Simple Solutions That Work! Issue 6

The following is an example of how an automated and integrated system for melting and furnace charging offered significant improvements, both in production and with regard to data logging over the system it replaced. A continuous casting foundry decided that it was time to replace one of two old 6 ton per hour electric furnaces with a new 7 metric ton per hour unit. The existing 6 TPH furnaces were both manually controlled and poured, via launder system, into a continuous casting machine producing cast bar. The new furnace, with a much faster melting rate was to be the primary metler with the remaining 6 TPH furnace to be used as an emergency back-up should the need arise. The original furnaces were mounted on a melting deck approximately 20 feet above the ground and were charged by hand with the charge material being lifting from the ground to the melt deck by an overhead crane. The charge material comprised of brass briquettes, brass swarf and general brass scrap. The furnace charging process was slow and labor intensive. This combined with the achievable melt rate was causing a bottleneck on the production. There were also reliability issues with one of the furnaces due to its age and general condition. So that replacement rather than a complete overhaul was decided to be a better solution. As part of the project, it was decided to install a new Acetarc charging system to match the melting rate of the new furnace. Neither the existing furnaces, nor the manual charging process had any way of giving any data feedback on the through put of scrap or the amount of metal poured. These were all issues that were addressed with the new equipment The new furnace and our charging system were to be fully automatic in operation and were to be integrated into the foundry’s data collection and control system. This monitored both the furnace and the charging system, automatically controlling the furnace melting cycle with the intention of removing operator variables, limiting slag build up and maximizing energy use. The charging system was directly controlled by the new furnace so that the scrap feed rate exactly matched the requirements of the furnace. In addition to fully automatic operation, the charging system could also be switched to manual operation for when the charging system was to be used with the remaining 6 TPH furnace and for maintenance. Our charging system comprised of a vibratory feeder at ground level with a large capacity storage hopper. The charge material was loaded using a JCB and transported to a melt deck storage hopper, located 20 feet above ground level via a skip bucket. The skip bucket incorporated weighing, and controlled the amount of scrap loaded into it via the ground level vibratory feeder. The skip bucket emptied into the melt deck hopper, which also incorporated weighing so that when this hopper was full it stopped the skip bucket cycle. The melt deck hopper emptied into a second static vibratory feeder that, when in automatic operation, was directly controlled by the new furnace with the feed rate set by the furnace. This second static feeder discharged into a vibratory feeder mounted on a swivel frame. The swivel frame enabling the feeder to be discharged into either of the two furnaces. When the discharge feeder was set to discharge into the original 6 TPH furnace operation switched to manual. The result… Since the equipment was installed and commissioned in 2013, it has been in full production. The foundry reports that production has significantly increased, both due to the increased melting rate of the new furnace and the ability of the charging system to keep the furnace supplied. The foundry also now accurately knows how much scrap material is being fed through the system and how much molten metal is being produced. Energy costs have been significantly reduced through more efficient operation. The working environment has been improved and virtually all of the manual handling associated with the old charging system has been eliminated. Contact: STEVE HARKER [email protected] 19