Squeeze Casting: Definition, Importance, How it Works, Applications, and Advantages
Squeeze casting, a distinctive blend of casting and forging methods, transforms the manufacture of metal components. Molten metal gets pumped into a prepared mold while the machine exerts pressure to guarantee complete filling and accurate shape.
Squeeze casting process.
Image Credit: https://www.researchgate.net/figure/A-schematic-of-squeeze-casting-process_fig5_342672124
The procedure is significant because it produces components with remarkable strength at nearly exactly your specified net shape. It is important to understand how to control variables like temperature, pressure, and die design to produce the best outcomes.
Squeeze casting shows up in complicated aerospace components and automotive engine parts, among others. Squeeze-cast aluminum alloys, for example, are used in the aerospace industry due to their lightweight yet durable characteristics. There are disadvantages to take into account, but squeeze-cast metal is usually less porous and has better mechanical properties than other types. This article will discuss the definition, significance, method, uses, benefits, and drawbacks of squeeze casting.
Squeeze casting is a manufacturing technique that combines casting and forging. It’s also known as liquid metal forging. This technique involves injecting molten metal into a heated die, allowing it to begin solidifying, and then closing the upper die to form the mold chamber. Pressure from the upper die forces metal to completely fill the casting cavities which results in outstanding surface quality and minimal shrinkage. Aluminum and magnesium alloys are the most common metals for this procedure, but it can accept others as well. Vehicle parts are very often squeeze-cast.
The history of squeeze casting, or SC, began with its initial patent in 1819 by Hollinggrak. It was later improved by Chernov in 1878. This innovative process combined high temperatures and 15,000 psi worth of pressure to reshape molten metal. The invention was meant to innovate metalworking techniques for improved material properties and applications.
Squeeze casting is a crucial manufacturing technique. It enables enhanced wettability of reinforcements, efficient mass production, precise process parameter control, superior metallurgical quality through pressure-assisted solidification, and the ability to selectively reinforce specific regions in components. These attributes make it a top choice for producing high-quality metal matrix composites.
Squeeze casting works by introducing liquid metal into a heated die alongside a preform created through powder metallurgy. Once the die is full, pressure is applied and the metal is allowed to solidify. This controlled environment minimizes porosity within the metal matrix and facilitates the creation of near-net-shaped components. Consequently, you’re left with less need for post-processing operations, making it an efficient and cost-effective manufacturing method for complex parts.
Squeeze casting distinguishes itself from other casting methods through its unique combination of high-pressure solidification and near-net-shaped component production. The technique reduces porosity, improves material properties, and minimizes post-processing, making it a preferred choice for manufacturing complex, high-quality metal components.
To learn more, see our guide on the Types of Casting.
No, squeeze casting is not the same as die casting. It is an adaptation of conventional die casting that incorporates both casting and forging techniques. Die-casting machines force molten metal into a mold cavity, whereas additional pressure is applied to squeeze-cast metal. The result is better mechanical properties and fewer defects.
The two types of squeeze casting are:
In indirect squeeze casting, molten metal is introduced into a shot sleeve. This is then forced through relatively large gates into the die cavity at low velocity (usually less than 0.5 m/s). High pressure is applied "indirectly" through the extensive gating system. This process controls solidification, so it prevents defects, but the gating complexity increases material and energy use.
Direct squeeze casting (DSC) involves pouring liquid metal into a heated, lubricated die and forging it as it solidifies. Pressure is applied shortly after the metal begins to freeze and is maintained until the entire casting has solidified. DSC is commonly executed using a vertical apparatus that resembles a forging press in its operation.
The metals used in squeeze casting are:
Zinc squeeze casting gets applied to zinc-based alloys, notable for their relatively low melting points. In this process, molten zinc alloy is carefully directed into a die cavity where pressure is applied to shape and solidify the item. Zinc's exceptional fluidity makes it ideal for intricate part geometries. Moreover, it demands less heat than most metals. However, that also means zinc-based alloy parts are only suited to cooler operating temperatures, and their mechanical properties may not match those of other metals.
To learn more, see our article on What is Zinc.
Magnesium squeeze casting relies on magnesium alloys, celebrated for their lightweight characteristics and impressive strength. During magnesium squeeze casting, molten magnesium alloy is poured into a preheated die and pressurized while it solidifies. Magnesium alloys offer excellent strength-to-weight ratios, making them particularly attractive for industries seeking lightweight yet robust components. However, precise temperature control is critical due to magnesium's flammability and susceptibility to oxidation.
