Stylus Tip Radius Research Articles

Stylus tip radius and wear estimation using the Rsk or the Rp and Rv parameter of a sine wave (Type C1) standard

Determination of the stylus tip radius and its wear or damage is a classical problem in tactile surface topography measurements. The determination of the stylus geometry may be tedious and inconvenient, therefore we looked for an easily applicable method. This study shows that the Rsk parameter and the difference between the Rv and Rp parameter may indicate the stylus tip radius as well as wear when using a sine-wave profile material measure, which is commonly supplied with a roughness tester for calibrating and/or adjusting the vertical amplification coefficient. This effect is derived from theoretical calculations on real and simulated styli and specimens and verified experimentally using two commonly used specimens and stylus tips with radii of nominally 1, 2, 5, and 10 µm. When using a standardized stylus with a nominal 2 µm tip radius and 60° cone angle on a typical C1 reference specimen with nominal parameters Ra = 3 µm and RSm = 100 µm, the Rsk value should be approximately −0.01. Any stylus wear will decrease the measured Rsk value. When the Rsk value decreases to a value of −0.06 or lower it may be time for closer inspection and/or replacement of the stylus.

On-machine non-contact roughness verification system based on Conoscopic holography

The surface quality verification of mechanical components is an essential activity in many applications where surface performance plays an important role in the functional behaviour of the part. Although many of the verification techniques commonly employed are based on the use of contact roughness profilometers, there are some limitations related to the morphological filtering effect associated to the stylus tip radius, as well as the difficulty in using these type of styli to carry out on-machine surface verification. The use of non-contact digitizing techniques helps to overcome some of these drawbacks, although the verification of surface quality using these non-contact systems still requires the development of scanning and data processing procedures similar to those described in the international standards for contact probing techniques. This work analyses the use of a non-contact sensor, based on Conoscopic Holography and integrated in a 3-axis machining centre, applied to the verification of the surface roughness of parts machined by face and cylindrical milling processes. After the calibration of the integrated system, a high-frequency noise filtering procedure specifically designed for roughness verification is proposed. The results demonstrate the feasibility of the system for verifying surface roughness grades from N5 to N12 in the two milling processes. Finally, specific filtering recommendations for each roughness grade of both milling processes as well as a surface verification procedure are provided.

Assessment of the effect of stylus tip radius on milled, bored, and honed surfaces

This paper deals with evaluation of the effect of the stylus tip radius on the roughness parameters on milled, bored, and honed surfaces of the crankcase of hermetic compressors manufactured in gray cast iron. Roughness measurements were carried out on machined surfaces of 10 hermetic compressors using a 2-μm and a 5-μm stylus tip radius. For milled and bored surfaces, Rp, Rv, Rz, Rt, Ra, Rq, and RΔq roughness parameters were obtained, whereas for honed surfaces, Rk, Rpk, and Rvk were studied. From the obtained results, it was concluded that for milled and bored surfaces, only the values of RΔq presented statistically significant differences, considering a confidence level of 95%. However, particular attention should be given to the Rv parameter whose p values were higher than 0.05, but very close to it. For honed surfaces, the average values of Rpk and Rk parameters were higher for measurements carried out using a 5-μm stylus tip radius, due to the increase of the peak radius of curvature. No statistically significant difference related to Rpk, Rk, and Rvk parameters was identified.

The effect of stylus tip radius on Ra, Rq, Rp, Rv, and Rt parameters in turned and milled samples

This study aims to investigate the effect of the stylus tip radius factor on the values of roughness parameters (Ra, Rq, Rp, Rv, and Rt) obtained by an electromechanical surface roughness tester. The study was based on a single factorial design, where the stylus tip radius was investigated in two levels (2 μm and 5 μm). The roughness measurement was carried out in samples of SAE 1020 carbon steel and gray cast iron, obtained by turning and milling processes for different cutting conditions. During the turning and milling processes, the cutting depth assumed 0.5 mm and 1.0 mm values; and the feed rate was equal to 0.1 mm/rot and 0.2 mm/rot. The uncertainty associated with the measurement of all the evaluated parameters was estimated by applying the GUM method. The analysis of variance (ANOVA) was applied, and it was observed that the stylus tip radius factor did not cause statistically significant effects on the Ra, Rq, Rp, Rv, and Rt parameter values for 54 % of all evaluated conditions. However, the differences between the Ra, Rq, Rp, Rv, and Rt average values obtained using 2-μm and 5-μm radius stylus tips were lower than the values of the associated expanded uncertainty (95 %) in 82 % of performed experiments.

