The problem with overheated alloy

08/06/2014

Porosity, miscasts and rough castings are just a few of the unwanted results from alloy that has been overheated. In fact, overheating alloy during the casting process can result in numerous problems, even issues you might not be able to see until it's too late. For example it can wreak havoc in the porcelain department in the form of bubbles in opaque and a lack of proper retention between the metal and porcelain.

To further complicate matters identifying overheated alloy can sometimes be difficult. The reason is that so many of the problems associated with overheating metal can also be caused by something else. With so many possibilities how can you check if you are overheating your alloy? To start, it really needs to be identified during or directly after the casting process. Once the castings have been separated from the sprues, and the metal has been finished, all of the problems will be beneath the surface. One tip we tell technicians is to examine the edges of the button on a casting. Sharp edges, usually accompanied by flashing, can often times mean that the metal was overheated. While the buttons of alloy that has been properly heated and cast will have more rounded edges.

Here are a few ways to make sure you are not accidentally overheating your alloy. First, always follow the manufacturer’s instructions for the alloy you are casting. Just because a process works for one alloy doesn't mean it will work for another. Check the casting and burnout temperatures as the can vary widely from alloy to alloy. Second, keep your casting equipment in good condition by replacing crucibles and torch tips when needed, or if you are using an induction casting machine be sure to perform routine maintenance. Third, be careful how you judge when an alloy is ready to cast and always use your your eyes. Placing complete trust in a machine, temperature gauge or other device can lead to overheating. While we've found that some of the newer casting machines have better capabilities than others, it is still a good idea to keep your eye on things.

Regardless of what metal you are casting, or even what ceramic you are pressing, N&V's Z4 Universal Rapid Cast Investment delivers outstanding results ring after ring. Along with a great casting and pressing solution you also get access to our technical support if you should ever run into any problems. So go ahead and request a free sample of Z4 today and see what it can do for your dental lab.

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