Pleased with its initial foray into servomechanical press technology, in 2021 Omex purchased another 630-ton DSF-M2, identical to the first save for a longer 168-in. bed. Omex teamed this press with a transfer from Linear Automation. At the same time, the company decided to outfit both servomechanicals with coil-feed systems from Colt Automation, designed for feeding high-strength steel and boasting four-over-five roller configurations for powered straightening. With two servomechanicals inhouse, Omex has discovered all manner of advantages this technology offers.
“We are fine-tuning our servo presses, especially in pendulum mode,” Slawek offers. “For example, we’ve just finished trialing an automotive-part program that previously ran at 25 strokes/min. We monitored the energy when forming at that rate, and by using pendulum motion to significantly cut back the dead (nonforming) cycle, we easily reached 40 strokes/min. Tool life remains the same, but output increases.
“Of course, this brings new challenges,” he continues, “such as dealing with quicker bin filling due to the increased output. With this logistics issue, we had to slow down a bit, rearrange resources and rethink how we remove these parts from the press.”
Press-stroke control inherent in servo-driven presses also comes in handy for stamping lighter-gauge material, “which tends to dance,” says Slawek. “Now we can lift softly, so that when the stripper or lifter plate raises, it does not stop abruptly and cause the strip to bounce.”
Slawek provides another under-the-radar advantage of servo-driven presses: stopping time.
“Everyone focuses on slide velocity and energy, which are important, but stopping time also is critical,” he says. “Compared to our traditional mechanical presses, stopping time on our two servomechanical presses is significantly quicker. Traditionally, we would try to finish our material feeding at top dead center in case something was out of position in the press. Now, as these presses stop more or less instantaneously, we can have material feed and use an extra 30 or 40 deg. of timing to speed up the stroke.”
Fine-tunability of these servomechanical presses, notes Slawek, also allows for better matching with movement of auxiliary equipment such as a transfer and servo-driven tapping unit, delivering greater accuracy.
Bringing in servomechanical presses did require a learning curve, acknowledges Slawek, but that has smoothed out, “and we’re very comfortable quoting jobs because we have inhouse expertise that knows how to get the most out of this technology,” he says. “At first, we almost quoted as a traditional stamping job and then had to learn the process. Now, given a tool design, we are confident in quoting based on how we can adjust and calculate the energy and motion.”
One challenging takeover job calling for Omex’s servo press capabilities: a seatbelt housing from 3.5-mm-thick 480-MPa high-strength steel. Another stamper had stamped and extruded, then tapped—one hole Imperial, a second hole metric—via a secondary process. Omex, in its 630-ton servomechanical press and with assistance from Aida to set up the process, coil-feeds a two-out die that forms the part and extrudes on vertical sides, then punches four tab holes on the horizontal. A servo-tapping unit then taps the two extruded holes. Integrated part transfer and the plug-in servo tapping operate off of press power and controls. Fully sensored, this job produces 50,000 parts/ week.
