Petr Kaftan


Last Name

Kaftan

First Name

Petr

ORCID

0009-0006-8470-8517

Organisational unit

Filters

2024 - 20253
Reset filters

Search Results

Publications 1 - 3 of 3
  • Thermal Error Compensation of High Precision Swiss-type Lathes
    Item type: Doctoral Thesis
    Kaftan, Petr (2024)
  • Reducing thermal errors with confidence: Uncertainty-based compensation for precision machine tools
    Item type: Journal Article
    Kaftan, Petr; Mayr, Josef; Porquez, Florian; et al. (2025)
    CIRP Journal of Manufacturing Science and Technology
    This work presents a new probabilistic method for the compensation of thermal errors of precision machine tools. The basis of the proposed method is the Gaussian Process Regression (GPR) model combined with a threshold for the predicted standard deviation. The key advantage of the GPR model is that it not only provides point estimates for predictions but also quantifies the uncertainty associated with each prediction. Additionally, GPR combines the thermal error prediction and thermal key point selection into a single model, which considerably reduces the overall model complexity. Thermal errors are measured with the recently developed torque limit skip (TLS) thermal error measurement method for precision machine tools. When the applied threshold is exceeded, the model triggers a recalibration feedback loop using previously measured temperature and thermal error values measured with the TLS function. Results show that the self-recalibrating compensation model significantly reduces the thermal errors of the investigated machine tool.
  • Thermal Error Measurement and Compensation with Torque Limit Skip in Swiss-type Lathe Manufacturing
    Item type: Journal Article
    Kaftan, Petr; Porquez, Florian; Mayr, Josef; et al. (2024)
    Precision Engineering
    This paper presents a new methodology for the measurement of thermal errors of Swiss-type lathes. The basis of the proposed method is the torque limit skip function integrated in the lathe's control which stops the motion of a linear axis if the torque on the corresponding axis servo is exceeded. The skip signal is triggered via a slow contact between a bar in the lathe's spindle and an artefact in the lathe's tool holder. Experimental results indicate that when a sufficiently low torque override limit is applied, the axis positioning repeatability under the repeated application of the torque limit skip is within ±1μm. The relative change in position of the axis after the skip measured over several hours is the thermal error which can be compensated. The proposed measurement technique offers significant advantages over conventional thermal error measurement with a touch-trigger probe or linear displacement sensors: if available on the machine's control, it does not require any specialized installation, can be used during production, and delivers comparable results without high additional equipment costs.
Publications 1 - 3 of 3