The RWE Maintenance & Engineering Centre possesses four DST boring mills: two Scharmann WFT units, a Scharmann FB 100 from the 1970s, and a Scharmann Heavycut manufactured in 1983. “We began the fi rst complete overhaul and modernisation together with DST in 1996” says Willi Spelter, long-time employee within mechanical production and current project manager for machine tool maintenance. “A major retrofi t was then lined up in 2013 for both WFTs, due to serious damage to the guideways. For them to be replaced, the columns and headstocks had to be removed.” The experts at the RWE Maintenance & Engineering Centre brought in DST, due to previous good experiences. “It was clear to us that we would only be able to execute this project with the machine manufacturer,” reckons Spelter in retrospect. “We had to dig deep into the substance of the machines” adds Thomas Pfeiffer, head of the department for product-oriented maintenance. “Another factor was the fact that we could not do without the machines for long and that we had to complete the project with total reliability. And that is not possible without the manufacturer, who has all the necessary documentation at their disposal.” 

Dörries Scharmann helped develop an initial maintenance strategy, the fi rst step of which grouped the boring mills into assemblies. “We depicted the 100-plus assemblies in a mind map and colourcoded them,” explains the project manager. 

The retrofi t was followed by a modernization of the safety plan of both WFTs and the nearby Heavycut. “We also needed to reliably prevent any unnoticed access to the working area,” says production engineer Herrmann. “It was also important here to take into account that very large components sometimes protrude out over the working area.” The task was therefore also very challenging, as both of the WFTs are located on the same machine bed. Pfeiffer: “The intensive dialogue with DST then led to a tailor-made solution, which was also received well by the responsible regulatory authority and the employees.” One feature is the relatively low fence bordering the central corridor; with a height of one meter, it is only half as high as standard fences and allows for the protrusion of XXL components. “We fenced in all three ram boring mills completely,” explains Ophüls. “What’s more, there are pluggable partitions between the machines, which can be removed when handling very large components.” Finally, encrypted access control system with selective intervention in the emergency stop levels of the three machines safeguards against the unauthorised or unnoticed entry into danger areas.

All in all, the assessment of the boring mills retrofi t in Frechen can be represented on a scale ranging from one star (adequate) to a maximum of five stars (excellent). Spelter: “Accuracy and availability increased from two stars previously to five stars.” Due to the satisfaction with the DST retrofi t of the three machines, the retrofit of the Scharmann Heavycut will start in November 2015, a further development of the WFT series of ram boring mills. Ophüls: “The task will involve a comprehensive package including the overhaul of mechanical parts and the modernisation of electronics.” The Heavycut will receive – due in part to the discontinuation of components by sub-suppliers – a new Siemens Sinumerik 840D sl, switching system and wiring system, as well as new motors and measuring systems. Ophüls: “We will not proceed step by step with this assignment, but rather continuously with a basic order. In addition, RWE already budgeted for all possible options that may exist after disassembly.” 

This elegant approach also enables RWE to avoid time delays resulting from renegotiations for extra tasks. After all, even if the product service is initially developed directly at the customer’s site, the level of success depends not only on their participation but also on prior exact planning.