The managers at Consolidated Industries in Cheshire, CT, knew they had to upgrade an obsolete hydraulic power system on their 2,500-ton forging press. Press performance was suffering, forging quality was uneven, maintenance and downtime were high, and replacement parts were unavailable. While replacing the hydraulic system with a modern equivalent undoubtedly would have produced improvements in performance, efficiency, and maintenance, Consolidated decided to try an alternative.
The results of Consolidated's implementation of the UniGY system, developed by Kadant AES, have surprised them. With UNiGY as the basis of the press's rebuilt hydraulic system, Consolidated realized a 69% reduction in power consumption. The new system is far simpler than the one it replaced, saving the company even more in acquisition and operating costs.
As a producer of high-precision aerospace forgings, Consolidated had an absolute need to replace the hydraulic system on its 50-year-old, 2,500-ton hydraulic press. "The system was just worn out," recalls Ian Mitchell, Consolidated's engineering manager. "There was a lot of downtime and maintenance involved, but the pump system was so obsolete, spares were no longer even available. As a result, it was creating serious operational problems for the press - especially with holding pressures - that were translating into product-quality issues."
Replacing the old system with a similar pump/motor unit was certain to result in more consistent performance, as well as greater efficiency and reliability. But, an alternative, the UNiGY system, was offered by the press's rebuilder.
UNiGY is an advance for traditional hydraulic pump-motor units. It was designed to operate more efficiently than conventional hydraulic systems, especially with hydraulic presses, where flow and pressure requirements vary widely during an operating cycle. Traditional hydraulic pump/motor systems, must run continuously, though demand is intermittent. This inefficiency is seen in wasteful heating of the hydraulic fluid, and the resulting need for cooling.
Many approaches have been tried to overcome these problems, including variable displacement pumps and PLC control systems. These improvements have limitations, too, ranging from high initial costs to high maintenance requirements.
By contrast, the UNiGY system integrates advanced computer controls with specially-chosen pumps and motors to match hydraulic power outputs precisely to hydraulic system demands. In this way, it eliminates excess flows and the problems they create.
"UNiGY offered huge energy savings, even when compared to the most efficient and expensive conventional pump/motor systems," says Colin Dinwoodie, the rebuilder's sales engineer assigned to the project at the time. "Plus, it would solve Consolidated's press control and maintenance problems. With all the long-term operational economies it could provide, UNiGY was clearly the most cost-effective solution we, as the rebuilder, could provide."
Saving energy costs-and more
Once Consolidated's UNiGY system was installed and operating, it performed well beyond expectations. Evaluations conducted by the press rebuilder and an energy consultant retained by Consolidated indicated that projected energy savings were in the 50% range. But, once in production mode, the UNiGY system actually reduced power consumption by over 69%, nearly 40% beyond the predictions. At current power rates, Consolidated's out-of-pocket costs for the system will be recouped by energy savings alone in less than two years.
But even before Consolidated's UNiGY system was in operation, it had already begun saving the company money. First of all, it substantially reduced engineering and installation costs for the hydraulic system rebuild. Able to precisely match hydraulic flow to press demands, UNiGY totally eliminated the complex series of control and bypass systems needed to modulate flow with conventional single-speed pump/motor systems.
Since UNiGY did not produce excessive heat-generating flows, designers were also able to eliminate the need for an oil-cooling system. This further reduced the new hydraulic system's complexity and initial cost by a significant margin.
Beyond installation and operating economies, the system is providing even more savings as time goes on. Operating costs were a primary reason for the replacement, but improving press performance was equally important. With UNiGY's more accurate flow control, forging operations are more precise and consistent, so Consolidated can meet the most demanding aerospace specs with lower scrap and rework costs.
Maintenance and downtime costs are minimized, too. Because UNiGY eliminates the need for control, bypass, and cooling loops, there is less to go wrong with the new system. Where the old pump-motor system was forced to run at full speed continuously, the UNiGY system operates at peak speed for only a fraction of each operating cycle. This reduction in wear and tear is a welcome change from the maintenance-intensive units that UNiGY replaced. Consistently running at lower speeds, the new system is far quieter than the old pump-motor unit.
But, perhaps the most surprising cost savings provided by UNiGY came courtesy of Consolidated's electric utility.
Thanks to UNiGY's energy-saving capabilities, Consolidated was able to underwrite 80% of the system acquisition costs through energy-incentive programs offered by Connecticut Light & Power. Like many power suppliers, CL&P must operate at or beyond its generating capacity during peak-demand hours. To make up the shortfall, the utility must construct new generating capacity, or buy power from other utilities - or offer incentives to reduce demand.
Because of UNiGY's potential to reduce electricity consumption, the installation qualified for CL&P incentives. A grant paid for 30% of the system cost outright, while a 0%, six-year loan covered an additional 50% of the total cost.
While there are unique aspects to the Consolidated application, the UNiGY system's basic cost-saving characteristics - starting with, but not limited to, decreased energy usage - can apply almost to any hydraulic press. The Consolidated forging press represents one of the biggest UNiGY applications so far, but the technology is scalable to smaller and larger systems. Any cycling hydraulic system where power requirements regularly fluctuate is a candidate for UNiGY technology.