864.990.0762 inquiries@buntyllc.com 444 Fairforest Way, Greenville, SC, 29607, US
High-Quality products
High-quality metal components.
Unbeatable customer service
Highest possible level of service
Get A Quote

Squeeze Casting Process

Perhaps the most flexible of all the casting processes, the squeeze casting can be used for a wide range of commercial applications due to its ability to be mass-produced.  

A unique metallurgical quality, a simple control process, and wettability features make this an all-in-one process for shaping and molding metal parts.  

In the following sections, we will cover what this process entails, the different types of squeeze casting available, the tools needed, and the advantages and disadvantages of using it.

What Is Squeeze Casting

Casting, in general, is the process of pouring liquid metal into a mold matching the shape and size of the desired part.  

Custom metal parts are important for many businesses in a variety of industries. To make those metal parts specific to the needs of those businesses requires a casting process that is flexible enough to shape and mold metal pieces that produce desired results.

That’s where squeeze casting comes into play.

Squeeze casting is a casting method that uses non-turbulent, high-pressure casting and forging processes to produce high-quality, thick and heat-treatable metal parts. 

Since the process is both economical and simple, it is the preferred method in the production of auto parts, such as:

  •  wheels
  • suspension components
  • aluminum front steering knuckles
  • chassis frames
  • brackets

However, because it employs both casting and forging processes, squeeze casting can pretty much be used for any part with mechanical properties.

This is especially true of those consisting of aluminum alloys. 

In fact, many industries like defense, construction, and even agriculture now prefer to use this manufacturing process since it creates stronger metal alloys that are more resistant to wear and tear, as well as heat.  

The squeeze casting process is known by a variety of names, which include liquid forging or pressing, extrusion casting and hydraulic die casting, among others.

Whichever name it is called, the process will always include liquid metal, die assembly, and a hydraulic press to cast and forge metal parts and components. 

Types of Squeeze Casting

There are two available squeeze casting methods, direct and indirect. 

Here’s a quick overview of what each process entails and the benefits they offer.  

Direct Squeeze Casting

The direct process, also known as liquid metal forging, is completed with equipment similar to the ones used in other die casting and forging processes.

Usually, this includes a hydraulic forging machine, otherwise known as a forging press.

In this process, liquid metal is poured directly into a lower die segment within the hydraulic forging press, while the upper segment is closed off. 

The pressure applied during the direct process is quite high, usually 100 or more MPa.  

The benefits of using the direct process are as follows: 

  • The resulting casting emits no gas, experiences no shrinkage, and has no porosity (empty spaces). 
  • The high pressure used results in a high cooling rate granting more control over the microstructure of the mold and liquid metal. 
  • Fine-grain structures can be made without having to resort to other additions or procedures that help create such structures. 
  • There is no need for any risers or feeders during the process. 

Another distinctive feature of the direct process is the controlled way the molten metal is poured into the mold. 

The slow rate of the pour allows the die to automatically flow into the metal at a controllable speed which produces the desired shape in a non-turbulent way.  

Indirect Squeeze Casting

The indirect casting process uses similar casting equipment to the kind used in the direct process, yet the procedure is quite different. 

Here, the liquid metal is first cleaned and then grain-refined before it is inserted into a casting machine.

The casting machine used in the indirect process can either be horizontal or vertical

After it has been cleaned, the heated metal is “injected”, instead of poured, through a small-diameter piston into the die through large gates in the machine at a very slow rate—approximately 0.5 m/sec

After this, the melt (i.e., heated/liquified metal) is pressurized (55 MPa-300 MPa) until it becomes solid.  

One major difference between this process and the direct one is that the pressure chosen to solidify the melt remains constant throughout the solidification process.

Although the indirect process usually results in lower-quality metal properties than the direct method offers, it is still an ideal process for heavy suspension automotive parts like steering knuckles

Both the direct and indirect processes share similar advantages over more traditional forging and casting processes.

Some of these include:

  • No internal/external defects requiring NDT (non-destructive testing).
  • Better quality mechanical properties. 
  • Shorter production cycle times (up to 66 percent less than other die casting processes). 

Both processes can improve a wide range of metal alloys as well (iron, steel, magnesium, zinc, and aluminum), helping to produce better machine parts with stronger and more flexible metallic properties. 

Tools Needed to Complete the Squeeze Casting Process

As with all forging and casting processes, the right tools and equipment are necessary to achieve the desired result. 

There are four main pieces of equipment (tools) needed for squeeze casting:

  • Squeeze Casting Machine
  • Oil Die Heating System
  • Vacuum System
  • Process Monitoring System

A brief explanation of each of them is given below:

Squeeze Casting Machine

This is the main tool used for squeeze casting. 

It is where the liquid metal is poured or injected into a mold full of dye and solidified under high pressure.

It can either come in a horizontal or vertical shape and usually weighs anywhere between 50 to 350 metric tons

Oil Die Heating System

This machine is used to heat the die before it is put into the squeeze casting machine and combined with the liquid metal. 

Vacuum System

This machine is used to create the high pressure needed to solidify the die and melt mix into the shape of the mold.  

Process Monitoring System

This tool helps to monitor the entire squeeze casting process from start to finish making sure that everything runs smoothly throughout and alerting fabricators when and where something breaks down during the process. 

It helps maintain regularities in:

  • casting alloy compositions
  • pressure levels and duration
  • die preheating, pouring and injecting temperatures
  • die coating (lubrication)
  • melt heating
  • punch temperatures
  • delay times needed for producing optimal temperatures

At first glance, the tools needed for squeeze casting may seem expensive.

However, in actuality, the machines used for this process and the process itself are less expensive than other forging and casting processes—like HPDC (high-pressure die-casting), for instance. 

