Rotating Equipment Repair, Inc., (RER) based in Sussex, Wis. has taken a major step forward in its machining technology with the use of a new manual CNC cycle-controlled lathe. By implementing this equipment for its piping, pump shaft and other long, heavy work pieces, RER has realized a 33% overall reduction in time-to-part, with some jobs involving a 50% reduction.
The company added a Weiler E70, a CNC lathe equipped with a dedicated graphical programming interface, designed by Weiler and based on the open architecture of the Siemens SINUMERIK 840D, for the specific needs of the lathe operator.
Andreas Schulz, Weiler’s general manager for North America, reported that the machine has been designed so that simple parts can be made in the same way as on a manual machine, while complicated parts can be made more easily in the same way as on a CNC machine.
In addition, the operator does not need a CNC background. According to Shulz, “An operator doesn’t need extensive G-code or CNC knowledge and can go from a drawing to cutting in far less time. Also, adjustments can be made on the fly, especially in the running speeds, to compensate for various factors, without interrupting the basic program.”
For RER, training was provided by Weller Machinery, the Weiler dealer located in Pewaukee, Wis.
Plant manager Bob Merriman noted that the company has cut its per part production, “by at least one-third and up to one-half on some jobs. The constant speed of the machine, the adjustable feed, the non-stop production rates and especially the programming set-up all contribute to an overall savings for us.”
A typical job Merriman cited involved a part where the previous run took 45 hours and was now being done in 28 hours with superior quality. He noted the straightness of the part, the tight tolerances were held to +/- 0.0005 in. and the finish quality, even on vertically heat-treated 416 S.S., was outstanding. RER typically works on 3 - 5 in. diam. multi-stage, high-pressure boiler feed pump shafts that need to run at 3,600-5,000 rpm. As a turnkey operation, this job shop also repairs and rebuilds impellers, sleeves and nuts for finished assemblies with extremely tight interference fits, in the .001 -.003 in. range. On its largest job to date, a 15 ft long pump shaft was machined for use on a vertical pump.
Workflow analysis
A job at RER that involves its Weiler lather begins with a pump being delivered, broken down and then analyzed for requirements. Next, the engineering department prepares a CAD drawing for the shaft work. Material requirements are determined and the particular material is cut to length, usually from RER inventory, on the in-house band saw equipment. The machine operator writes the program on his laptop and the material is loaded. The program is transferred to the machine and the cutting begins. One-off is the standard at RER, with a typical work piece starting as a 600 lb billet and finishing as a 400 lb. machine shaft.
With the look-ahead feature of the Siemens CNC, the Weiler control can maintain a constant cutting speed, while adjusting for angle to radius changes and especially on precise internal threading.
The machine and its uses
The Weiler designed controller, based on Siemens CNC architecture and its Wizard template, comes with customized screens for particular machining functions, tool management, thread cutting cycles, part profiling and cut simulations. A drilling axis in the X- or Z-axis can also be selected for machining of bore holes and threads. As a demonstration of the company’s commitment to continuously improve the control of the machine, four software engineers at Weiler have SINUMERIK 840D CNCs at their workstations to simulate all possible screen variations, based on the input from machinists worldwide. Weiler R&D receives new or unique application data from the field almost daily, then incorporates the machine motions and tool management schemes into the architecture to make the control as adaptable onsite as possible. Weiler lathes have been used in the oil and gas industry for heavy sections of drilling equipment and other rotating devices for a long time, and are now finding applications in the aircraft, steel and power industries.
“Anything you can do on a conventional engine lathe, you can do on this Weiler machine, only better and faster,” said Merriman.
