Molten Metal Filter Boxes (typically utilizing ceramic foam filters) allow for superior quality die-casted aluminum components. For applications requiring high quality die-cast parts/components, it is integral to remove all possible contaminants from the aluminum prior to completing the casting process.
New Century Heaters has engineered our immersion heaters specifically for molten metal. For more information our Immersion Heaters, contact us.
Aluminum casted parts with inclusions present can suffer from structural issues that will be discussed in detail. Additionally, if further modification to the casted parts is required such as extruding, rolling, and forging, aluminum part failure due to inclusions can compound the efficiency and profitability of the entire manufacturing process if components fail or need to be rejected.
Die-Casted Rolled/Extruded/Forged Components
In the die-casting process there are generally three basic methods to mechanically remove inclusions (impurities) from the molten metal which are sedimentation, flotation, and positive filtration.
The majority of these impurities come from the following sources:
- Aluminum oxide that is “drawn in” from the surface of the molten aluminum
- Fragments that become “loose” from the actual furnace lining and other components and become mixed within the aluminum
- Other insoluble impurities that are present (intermetallics, borides, carbides, chlorides, etc)
Focusing on positive filtration, two commonly used historical methods to filter molten aluminum are: “glass cloth screen filtration” and ‘deep bed filtration’ which uses “alumina particles/balls. A downside to glass cloth filtration is that it only removes the larger inclusions, and can easily be broken as the glass fibers become weak during exposure to the molten aluminum temperatures. Deep bed filtration also has the downside of passing solid inclusions through and can be difficult to maintain a proper filtration level as the “pore size” of the filter changes continuously over time during usage.
Ceramic foam filters have been designed consisting of a web of ceramic comprised of an open-cell structure and contain “voids” that the aluminum can pass through while molten.
Aluminum casted parts without proper filtering can suffer from diminished ductility, tensile strength, and a lower-quality finish appearance.
Properly filtered aluminum casting will also improve the productivity of the casting process as casting time can be decreased, and well as increasing the casting yield.
Contact NCH for our full immersion heater catalog, based on your specific requirements and application we will work with you to find the optimal solution.