Burly giant undergoes rejuvenation cure

Retrofit of a 30-year veteran Schiess portal milling and drilling machine assures sustainable future.

«Our largest excavator boasts a bucket volume of 42 m3», thus Ralf Petzold, Works Manager of the Komatsu Mining Company GmbH. This corresponds to a handling capacity of approximately 75 tonnes of bulk material, a volume that becomes all the more impressive when one thinks of two lorries capable of being loaded almost completely by a single bucket. In the colossal factory building one is flabbergasted at the huge components manufactured at the Düsseldorf-based plant and assembled to form enormous hydraulic excavators. A Schiess portal milling and drilling machine type 40 FZT has been responsible for machining these outsized components,
among others, for the past thirty years. Other imposing features of this gigantic facility include its overall height totalling 7.80 metres and a traverse range extending to 14 metres. The machine has aged over the years so that the management of Komatsu Mining joined forces with Starrag Group Service department located in Mönchengladbach to seek means and ways of rendering it fit for future service.

Decision in favour of unusual retrofit package

Several factors spoke in favour of a retrofit package, which was tantamount to subjecting the FTZ 40 to a thorough overhaul. The outdated machine still revealed excellent and substantial engineering qualities.

As far as Komatsu was concerned, the production technology integrated into the FTZ 40 was worth preserving. Both the machining accuracy and stock removal rate were highly efficient. Nevertheless down times, wear and outmoded control and safety technology had led to increasing problems occurring. «This having an impact on the arterial lifeline of our enterprise» as Ralf Petzold emphasised. Material flow and production layout had undergone various processes of optimisation over the years so that the company was reluctant to make any changes in that respect. The machine bed was also capable of being reused. The alternative would have been to purchase a new machine. What spoke against this option was the high re-placement value. The essence of the old machine was worth preserving so that a fundamental decision was made to opt for a retrofit. Provided one has found the right partner to work with, a retrofit project can be economically attractive. After carrying out an intensive market search and competitive analysis, the company decided to call on the service organization of Starrag Group to tackle the job. «Rating of the evaluation matrix and personal impressions finally tipped the scales in favour of Starrag Group», admitted Ralf Petzold. In Starrag Group the company had identified its own philosophy: A solid enterprise that would vouch for what it promised.

Starrag Group Service implements modernization project with Schiess know-how

«We chose the right partner at the right time”. In the event of unexpected problems cropping up, Starrag Group is well equipped to deal with the situation. Owning all former Schiess documents – software and hardware diagrams together with all hydraulic plans and construction documents including all component drawings – Starrag Group is in a position to rebuild individual parts of any machine applying tested quality standards. The complete store of know-how relating not only to Schiess facilities, but also to those of other system specialists – Froriep, Wotan and Köllmann – has passed to Dörries Scharmann along with former personnel.

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That’s not all: the Starrag Group Service Unit has access to the full range of components traded in by the new machine business enterprise. This comprehensive retrofit range adapted to meet customers’ individual needs accounts for a vast share of the aggregate turnover generated by the company. Ralf Petzold concludes: «This pooled cooperation alliance was successful all along and we are now well equipped for the future». The results speak for themselves: Proceeding from an ultra steep start-up ramp, the retrofitted machine attains a 98% level of availability. Performance even exceeds that when the machine was first delivered to the works and accuracy values are fully compatible with those of a new machine.

Complex operations to ensure speed and safety

The immediate impression gained when approaching the machine in its new enclosure is that a major aspect of the upgrading process lay in updating technical safety standards. Achieving a high level of safety was vital in order to protect the operating personnel from hazardous situations without imposing restrictions on work. This included a new mobile portal lifting platform. A special feature of this concept is a fall arrester designed to facilitate safe access to even higher work pieces from the cockpit. Illumination of the work area is another distinct improvement from the angle of visual control and thus too, overall safety. A further important issue relating to the retrofit lay in modernising the system technology. The previous tool manipulator had become prone to failure and was replaced by a high-tech industrial robot integrating a whole number of advantages: Apart from essentially more straightforward features of design, the new robot system is capable of reacting more quickly, responding as it does with all necessary degrees of freedom not hampered by set axes and traversing limitations. This results in shorter toolchanging times. One of the fundamental aspects in overhauling the outdated machine lay in testing and replacing essential components. Starrag Group is ideally equipped in that respect, having access to in-plant production and design components, including all original drawings, and thus capable of exemplifying more or less every in-house task needed to be accomplished. This ensures high standards of quality combined with reduced turnaround times. The principal components, including drive units such as the motor, gear mechanism and milling head, were overhauled and subjected to a fatigue testing process using Starrag Group in-house test rigs. Whenever new components are required, Starrag Group can help itself, so to speak, within the Starrag Group and come up with complete solutions derived from other machine-tool segments. The meanwhile obsolete electronic system was likewise replaced by modern units of equipment. All these measures contribute essentially to enhancing operational reliability, thus ensuring process sustainability on this industrial system.

Rejuvenation cure to meet future demands

Also brand new is the air suction system which has brought about a distinct improvement to the quality of air circulating in the work area. This installation is conducive to the health of the machine operators and an item of equipment from which the entire factory building benefits owing to its reducing the concentration of cooling lubricant present in the breathing air. Indeed, the quality of the air during the heavy-duty machining process applying coolant feed is better inside the work area than outside the machine. Optimisation has also extended to feeding of the coolant. The old cooling lubricant system revealed shortcomings and operational failure caused delays to occur in the machining times. Starrag Group developed a modified design to control waste-water treatment and the cooling lubricant mix. In replacing the hydraulic, pneumatic and electrical components Starrag Group transformed the redundant system into a state-of-the-art solution in compliance with current environmental stipulations. The control technology system has skipped an entire generation. The old control system was replaced by a modern Siemens Sinumerik 840 D sl. It was of importance to Komatsu to be able to reutilize all existing programs and for the interface to undergo simplification for convenient tool management.

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A partner to share expertise with

«You never can tell what you’re going to find when opening a machine», remarks the Works Manager, Ralf Petzold, and adds: «Then you have a list of contingencies to sort out of what needs to be done first». This is critical issue since the customer and service provider sometimes tend to set different priorities.

At this point, the Works Manager pays tribute to the extremely constructive cooperation with the Starrag Group Service Unit. The know-how possessed by Starrag Group and the staff of the Komatsu maintenance group with its vast store of experience accumulated over a period of many years has always succeeded in bringing about amicable solutions. Demands imposed on quality and precision were particularly fastidious. This led to highly complicated repairs being carried out by the Starrag Group Service Unit such as thermal metallization of bearing seats followed by spindling and restoration of the hydrostatic system on the Y- and Z axes. Despite extensive project planning measures and a detailed catalogue of specifications elaborated by Starrag Group with highly committed project managers in accordance with the specific needs of the customer, wear at certain points is unexpected. In the project planning phase it goes without saying that Starrag Group conforms to customer requirements while also drawing attention to the potential offered when retrofitting a machine in the effort to achieve optimum performance characteristics. Hand-inhand with the customer, the scope of performance is then defined and the duration of the project assessed. After all, the transitional phase needs to be bridged over by outside enterprises. As far as Komatsu was concerned, the logistic challenge was certainly worth the effort.

Results productive of maximum reliability

Enthusiasm was palpable on the part of all involved in retrofitting and updating the old machine. Works Manager, Ralf Petzold, summed up by saying «We are absolutely satisfied with the results». Starrag Group Project Manager added «The machine is even better than it was when it was first delivered».

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