Mechanical presses still dominate the manufacturing industry and stamping press market, but according to a capital equipment survey from the Fabricators & Manufacturers Association Intl., the servo-driven press is coming on strong. Spending projections on servo presses for 2013 were nearly triple of the previous year.
Instead of a flywheel, main motor, and clutch, a servo press uses a servomotor that basically makes the slide a controllable axis. In the last 3 years, for example, press-makers have come up with a variety of types, but whatever the specific design, the servo press is able to overcome issues associated with flywheel-clutch mechanical presses.
In a traditional mechanical press, energy is delivered from the flywheel through a clutch, down the connecting rods, which drive the ram that produces maximum tonnage at some point above bottom dead center. The main drive motor then has to speed up the flywheel again before the tool hits the material. Therefore, the mechanical press stroke must be a certain speed, because the minimized speed of the flywheel won’t be able to provide enough energy to produce the needed force to cut through and form the metal. A press with a servomotor, however, can deliver maximum torque at any speed.
With the push toward high-strength-to-weight metal ratios, engineers have become creative with the servo press’s forming capabilities. It comes down to the ability to control slide position and velocity—within microns. With the control of the forming stroke comes control of speed, velocity… plus performance and efficiency.
So while traditional mechanical presses remain dominant in industry for now, sales of servo presses continue to make headway into the market. Controlling the press stroke has many advantages, and during recent years, many smaller-tonnage servo presses have started serving aerospace, defense, and other high-tech sectors.