Melting

All foundry operations are centered on the aspect of energy saving. Every process, be it minute, complicated and tedious, has to be cost effective and reduce energy levels. This increases the importance of melting as an important cog in the foundry machinery. Energy savings in terms of procedures, equipment, human resources and raw materials is crucial to the scale and level of profit and production in a foundry.

Energy can be saved in myriad ways during the process of melting. One has to look at the operatives of safety, cost and preheating. All these simple processes and equipment combine to save energy earning the foundry a huge profit in the long run.

Preheating of the charge is a sure way of saving energy. It is safe and cost effective. Preheating actually increases efficiency by decreasing the amount of energy required inside the furnace. This makes melting process faster and easier. The melting procedure also comes out dry and non-greasy for the worker. Usually, the gases emitted during g preheating are used for melting. This ultimately cuts into cost figures.

Proper selection and installation of the burners inside the furnace also cuts energy levels. Correct installation techniques of the burners ensure energy efficiency. The gas burnt is used to create high turbulence which in turn completely burns up all the fuel resulting in fast and full heat transfer. This naturally allows the furnace to use up a less amount of energy to melt. This could not have been possible if the burners were installed in the wrong location or were flexible in nature. The time when the burners are lit also determines the amount of energy spent or saved. In fuel melting furnaces of the manual traditional type, one burner has to be turned off during the initial stage of melting.

Furnaces have to be adequately insulated to prevent excessive heat loss due to radiation. It is extremely essential to reduce the level of radiation to minimal to have efficient furnace melting. In addition, heat can also escape from the furnace if it is not properly maintained. Maintenance includes proper enclosures around the furnace area. Radiation can be effectively controlled by following a few basic steps of damage control and prevention.

• checking regularly the insulation coverage in a furnace
• ensuring that the furnace is not missing any doors, tubes, pipes or blackened covers
• replacing the furnace tube lining with low density having low thermal conducive material
• Making sure the furnace surface is lined with ceramic fiber to reduce heat transmission
• Making sure that there is no air leakage by installing a thermograph for checking insulation levels
• Ensuring that the furnace enclosure is flanked by low temperature or LT boards, high-density brick or castables

Energy is duly preserved inside a furnace enclosure provided there are effective and vigorous control and monitoring systems in place. These usually include the inbuilt features of PLCs inside the furnace to control the temperature of the molten metal. Other control devices constitute zirconia-based oxygen probes inside the furnace to drastically reduce levels of energy consumption. Monitoring controls of oxygen trim equipment coupled with stack gas analyzers also contribute to the worthy cause. In addition, foundries also extensively use flue stack damper control systems. These devices help to maintain and control scale and level of desired temperature and pressure inside the furnace chamber. The usage of computerized control and monitoring equipment makes it easier, convenient and simpler to save energy without loosing out on time and manpower.

Modern electric furnaces have low combustion levels with quicker melting periods. In other words, electric furnaces are vastly preferred due to their energy saving attributes. These furnaces are generally made of iron and its various alloys. Electric furnaces have low thermal aptitude calling for no radiation at all. The common electric furnaces used in foundries today usually come equipped with electrical resisters, heat conduction qualities and adequate induction virtues.

Electric arc furnaces are comprised of iron with supplies of gray, ductile and stainless steel iron. The arc furnaces require high voltage supply coupled with metering and demand controlling equipment. This ensures that the furnace never crosses its limit in terms of temperature, pressure and metal supply. Specifically, the arc furnace uses an approximate amount of energy equaling to 550kWh.

• Proper installation and location of grounding straps and rods at the bottom of the furnace so that they remain immobile at all times
• Continuous stream of power supply with ample and proper distribution channels throughout the furnace. At no time should power be centered at a single location
• Controlling and maintenance of the power supply to all levels
• Regulation and installation of proper operation or functional procedures including the speed of arc control and rotation. There should be proper human resource management of the heat supplied in the furnace with time allotted to delays, procedural failures and equipment failures.

The very foundation of a foundry rests on energy saving methods. Energy consumption due to irregular furnace equipment and structural faults has to be strictly abhorred. Proper melting procedures go a long way in ensuring adequate pouring and casting procedures. So, the next time you try your hand at melting wax at home, just think a second about energy saving methods.