Performance comparisons with Triamec's latest drives

The Reference at Fraunhofer IPT since 2010

New servo drive generation stands 2x as still

2-6x better path fidelity

Results on customer machines

From 2010-14, Dipl.-Ing. Dominik Lindemann conducted independent comparisons of control and drive systems for ultraprecision machining under Prof. Dr.-Ing. Christian Brecher at the Fraunhofer IPT in Aachen.

Triamec's TS151, TS351 and TSP700 performed so well against their competitors at the time, that the TSP700 was used as the reference drive for the comparative measurements in the project. The decisive factors for this choice were, on the one hand, the outstanding performance of Triamec's 100kHz control and, on the other hand, the ability to read out and graphically display the encoder values with unrivaled precision at a measurement bandwidth of 100kHz.

At that time, nm steps were already visible, (red graph).

Since 2015, Triamec has been launching a new EtherCAT compatible drive generation with 1-36kW. A total of five 2-axis drive models (TSD series) and six 1-axis drive models with integrated power supply (TSP series) are planned. To date, the first four models of the TSD series and the TSP700-10 have been successively introduced.

Thanks to once again improved current and position measurement, true nm steps become possible with the new generation: on the IST test bench with an air-bearing axis with linear motor and 250nm encoder, which was already used for the earlier measurements, the TSD80-2 achieved a 1σ standstill noise of 140pm. This at a measurement bandwidth of 17.4kHz (blue graph).

For comparison, 140pm is the diameter of an aluminum atom. To confirm the IPT results, Triamec compared the TS151 and the TSD80-10 in its own lab in December 2020 on a 2μm scale cross-roller bearing machine tool axis with a linear motor. The TS151 achieved a 1σ standstill noise of 445pm. The new generation TSD80-10 achieved 182pm, more than twice as good.

Standstill noise is a parameter for the quality of the signal processing and control of the drive. Equally important for machine tools is the dynamic behavior: how precisely can the drive follow a path, how does it control acceleration and jerk in such a way that no resonances are excited, how does it respond to disturbances?

To measure and illustrate progress in this area, we compared the TS151 and the new generation TSD80-10 on a fast-tool servo application (coloured graph). Freeform surfaces with amplitudes up to ±0.5mm are produced on a diamond lathe at 1000 revolutions per minute. Accelerations up to 100m/s² occur. The position error refers to the deviation between target position and actual position measured at the encoder. TAMA programs in C# were used for feedforward control of the axis dynamics. In the TSD80, additional adaptation algorithms can be used thanks to the more powerful real-time processor. The peak-to-peak deviation was ±600nm for the TS151. With the new TSD80-10 it was reduced to ±100nm.

In December 2020, a customer compared the previously used ultra-precision drive of a leading competitor with the TSD80. With both systems, standstill noise below 100nm 1σ was possible. For currents up to 5A, the Triamec Drive had the lowest noise; at 15A, the competitor may have been better. The smaller measurement bandwidth of the competitor has an important impact on the measurements, as can be seen in the red (1kHz measurement bandwidth) and blue (20kHz measurement bandwidth) graphs. This makes a direct comparison difficult. Trying to do one with an encoder splitter has not been successful yet (EDIT 2023-07-26: further testing with 3rd party measurement tools showed 37% lower standstill noise for TSD80-10 compared to the competitor). The Triamec Drive was superior in dynamic motion, with faster move-and-settle and better path fidelity. At 300mm/s traverse speed, the competitor's position error was 1.36μm peak-to-peak. The TSD80-10's position error was an order of magnitude smaller at 0.17μm peak-to-peak. In terms of price, the two solutions are comparable. The commissioning and optimization of the axis and the measurements took 3 days. The better control is also perceived by customers intuitively: With 100kHz Triamec Drives, the machine moves significantly quieter than with drives with lower control frequencies.

In November 2020, another customer, who was working with a different competitor, halved the position deviation of their machine (3σ) from 20nm to 9nm, just by changing the servo drives.