Aluminum squeeze casting centers around aluminum-based alloys, cherished for their strength and low density. Liquid aluminum alloy is introduced into a preheated die and molded under pressure during the solidification phase. The excellent strength, corrosion resistance, and versatility of aluminum alloys make them popular options for a variety of applications. However, good aluminum squeeze casting depends upon precise alloy selection and strict temperature management.
To learn more, see our guide on Aluminum Physical Properties.
Squeeze casting with copper alloys encompasses materials like brass and bronze, valued for their durability and exceptional electrical conductivity. The procedure channels molten copper alloy into a heated die and shapes it under pressure as it solidifies. Copper alloys excel in applications where electrical and thermal conductivity, as well as wear resistance, are paramount. However, their cost and specific material properties limit their reach in the market.
Yes, stainless steel can be squeeze-cast. Squeeze casting is a versatile process that shares similarities with both casting and forging, making it ideal for alloys like stainless steel that require controlled solidification.
To learn more, see our guide on Stainless Steel Metal.
Many industries use squeeze casting to create complicated, high-quality metal components. A few examples are found in the production of: steel bevel gears for machinery, aluminum domes for architectural use, iron mortar shells, pistons for internal combustion engines, aluminum automotive wheels, and bronze and brass gear blanks. This procedure guarantees superior mechanical qualities and dimensional accuracy in these components.
Squeeze casting products find use in: automotive, defense, aerospace, and manufacturing industries, among others. In the automotive sector, components like pistons and wheels enhance engine efficiency and vehicle performance. The defense industry relies on squeeze-cast iron mortar shells. Critical aircraft structural elements also get cast this way.
Squeeze casting products exhibit exceptional quality and durability. The process generates high-density, nonporous structures by reducing solidification shrinkage and eliminating gas compression. This results in excellent surface quality and superior mechanical properties, making squeeze-cast components highly durable and reliable.
Yes, squeeze casting products are ductile. The rapid solidification in squeeze casting results in fine secondary dendrite arm spacing within castings, which enhances their strength and ductility. This microstructural refinement contributes to their ability to withstand deformation without fracturing. Specific ductility properties depend on the material, though.
No, squeeze casting products are not inherently brittle. However, some alloys are naturally more brittle than others, no matter how they’re cast. Be careful to make design, material, and process parameter choices that will meet your ductility, toughness, and other mechanical property requirements.
Squeeze casting precision typically ranges from 0.25 mm in 100 mm to 0.6 mm in 500 mm, making it comparable to die casting. The great dimensional accuracy means it can be used in applications that demand exact tolerances.
Material choice, usage circumstances, and maintenance are only a few of the variables that affect how long squeeze casting products last. These components typically have long lifespans when made with the proper materials and maintained properly.
The advantages of squeeze casting include:
- Squeeze-cast parts can be heat-treated to enhance their mechanical properties.
- The process offers consistent and reproducible results.
- Squeeze casting yields components with excellent mechanical properties, including strength and ductility.
- Squeeze casting results in low porosity, ensuring high-density components.
The disadvantages of squeeze casting include:
- It can be expensive due to its specialized equipment and tooling requirements.
- Squeeze-cast parts may require extensive machining to achieve precise tolerances.
- It is less versatile for complex shapes compared to other casting methods.
The cost of squeeze casting can vary significantly depending on factors such as: the complexity of the part, the material used, and production volume. The initial tooling and equipment are typically more expensive than for other casting methods.
Centrifugal casting is generally considered more cost-effective as it doesn't demand expensive tools or materials. The process is relatively simple and doesn't require highly skilled labor. Centrifugal castings usually have smooth, high-quality finishes.
High-pressure die casting (HPDC) is an alternative to squeeze casting. It uses high pressure to pump molten metal into a mold cavity to make detailed and high-quality pieces, particularly in aluminum, magnesium, and zinc.
Squeeze casting and high-pressure casting are both metal casting processes, but they differ in the application of pressure. Squeeze casting applies notable pressure, but it’s considered low to moderate pressure compared to that seen in high-pressure die casting. HPDC can turn out higher-quality and more intricate parts.
This article presented squeeze casting, explained it, and discussed its various applications and advantages. To learn more about squeeze casting, contact a Xometry representative.
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