Technological challenges

Precision vs. Speed
Precision vs. Speed

The constantly increasing requirements for productivity and accuracy lead to new challenges for drive systems and thus for servo drives as well. Mechanical vibrations and system robustness, however, set limits to this urge for speed and precision that must be overcome time and again.

The Triamec Motion Solution breaks through previous limits and gives your application a significant performance advantage by providing outstanding solutions to the following technical challenges:

Highly dynamic mechanisms with low bearing damping and pronounced resonances

Linear Pick&Pace
Air-bearing pick-and-place: travel distance 330mm, speed 4.5m/s, acceleration 14g, position on path <1μm, cycle time 114ms

Fast reaction of the control system allows damping of the system. Resonances are actively suppressed.

To accelerate processes and improve accuracy, direct-driven axes are increasingly used. The elimination of backlash or backlash-free but elastic gears has a very positive influence on process accuracy and cycle time. However, it is now more difficult to achieve a good adaptation of the load to the motor. In addition, the sliding friction of the gear unit is eliminated, which helps to dampen the drive.

Mechanical resonances occur as a result with greater superelevation and can quickly become disruptive to the process. All in all, the control in the servo drive is therefore much more demanding than before. To counteract these disadvantages, an advanced control system must have a significantly higher bandwidth in order to actively dampen the system as a whole and also resonances. Triamec servo drives with a 100kHz control perfectly meet this requirement, with impressive results.

Low backlash, highly preloaded ball bearings: High friction

Precision axis from Schüssler Technik

Only a fast reaction of the control system effectively dampens the jerk between static and sliding friction and allows the smallest path deviations during travel.

One approach to guiding precision axes even more precisely is the higher preload of the ball bearings. Such systems are mainly used in production machines that rotate very slowly, at speeds well below one revolution per minute. In addition to position, synchronism plays a particularly important role here: the drive must follow the set speed exactly at all times, i.e. with minimal deviation.

The high preload of the bearings leads to a very high sliding friction and even higher static friction. Due to the slow rotation, the axis is constantly between static and sliding friction, a very unstable zone which is therefore hardly controllable. Experiments have shown that a fast control, such as the Triamec servo drives, brings enormous improvements of considerably more than one order of magnitude in synchronous operation.

Further Information on Schüssler Technik

Fast processes in the millisecond range

ESEC Wire Bonder
ESEC Wire Bonder

Sufficient sampling is essential for good process control.

Fast processes such as wire bonding, where up to 30 wires per second must be drawn between the silicon chip and the package connections, require a high sampling frequency: The 20μm thick wire is drawn in only 15ms in a complex path in space. It goes without saying that this trajectory must be mapped with sufficient scanning frequency to make the process stable and robust.

The Triamec servo drives work with a path planning in 10kHz cycles, which can be reprogrammed within 100μs. The 10kHz set data are interpolated to 50kHz in the drive for position control.

Noise suppression

Noise suppression for different dead times of 250μs (blue) and 25μs (red).

A fast control reacts faster to deviations and can therefore suppress or compensate them better.

Good interference suppression is the goal of every control system, in addition to high damping and good control behavior. This should be aimed for up to the highest possible frequencies. The customer's application thus achieves a significantly higher robustness, better surface qualities and thus an overall better process quality.

With a current control of 100kHz and a position/speed control of 50kHz, Triamec sets standards in this area.