SHOULD I USE ALUMINUM DIE CASTING OR PERMANENT MOLD CASTING/SAND CASTING?

​When looking to manufacture your product parts, you may be faced with the choice between using aluminum die casting, sand casting or permanent mold casting as your process. What is the difference between these various processes, and which one is right for you? Read on to learn more.

What Is Aluminum Die Casting?
The process of aluminum die-casting involves liquefying an aluminum alloy and forcing the molten metal into a die at high pressure. The die is a steel mold in the shape of the part you are trying to make. Once the metal is solidified, we remove the casting shot from the mold and prepare it to make the next unit. One of the big advantages of this type of metal manufacturing process is the speed with which we can prepare the machine for the next unit, which can be under a minute. This allows us to generate very high production runs.
 
What Are Permanent Mold Casting and Sand Casting?
Permanent mold castings are very similar to sand castings, with the main difference being the type of material you use to make the mold. A permanent mold is made from steel or cast iron and you can have multiple cavities for making parts, which could be important since this mold is designed to be reusable. These molds can only be used with non-ferrous metals.
 
Sand mold castings have a similar idea, except the mold is made from a sand mixture, which is broken away when the process is complete to reveal the cast part. The sand is then recycled and reused for more casting molds. While tooling costs for this type of casting are very low, it also takes a long time to set up again, so it is not ideal for short timeframes or large production runs.
 
Should I Use Aluminum Die Casting or Permanent Mold Casting/Sand Casting?
There are several advantages to using aluminum die casting over permanent mold casting or sand casting. With die casting, you get great dimensional tolerance and little post-machining. Aluminum dies casting is ideal for high volume production runs, as you can produce many parts very quickly with terrific part consistency. You can also make parts with thinner walls and smoother surfaces.

• Permanent Mold Casting

Permanent mold casting gives you a mold for multiple parts that you can use over and over again with good surface finish and dimensional accuracy. You can also use permanent mold casting for high production rates. However, you can only use non-ferrous metals with a permanent mold which is also true with die casting. Besides, the costs of making the permanent mold die are high (similar to die casting but slightly less costly) and the life of the mold is relatively short, so if you are casting parts for a long-term project, permanent mold casting is often not cost-effective. In summary, permanent mold casting features to moderate tool cost, moderate tool development, fine as-cast finish, broad alloys, medium in size & weight, heat treatable and generally moderate volume with long tool life. It also provides a good finish and better metallurgical properties throughout the casting than sand or die-casting.

• Sand Casting

Sand casting, which usually uses silica as the molding sand, but can use other types, like chromite or zircon, is great if you are looking to reduce tooling costs, as making a sand cast mold is relatively inexpensive versus a die-cast mold. It is also a great choice if you are making a lot of different types of parts with very short production runs. However, sand casting is not cost-effective per part cost for larger production runs, as it takes so long to reset the mold.
In most cases, companies that need a steady stream of very specific parts will opt for aluminum die casting. The greatest expense in aluminum die casting is the manufacture of the die itself. But once we have manufactured the die, producing many durable, complex parts in a short amount of time is relatively easy and low-cost as compared to sand or permanent mold processes. In summary, sand casting features to low too cost quick tool development, rough ad cast finish selective alloys, unlimited in size & weight, heat treatable and generally low volume.

• Die casting

High tool cost, long tool development, best as-cast finish, few alloys, small/light part size & weight, not heat treatable and generally hight volume. These parts have a nice “shell” but have a porous center, which makes them brittle as compared to other casting methods.

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CASTING METHODS TO CONSIDER

Issues to Address	​Permanent Mold	Sand Casting	​Die Casting
​Strength	A	B	C
​Surface finish	B	C	A
Complex shapes	A	A	C
Dimensional accuracy	B	C	A
Tooling or mold costs	B	A	C
Cost per part	B	C	A

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