Metal casting is an ancient manufacturing technology. With the advancement of time, metal casting technology and casting methods have made great strides. This article helps readers to understand the information on present metal casting technology.
The Concept of Metal Casting
Metal casting is melting the metal into a liquid that meets the requirements and poured into the casting mold. After cooling, solidification, and cleaning treatment, manufacturers get the metal casting parts with qualified shape, size, and mechanical performance. Metal casting is the basic technology of the modern machinery manufacturing industry.
Advantages of Metal Casting
Low cost | Costs of metal casting production are low. Especially for complex-shaped parts with complex internal cavities, metal casting could save lots of money.
Better Efficiency | The shape and size of the casting part are very close to specification requirements, reducing the amount of subsequent lathe cutting.
Materials & Designs | Nearly all metal materials that are commonly used in industries can be used for casting. So, metalworkers have more design options.
Wide Application | It is suitable for producing both small and large parts with various sizes, shapes, and complexity. 40%~70% of agricultural machinery and 70%~80% of machine tools are made by metal casting.
Comparison of Metal Casting and Metal Forging
| Item | Casting | Forging |
| Forming Method | Metal forming in liquid state | Metal forming in solid state |
| Cost | Low | High |
| Weight of Casting Parts | Unrestricted | Restricted |
| Shape of Casting Parts | Unrestricted, complex | Restricted, relatively simple |
| Mechanical Properties | Relatively low | Relatively high |
Types of Metal Casting Processes
Sand Casting
Sand casting usually relies on silica-based materials such as synthetic or natural sand. The casting sand usually consists of finely ground spherical particles that can be packed closely together to form a smooth molded surface. Sand particles can also be made more tightly bound by adding clay. Many automotive products, such as engine blocks and housings, are manufactured through sand casting.
Advantages of Sand Casting
Wide adaptability and low cost, especially in low-volume production.
For material with poor plasticity, such as cast iron, sand casting is the only process to manufacture the casting parts.
Suitable for making parts with complex internal cavities.
Image Source: In3dtec
Investment Casting
The model is made of fusible material, and the shell is made of several layers of refractory material covered on the surface of the model. After hardening, the model is heated again, so that the fusible material melts and is discharged out of the model, thus obtaining the casting model, and then the liquid metal can be poured to obtain the metal casting parts. Because the main component of the fusible material is paraffin, therefore, investment casting is also known as lost wax casting.
Advantages of Investment Casting
High dimensional and geometric accuracy.
Ability to produce thin-walled parts with complex geometries.
The surface of the casting is smooth, which can reduce the cost of subsequent processing.
Image Source: Americancastingco & Linkedin
Pressure Casting (Die Casting)
Die casting is under high pressure to inject molten metal into the mold. This pressurized insertion is rapid, preventing the metal from hardening before molding. After the process is complete, the component is removed from the mold and all scrap is removed.
Advantages of Die Casting
Good product quality and high dimensional accuracy.
Good dimensional consistency and interchangeability of castings.
High production efficiency. Die-casting molds could be used for times.
Suitable for mass production, and good economic efficiency.
Metal Casting Process Comparison Chart
| Sand Casting | Die Casting | Investment Casting | |
| Strength | Good | Good | Good |
| Design Complexity | Fair to Good | Fair | Highest |
| Size Limitation | Highest | Good | Fair |
| Pressure Tightness | Good | Fair | Good |
| Reproducibility | Fair | Highest | Good |
| Structural Density | Good | Fair | Good |
| Relative Cost | Low | Low | Average |
| Rate of Production | Fair | Highest | Low |
| Surface Finish | Fair | Highest | Highest |
| Tooling Lead Time | Highest | Good | Good |
| Tolerances | Fair | Highest | Highest |
| Alloy Range | Highest | Fair | Good |
| Casting Weight Range | Unlimited | 1 oz. – 75 lb. | Less than 1 oz. – 25 lb. |
| Dimensional Tolerances | ±0.001″/±0.030″ | ±0.001″/±0.0015″ | ±0.010″/±0.020″ |
| Minimum Wall Thickness | 1/10″ | 1/32″ | 1/16″ |
| Draft Angle | 1/4°-1/2° | 1°-5° | 1/4°-1/2° |
Classification of Casting Materials
Iron | Iron is a kind of iron and carbon alloy with carbon content greater than 2%, which has the advantages of good density, high mechanical strength, and high heat resistance. According to different uses, iron can be divided into gray iron, ductile iron, and other types. It is widely used because of its low price. Gray iron accounts for more than 80% of the output of cast iron.