3-Dimensional profile distortion measured by stylus type surface profilometer

In this paper, the distortion effect in measured profiles caused by stylus tip radius size of stylus-typed surface profilometer was analyzed in terms of 2D and 3D. On the basis of our analysis results, we propose selection criteria for the stylus tip radius to improve the reliability of measurement results. For this purpose, a simulation algorithm has been devised and implemented for 2D and 3D measurement simulations, and the 3-dimensional surface texture used in simulation was obtained using an Atomic Force Microscope (AFM) on an actual machined surface to improve the reliability of simulation results. The simulation results are compared with the measured results from the same specimen using a roughness tester, and the validity of analysis via the simulation proposed in this study is confirmed. Cumulative power spectral analysis was performed for the 2D and 3D simulated profiles obtained from simulation. On the basis of the analysis results, an effective frequency components field using a stylus type profilometer is clarified, and the selection criteria of the stylus tip radius for measurement is proposed considering the surface texture characteristics of the specimen. The purpose of this paper is to provide a basis of a simple and effective method which could be an alternative of some engineering standard that specifies selection of stylus tip radius for the measurement using only nominal Rq for machined surface.

Assessment of surface profile data acquired by a stylus profilometer

This paper analyzes the 2D and 3D distortion effects of a measured profile caused by the stylus tip radius of a stylus-type surface profilometer. On the basis of our analysis results, we propose the selection criteria for the stylus tip radius to improve the reliability of measurement results. For that purpose, a simulation algorithm has been devised and implemented for 2D and 3D measurement simulations, and the 3D surface texture used in simulation was obtained using an atomic force microscope from an actual machined surface to improve the reliability of simulation results. The simulation results were compared with the measured results from the same specimen using a roughness tester, and the validity of analysis via the simulation proposed in this study was confirmed. Cumulative power spectral analysis was performed for the 2D and 3D simulated profiles obtained from simulation. On the basis of the analysis results, an effective frequency component field was clarified using a stylus-type profilometer, and the selection criteria of the stylus tip radius for measurement were proposed considering the surface texture characteristics of the specimen.

A comparison of surface roughness analysis methods applied to urinary catheters

The resolution of conventional tactile surface roughness measurement is limited by the stylus tip radius since the stylus can only make a good contact in a valley wider than tip diameter. A 3D scanning electron microscopy (SEM) technique, namely SEM stereo-imaging, was used to reconstruct the surface features of 12 different catheters to validate tactile measurement results. It is demonstrated that if the surface roughness and the stylus tip differ by one order of magnitude, the results of the tactile measurement may not be reliable.

Uncertainty of wavelength limitation due to stylus tip radius for engineering surface texture based on wavelength and amplitude by FFT

In contact stylus measurement, profiles are affected by the radius of the stylus tip. This fact has been presented in the annex of ISO 3274:1996 as the uncertainty of wavelength limitation due to the stylus on a chart of the transmission characteristics. In this standard, however, the logical process to introduce the wavelength limitation has not been mentioned. This paper reveals that the gain of transmission is given by the enveloping sinusoidal curves of Fourier series with a contact stylus tip. The relationship between wavelength and amplitude for this analysis is introduced by applying power law index to Fractal-like or Markov-process-like power spectral density function of the surface asperities. The results presented in this paper are very close to the wavelength limitation shown in ISO 3274.

