“Developments in Melting and Melting Technologies”

Nikolas Sachinopoulos Ajax Tocco International Ltd

Friday, 10 November 2017

Senior Branch Vice President Darren Pritchard, MICME, welcomed members and guests to the third branch technical lecture and then introduced Nikolas Sachinopoulos and his lecture on melting and melting technologies.

Nikolas began with an introduction to Ajax Tocco Magnethermic. They are a subsidiary of the ParkOhio Holdings Group. They design and manufacture induction heating and melting equipment for a variety of industries and applications from foundries and forges to snow melting. They offer new and reconditioned plant as well as providing upgrades, servicing, after market support and technical advice.

Moving onto the main part of the presentation Nikolas spoke of developments which had helped Ajax Tocco maintain its position as one of the leaders in this technology. He referred to 3 aspects, dual frequency, Magne-Stir and oxygen free atmospheres.

Dual frequency is a development primarily for the jobbing foundry that produces both ferrous and non-ferrous castings. It is a technology which also benefits foundries with a need for improved stirring to create greater homogeneity, or foundries who have to deal with varying qualities of scrap in their charge.

In a conventional 2 coil melting system power is divided equally between the two coils but with a Magne-Stir system power, when melting, is delivered via the bottom coil only. During holding a conventional system again shares the power between the furnace coils but with Magne-Stir the power will go in turn to the bottom and top coil. This method provides better mixing and therefore a more homogenous metal bath together with a significant saving in power usage. The stirring action created also results in less wear on the lining.

Providing an argon, or nitrogen if the metal being melted will tolerate it, atmosphere over the furnace throughout charging, melting and holding will result in low levels of hydrogen pick up and a cleaner metal due to lack of oxidation. The controlled atmosphere over an Ajax Tocco furnace will contain less than 1% oxygen ensuring these benefits are achieved.

Energy efficiency is key to reducing the cost of melting and in a typical melting system only around 65% of the input power actually goes to load. Losses occur from several sources but the biggest energy loss is via the coil, and from radiation and this is in the region of 20%. The Ajax design brings total losses down so some 80% of energy goes to load. Its achieved by having well designed lids, controlling stray magnetic fields having short bus bar runs and the use of fibre optics. Having a furnace which has been designed for best energy use must be backed up with good foundry practice otherwise the foundry is not taking full advantage. The Ajax support team can help by giving guidance on best practice. Preventative maintenance, including having the right spares to hand, is essential to getting the best results in practical and financial terms in the long term. Here again the support team are able to help.

EMF mapping was discussed further in the Q & A session which followed the presentation. Under the EMF Directive, 2013/35/EU all employers have a duty to assess the risks and provide measures to reduce any risks identified. It is a potential problem for the foundry industry particularly those operating older plant and it was recommended that guidance is sought by companies to ensure compliance.

Eddie Lindsay, Prof. MICME, gave the vote of thanks for a paper full of content, providing both information and food for thought after which the members and guests enjoyed a splendid buffet sponsored by CMF.