Supersized Castings’ Value Enhanced with High-Power CNCJun 2, 2015
Oversized parts and one-off runs are a steady challenge, but a common CNC platform offers many benefits to Voith Hydro’s Pennsylvania machine shop
Voith Hydro manufactures hydroelectric power generation equipment, in particular the highly complex turbines used in such operations, supplying hydroelectric generating companies and municipalities throughout North America. Over 12,000 units have been commissioned in the field with more than 65,000 MW of installed capacity. In addition, Voith Hydro has also upgraded more than 600 existing power generation units. As a turnkey supplier to the industry, the company manages all phases of power plant projects, from analysis and planning, design and implementation, to commissioning and operation. Voith Hydro is ISO 9001- and ISO 14001-certified.
At its York, Pa., facility, very large multi-axis machining centers produce carbon and stainless steel workpieces, most often in a one-off mode and at sizes frequently exceeding 35 ft. in diameter. Adam Ward, the manager of maintenance and facilities at Voith Hydro, said the machining done typically holds +/- 0.002 in. tolerances nonetheless. “We do turning, line boring, and milling on extremely large and heavy workpieces that often challenge us to design the optimal machining cycle. Our long cycles can frequently result in heat distortion on material surfaces and so we take great care in looking for problems before they occur.”
Voith Hydro maintains an impressive array of machine tools and multi-axis machining centers at the York plant. Despite a variety of builder brands, most of the machines have one common component — the Siemens Sinumerik 840D CNC onboard.
“Our operators are quite comfortable with the CNC from Siemens and they use it for all motion control,” Ward noted, “plus the operator interface has the ability to afford us great troubleshooting capability and something else we value greatly, the commonality of the HMI on the control.
“That fact allows us to do a great deal of cross-training and that’s very important to us,” he continued. “We need to be highly flexible, given the one-off nature of our work here.”
Most of Voith Hydro’s operators are capable of running multiple machines, while the maintenance crew can more easily service the machining equipment in the facility, according to Ward. He credited the machine builders and the Siemens team led by Howard Weinstein and Robert Stiefel for this ongoing flexibility.
Voith typically takes a customer design, runs it through a CAM system and simulates the cycle offline, in order to preserve valuable machine uptime. Because the work involves highly complex geometries on the turbine sections, the simulation must be equally complex and account for all machine motions and collision avoidance. Once the program is finally determined for a part, it is fed over the Voith Hydro network to the appropriate machine tool or machining center for scheduling and production startup.
During production, a system of real-time remote condition monitoring is available through the CNC, for troubleshooting by both the Voith Hydro maintenance personnel and, when required, machine builder personnel, working offsite.
Ward cites one example where an Ingersoll milling machine was completely retrofitted both mechanically and electrically by a Siemens Solution Partner, with a new CNC, motors, drives, encoders, other hardware and software. “Working with the builder and Siemens support personnel, we were able to resolve issues and implement changes to the programming, right on the CNC of the machine…and all done remotely, in a very short time period.”
At the York plant, Voith Hydro is able to machine workpieces over 42 ft. diameter and weighing up to 350 tons. Surface finishes are typically 250 and 125 Ra, though occasionally 64 or 32 Ra is required, finishes it achieves by both machining and secondary finishing.
Adam Ward further noted that, on most new machines required at Voith Hydro, “the cross-training capability of the CNC, the standardization of the HMI on various types of machines, the support provided and the previous successes our operators and maintenance personnel have realized, all combine to make specifying Siemens as our control of choice an easy decision.”