The ES-Automobilguss foundry has committed an investment volume of EUR 10 million to the current modernization of its production facilities. The primary goal is to expand its portfolio of casting materials, with maximum cost efficiency in production to be achieved in line with state-of-the-art technology. First steps included the partial upgrade by OTTO JUNKER of a pouring furnace dating back from the early 1970s. The outcome impressively demonstrates that even fairly modest measures can exert a large effect. A significant reduction in rejects, costs and maintenance needs was accomplished.
Since the mid-1990s, ES-Automobilguss GmbH – a foundry with a long tradition based at Schönheide in the Ore Mountains region of Germany – has been earning renown as a specialist producer of differential housings made of blackheart malleable cast iron. Automotive manufacturing groups such as VW and Renault have placed their trust in castings sourced from this foundry, which has been in operation continuously for 450 years. At the customer's request, ES-Automobilguss can supply its products directly to the assembly line, ready for mounting – turned, milled and ground. Even patternmaking is an in-house activity at Schönheide; starting from just a set of drawings, the company can handle the entire casting design.
No longer in fashion: blackheart malleable cast iron
Until 2016, ES-Automobilguss enjoyed good years as a supplier to the automotive industry. Then, it had to pay the price for its strong focus, over the past 20 years, on one casting material and branch of industry.
"It became difficult for us because blackheart malleable iron just fell out of fashion. Everybody now wants ductile iron castings. Young engineers often don't even know malleable iron any more", explains Marcel Tröger, Development Project Manager at ES-Automobilguss. Although he is positive that the material continues to be perfectly suitable for differential housings, it was clear to him and his team that there existed only one way out of the crisis. The company had to invest in technology while expanding its material and product range. "This is going to give us a more broad-based market presence and will enable us quickly to fulfil many customer demands.”
The path of reason: expanding the portfolio
In April 2018, Marcel Tröger and his team submitted their plans for safeguarding the foundry's future to the Prevent Group. They managed to convince their investor. With a budget of EUR 10 million, the groundwork for mastering tomorrow's challenges is now to be laid by September 2019. Marcel Tröger views the future role of ES-Automobilguss as that of a jobbing foundry producing small lot sizes from diverse casting materials including blackheart and whiteheart malleable cast iron as well as ductile cast iron. He sees potential customers in the construction, scaffolding and agricultural industries and manufacturers of sanitary fittings.
"In order to minimize investment costs in the initial phase, we went for the path of reason. Our aim is to upgrade existing machinery and equipment wherever possible and practical", explains Mr.Tröger. He adds that the primary target now consists in gaining the ability to effectively produce the new portfolio.
Partial modernization yields state-of-the-art technology
One successful example of how a mere partial upgrade can deliver impressive results is the pouring furnace on the No. 2 casting line. The basic vessel, inductor and control system of this Inducal siphon-type channel furnace from the early 1970s have been preserved in their original form.
"Little over 10 years ago, the tap changing circuit for the inductor was modernized by OTTO JUNKER", reports Marcel Tröger. But along with the installation of a new DISA moulding line, the peripheral foundry equipment was to be upgraded to cutting-edge standard as well. "OTTO JUNKER knows our furnaces, so it was clear that we would work together on this again", Mr. Tröger adds.
The centerpiece of the renovation was the metering unit, or rather the task of delivering an accurately controlled amount of melt into each mould. Likewise, the pressurizing system and the entire control architecture behind it were renewed. Georg Renftle, After Sales Engineer / Foundry Plants, who supervised the project on behalf of OTTO JUNKER, gives this account: "Before the upgrade, pouring was performed in a virtually uncontrolled manner. The foundry was prepared to tolerate overflow, rather than risking underpours."
Belycast system adds efficiency
Although individual pouring curves were stored in memory to cast different products, causing the stopper to open and close as taught, there was no feedback control, just open-loop control action. Today, the teach-in function is still available and, indeed, is indispensable for defining start parameters. However, it is now supported by the Belycast automatic mould-filling system. The latter mainly consists of a stopper actuator with linear motor, pouring sensors (cameras), an intelligent controller, and an intuitive, operator-friendly human/machine interface (HMI). The advantages of the stopper actuator are its high closing and opening velocity, the adjustable closing force, and the fact that the linear motor is virtually wear-free. The pouring sensors are based on black & white Ethernet cameras. These units are water cooled and mounted in housings for effective protection from harsh environmental conditions. They are easy to install, provide quick and accurate measurements, and are suitable for all sprue cup shapes and sizes from 70 to 300 mm.
