What is Aluminum Die Casting? The Process Explained
Complex aluminum parts can be produced using the metal-forming technique known as aluminum die casting. Aluminum alloy ingots are heated to extremely high temperatures until they completely melt.
You can see an example of a mold for automobile parts above. The liquid aluminum is injected under high pressure into the cavity of a steel die, also known as a mold. After the molten metal has solidified, the two parts of the die are removed to expose the cast aluminum component.
The resulting aluminum product is precisely formed with a smooth surface and often requires minimal or no machining processes. Given that steel dies are used, the process can be repeated many times using the same mold before it deteriorates, making aluminum die casting ideal for the high-volume production of aluminum parts.
- The Advantages of Aluminum Die Casting
In comparison to other metal-forming techniques, die-casting aluminum has a number of benefits that may make it the best option for producing your aluminum parts.
The capacity to make extremely complicated geometries that neither extrusion nor machining can efficiently manufacture is one of the most notable. The manufacture of intricate vehicle components like engine blocks and transmissions serves as a prime illustration of this. Other techniques are unable to consistently provide these items' high levels of complexity and precise tolerances.
The capability to handle both large and small pieces, as well as the option to have rough or smooth surfaces, are further benefits.
- The Top Considerations During Part Design
When creating the casting portion, a few factors must be taken into mind.
First, the mold needs to be made such that it can separate and release the solidified metal component. A separation line must be taken into account in the initial phases of die design since it designates the point at which the two sides of the mold separate.
Another important consideration is the location of injection points. The die can be designed with several injection points in cases when the molten metal would otherwise solidify before reaching every crevice in the die. This can also help if cavities are included in the design; you can surround them with aluminum and still have the part come off when the mold is separated.
You must also consider the thickness of the part’s walls. There are usually no guidelines for a minimum wall thickness, thanks to recent technology developments, but having walls with consistent thickness is often preferred.
- How it Compares to Green Sand and Permanent Mold Casting
An operator pouring molten metal into a sand cast mold
Alternative casting methods to aluminum die casting include green sand and permanent mold. Green sand techniques are less expensive than the other two because they employ wet sand to make the mold for the cast. An employee is depicted above pouring molten metal into a sandcast mold.
Permanent mold castings need the molten metal to be gravity poured into the mold, as opposed to die casting, which employs injection. Casts made with a permanent mold could possibly be stronger.
However, compared to the other two procedures, die casting delivers greater tolerances and better-finished surfaces, frequently negating the need for additional surface preparation.
- Options for Machining and Finishing
Die cast aluminum pieces frequently only need little machining, and there are various alternatives for surface finishing. By casting standards, die casting has a very good surface polish, although it is still possible for there to be flaws, such as metal seams where the mold halves connect. Sanding, sandblasting, or orbital sanding can be used to smooth out a rough surface or other flaws that are unsuitable for the part.
Shot peening, a cold working technique, is frequently used on die cast aluminum to increase fatigue resistance. As an alternative, a protective or ornamental coating, such a powder coat, might be added to the finished part. After casting, the pieces can potentially undergo additional adjustments like drill tapping.5. The Most Common Aluminum Die Casting Alloys
Aluminum ingots which will be melted down for production
A few of the most commonly used aluminum alloys for die casting are A380, 383, B390, A413, A360, and CC401. The primary consideration when choosing an appropriate alloy is your intended application.
For example, A360 offers excellent corrosion resistance, pressure tightness, and very good fluidity when molten. B390 offers outstanding wear resistance and high hardness while having the lowest ductility of all cast alloys, which is why it is used for applications such as automotive engine blocks. Alloy A380 is the perfect jack-of-all-trades, offering a good combination of casting and product properties, and is the most commonly specified alloy for casting a wide variety of products.
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