Kazuhisa Yanagi

Development of a roughness measurement standard with irregular surface topography for improving 3D surface texture measurement

In this study, measurement standards with irregular surface topography which can be used for surface texture measuring instruments of various measurement principles are proposed, and the verification system for surface texture measuring instruments is established using the measurement standard. We have generated the software gauge data with 3D irregular surface texture using the non-causal 2D auto-regressive model (2D AR model). This model can generate periodic irregular surface topography data from specified surface texture parameters, and based on the generated software gauge data, the measurement standards were manufactured by machining with a diamond ball end mill. The short wavelength components which cannot be processed by the ball end mill were removed from the original machining data by the morphological filter. Manufactured measurement standards were measured using three types of surface texture measuring instruments. Proposed measurement standards can be used for various types of measuring instruments.

An optimal discrete operator for the two-dimensional spline filter

Digital filtering techniques are indispensable tools for analyzing and evaluating surface topography data. Among the conventional digital filters, the Gaussian filter is the most commonly used filtering technique for both one-dimensional and two-dimensional data. This is because of isotropic and zero-phase transmission characteristics. However, in the filtering process with the Gaussian filter, additional run-in and run-out regions are usually needed due to its large end-effects. To overcome this disadvantage that supplementary profile data are needed to reduce the end-effects, the one-dimensional spline filter was introduced. At present, it is widely accepted as a practical filtering technique and published as ISO/TC16610-22. In fact, a successive application of the one-dimensional spline filter to the two-dimensional data in the orthogonal directions may lead to an anisotropic amplitude characteristic. In this paper, a purely two-dimensional discrete spline filter is proposed and its computational procedure is also described, which is able to approximate the isotropic frequency response in an ideal manner through a least-squares optimization technique.

An outlier correction procedure and its application to areal surface data measured by optical instruments

An outlier correction procedure for areal surface topography data based on surrounding data for outlier detection and correction is reviewed. The outlier detection is based on the median relative height of the surrounding data within a defined detection window. The threshold value is calculated from a cumulative probability curve of the medians of all data points. The detection window size is selected based on the size of the largest outlier cluster observed on the topography data. The application of the procedure to dental implant surface topography data measured by a confocal laser scanning microscope shows excellent outlier removal compared to typical filtering methods. The procedure only affects outliers, and the information on normal data points remains unchanged. The application to topography data from 21 repeated measurements of a deterministic measuring standard shows great improvement in accuracy and repeatability of surface roughness parameters. The flexibility of the outlier correction procedure is observed through its application to several types of topography data from various types of optical surface measurement systems.

Surface Topography Assessment of High-Precision Coated Abrasive Tape and Estimation of Its Machining Performance

Summary A topography assessment of coated abrasive tape was dealt with for distinguishing its functional performance. The three-dimensional distribution of projecting abrasive grains on a tape surface was presented and the related geometrical parameters for classifying the coated abrasive tapes were proposed. A comparison was made between those parameters of the tape surface and the generated surface textured on the aluminum alloy substrate fur magnetic rigid disks. The topographical parameters of textured substrate surface which are based on the profile amplitude. microgeometry near the valley bottoms and their number were correlated fairly well with the spatial distribution of the effective coated abrasive grains in conjunction with working fluid or coolant.

The allowable spacing for lattice data sampling by a round stylus tip and an assessment of the envelope surface

Abstract This paper deals with surface waviness assessment by a commercial three-dimensional stylus instrument. To measure macroscopic waviness curve on an engineering surface, it was proposed to use a round stylus tip of relatively large radius. Developed in this paper, is a method to obtain the appropriate stylus tip radius in accordance with the sample surface texture and the corresponding discrete spacing for lattice data sampling. On condition that any two adjacent height data points are well-correlated, the statistical mean height and the overall deviation of the 3-D undulation summit height are also presented for a functional evaluation of waviness curves or envelope surface.

Analytical study on optically measured surface profiles of referential geometry using a finite-difference time-domain method

This paper deals with the functional performance of optical surface texture measuring instruments on the market. It is well known that their height response curves against certain referential geometry are not always identical to each other. So, a more precise study on the optical instruments characteristics is greatly needed. Firstly, we developed a new simulation tool using a finite-difference time-domain technique, which enables the prediction of the height response curve against the fundamental surface geometry in the case of the confocal laser scanning microscope. Secondly, by utilizing this new simulation tool, measurement results, including outliers, were compared with the analytical simulation results. The comparison showed the consistency, which indicates that necessary conditions of surface measurement standards for verifying the instrument performance can be established. Consequently, we suggest that the maximum measurable slope angle must be added to evaluation subjects as significant metrological characteristics of measuring instruments, along with the lateral period limit. Finally, we propose a procedure to determine the lateral period limit in an ISO standard.

A Study on Surface Material Measures for Areal Surface Texture Measuring Instruments: Measuring Conditions for the Areal Profiling

This paper describes the software gauge data for surface texture standard using the non-causal 2D auto-regressive model (A-R model). This model can provide with 3D irregular surface topography and intentional geometrical characteristics from specified surface texture parameters. The measurement area consists of a periodical combination of the generated sampling area data. The surface roughness parameters introduced from the gauge data on a defined evaluation area can be insensitive to size and location of the evaluation area size. Adequate measuring conditions to utilize the surface material measures were investigated and then the evaluation area and sampling distance for areal profiling by a stylus instrument were clarified.

Surface texture assessment in the tangential direction of a rigid magnetic disk to reduce the friction force between head and disk surface

The disk surface texture was assessed in both the radial and tangential directions to estimate the size and number statistics of real contact spots at the head-disk interface and the friction force between head and disk surface. It was demonstrated that textured disks having similar characteristics in the radial direction show different profile features in the tangential direction. The relatively large values in wave peak undulation and its tangential spacing in the tangential direction reduced the frictional force in CSS tests. The friction force increases with apparent radius of curvature of the significant wave peaks determined by rolling a virtual circle over the macroscopic profile in the tangential direction. >

A practical method of optical measurement for the minute surface roughness of cylindrical machined parts

Abstract An optical measuring method is presented for estimating a statistical parameter of surface roughness in both plane surfaces and cylindrical surfaces. The experimental apparatus using this principle consists of an He-Ne laser beam, a cylindrical lens, a one-dimensional charge-coupled device image sensor and some data-processing devices, and it can measure the intensity distribution of reflected laser light with fine resolution of the linear location and also compensate for the effect of cylinder diameter on the measured data. Through the experimental investigations suitable measuring conditions have been obtained, and it is verified that the present measuring system is applicable to the in-process measurement of surface finish for high-toned engineering surfaces.

A geometrical assessment of machined ceramic surface for estimating fatigue strength

Abstract Effects of surface micro-geometry on fatigue strength of silicon nitride(Si 3 N 4 ) were discussed and the data-processing techniques for a geometrical assessment of its surface finish were developed. Taking no account of conventional roughness standards, new topographical parameters based on profile valleys were proposed to correlate with the fatigue strength of test specimens. The sampling conditions and the calculation method were examined in detail. Judging from the experimental results of fatigue tests, it was made clear that the fatigue strength of Si 3 N 4 can be estimated to some extent with the statistical values on the micro-geometry at the bottom of valleys. The metrological discussion on the correlation was also made.