March 11, 2008
This multi-source article offers readers advice on the criteria to consider when buying a press. The article examines application suitability, drives, and controls as well as other considerations such as tonnage, frame construction, speed, and horsepower.
The following questions–and their answers, provided by industry equipment manufacturers and experts–are intended as a general guide to help you simplify the daunting task of selecting a press or press system.
So, getting back to that all-important, most often asked question regarding press selection:
9. Which Category of Press Is Right for My Application? Will a flywheel fly? Would a servo serve better? How can hydraulic help? Time for a transfer? New pneumatic? Or should I order a combo?
"Coming with a higher price tag, servo-mechanical press technology is not suitable for all applications; thus, it will not replace all hydraulic and mechanical presses in the future," Schuler's Kinzyk said.
"Despite the recent progress in servo-mechanical press technology in the100- to 800-ton range, there still is a need for cost-effective hydraulic presses with advanced control and fluid management, suitable for a wide range of applications, such as deep draw operations or difficult-to-form parts," Kinzyk continued. "However, there are a number of applications that greatly benefit from the ability to synchronize the slide speed to the conditions over the entire process, leading to a higher output rate and increased quality," he concluded.
Minster's Cattell offered his perspective: "Justification for a servo press must be based on need and the value you place on that need. Can it perform a function that a flywheel mechanical press cannot? Servo-mechanical presses allow very fast tryouts. You can change slide velocity at the point the die contacts the material, during the start and finish portion of the working stroke, and adjust the slide velocity via the press control screen up to the material's failure point, then read what the velocity is—not guess, calculate, or look on charts. You can adjust stroke speed to suit the application; eliminate springback; reduce noise. The servo press is a toolmaker's dream come true," Cattell said.
"However, once you have all this information, eight times out of 10 you will find it will fall into the adjustments or specifications of a mechanical press that you may have. Once the parameters are set on the mechanical press, it will outperform the servo press on production speeds and cost—more parts in the bin at the end of the day. But the science of getting there with a mechanical press is difficult. Experience is needed," Cattell said.
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Ultimately, your press selection decision will be based on part characteristics and application, materials, volumes, your current press and work force capabilities, and future opportunities, as well as the press manufacturer's commitment to quality, reputation, and service record.
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