Every automobile manufacturer has made it clear to their metal casting suppliers: reducing vehicle weight is increasingly important. Besides solid castings, hollow casting, a variation on the permanent mold process, is an option for producing complex lightweight structures. It can produce individual components that replace an assembly of metal parts, saving weight and handling costs. Weight reductions of up to 40% are possible.
Moreover, parts cast using Kurtz low-pressure casting technology can achieve significant mechanical values. Depending on the part design and casting recipe, low-pressure die cast parts can achieve a yield-strength of more than 260 MPa; ultimate tensile strength of more than 340 MPa; and an elongation of more than 12%. With these values, safety-critical automotive parts such as knuckles, control arms, or subframes can be redesigned to reduce material. Along with the additional possibility of using sand cores, they can be made even lighter by hollow casting.
In order to make this process economical for the high-volume automotive industry it became faster. Kurtz realized this among other measures by increasing the size of the low-pressure die casting machine to make multiple parts casting possible. Furnaces between 2,000- and 3,300-kg capacity have become standard for Kurtz. Large furnaces make it possible to use multiple feed tubes at large distances and casting boxes are avoided. Direct gating improves yield, increases quality and saves operational costs.
Additionally, the casting process had to become quicker. By means of sophisticated cooling units the casting cycle will be reduced and at the same time quality of the finished parts be improved. Larger machines are designed from 48 cooling circuits, and often may have more than 100 circuits. In cooling, besides air and mix, the trend is clearly going toward water.
The overall result: the foundry customers are able to successfully cast with Kurtz eight knuckles at once in less than three minutes. n
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