Efficiency and speed – a win/win for IGBT technology

Building an extensive business refurbishing and upgrading second-hand furnaces from through the noughties has introduced expertise and entrepreneurship at Meltech Ltd which saw them swiftly move on to build their own coreless induction furnaces, including the development of their own invertor system. Now, 23 years later, the company has become synonymous with IGBT technology.

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Now occupying a 1,000sq mtr site, with the capability of even further expansion, the company is riding high thanks to its refinement of IGBT inverter technology and ability to offer a wide range of induction melting furnace bodies including tilting, rollover and crucible drop coil styles, plus a vast range of spare parts and service for various brands of furnace and melting equipment. Commercial director Steve Macey details the history: “We had built a very nice business refurbishing existing equipment and bringing it up to modern standards, then when Electro Magnetic field emission standards came into effect in the s, we were faced with the dilemma that the cost of rebuilding and upgrading older equipment was becoming prohibitive. So, we decided to make new furnace bodies.”

The foray into part-new machines then led to the inevitable, as Macey puts it: “We got a taste for making new stuff.” As a team of experienced electronic and mechanical engineers, the desire to find solutions to customers’ induction melting dilemmas demanded a more all-encompassing approach. Thus, by Meltech had developed their own range of induction furnace bodies which were branded as Mag-Melt, an abbreviation for magnetic melting. Soon after the company ventured into IGBT inverter technology. “We learned pretty quickly that this technology was noticeably faster and more efficient,” Macey explains. “By we had developed our first IGBT invertor which was out for trial at Yeovil Precision Castings (now Tritech UK). When we accessed the performance data, we discovered it was significantly better than previous systems. Melt time was significantly reduced, as was energy consumption. We then went on to sell more.”

REMOTE MONITORING

There then followed constant product development with bigger machines being built up to 750kW power rating. Extra functionalities were also incorporated with constant software improvements. Auto sinter, interconnectivity, data download and monitoring, fault finding – all able to be accessed remotely using portable devices. “Basically, we have made the system totally flexible,” Macey says. “The software lives with the machine and always evolves thanks to the upgrades we undertake as we service each machine, essentially the system or its software never becomes obsolete.” The extension to the life of machines has been a real bonus for customers and has enabled Meltech to grow the business, as has the adoption of digitised control which has further extended the flexibility of the furnaces.

The move into digital technology and remote monitoring has been an ongoing trend in recent years and this is very much a part of standard thinking now. The equipment and software has been designed for ease of detection and solution. Macey says: “Everything the machine is doing is being measured constantly. There are multiple sensors which are constantly monitoring and displaying the system conditions, in the event of a fault, pressing the HMI indicator brings up the relevant page on the digital manual and suggests possible causes and solutions. There is also a detailed alarm history on the machine, both can be analysed online and by USB backup. We and the customer can access the machine remotely from anywhere in the world, we can advise how to fix a problem or we can initiate a call-out.”

INTEGRATED SYSTEM

Having mastered the melting technology, the next step has been integrating into the auxiliary equipment such as PLC control and water cooling systems. “The inverter now talks directly to the water cooling PLC,” Macey explains. “Everything on the system – temperature, overrun times, settings – are all set up and run from the HMI on the inverter. It also controls the water cooler with individual controls for every single fan – this means that you only run the individual fans that you need, rather than having pairs or triple sets running. It’s such a bonus in terms of energy efficiency.”

Efficiency is very much the order of the day and another tweak to original thought process that aids this is the use of magnetic shunts in each furnace body. Instead of butting up against the induction coil, In smaller furnaces Meltech advocates pushing the shunts away from the coil in order to reduce magnetic field density and enable the furnace to run cooler, another advantage is that there is a significant reduction in the use of insulators which reduces the chance of coil arcing whist making maintenance simpler and quicker.

“Our systems consume less energy than equivalent SCR or thyrister driven induction furnaces,” Macey says. “It’s all about melting for less cost and less energy.”

Macey puts the company’s success down to their many years of working with a range of furnaces and customer requirements plus their adoption of IGBT technology which, he says has been widely adopted elsewhere. “In other industries, IGBT’s have wiped out SCR technology as a switching device. For example, all electric vehicles are IGBT driven along with almost all AC motor drives. SCR’s have been superseded by IGBT transistors in most industries.

