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西班牙语Squeeze casting is a type of manufacturing process that converts solid metal into liquid and then into a solid form again. It is very useful for a variety of industries needing complex shapes with high structural integrity.
Squeeze casting is a derivative of die casting, a process that dates back to the Industrial Revolution, which allows you to create high volumes of castings for mass production.
In terms of materials, squeeze casting can involve alloys, aluminum, magnesium, and more.
We bring you more details about the squeeze casting process, its applications, and compare it to other casting methods.
What Is Squeeze Casting
There is some confusion about what squeeze casting is because it can be similar to other metal shaping processes.
Squeeze casting is a type of die casting process that allows you to create metal pieces that are less porous and more mechanically sound.
For this reason, it has become very popular in the manufacturing world.
Squeeze casting helps prevent the entrapment of air bubbles when pouring metals into molds.
This allows manufacturers to create high volumes of high-quality metal parts that have no pores throughout the piece or on the surface. It can be done with die casting machines in mass production environments.
Squeeze Casting Process
Squeeze casting involves a modification of the conventional die casting process. To understand the squeeze casting process, it is first helpful to understand casting on a general level.
During casting, a manufacturer pours a liquid, usually molten metal alloys or plastic, into a mold. A mold is simply a cavity that shapes the liquid and allows it to cool into a particular form. As molten metal solidifies, it takes the shape of the mold cavity.
Casting utilizes either temporary or longer-lasting molds to create objects in a variety of sizes and shapes. It usually allows manufacturers to reproduce surface details.
Molds can be temporary or longer-lasting. They are typically used to provide more specific surface details.
As a variation of a die casting process, squeeze casting uses high pressure yet non-turbulent forging to create the end product.
Many popular and low-cost consumer items used today are created with squeeze casting, such as aluminum and zinc alloy metal items.
For instance, the following parts can be made in this way:
- Brackets
- Chassis Frames
- Wheels
- Suspension Components
- Aluminum Front Steering Knuckles
The process of squeeze casting is also known by a variety of different names, including extrusion casting, hydraulic die casting, die assembly, and liquid forging or pressing.
However, the former is the term we will be using in this post.
Types of Squeeze Casting
Manufacturers have developed two broad types of low porosity casting: direct squeeze casting (also known as liquid metal forging) and indirect squeeze casting, which allow for the creation of unique products and parts.
Each type has its particular uses and advantages over the other.
Let’s take a look at what differences do these casting types entail.
Direct Squeeze Casting
The direct method of squeeze casting is also known as liquid metal forging.
Here, like in other forging processes, a forging press, also known as a hydraulic forging machine, is used.
For direct squeeze casting, the process includes liquid metal.
The liquid metal is poured into the forging press in the lower die region. Meanwhile, the upper segment of the forging press is closed off.
After this, the molten metal is allowed to cool slightly. That is when the pressure is directly applied to the liquid mixture. The amount of pressure can be very high, often reaching 100 MPa or more.
With the direct method, the molten is poured in a very controlled way. The slow rate allows for a non-turbulent process.
Indirect Squeeze Casting
While indirect squeeze casting uses similar equipment to direct squeeze casting, the process differs a lot.
The liquid is first cleaned and grain-refined, then injected (instead of poured) inside of the die. The pressure remains constant, eventually resulting in liquefied metal.
During both types of casting, manufacturers may perform squeeze casting operations in vacuum-controlled environments in some settings.
The use of the metal parts created through direct or indirect squeeze casting as well as the properties of the raw materials used during production influence the choice of casting technology.
Nevertheless, both squeeze casting methods have increased in popularity in recent years because these techniques provide a way to minimize the porosity of castings.
Squeeze Casting Materials
During squeeze casting, there are some procedural differences compared to other types of die casting.
The process allows you to use a variety of materials, including lightweight metal alloys such as zinc, aluminum, and magnesium. However, there are also longer cooling times.
Thus, certain lubricants are also needed to achieve the final result.
This requirement can increase the investment needed to produce these parts, making it advantageous to outsource this process to specialists such as Bunty.
If aluminum castings are used, they should be without iron aluminide needles. These can impede mechanical properties that are necessary for high-quality products.
In addition to raw materials, there are certain tools needed for proper squeeze casting:
- Squeeze Casting Machine. This is the primary tool needed for squeeze casting. Metal is poured (or injected) into the mold. It is filled with dye, and then high pressure solidifies it. There are two shape options for the machines: horizontal or vertical. Casting machines typically weigh somewhere between 50 and 350 metric tons.
