First phase of melting strategy completed at Thomas Foundry

For melt shops using induction equipment optimising melting cost-per-ton starts with minimising kW and kVA demand. However, to minimise exposure to the high-power rates, these melt shops should optimise operating and maintenance practices and evaluate the equipment and generator systems in use, so they too are being optimised.

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).

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.

The melting platform where the new Inductotherm one ton induction furnace has been installed. The new furnace has been supplied and installed by Cerefco

For many foundries, the largest energy 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.

“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,” said Thomas Foundry CEO Clayton Anderson.

“It was not hard for us to make decisions. We needed to replace our 30-year-old plus furnaces that had served us well over the years but had reached a stage where they were no longer economically viable. Added to the equation was sourcing OEM spares to keep them operating is a real difficulty,” said Anderson.

“The risk-management perspective and the shear frustration from the staff had also reached its maximum tolerance. And, at the end of the day, the good quality of the castings that we pride ourselves on manufacturing was being called into question.”

Other restrictions
“We had reached a stage where the smallest size furnace that was in use had a three ton capacity. This limited us in a number of ways with the biggest impact being when we were called to cast smaller size castings or a smaller amount of castings. For example, if we only had a total weight of one ton of metal to pour it was not viable to heat up three tons of metal. So the castings had to wait until we got in other orders to cover the other two tons of metal and this would stretch out our lead times. With longer lead times you are not going to score brownie points with clients who always want their castings today even though they only give you the order tomorrow.”

“Having to maximise our furnace capacity also presented its challenges when running trials for new clients or new components for existing clients. Again the lead times were a problem because again we had to fill the furnace capacity.”

“Then there was the time it took to get the metal up to optimal melting temperature as well as the co-ordination and timing between the melting department and the moulding teams. If you encounter a problem with a mould you could have metal stewing in a furnace, which does not make the melting guys happy, notably if it is close to the end of a shift. So yes our management of metal pouring was not ideal especially if you consider that one of our old five ton furnaces could take five hours for the charging and pouring processes.”

New Inductotherm furnaces
“In order to maximise your achievable production for demand, it is important that your melt system has the ability to pull full power throughout the entire melt cycle. We all know that all of us in South Africa – companies and individuals – are severely hampered with a number of challenging situations, nothing more so than with the lack of dependable electricity supply. If you get stuck with the power going off halfway through a melt it can be costly.”

“We had to take into account all these challenges when deciding on our mix of furnaces with an emphasis on reducing electricity consumption metal melting and holding times, improving our casting quality, environmental compliance and productivity and reducing maintenance costs.”

“Although, efficiency, higher power utilisation and lower costs of operation have been our primary concern another big consideration for us to include was to enhance our flexibility when it came to pouring and the amount of metal used. We did not want to exasperate or duplicate the situation that we have had for the last 30 years.”

The new Inductotherm one ton induction furnace body has been fitted with an extraction hood to comply with environmental regulations

“Last year we ordered four furnace systems from Inductotherm and they arrived in September 2020. These included two six ton furnaces that will eventually replace our two five ton furnaces, a ton furnace and a 500kg furnace. Although they have essentially been purchased to replace ageing equipment, once all installed, they will give us an extra 2.5 ton capacity.”

“The first to be installed, which is now fully functional, is the one ton system. A new platform has been constructed alongside an existing platform that houses a 3.5 ton Inductotherm furnace. Civils are currently in progress so we can install the 500kg furnace and once operational it will give us real flexibility in the smaller size casting market.”

Six ton furnaces
“The two new Inductotherm furnaces will only be installed later this year once we have all our operational plans in place. Installing these melting systems is a major project and we have gained a lot of experience installing the smaller systems first, which we can carry over to the bigger systems.”

“What we are looking forward to with the bigger furnaces is again the huge reduction in charge time – from five hours down to one hour – and the new platforms that will house them will afford us crane access that we have never had.”

“In the short-term we are going to have excess capacity – we will not decommission the existing furnaces until the new ones are fully functional.”

“When we look at what we can achieve with this new equipment in the near future we realise that our melt shop performance and power utilisation was dismal. Although, we have spent a sizable amount on capital equipment the savings we are going to make will afford us the opportunity to spend in other areas of the foundry.”

For further details contact Thomas Foundry on TEL: 011 873 3200 or visit www.thomasfoundry.co.za