of structural reliability, while casting is more suitable for preparing parts with complex structures and more internal cavities.
· The main purpose of forging is forming and modification (improving mechanical properties and internal structure). Under the same material conditions, forging processing can obtain dense metal structure, so the mechanical properties of forgings are generally better than castings.
Process principle | Forging | Casting |
Advantage | A processing method that causes the billet or ingot to undergo plastic deformation under the action of pressure equipment and tools (dies) to obtain parts or billets of a certain geometric shape and improve their organization and performance. | A processing method in which the metal is melted and poured into a mold to solidify and form to obtain specific structural parts or blanks. |
Disadvantage | By controlling the uniformity of deformation, the anisotropy of the material can be improved; by constraining and controlling the deformation of the die, a certain metal flow line is formed to improve the mechanical properties of the forging. The structural complexity of the forging is relatively low, and the material utilization rate of the forging is relatively low. | It can produce parts with complex shapes and inner cavity structures. |
Material properties | Forging properties: the formability and deformation resistance of a metal. | Castings are prone to defects such as looseness, pores, shrinkage, etc., resulting in poor mechanical properties of castings. Casting properties include fluidity, filling capacity, shrinkage, segregation tendency of liquid metal, etc. |
Application Scenario | It is the preferred forming process for important and key structural components that pursue structural reliability and harsh use conditions. | It can be used to manufacture parts with complex structures and complex internal cavities. |
Which is better for forging or casting to manufacture complex parts?
In the field of complex parts manufacturing, casting technology shows significant advantages due to its ability to efficiently inject molten metal into molds to form complex geometric shapes and internal structures, especially suitable for manufacturing large or complex parts with cavities and details, such as engine blocks. In contrast, although forging technology is good at manufacturing simple-shaped parts with high strength and excellent mechanical properties, it is relatively limited in processing complex shapes. Liquid forging, as a fusion innovation of casting and forging, takes into account the advantages of both. It can solidify metal under high pressure and reduce defects while retaining the ability to manufacture complex shapes. It is particularly suitable for fields with high requirements for material density, mechanical properties and shape complexity. In addition, there are obvious differences between casting and forging in terms of material selection and production efficiency. Casting is widely applicable to various metals and alloys, has high production efficiency, and is suitable for large-scale production; while forging focuses on high-strength and tough materials, has high production costs, and is more suitable for small batches or high value-added products. Therefore, process selection needs to comprehensively consider multiple factors such as part design, material properties, and production efficiency.
What are the advantages of liquid die forging compared with traditional casting?
Compared with traditional casting methods, liquid forging technology shows significant advantages in multiple dimensions, greatly enhancing its attractiveness in specific industrial applications. Its core advantages include: by applying pressure during the solidification process, it effectively eliminates common defects such as pores, shrinkage cavities, and looseness in castings, ensuring the density and integrity of the product; at the same time, liquid forging promotes metal grain refinement and organizational homogenization, significantly improving the mechanical properties of the product, approaching or even reaching the standards of forgings, thanks to the denser and more uniform organization formed under pressure. In addition, the high flexibility of the process in shape and size enables it to efficiently manufacture parts with complex structures and large wall thickness differences such as cup-shaped parts and box bodies, expanding the boundaries of design and production. In terms of production efficiency, liquid forging achieves rapid prototyping and large-scale production with its streamlined process flow, covering four main stages of smelting, pouring, pressurization, and demolding, meeting the needs of large-scale customization. The product has a high surface finish, which reduces the necessity and cost of subsequent processing and improves overall manufacturing efficiency. It is worth noting that the material adaptability of liquid forging technology is very wide, from non-ferrous metals (aluminum, copper, magnesium, zinc, etc.) to ferrous metals (steel, iron), and even high-temperature alloys and composite materials. This wide applicability has laid a solid foundation for its application in diversified industrial fields. In summary, liquid forging technology is gradually becoming an indispensable high-end manufacturing process in modern manufacturing industry with its comprehensive advantages in eliminating casting defects, strengthening mechanical properties, design flexibility, production efficiency, surface quality, etc.
What are the differences between forging and casting in material selection?
The significant differences between forging and casting in material selection are mainly reflected in three aspects: material type, material properties and cost-effectiveness. The forging process tends to use high-strength steel, aluminum alloy, titanium alloy, etc. These materials can withstand high temperature and high pressure during the forging process, and achieve the densification of internal organization and significant improvement of mechanical properties through plastic deformation. Therefore, they are suitable for manufacturing key components that need to withstand high loads and stresses, such as aerospace, automobile, and heavy machinery. In contrast, casting technology shows a wider range of material adaptability, covering various metals and alloys such as cast iron, aluminum, copper and its alloys. It is particularly good at processing parts with complex shapes and internal cavities, and is widely used in the manufacture of large or complex structural parts, such as engine cylinders and pump bodies.
From the perspective of material properties, forging materials are known for their excellent mechanical properties. Forging parts usually have high strength and toughness, which are suitable for high-load working environments; the directional arrangement of metal grains during the forging process further enhances the material's bearing capacity. Although casting materials are widely used, their mechanical properties are relatively weak. Porosity, shrinkage holes and other defects inside castings may limit their strength and durability, and are not suitable for the manufacture of parts under high stress conditions.
From the perspective of cost and economy, the forging process is complex and relatively expensive, and is more suitable for the production of small batches and high value-added products, but the material utilization rate is high and the amount of waste generated is small; while the casting process is relatively simple, and has obvious economic advantages in large-scale production and manufacturing of complex-shaped parts.
What are the main application scenarios of liquid forging technology?
As an advanced metal forming process that combines the advantages of casting and forging, liquid forging technology has penetrated deeply and significantly affected multiple industrial fields. In the automotive industry, this technology has become the preferred solution for manufacturing high-strength and durable key automotive parts such as suspension and brake system components due to its excellent mechanical properties and dimensional accuracy. In the aerospace field, the high-density and high-strength characteristics of liquid forging are fully utilized to meet the production needs of high-performance structural parts and components (such as wing supports and engine components) under extreme load and temperature changes. In the machinery manufacturing industry, the dual pursuit of mechanical properties and processing accuracy of complex-shaped parts such as boxes, wheel covers, and forks makes liquid forging technology an indispensable manufacturing method. The electrical and electronic industry has also benefited from this technology, realizing the production of high-precision connectors and housings, effectively meeting the high standards of electronic equipment for material strength and conductivity. In addition, in the field of medical device manufacturing, liquid forging technology has shown great potential in the manufacture of high-strength and biocompatible parts such as surgical instruments and implants, and has contributed to the progress of the medical industry.
What is the difference in production efficiency between forging and casting?
There are obvious differences between forging and casting in terms of production efficiency, cost-effectiveness and applicability. The casting process has a high degree of automation after mold production, which is particularly suitable for large-scale production scenarios. It can produce a large number of parts quickly, greatly reducing unit costs, and has high flexibility, which can effectively cope with complex geometric requirements, especially when manufacturing large or complex internal structure parts (such as engine blocks). In contrast, forging has low production efficiency, especially when producing small batches or high value-added products, because its process is complex and there are many heating and pressurizing steps, resulting in a long production cycle. Although forging requires a higher initial investment, it has less material loss and is suitable for manufacturing parts with high requirements for strength and durability, such as gears, shafts, etc. Although its shape complexity is not as high as casting, it is irreplaceable in applications with strict requirements on mechanical properties. In summary, the choice of forging or casting process needs to comprehensively consider production efficiency, cost-effectiveness and specific application scenario requirements.