The Belycast system by OTTO JUNKER provides direct monitoring and closed-loop control of the pouring cycle, but also supervises the pouring process. While the first camera captures the sprue cup, the second is directed at the surface of the mould being filled. The detected in-mould melt level can be relied upon to correct current pouring parameters. Thus, if the moulding sand quality changes due to external factors, which will affect the mould's intake capacity, the controller will take appropriate action automatically.
"Our Belycast solution has been around for close to five years now and is performing well in every instance –- some 12 or 13 plants altogether," summarizes Georg Renftle. Pictures of cast moulds attest to the quality of that performance.
Marcel Tröger comments: "I estimate that we are saving 10% on returns and have been able to reduce our rejects rate from around 5% to around 1%."Further advantages of the Belycast-based automated casting process consist in the optimized pour time and higher throughput, resulting in marked efficiency gains overall.
Bath level control provides additional savings
Scope for additional savings was identified elsewhere: in this specific channel furnace, the melt is forced into the pouring box by the pressure of nitrogen applied to the bath. Due to numerous leaks, the bath level control system had never really functioned properly before the modernization project. However, for purposes of casting quality, it is essential that the head pressure of the metal column remain constant at all times. To ensure that the molten iron would fill the moulds quickly enough, it had to be supplied with at least 2.5 bar on the inlet side. Only thus could the requisite level of 200 mbar in the furnace be achieved. Now, following the installation of a new pressure controller, a float-type bath level sensor delivering an analogue output signal and proper sealing of the furnace, the pressure is around 200 mbar both on the inlet side and in the furnace. OTTO JUNKER had gone to the length of having a backup vessel shipped to Lammersdorf so as to be able to conduct its own local pressure tests as well. And since nitrogen is exceedingly energy-intensive to produce, Marcel Tröger puts the energy saved on nitrogen production at around 15 – 20 %.
He concludes: "In the ultimate analysis, we got even more out of the modernization of our channel furnace then we expected. The costs should be recoverable within two years, even under the present difficult conditions. "Aside from saving resources, benefits have been gained in terms of reduced maintenance and markedly fewer repairs.
Fit for the future as of September 2019
Marcel Tröger will be glad to hear it, being a person who, in Georg Renftle's words, doesn't accept problems, only solutions. He and his team can now dedicate all their efforts to the modernization activities ES-Automobilguss intends to implement by September 2019. These include a new, fully automated stoppered pouring ladle for the No. 1 casting line and a new medium frequency coreless induction furnace system that will replace the cupola as a melting source. Both the melting furnaces and the stoppered ladle – strictly customized for ES-Automobilguss – will be supplied by OTTO JUNKER.
The new fully automated stoppered ladle, having a useful capacity of 1.2 tonnes, is basically an unheated vessel that allows molten iron to be directed into the mold by raising the graphite stopper. It will be used for pouring ductile cast iron in the future.
"Although we knew from experience that OTTO JUNKER will go beyond standard efforts to satisfy my wishes as a customer, we awarded our contract for the medium-frequency coreless induction furnace, a dual-furnace system with two melting crucibles and 6 tonnes capacity each, through a regular tender call“, Mr. Tröger notes.
Nevertheless, it soon emerged that OTTO JUNKER was the best choice for ES-Automobilguss as regards its offering of products and services. Marcel Tröger was particularly impressed by the advanced IGBT converter technology with its ability to change frequencies from 250 Hz to 125 Hz. The furnace is now being built at OTTO JUNKER, while at ES-Automobilguss the civil engineering work is being prepared in an existing shop building. For the on-site installation scheduled for the summer of 2019, ES-Automobilguss will once again rely on the services of local contractors – not least as a signal to the region that business is moving ahead at Schönheide. However, before the two furnaces are erected, one of the furnace bodies will be put on exhibit for visitors to view up close in OTTO JUNKER's booth at the upcoming GIFA 2019.
With its modernization drive, ES-Automobilguss has paved the way for conquering new fields of business once again. Growth in output of whiteheart malleable castings is already on the horizon for the second half of this year. ES-Automobilguss is committed to achieving profitability again as early as in 2020. The outlook for this target appears favourable, as the company has modernized reasonably and with measure and purpose, proceeding with caution and a close eye on costs.