- Oil Die Heating System. Die needs to be heated up before entering the squeeze casting machine. The oil die heating system performs this function and combines the die with liquid metal.
- Vacuum System. High pressure is a key component of squeeze casting. The vacuum system creates this pressure to solidify the die, melting the mix later to fit the shape of the mold.
- Process Monitoring System. Quality assurance is of the utmost importance in this process. The process monitoring system ensures that everything is working as intended, alerting fabricators if something goes wrong during the process.
Now that we know what tools are needed for squeeze casting, let’s take a look at its many applications.
Squeeze Casting Applications
Unlike some other processes, squeeze casting is very versatile. There are numerous applications for squeeze casting, and they span across different economic sectors.
One of the primary industries that demand a lot of parts from squeeze casting production methods is the automotive sector, so that’s what we shall focus on here.
Chassis frames are one component that needs squeeze casting, as well as others that benefit from lighter materials.
The boat and airline industry also require squeeze casting in the production of small turbine blades and boat propellers.
Motorcycle parts also need minimized gas porosity inside the casts.
Squeeze filling can minimize in-gate velocity and maximize intensification castings with indirect squeeze castings.
Tests have demonstrated that squeeze casts pass blister tests for over 2 hours at 490 °C.
In the car industry, aluminum steering knuckles, nodes, and brackets are additional applications of squeeze casting.
For carmakers, being able to cast alloy instead of making a permanent cast allows for faster production and lower costs in an industry with stiff competition.
The parameter control is easier and more simple on squeeze casting, as well as the wettability of reinforcements.
It has applications for overcoming issues with this wettability and using high volume fraction MMCS.
Advantages of Squeeze Casting
There are numerous advantages of squeeze casting over other methods.
Typically, in other types of casting, manufacturers deal with the issues of air bubbles, which can cause quality problems with the castings.
However, squeeze casting is unique in this aspect.
Squeeze casting creates fewer trapped air bubbles. This also means metal parts made with squeeze casting sometimes reach higher market prices due to increased quality.
Such parts are also more resistant to shrinking.
Shrinkage can be a big problem for manufacturers. It means they have to reject castings, resulting in higher expenses.
So a direct bottom-line benefit is cost savings in terms of fewer rejected products and lower waste byproducts.
Manufacturers can use composite fibers without losing fine detail or quality. This is because squeeze casting allows them to use non-ferrous materials and ferrous alloys.
Finally, squeeze casting does not emit gas, and the cooling rate allows more control over the final structure.
Squeeze vs. Continuous Casting
There are many misconceptions surrounding squeeze vs. continuous casting. Continuous casting is quite specific.
Continuous cast forms are made with molten metal being introduced into a horizontal or vertical mold. These molds have the ability to chill the metal rapidly until it is solidified.
This is unlike squeeze casting, which takes a longer time to solidify the metal.
However, there are some positives to rapidly chilling materials.
It creates a uniform grain structure that is better than sand castings as it is fine and contains better physical properties.
Furthermore, it can be applied to different things since it can be cut to size accordingly.
There are many shapes possible such as:
- Rectangular
- Hexagonal
- but square
- Solids
- Tubes
As a result, they are able to fit different part profiles.
The process of continuous casting involves being fed directly into an induction furnace. This is often used in the foundry industry, for instance.
Also, continuous castings can require less machining stock and remain straight and true.
Squeeze Casting vs. Die Casting
Like all casting, there are some similarities between squeeze casting and die casting. However, there are some important differences.
Die casting uses a furnace, raw materials, and a die casting machine. During the production, metals are melted in a hot or cold chamber furnace. However, during most die casting, the metal is rapidly cooled.
The primary difference between die casting and squeeze casting is the speed at the gate.
Squeeze casting is slower and avoids turbulence when filling.
This means that squeeze casting can take longer but produce a higher quality product.
With squeeze casting, you can also create finer details because the liquid cools faster before it becomes solid.
Whereas squeeze casting may be used to create parts such as chassis, die casting is used for parts like engine blocks, cylinder heads, and pistons.
Die casting is also used in industrial settings such as making housings, bushings, pumps, and propellers.
Also, die casting is semi-permanent and can be used for various identical parts with one casting, allowing it to be cost-efficient in certain settings.
Conclusion
When it comes to the process you will use for your manufacturing, there are various options to choose from.
However, each one will have its own unique advantages and disadvantages. This is the case for squeeze casting as well, of course.
Squeeze casting is an excellent choice when manufacturing parts for certain industries, thanks to the slower cooling and alloys it can use.
This includes airlines, automotive companies, and boat manufacturing companies.
