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Castings – Part 1: An Introduction
By Mark L. Casey | August 6, 2010
Almost anything your mind can conceive of that requires a product to be cast or formed can be manufactured. We will save a discussion of plastics and other materials for later, but if your design requires a mold or die and a metal casting, you have many options. Your specific application will drive the material, but let’s do an overview of the options available for casting.
First a definition from dictionary.com:
Casting. –noun. 2. something cast; any article that has been cast in a mold.
That is general enough. Now, let’s get more specific.
Die Casting
Die casting is the process of forcing a molten metal into a mold in order to form it into a shape. The molten metal is typically forced into the mold via hydraulic pressure, and the new part is then cooled inside the mold (or tool) before it is ejected from the mold. The tool is typically a two-part mold that closes to allow the molten metal to be injected and then opens to allow the newly formed and cooled tool to be ejected.
Toolmaking is an art and a science. Tools are usually expensive because they require not only expensive base materials, but they also require precision machining in order to correctly create the end part. Some tools contain very tight tolerances as required by the customer, and some are not that critical in terms of tolerances.
Common metal alloys used in die casting are aluminum (AL), magnesium (MG), and zinc (ZN). Each of these metals have specific properties (weight, strength, thermal, etc.) that make them appropriate for certain applications.
Here is a video from the Society of Manufacturing Engineers (SME) describing the cold chamber process of die casting:
Investment Casting
Another type of casting is investment casting, a process which has been used for thousands of years.
Investment casting is a casting process in which a wastable wax pattern is layered with an investment compound which is then baked so that the investment is hardened to form a mold. The wax pattern material is then melted away leaving the investment mold. The molten alloy is then poured into the mold to form the final part. The investment material is removed via vibration or water spray leaving the final part, which is a replica of the wax pattern that began the process.A definition like this is greatly enhanced by seeing the process. To learn more, watch this excellent video from The Discovery Channel:
Sand Casting
As the name implies, sand casting is the process of producing a cast part by by pouring molten metal into sand molds. This process is typically used for parts that are low in volume and that do not have high precision and tolerance requirements.
The following silent video of the sand casting process was produced by German firm Deloro Stellite:
Conclusion
We have briefly introduced three casting approaches, each with its own application. In our next article we will explore cast iron, miniature zinc, and brass casting.
Topics: Aluminum, Contract Manufacturing, Die Casting, Electronics Manufacturing, Inventors/Inventions, Investment Casting, Manufacturing, Metals, Sand Casting, Services, Supply Chain Management | 3 Comments »
3 Responses to “Castings – Part 1: An Introduction”
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August 6th, 2010 at 9:57 am
[...] out my latest article on metal casting manufacturing over at Artful [...]
April 27th, 2011 at 3:54 pm
[...] Castings – Part 1: An Introduction [...]
April 27th, 2011 at 4:08 pm
[...] I of our Artful Sourcing series on castings can be found here. Part II of our series will be posted this week, but if you are interested in exploring die casting [...]