Die Casting Parts: How Aluminum Die Casting Works


Posted on: April 19, 2019, | By Candy, WayKen Marketing Manager

Die Casting is an extremely efficient process that enables manufacturers to produce complex and precise metal parts in a very short span of time. It is even more widespread for aluminum parts. A large portion of automobile parts such as car disks, pump elements, aluminum valves and fittings, aesthetic components, etc. are actually die casting parts. This process offers a lot of advantages with few limitations. Let’s try to understand the way die casting processes to work, what kind of properties you can achieve, and in which case aluminum die casting is the process to stick with to get the best profit.

What is Die Cast Aluminum?

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Aluminum alloys have the perfect qualities for casting. They have low melting temperature, the great filling rate of the mold, little to no cavity formation. All of that resulted in an advanced development of the aluminum cast parts production methods. Nowadays, there are literally hundreds of ways to cast an aluminum part. There are different mold materials and forming types, different master-model types, a large variety of ways to actually pour the metal, and, naturally, conditions for its solidification and cool down. The most popular casting method in the modern industry is aluminum die casting.

Aluminum dies casting consists of pouring liquid aluminum alloys into a cavity formed by two or more steel dies clamped together. The liquid is usually under pressure to ensure the complete filling of the cavity. Once the aluminum has filled the cavity completely, it is left to solidify and cool down for the ejection. At last, the solid part is ejected by unclamping the steel dies and a new one can be formed.

The Advantages of Aluminum Die Castings

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Aluminum casting products formed by die casts have a lot of advantages.

Complex parts are often created by manufacturing different components and welding them together, however, casting can avoid that and enable you to create one single part without the need for welding and consequent post-processing of the joint.

Aluminum die castings have an outstanding surface finish and precision so you can significantly decrease the machining volume.

Aluminum casting has great repeatability.

Cast and polished surfaces can be used as a contrast to create pleasing aesthetic effects.

Capital investments are not so big as for wrought products.

Die complexity can vary from simple cavities to complex tool steel dies depending on the production batch and technical requirements.

You can actually cast bimetallic parts.

Die casting provides outstanding material properties.

Die-cast parts have a very good cost/quality comparison when a lot of parts need to be manufactured.

Now, the last point needs further discussion.

Die-cast Aluminum Properties

Aluminum die casting parts can have tensile properties of most forgings, extrusions, and rolled plates. However, there are differences to the microscopic structure of the aluminum after the mentioned processes.

Wrought products are usually characterized by a finely recrystallized grain structure with significant anisotropy and highly structured features, ductility in longitudinal directions is typically greater than in castings.

Castings have a uniaxial grain structure and absence of anisotropy in their structure, so they do not pose the challenges associated with anisotropic properties in different directions.

Reusable mold dies can be manufactured on various scales ranging from less than a kg to more than a ton. Die Casting surface finish is usually in the range of 150 to 400 μin. (3.8 to 10 μm). The tolerances vary around 0.01 in./in. ( 10 mm/m). The minimum wall thickness to be achieved is about 0.100 in. (2.5 mm).

Aluminum Casting Process Variations

All types of die casting processes use reusable highly durable dies made of steel. The longer the Die is supposed to work, the more complex the steel composition. In order to increase or decrease heat exchange between the dies and the casting, the cavity is often covered with special coatings such as talc suspension, zirconia, chromium, or iron oxides. These coatings serve to prolong die life and help with the ejection of the coating as well.

There are two main variations of manufacturing die-cast aluminum products. Those are low-pressure and high-pressure die casting. Their main difference is the way pressure is administered. Let’s review each of them.

Low-pressure Die Casting (LPDC)

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LPDC equipment has an unusual structure. The dies are suspended over the tank with molten metal. In riser systems, a pipe starts from the bottom fixed Die and goes down towards the middle of the tank. When the Injection starts, the pressure is administered to the molten metal tank so that the liquid goes up the pipe and fills the cavity between the dies. Once the casting is solidified, the pressure is disabled. In a non-riser system, there is no pipe and the whole system is enclosed in a vacuum chamber. During the Injection, the cavity has negative pressure so the metal flows inside under the effect of the vacuum. The second system eliminates any kind of undesired additions in the molten metal but requires stronger dies.

High-pressure Die Casting (HPDC)

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High-pressure die casting is a process that involves rapid Injection of molten aluminum into water-cooled dies. The rapid Injection is ensured by a hydraulic ram and a shot chamber. The pressure is maintained until the ejection. This process is much faster and yields a part that has a considerably smaller grain structure, which is crucial to get finer tensile properties.

Aluminum Die Casting Services

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However efficient, the die casting processes require a lot of experience and proficiency. Oh, and, of course, equipment. All of that requires considerable time and money to create. If you are just starting out, by the time you fix all the possible aluminum casting defects (such as cavities, cool down cracks, incomplete filling of the mold, and lots lots more) reasons and finally get a high-quality part, you’ll be bankrupt. In order to resolve this issue, a good idea might be to use aluminum casting services. Such companies offer outstanding design and engineering support of the future castings but the manufacturing support and realization as well. Especially widespread are the aluminum die casting China companies. They offer the smallest price at a very fast turnaround time as well as outstanding die casting parts quality.

WayKen Can Meet Your Die Casting And CNC Machining Needs

No matter which you need one, the other, or both, we can provide both die casting and CNC machining for each customer to deal with aluminum die casting problems. If you have any metal parts (eg, aluminum components) or products project, please feel free to contact us with our experienced manager and whether die casting, CNC machining, or combinations of the two will be the best approach for your business. In the future, we wil be dedicated to providing and improving our prototype machining service include CNC machining, Vaccum casting, Die casting. rapid injection molds for the globe customer to create affordably and effectively rapid prototypes and end-use parts.

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