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Solutions Progresive & transfer presses
On one hand, the spm on servo-driven presses is usually higher than on conventional ones because the stroke required is almost half that of a conventional press.
Servo press stroke: 2x max. part height
Conventional press stroke: 3.5 max. part height
On the other hand, with drawing speed limitations the average productivity improvement of servo technology versus conventional could be between 20% and 400% in the most critical cases depending on the part, material and die. In these cases, the servo allows to reduce the drawing speed to the limit required during the critical part of the drawing and increase the speed out of this window, whereas the speed on a conventional press will be defined but the bottleneck of the drawing process and cannot be changed.
Drawing speed limitation due to part or to auxiliary die movements (conventional press on the left and servo press on the right).
It may be that the die doesn’t allow a good access to the automation or that the lifting of the part doesn’t allow a proper picking. In this case the automation window should be increased to allow more time for the picking and the transfer of the part. Thus , the servo will increase the speed during the drawing operation and decrease it during the rest of the cycle.
Drawing speed increase to allow more time to the automation (conventional press on the left and servo press on the right).
In a press shop with a mix of production of transfer type parts and progressive parts of less than 120mm drawing, the pendular mode is a must as you can use the same press to produce progressive parts and blanks in pendular mode, even doubling the productivity in some cases.
This feature, also allows a reduction of the shop floor increasing all profit ratios, revenue per employee and revenue per square meter.
In addition to the advantages described previously, the flexibility of the servo press makes this technology really suitable for high strength materials or to include operations that are usually done in additional steps out of the press, as screw and bolt insertion or in-die welding, for instance.
The cost of maintenance of the dies will also be lower because of the higher precision of the servo press compared to the conventional.
Nonetheless, servo technology is not advisable when the mix of production is formed by parts of similar characteristics without drawing speed limitation.