Robert Jankovych

RELATIONSHIP BETWEEN VALUES OF PROFILE AND AREAL SURFACE TEXTURE PARAMETERS

This paper presents a regression analysis of the relationship between values of profile and areal surface texture parameters extracted from the same surfaces. The problem of tolerancing for areal surface texture evaluation is briefly introduced. Basic concepts of and differences between areal and profile evaluation are discussed. Measurements of 21 samples of diverse origin are used as data for linear regression of dependencies of areal surface texture parameters Sa, Sq and Sz on their roughness profile equivalents Ra, Rq and Rz. Recommendations for calculation of areal surface texture parameter’s tolerance values are discussed based on the results of the analysis. The resulting regression equations provide a fast method for selection of areal surface texture tolerance values based on previous experience with profile parameters.

NOISE AND STEP HEIGHT PERFORMANCE OF SELECTED OPTICAL SURFACE MEASURING INSTRUMENTS

jankovych@fme.vutbr.cz Increasing demands for manufacturing quality and new standards in surface metrology foreshadow a widespread adoption of 3D surface topography measurement in manufacturing quality control. This raises the question of instrument selection. Coherence scanning interferometry and laser scanning confocal microscopy are some of the most common technologies in optical measurement of surface topography. These methods differ significantly in their suitability for different types of measurement. This article provides a comparison of the measurement noise and step height measurement performance two measuring instruments based on these two principles in relation to objectives used for measurement. Such data can be used to inform instrument selection in an industrial environment.

AUTOMATIC STRAIGHTENING OF HARDENED SHAFTS

The main purpose of this article is to present a new way of straightening hardened shafts. The straightening of regular shafts is usually not difficult, but the situation is very different in case of hardened shafts. The regular shafts are usually straightened by bending of the shaft in the opposite direction than the original deformation. Sadly, this approach cannot be applied on hardened shafts, because of the brittleness of highly hardened material. Mesing Ltd. in cooperation with Brno University of Technology are now trying to automate the process of straightening by changing the stress inside of the hardened material. This method uses controlled impacts of a ram on the surface of the shaft which has to absorb the energy of the ram. The impact causes a plastic deformation of the surface of the shaft and changes the inner stress. At the end of this article is the design of such measuring and straightening setup shown and described.

Operational limits in vibration diagnostics

The paper discusses some practical problems occurring at ISO 10816-1 application in technical practice. Technical diagnosticians find out frequently that the zone boundaries proposed by the standard are not sensitive adequately to the changes in vibrations during operation resulting from a change of technical condition of the machine. The principle of statistical determination of individual operational limits from the measured overall level of RMS vibration velocity (overall level) with utilization of statistical regulation of individual values is also described in the paper. The alarm limit for the overall level (boundary between the B and C zones) in the range 10–1000 Hz is specified in the paper on the basis of measuring of vibrations on the electric motor of Bosch Rexroth hydraulic unit.

VIBRATION AND RELATED DIAGNOSTICS OF MOTORS AND GENERATORS

This article is devoted to diagnostics of rotating machines – electric motors and generators. It describes their basic characteristics and failure modes in terms of statistics and experience. The methods of multi-parametric approach to electrical machines diagnostics are listed. The analysis methods based of vibration measurement are emphasized due to the fact that vibration analysis is the best way to define the condition of any rotational machines. In addition, vibration can be, in some circumstances, successfully used for the evaluation of electromagnetic faults as well. The article introduces actual examples of deficiencies of mechanical and electrical motors using different diagnostics methods.

ACCURACY OF MEASUREMENT IN NANOMETROLOGY

The presented article focuses on measurements of extremely small dimensions in nanometrology using tactile probes. It addresses a newly developed method of precise measurements in nanometrology by touch probes, where the measurements are carried out on the machine SIOS NMM-1. The aim of this work is to determine accuracy of measurements on this machine. The main contribution of this work is a creation of a methodology for the measurement of precision parts and determination of accuracy of measurement when using this device in nanometrology. The work also includes methodology for the calculation of measurement uncertainty, a keystone in determining the accuracy of measurement in nanometrology. The article provides results of representative sets of measurements of ruby ball diameters, including the evaluation of statistical parameters and determination of the combined measurement uncertainty.