Welding technology manufacturer assists in implementation and optimisatio
Bell establishes own welding production line with EWM
Articulated dump trucks (ADTs) made by South African heavy equipment manufacturer Bell Equipment are built to carry huge loads over challenging terrain. The production of these large vehicles can be challenging too. It requires specialist welding machines and accessories able to withstand long weld seams and high duty cycles at high currents in a two-shift operation. During 2019, Bell Equipment's German factory in Eisenach-Kindel moved from an assembly operation to one that now also produces the requisite components itself. To help with the planning and implementation of their own welding product line, Bell Germany enlisted the country’s largest and one of the most important worldwide manufacturers of arc welding technology, EWM AG.
Bell Equipment’s German operation was established in Alsfeld, in the German state of Hesse, in 2000. An assembly facility followed in 2003 in Hörselberg-Hainich near Eisenach, which today supplies 22 European countries and North America with Bell dump trucks and associated spare parts. Individual components come predominantly from European suppliers while the core assemblies are delivered from the South African parent plant. This was also the case for the bins up until 2018. To manufacture these, the company shipped plates from European production lines to South Africa, where they were cut, milled, edged, and welded and then shipped back to Germany as finished bins. Bin production and shipping to Germany typically took four to six months after receiving the order. There clearly was room to streamline this process to bring it in line with the environmental ideas rooted in the company’s principles, including a more sustainable and economical bin production, explains Steffen Zitter, a member of the strategic purchasing team responsible for carrying out global projects at Bell Equipment.
Internal welding production line started in 2019
As a solution, Bell Germany started its own welding production line near Eisenach-Kindel in 2019 and has been mass producing bins for ADTs for Europe and North America for six months. Bins to fit ADTs with 20- to 50-ton load capacities are now welded at various stations in the new, modern 12,000-square metre hall. The hall hosts both fully mechanised, automated stations and manual welders. Manual welders are required primarily for the harder-to-reach seams. The dimensions of these vehicles are immense, so are the weld seams, with the smallest bin measuring 4.70 metres long and the largest, built in Thuringia, measuring 5.30 metres.
EWM already involved in planning
When Bell Equipment finally decided to take the leap and establish their own welding production line at their site in Eisenach-Kindel, EWM AG, Germany’s largest manufacturer and global leader in arc welding technology, was right there. To start the ball rolling, Stephan Giese, Technical Director at Bell Germany, gathered information about the possibility of an internal welding production line. During his research he got to know Ralf Rauh, the Site Manager for EWM in Nossen, who was already involved in the initial planning phase. As part of EWM maXsolution, the extensive consultation service, Rauh worked on a complete custom solution for the company. With EWM maXsolution, the customer’s entire production process chain is optimised in a way that saves the company energy, resources, and time. To do so, he became familiar with Bell Germany, its production site in Eisenach and its users and learned all about the required specific needs. The specifications from the parent company played a huge role in creating a suitable solution. “Processes set by South Africa are reflected in our work,” explains Steve Rudolph, head of assembly production and quality control.
Preparing for the EU Ecodesign Directive
Robust machines with a high duty cycle that can withstand long seams and welding times are needed for metre-long metal plates made from wear-resistant steel in thicknesses from 6 to 32mm. For this, the production line in South Africa uses step switch controlled machines that require the user to find and set their own operating point. This means that the same machines needed to be purchased in Germany too. However, despite his endeavours to take all the customer’s wishes and specifications into account when creating his solution, Rauh intervened on this requirement. “In the coming year, the Europe-wide Ecodesign Directive will come into effect, including for welding machines. From 2023, power sources will have to use no more than 50 watts of power in open circuit.” Rauh therefore offered the Taurus Basic instead, a welding machine with energy and resource-efficient inverter technology.
As the customer wanted one type of welding machine for the entire production line, and indeed one that allowed the user to manually set the operating point, all production employees now weld using the Taurus 505 Basic. This power source is like a step switch controlled machine in its operation, yet, thanks to digital technology and the EWM quality, it saves a lot of energy. The decision maker in South Africa ultimately gave the greenlight for the EWM complete solution which, as well as the welding machines, also included wire feeders, hose packages, drum connection, welding consumables and work safety equipment such as welding helmets.
Non-stop welding time in two shifts per bin
The close attention EWM pays to quality, performance, high power reserves and mains voltage tolerance, makes its welding machines perfect for the seams measuring up to 6 metres long. So EWM offers a full three-year guarantee in three-shift operation, all without a limitation on operation hours, for good reason. The company even offers a five-year material guarantee on its main transformers, output chokes and secondary rectifiers. Even when it comes to the duty cycle, EWM has its own measures in place that go beyond the legal regulations. The Taurus Basic 505, for example, has a duty cycle of 100% at 430 amperes. “Welding bins require high currents of around 290 amperes over a long period of time. One bin takes at least two shifts of non-stop welding. The EWM machines are perfectly equipped for this,” confirms Zitter.
As part of his complete solution, Rauh planned various improvements for users and optimisations for the company, which are different to those in South Africa. As a result, welders work with decompact systems with separated power sources and wire feeders. Intermediate hose packages from 10 to 15 metres increase the working radius. This makes it easier to work on large components and hard-to-reach seam positions. The switchover to a drum connection for the weld wire saves around 17 spool changes per workplace. As part of internal solutions, Bell flexibly attached wire feeders to the metre-high manipulators, on which the bin components are conveniently positioned. The welder can change the welding parameters directly on the wire feeder control instead of having to set them on the power source. This increases mobility and saves any long back-and-forth and unnecessary climbing.
The welders were trained in groups and individually by employees from the EWM site in Nossen. Bell has set up a small warehouse for wear parts. Experiences and outcomes are discussed with Ralf Rauh. The whole approach follows the construction machinery manufacturer’s concept: “As an Original Equipment Manufacturer (OEM), we prefer to work directly with the manufacturer,” explains Gert Van Zyl, the head of bin production in Germany. “This allows us to improve processes together and make use of synergies.”
Short delivery time and great service
The fact that all 22 machines were delivered in just three weeks was yet another reason to work with EWM. “The time factor and pricing played a role, but also the personal contact and great service,” explains Zitter. All this meant that production could start quickly, with mass production being ready in just a few months. Together with EWM, the aim is to continue to improve the production process in the coming years. “All experience relating to machine technology or welding consumables is shared intensively with South Africa. If we find that something could be improved, it is discussed and improved,” he adds. To find such areas for improvement, Rauh regularly visits the welding production, having welders test an EWM welding torch or answering any questions. The results speak for themselves. “With the EWM welding torches we only needed five EWM contact tips in two and a half weeks,” Steve Rudolph responds to Ralf Rauh’s enquiry. “Working with EWM, in particular in the area of torch technology, in no time we were able to save up to 30% on consumables and wear materials, depending on the use and workplace.”
With its own production line, Bell Germany can now respond to enquiries and orders faster and with more flexibility. It also means production is significantly more economical and sustainable. The plates come directly from the steel mill – 6,000 tons of steel per year are now completely cut, edged, tacked, and welded in the new production hall. One bin is ready in two to three weeks and can be assembled next door, in the 6,000-square-metre assembly hall. Later this year, Bell Equipment will also begin production on engine hoods as it gradually expands its production portfolio with further assemblies.
Date: 01 July 2020
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