Developed by the Department of Energy Cast Metals Consortium program, thin wall zinc, AKA HF alloy, is an alloy created to have ultra-high fluidity properties. Fluidity is the ability of metals and alloys to flow through the gating system, filling the cavity of the casting mold and conforming to its shape. Up until now, Zamak 7 has been the go-to option when thinner walls were required. Developing HF alloy was an effort to improve upon Zamak 7’s fluidity without sacrificing its strength.
Higher fluidity materials allow us to create products with thinner walls, and therefore, less material and less weight.
Less weight means less energy:
• Energy savings in alloying and melting
• Energy savings in transportation
• Energy savings in end use and recycling
The new HF alloy is relatively easy to manufacture and maintain. Since its chemical composition does not significantly deviate from those of ZAMAK alloys, scrap HF can be re-melted with Alloys 3 and 7. This is also an advantage for zinc die casters because these thin wall capabilities make zinc more competitive in areas where it may not have been considered before.
Heat sinks are the perfect application for a thinner wall zinc. HF can produce thinner walls than aluminum alloys, and when it comes to heat sinks, many thinner pieces is most effective. Casings and enclosures for electronic devices can be made using HF. These would typically be made with Aluminum, but if they can be created with the HF alloy, the walls can be thinner and tooling costs will be smaller long term, something that can’t be said about Aluminum.
Electroplated parts would be another good application because zinc’s superior castability provides a better surface than aluminum.
More and more, decorative components call for thinner walls. HF can be made with thinner walls (.3mm) and zinc has a much better surface for finishing.
The studies done on casting fluidity have shown that increasing the aluminum portion while decreasing magnesium is the best way to increase an alloy’s fluidity. In HF alloy’s case, the Aluminum portion is between 4.3-4.7% and Magnesium is .005-.012%. Copper, iron, lead, cadmium, and tin are also added in very small amounts. The remainder of the alloy is made up of zinc.
Yes. When a design calls for especially thin walls, Brillcast engineers will determine whether or not it makes sense to make use of High Fluidity alloy.
New zinc die casting alloys developed in the Department of Energy Cast Metals Consortium program displayed much improved fluidity in laboratory tests. Such improvement in fluidity has been further confirmed in a die casting trial at Brillcast, Inc. At similar die casting conditions, a newly developed alloy demonstrated enhanced cavity fill capability and resulted in noticeable increases in sample weights in comparison to Alloy 7. Mechanical tests revealed that samples made of the new alloy exhibited higher tensile strength and lower elongation than the reported values for Alloy 7. Samples cast at more favorable cavity filling conditions, hotter die and shorter fill time, showed increased tensile strength, impact energy and elongation. Overall, however, the micro-structures and mechanical properties of samples made of Alloy 7 and the new alloy were comparable.
*An update of this research project was given by Dr. Frank Goodwin in a recent paper presented at the NADCA 111th Metal Casting Congress.