One-ton Inductotherm coreless induction furnace installed.
The heart of every foundry is the melting platform and the furnaces that it uses to melt its metal. These furnaces use different technologies to melt the material and the technology used is dependent on a number of factors. However, the aim of every furnace manufacturer must be to manufacture a product that will consume as little heat and fuel as possible. Today foundry owners, when deciding to invest in new equipment, particularly in the melting department, need to take into account that they need to reduce emissions to achieve environmental compliance, achieve quality improvements, reduce direct costs and enhance its safety incident awareness accordance.
“For many foundries, the largest energy and resultant cost savings can be realised by replacing their current melting equipment with equipment that is more productive and energy efficient. But whether or not you are ready to make that investment, you should investigate operational changes that may also produce significant cuts in your power use. Many of these can be made at little or no cost,” said Grant Estman, Managing Director at Viking Foundry.
“We have been looking for ways to improve our melting, casting and finishing processes while at the same time decreasing our energy usage. Just under three years ago we invested in a new shotblast machine and then we brought some discipline and order into our whole operation by implementing ISO9001:2015.”
Cerefco has recently completed the commissioning and start-up of an Inductotherm 900kW VIP Power-Trak Li Power and Control System at Viking Foundry
“We then determined that one of the best ways to accomplish both of those goals was to replace our old reverberatory and underperforming furnaces from the 1970s with modern high-efficiency units.”
“By examining a typical melt shop and its energy usage you will find that melting represents the highest percentage of energy consumption in a foundry. Melting typically accounts for over 50% of the overall foundry energy usage and this figure could go up to 80% depending on the foundry’s efficiencies. Therefore, the melt shop offers the best opportunity for energy demand and usage cost reduction.”
Questions in advance
“When purchasing a melting furnace, several factors must be taken into account. Foundries must clarify which alloys are to be melted in the furnace and what their melting point is, what quantity of metal is to be melted and how high the required melting capacity is, is the installation and operation of the furnace economical and which environmental and disposal requirements have to be considered?”
Selection of the most suitable furnace technology
“The second step is to select a melting furnace. Metal casting equipment manufacturers use a wide variety of furnace technologies. Equally foundries need furnaces that can produce metal alloys and additives in a wide variety of casting qualities.”
Metal yield
“Metal weight loss during melting represents an immediate financial loss for the foundry. An increased metal yield of the melting furnace, on the contrary, means shorter periods for return on investment (ROI) and therefore represents an important investment criterion.”
“Optimising your metal melting system to reach the lowest possible kilowatts (kW) and kVA of demand as part of your overall energy management programme is critical to competitiveness in an industry where energy costs are a constant concern. The importance of melt shop power supply utilisation, efficiency and performance, and how it impacts power demand should be examined carefully. It directly influences the connected kW or kVA of demand for a given production rate. By increasing your melt shop power utilisation rate you will increase and maximise the volume of metal poured per kW and kVA of demand. There are various ways that you can review these factors within your own foundry to find additional opportunities for conserving melt shop energy demand and usage.”
Environment
“Environmental impact and use of energy and materials are relevant topics in companies. To achieve energy savings and enhance environmental performance, managers can invest in technologies (technical measures) and/or implement management practices (low-cost and non-technical measures).”
Linking cost to performance keeps technology advancing
“For equipment and consumable suppliers, linking cost to performance keeps technology advancing if they are serious about being in the business. Therefore there should be no difference in the foundries. For far too long, and I am also guilty, owners try to maximise the life of their equipment and in most cases to the detriment of their business.”
“They say that the two principal cost drivers in the production of liquid metal are metal loss and energy consumption. When considered over the service life of a melting furnace, these factors are responsible for up to 95% of the overall costs,” explained Estman.
“To address the specific concerns of foundries, OEMs are regularly introducing new furnace models. So it is not an easy decision to make when you want to purchase a new coreless induction furnace.”
Induction furnaces
“As the name implies, these furnaces use induction technology with alternating electric currents to achieve the required melting temperature of the metal. Induction furnaces are widely used in foundries because they are high quality, easy to operate and energy efficient. A further advantage of this type of furnace is that it can melt both small quantities of less than 1kg up as well as larger volumes of up to 100 tons.”
“A coreless induction furnace is essentially a refractory-lined vessel surrounded by an electrically energised, current-carrying, water-cooled copper coil. Electrical current in the coil induces an electromagnetic field, which magnetically ‘couples’ with the magnetic charge, producing electrical current within the charge itself. Each piece of metallic charge has its own internal resistance that, when energised by these internal currents, will heat up and eventually melt. The resulting magnetic field in the molten metal causes a stirring action, thus ensuring a homogenous liquid mass.”
The system includes a one-ton Dura-Line melting furnace, which has already been commissioned, and a two-ton furnace that will be connected later this year
“In all coreless induction furnaces, there is an ‘ideal’ refractory wall thickness, carefully calculated by the furnace manufacturers for optimal melting performance. This calculation includes safety considerations, electrical characteristics of the coil, metallic charge resistance / electrical conductivity, structural and refractory considerations, operational constraints and production needs. When the furnace melt diameter is reduced by build-up, the melting process efficiency becomes compromised. The result is a reduction in the per cent power utilisation and energy consumption increases.”
Inductotherm VIP Power-Trak and Dura-Line melting furnaces
Cerefco has recently completed the commissioning and start-up of an Inductotherm 900kW VIP Power-Trak Li Power and Control System. The system includes a one-ton Dura-Line melting furnace, which has already been commissioned, and a two-ton furnace that will be connected later this year.
In its standard configuration, Inductotherm VIP power supply units include an intelligent digital control board with fibre-optic connectors for clear signal processing, a bright LED panel system information display and an integral keypad for control and information display entry. All control board functions can be configured via the keypad.
“The VIP power supply units have one of the fastest melt rates from cold charge to pour, and melt more per kWh and kVA for lower melting costs and greater productivity.”
“Induction melting holds many benefits for foundries over the traditional fossil-fuel furnace. Prinicipally, in the ferrous trade, it enables high-alloy irons and steels to be melted quickly and efficiently in small or large batches. Therefore the degree of control is superior to other melting equipment.”
“Furthermore, the furnaces are compact, as well as operator- and environment-friendly, compared to fossil fuels.”
For further details contact Viking Foundry on TEL: 011 873 5093 or visit www.vikingfdy.co.za or Cerefco on TEL: 011 845 3253 or visit www.cerefco.co.za or www.inductotherm.com
