2/18/2024 0 Comments Too casting copper cathodeOnce the liquid copper is at the correct temperature, the furnace is tilted hydraulically to pour a controlled amount of liquid copper into a ceramic cup (see Figure 9.4.2.2). To protect the liquid copper from oxygen pick-up, a metal or ceramic cover is placed on top of the crucible, and a melt cover of nitrogen-5% hydrogen applied to the top of the liquid bath. ![]() The larger crucible size allows greater flexibility in the choice of charge material, including sheared copper cathode, high quality electrical grade copper scrap, shop run around scrap (biscuits and runners), or chopped wire rod. In this approach, a larger amount of copper is melted in the style of induction furnace shown in Figure 9.4.2.1. 9.4.2 Tilting Furnacesįor the high productivity associated with continuous production, it is recommended that a tilting furnace be used. However, if a cover gas proves necessary, a blanket of inert gas (typically nitrogen) or reducing gas (nitrogen with 5% hydrogen added) can readily be applied to the top of each crucible. Double push-up furnaces can be purchased in a range of sizes meeting the throughput required of most copper rotors.Īs the melting time used for single shot melting is very short, it may not be necessary to use a cover gas to prevent oxygen pick-up by the liquid copper. Rotors requiring a shot weight larger than 3.6 kg would simply use a bigger induction power unit to meet the targeted cycle rate (typically 2 to 2 minutes for rotor casting). During development trials, a 60kW induction power source was shown to be capable of melting 3.6 kg (8-lbs) of chopped copper rod in less than two minutes. The double push-up style of furnaces can provide the cycle rate required for rotor die-casting. Such chopped rod is often widely available around the world, and is only marginally more expensive than sheared cathode. The copper rod in the crucible shown in Figure 9.4.1.1 is approximately 12.5 mm ( -inch) diameter chopped into lengths of about 19 mm (-inch). Instead, chopped copper wire rod provides an increased surface area and better packing density, leading to more rapid melting. ![]() In an automated cell, a robot would pick-up the crucible and transfer it to the die-casting machine.ĭue to the smaller size of the crucibles used for single-shot melting, sheared cathode is not typically used as the melt stock. ![]() Figure 9.4.1.3: Double push-up furnace, showing the heated crucible in the elevated position for pouring.
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