“In terms of our product lines, below 750kW most mainstream melting tends to be IGBT although higher power systems are in development right now.” This transformation has been a positive for Meltech, having got on board with the technology early on it has seen a decline on the company’s original primary business. “Up until eight years ago we were the foremost supplier of rebuilt furnaces in Europe, but as IGBT sets were introduced customers were given a compelling choice to make, at double the cost of a rebuilt second hand machine, an IGBT system could pay back that difference in less than three years in reduced energy costs, furthermore UK tax incentives introduced for capital equipment purchases during and after Covid, have enabled foundries to invest in the latest melting technology, and we are thankful for that.”

The company also still houses an extensive spare parts facility, carrying parts for a wide range of their own and competitor equipment and operates an easy to use spare parts online catalogue. Indeed, such has been the demand for new furnace technology that the company has expanded into the full 1,000sq mtr of its site in Haverhill, Suffolk (UK), including extra production and administration space, a new boardroom and increased test room facilities.

MODULAR INSTALLATIONS

In recent years, Meltech has become particularly experienced in the provision of modular systems, where platforms are part of the installation. Furnaces are pre-assembled in the Meltech factory, then dismantled, transported and re-assembled at customer’s sites as a modular install – an overall design that has been embraced by many customers requiring a quick installation. Andrew Drage, sales manager, says repeat orders are now a significant part of the company’s business. “Around half of our orders now come as a result of the customer buying their first Pulsar IGBT then realising the benefits, decide to replace their other SCR’ sets.” he says.

Back in early Archibald Young Ltd invested in a brand new Meltech induction melting system to replace a now unreliable machine which dated back to the s, the new furnace comprised of 150Kw Pulsar IGBT Inverter with a twin crucible body drop coil arrangement at 100kg and 200kg capacities. As managing director Andrew Young explains: “The technology offered with this system was a departure from the existing equipment and the benefits were quickly felt with an improved efficiency and shorter melt time. So much so, when deciding to invest in new furnaces at our subsidiary company, Peel Jones Copper Products Ltd, the purchasing decision was an easy one and we installed another Pulsar IGBT Inverter, this time with two off 500kg fixed body tilting units”.

Andrew Drage says: “We are also known for special products such as carousel furnaces, Pre Tilt systems for accurate pouring and of course our IGBT power share where a single control panel feeds two furnaces simultaneously. This is a recent development for us, and I am not aware if any other company does this with a series driven IGBT inverter.” From humble beginnings to cutting edge technology, Meltech has invested in an efficient and controllable future for induction melting needs and continues to grow the business to support its extensive customer base.

Contact: Andrew Drage, sales manager, Meltech Ltd, : + 44 (0) , : [ protected] web: www.induction-furnaces.com

IGBT

Used as switching devices in the inverter circuit – for DC to AC conversion – for driving small to large motors, IGBT is considered an option to improve efficiency. With lower on-state resistance and conduction losses, and an ability to switch high voltages at high frequencies without damage, IGBT is ideal for driving inductive loads such as coil windings, electromagnets and DC motors.

Andrew Drage, sales manager at Meltech explains why the company’s Pulsar IGBT inverters have been making a difference in recent years. “The IGBT technology is all about efficiency and speed, with some installations having shown savings of up to 30 per cent via improvements in energy consumption and melt times. The Pulsar inverter is a thoroughbred IGBT series inverter, so it offers better efficiency like for like than other traditional SCR or thyristor driven system. The Pulsar IGBT can connect directly to a standard distribution transformer to drive all makes and types of induction furnace body.

“During customer installations, there have been instances where melt times have been reduced from 90 minutes to 55 minutes. While the performance exhibited during the melting and holding cycle has in certain circumstances reduced energy consumption to give the customer a very tangible cost saving and payback. One customer noted a decrease in power consumption from 125 to 60kW during their holding cycle.”

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Electric aluminum furnace: deep integration of technological innovation and industrial application

As the "silver blood" of modern industry, the innovation of aluminum smelting technology directly promotes the progress of aerospace, automobile manufacturing, electronics industry and other fields. With its high efficiency, environmental protection and precision, electric aluminum furnace is gradually replacing traditional gas furnace and becoming the core equipment in the field of aluminum processing. This article will analyze how this technology reshapes the ecological pattern of the aluminum industry from the dimensions of technical principles, equipment structure, process advantages and future trends.

1. Technical principles of electric aluminum furnace

The core of electric aluminum furnace is to efficiently convert electrical energy into thermal energy, and its technical route is mainly divided into two categories: resistance heating and induction heating.