Aluminum Alloy | Aluminum alloy is also a common casting material with the advantages of lightweight, high corrosion resistance, good thermal and electrical conductivity, and easy processing. Because of the low density of aluminum alloy, easy to form and process, aluminum alloy is particularly suitable for the die casting process. However, the strength and hardness of aluminum alloy are relatively low.
Copper Alloy | As a common casting material, copper alloy has the advantages of good thermal conductivity, electrical conductivity, corrosion resistance, and machining performance. However, the price of copper alloy is higher, mainly used in the manufacture of high-grade castings.
Steel | Steels are composed of iron and carbon alloys with a carbon content of less than 0.5%. Cast steel is characterized by high strength and good welding performance. In the process of manufacturing, steel castings require a higher melting temperature.
Titanium Alloy | Titanium alloy is a high-strength, highly corrosion-resistant casting material. However, titanium alloy is very expensive, mainly used in the manufacture of high-grade, high-strength, and highly corrosion-resistant castings.
Zinc Alloy | Zinc alloy is an alloy made of zinc and other elements, such as aluminum, copper, magnesium, cadmium, lead, and titanium. A variety of surface treatments are available for zinc alloy casting products, such as plating, spraying, painting, and polishing. The melting point of zinc alloy is low and the surfaces of zinc alloy casting parts are smooth, which makes it an ideal casting material for die casting. By die casting, the zinc alloy is used to produce casting parts with complex shapes and thin walls.
Magnesium Alloy | Magnesium alloy is lightweight but has excellent strength and stiffness. This makes magnesium alloys ideal for manufacturing aerospace castings. Magnesium alloys could be resistant to moisture and chemicals. This is why magnesium alloy castings are used in marine environments.
Applications of Metal Casting
The demands for metal casting have been increasing in recent years.
Image Source: Noveltystructures & Vantagemarketresearch
Outdoor Equipment | Casing products are dense and non-porous inside, so the load-bearing capacity is also very good. The metal casting products also have a unique beauty of power. That is why metal castings are so popular in outdoor equipment. The main metals used in outdoor equipment are iron and aluminum.
Fitness Equipment | Many fitness equipment components are made through the casting process. Iron is the most commonly used metal.
Automotive Industry | Aluminum castings reduce the weight of cars and the cost of manufacturing. They are widely used in the automotive manufacturing industry.
Medical Equipment | Casting products are also used in the medical field. For example, titanium is non-toxic, lightweight, strong, and has excellent biocompatibility, it is a very ideal casting material for medical use.
Aerospace | Due to their corrosion resistance and lightweight, magnesium alloy castings and titanium alloy castings are now used in aerospace applications, such as turbine blades. A turbine blade is a kind of product with complex shapes, high precision requirements, and high manufacturing difficulty, which are made through the investment casting process.
Our Metal Casting Service
With years of experience in metal casting, Tengye has adapted the manufacturing and services we offer to meet the evolving needs of our clients.
Experiences | Our team has years of experience in metal casting for various industries and can handle those challenging projects.
Tight Tolerances | Our services in high-end industries lead to the production of precise parts with tight tolerances.
Wide Range of Materials | We have served a wide range of clients and could offer a variety of rapid prototype materials and finishing processes.
No MOQ | We can handle one-off prototypes and low-volume parts.
Rapid Turnaround | Our capacities allow us to finish your prototyping projects in days.
