Metal Casting Process Overview
Metal casting involves the process of pouring molten metal into a mold, and offers a simple and more affordable option when compared to subtractive manufacturing. The five basic steps of metal casting include:
- Patternmaking. The process of creating a metal casting mold with computer-assisted design systems.
- Coremaking. Most casting methods necessitate the inclusion of a core to create the interior surfaces of the component you are casting.
- Molding. Manufacturers can create molds out of many materials including sand, plaster, and metal, depending on the casting method.
- Melting and Pouring. Once the manufacturer has created the mold, they will pour or inject molten metal into it.
- Finishing. Manufacturers may need to sand or buff the completed piece.
There are many types of metal casting methods, including:
As one of the most popular options, sand casting utilizes hardened sand to create parts with complex shapes. This works with almost every alloy, and is affordable in both high and low volume runs.
This method involves drawing metal through a forming die, creating both solid and hollow parts. It is best for parts with simple structures, such as rods.
For centrifugal casting, manufacturers pour metal into a spinning die. This method is not ideal for complex, non-symmetrical parts. It works well with almost any alloy, and the rapid rotation creates an unparalleled level of material cleanliness.
Shell Mold Process
This process involves coating a metal pattern with thermally bonded sand, creating two half molds, which are pressed together. This process is highly repeatable and creates detailed parts.
Lost-Wax Investment Casting Process
Involves the process of creating metal casting molds by injected wax into a die, which is then coated in a ceramic slurry. The manufacturer will then melt the wax and pour the metal in its place. This process is perfect for prototypes and any parts requiring thin walls and smooth finishes.
Manufacturers will force molten metal into steel die molds under high pressure, creating parts free of air bubbles and discontinuities. A significant advantage of this die casting method is that it allows for versatile, high volume production runs.
This method is similar to the sand casting process, but utilizes unbonded sand and vacuum pressure. It produces little waste, and creates parts with very fine finishes.
Graphite Permanent Mold
This type of casting works best with aluminum alloys and creates precise details and a fine finish. Manufacturers will often use this method for everyday tools and household products.
Plaster molds are disposable and are only able to shape non-ferrous metals. Common products created with this method are lock components and gears. This method is also good for small volume casting.
Which Technique Should You Choose?
The appropriate metal casting method for your project depends heavily on the specifications of the part you are creating. Answering the following questions will allow you and your manufacturer to choose the best technique:
- How rapidly do you need to create your parts?
- How strong must the final part be?
- What quantity do you require?
- Are you creating a prototype or committing to a long run?
- What kind of surface finish do you require?
There are many options when it comes to metal casting, and the experts at Mardek are here to assist you in choosing the right one for your needs. Contact us today to learn more about our services or receive a quote.