1. Principle of resistance heating

The resistance electric furnace converts electrical energy into radiant heat through high-resistance alloy heating elements (such as silicon carbide) and directly acts on aluminum materials. Taking Schaefer Group's wet bath electric furnace as an example, its silicon carbon rod element only requires 0.20-0.23 kWh of electricity per pound of aluminum, and the cold start efficiency is 30% higher than that of traditional furnaces.

2. Induction heating principle

The induction furnace is based on the electromagnetic induction effect: the alternating current generates a high-frequency magnetic field through the coil, and the aluminum material generates heat due to the eddy current effect and resistance loss. For example, the 5-ton induction furnace of APS uses a 1.8kHz medium-frequency power supply with a penetration depth of about 5mm, combined with electromagnetic stirring technology to ensure uniform composition of the molten pool and reduce the metal oxidation rate to less than 0.5%.

2. Equipment structure and key technologies

The modular design of modern electric aluminum furnaces takes into account efficiency and flexibility. Its core components include:

1. Power supply system
IGBT inverter technology has become the mainstream, and compared with traditional thyristors, the power conversion efficiency is increased by 15%-20%. For example, the IGBT induction furnace of a manufacturer in Shandong adopts a dual three-phase 12-pulse design with a power factor of 0.95 and an energy consumption of ≤520kWh per ton of aluminum.

2. Furnace lining material
Multi-layer composite refractory materials are the key. The inner layer usually uses alumina-silicon carbide composite materials with a temperature resistance of ℃. The aluminum borate lining developed by ABP in Germany has a 40% higher corrosion resistance and a service life of more than 300 furnaces.

3. Tilting mechanism
The hydraulic servo system achieves 0-95° precise flipping, with an angle error of <0.1°. With the splash guard design, the metal liquid transfer loss rate is <0.3%. The hydraulic tilting furnace of Kalyani in India adopts dual pump control, and the pouring speed can be adjusted in the range of 1-5kg/s.

4. Intelligent control system
Integrates infrared temperature measurement, vacuum degassing and composition analysis modules. Thermtronix's Fleet Commander system supports PLC control, and the 7-day timed preheating function can reduce startup energy consumption by 18%.

III. Process advantages and industrial value

The electric aluminum furnace shows multiple advantages in terms of efficiency, environmental protection and quality:

1. Energy efficiency revolution
The thermal efficiency of the induction furnace reaches 65%-85%, far exceeding the 30%-55% of the gas furnace. The DC- electric furnace of Rayteq Company in the United States melts 1,000 pounds of aluminum per hour, with a unit energy consumption 40% lower than that of traditional furnaces, and an annual reduction of 460 tons of CO₂.

2. Improved metal quality
Vacuum melting technology can control the oxygen content of aluminum liquid to below 10ppm. Patent CNA shows that after adding rare elements such as scandium (Sc) and tantalum (Ta), the tensile strength of aluminum alloy wire is increased to 250MPa, and the conductivity remains at 62%IACS.

3. Contribution to the circular economy
Electric furnaces are highly compatible with scrap aluminum, with a melting loss rate of <1%. A recycled aluminum company in Jiangxi uses a 10-ton induction furnace to process 32,000 tons of electronic waste annually, with a metal recovery rate of over 98%.

IV. Technical Challenges and Innovation Directions
Despite its significant advantages, electric aluminum furnaces still need to break through the following bottlenecks:

1. Lining Life Optimization
Lining cracks caused by aluminum liquid penetration are still a problem. The nano-coating technology developed by QIT forms an Al₂O₃-TiC composite layer on the surface of the lining through vapor deposition, which improves the anti-permeability by 50%.

2. Intelligent Upgrade
Digital twin technology has begun to be applied to smelting process simulation. For example, Elka Mehr Kimiya implanted AI algorithms into the control system to predict the flow state of the molten pool in real time, reducing the defect rate by 12%.

3. Zero Carbon Exploration
Swiss ABB tested photovoltaic direct-drive electric furnaces, combined with molten salt energy storage systems, to achieve zero-carbon smelting in off-grid conditions. Preliminary data show that carbon emissions per ton of aluminum can be reduced by 85%.

V. Future Trends and Industry Impact
The evolution of electric aluminum furnaces presents three major trends:

- Distributed manufacturing: containerized small furnaces (such as the Rayteq DT series) support on-site smelting and reduce metal transportation losses.

- Material genome engineering: High-throughput computing accelerates the development of new refractory materials. The U.S. Department of Energy plans to increase the life of furnace linings to 500 furnaces by .

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