Squeeze Casting Overview

Squeeze casting dates back to the 1960s, when it was first introduced to metal fabrication manufacturers in the United States. 

Since then, squeeze casting has been simplified and optimized to get the job done in only four steps.

These steps include melting metal, pouring and mixing melt into die, then closing it and applying pressure.

Finally, after the process is complete, the end result is ejected and the entire process repeated.

Each of these four steps is explained below.

Melting Metal

In this step, the metal being used will be preheated before it is poured into the casting machine and mixed with die. 

A melting furnace is typically used to liquefy solid metals. 

The temperatures needed to heat different metals varies widely and can range anywhere from 660°C (1220°F) to 3400°C (6152°F) depending on the metals being used. 

Pouring/Mixing Melt Into Die

The second step involves pouring or injecting the molten metal with the help of a launder into the mold cavity (bottom die cavity), where it is mixed with the bottom half of the pre-heated die. 

Closing Die and Applying Pressure

Here the top half of the pre-heated die (punch) is used to close off the melt. Once the melt is closed off, pressure is applied through the use of a ram to form the cast in the shape of the mold. 

Pressure levels of 50 to 140 MPa are typically used to shape the metal/die mix. 

Ejecting/Repeating Process

After the solidification process is complete, the punch is withdrawn. 

The cast component is ejected, the die is cleansed, and the melt stock is charged so that the process can be repeated as soon as it is needed. 

As was mentioned earlier, pressure levels of 50 to 40 MPa are used to form the cast, but this must also be accompanied by temperature levels of 6-55 degrees Celsius so that enough cooling can take place to solidify the cast.   

Advantages of the Squeeze Casting Process

One of the biggest advantages of this technique is the high-quality metal properties that are formed when it is applied. 

The favorable mechanical properties that are formed using squeeze casting are comparable to those produced by forging methods, which allow metals to take on various geometric shapes. 

The other major advantages of employing this casting process include:

  • A variety of molds and shapes
  • Little to no machining (metal cutting/forming) after casting completion
  • Low porosity (few to no spaces) in the cast
  • High-quality surface texture
  • Better grain with no shrinkage, i.e., high strength with fine microstructure formation, due to the cooling portion of the process
  • Little to no material wastage during the entire process helping to cut down on manufacturing costs
  • Metal variety; almost any metal can be used during the process except for those that liquefy at room temperature (mercury), dangerous radioactive metals (plutonium), and high-melting ones since they would end up melting the die

Aside from the above main advantages, there are a couple of other economic and manufacturing benefits associated with this process.

These include higher-quality workpieces that garner higher prices for businesses that utilize them for their machine parts, as well as the long-lasting parts with little to no defects.  

To sum up, squeeze casting can be described in three words: functional, economical, and long-lasting. 

Disadvantages of the Squeeze Casting Process

Although squeeze casting solved many of the problems associated with other casting processes —low dimensional accuracy, low strength, high porosity, and post-processing requirementsit does come with some drawbacks. 

The major disadvantages to using this process include the following: 

  • An initial high manufacturing cost due to complex tooling procedures. 
  • Little to no flexibility in parts production as the tooling (designing and engineering of tools) associated with squeeze casting is dedicated to the creation of specific metal components.  
  • Slow production cycles due to the intricate control process required for successful casting.
  • A necessity for high production volumes to justify the cost of the equipment needed to complete the process. 
  • Macro defects which occur if the process parameters (from alloy composition and pressure levels, to die and pouring temperatures, among others) are not correct

While these drawbacks to the process may put off some companies from using the process for their products, it should be noted that its applications in manufacturing are widespread.

It allows for the creation of different parts for different industries such as aluminum domes, ductile mortar shells, steel bevel gears, automotive wheels, etc.

Conclusion 

Squeeze casting is a hybrid metal forming process that combines mold casting procedures with die forging ones and so brings more advantages than either of those processes can deliver alone. 

Squeeze casting has become one of the most popular metal forming methods for many industries due to its practical applications in commercial product manufacturing. 

While there are some high upfront costs to acquire the equipment and tools to run the process smoothly, it has many financial benefits.

These come in the form of its mass production capabilities and the multiple metallurgic improvements it brings to metal alloys.

While squeeze casting is most popularly linked to its effectiveness in producing automotive parts, it is now widely used in many other industries including defense, aerospace, agriculture, and consumer goods.

The continuing improvements to its process and procedures help create higher-quality metal parts at lower costs.   

About Bunty LLC

Bunty LLC was formed in the year 2,000 and its headquarters reside in Greenville, South Carolina, U.S.A.

We provide custom-machined, forged, and cast metal parts fabrication for a variety of industries across the globe including aerospace, automotive, medical, robotics, energy, and many more. 

Bunty specifically uses the squeeze casting process to produce high-quality, custom-made parts specific to customer requirements.  

Some of the more prominent features of the company are as follows:

  • AS9100D and ISO 9001:2015 certified quality management system (QMS).
  • A long history of producing and delivering high-quality parts to customers and clients. 
  • Premier custom-metal parts manufacturer, specializing in metal parts modifications according to client specifications. 
  • Supplier of custom-metal parts to large brands such as NASA, Gillette, and BMW. 
  • Strong and innovative design process capabilities including squeeze casting that allows for on-time, on-budget, and on-spec deliverability.  

If you are looking for a trusted and proven metal parts manufacturer that can build and deliver what you need and how and when you want it, contact us here

We will be happy to answer any questions you may have about squeeze casting specifically or metal parts manufacturing in general.  

About us

From a contract manufacturing firm, BuntyLLC evolved into a full service custom machined, forged and cast metal parts fabrication enterprise. We supply global solutions from our headquarters in Greenville, South Carolina.

Get A Quote