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| April 2009 | Courtesy of BEGO USA |
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Watch Your Speed When Casting One critical factor that many technicians overlook when torch casting, is the specific gravity or density. The density of the alloy is the most important consideration to keep in mind when determining how many turns to wind your casting arm. If you were to take two equal size pieces of alloy, a high noble alloy and a non-precious alloy, the noble alloy would weigh more on a scale. One could also say the specific gravity or density of the noble alloy is greater. Why is this important? When casting a heavier alloy (like gold) at a faster speed, it may hit the casting ring too hard and break down the investment or penetrate right into the investment wall. The result is a rough casting surface and extra finishing time. When casting lower density alloys (like non-precious or high palladium) and not enough speed is used with the casting arm, the results will often be a short casting. Lower density alloys have a tendency to be sluggish and not flow very well. Each broken arm casting machine arm is different. Test castings will help fine tune your correct speeds for different alloys. Example: if you use 5 turns for your NP alloys you may want to use 2 or 2 1/2 turns for your Type III or IV Gold alloys. Refer to the physical properties chart in the alloy instructions and remember the larger the density the fewer number of turns for the casting arm. |  Flashing was caused by the heavier, denser gold alloy cracking the investment during casting.  Too low of a casting force could be a reason for short castings. |
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 For more information, call your local dealer or BEGO USA, 1.800.342.2346 www.begousa.com | |
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