The influence of stylus flight on change of surface topography parameters

Theoretical and experimental work on stylus flight is described. The paper describes the development of a simulation model for assessing the magnitude of surface topography distortion by stylus flight. Experiments on the surfaces support the theoretical model, which predicts stylus flight. The measurements of different surface topographies (including surfaces after grinding, turning, honing, milling) were done using Talyscan 150 measuring instrument with four traversing speeds (0.5, 1, 2 and 3 mm/s). The results of theoretical considerations and experiments were compared. The effect of stylus flight on surface topography parameters of measured surfaces basing on experimental investigation was assessed. The tendency was found that slope decreased, decrease of amplitude parameters and increase of horizontal parameters took place, but these effects were different for various surface types. The simulation procedure assured good accuracy of surface topography parameters changes. Based on theoretical investigation, the effect of stylus flight and stylus tip radius on parameters of computer-generated profiles was predicted. The choice of traversing speed to different types of surfaces was done. The parameters of biggest changes caused by error in measurement due to stylus kinematics were selected.

Effect of SiO2Oxide Film on Microfrictional Characteristics of Single Crystal Silicon.

With the development of micro fabrication, single crystal silicon has been used in many microelements such as micromachines. The aim of this research is to clarify the microtribological properties of single crystal silicon to improve their characteristics by silicondioxide overcoat. The specimen used in this experiment is single crystal silicon of (100) and with a overcoat of silicondioxide. Thickness of silicondioxide is 988 nm and 94.7 nm which is coated by plasma CVD method. In this experiment, frictional force between diamond stylus tip (radius of curvature 2 μm and 10 μm) and the surface of single crystal silicon and micro hardness are measured by using scratch tester and dynamic hardness tester. In this paper we show the results of micro friction characteristics of single crystal silicon by silicondioxide overcoat.

Measurement of a Stiffening Layer Density by Acoustic Microscopy

Measurement of a Stiffening Layer Density by Acoustic Microscopy

Dependence of measuring errors of rms roughness on stylus tip size for mechanical profilers

Tracing of a random profile with a mechanical profiler with a spherical tipped stylus has been investigated by means of computer simulation. It is shown that the fractional measuring errors of rms roughness depend on only the ratio of rms roughness varsigma to the stylus tip radius r and the ratio of rms roughness to the 1/e correlation length rho(c). The ratios varsigma/r were in the range of 0.005-0.05 and the ratios varsigma/rho(c) were equal to 0.028 and 0.048.

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

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.

スタイラス走査方式による表面輪郭形状の離散測定条件に関する研究

This paper deals with the three-dimensional surface height profiling at lattice sampling points by a stylus instrument for an assessment of relatively long wavelength of isotropic surface texture. The shortest wavelength was derived from the mean spacing between profile peaks at the mean line obtained by a two-dimensional premeasurement using a sufficiently sharp stylus tip. The allowable measuring conditions such as sampling distance and stylus tip radius were determined by considering both the amplitude sensitivity of the displacement transducer and the virtual autocorrelation curves obtained by rolling imaginary circles over the profile. As the number of discrete sampling points is based on the main memory of an ordinary personal computer, the maximum measurement area was inevitably determined. The macroscopic asperity summits were specially taken into account for a purpose of analyzing the interface between two surfaces in contact. The functional summits were detected from an 8-nearest-neighbor analysis. It was demonstrated that the number and location of the obtained summits are influenced markedly by the measuring conditions and the proposed method for choosing stylus tip radius and sampling distance effects a settlement.

イオンプレーティング法によるＴｉＮ皮膜のスクラッチ試験における密着性の評価

Adhesion is one of the most important properties in the field of ceramics coating. To evaluate adhesion, the scratch test is widely used because of its easy operation. Adhesion is generally evaluated by measuring the critical load Lc, but it is well known that Lc depends on many factors such as substrate hardness. However, the dynamical meaning of Lc and the mechanism of coating failure have not been sufficiently clarified.In this study, scratch tests were carried out on TiN films applied to SKH 51 by ion plating to clarify the relationship between the modes of coating failure and the frictional force, and also some factors that influence the critical load were investigated from the point of plastic deformation. The experimental results obtained were as follows: (1) In the scratch channel, three types of cracks, partial coating loss, and overall coating loss were observed with the increase of vertical load. Partial coating failure involved oblique cracks extending from the edge of the channel. (2) Frictional force changed similar to vibration corresponding to the partial coating loss and increased rapidly corresponding to the overall coating loss. These changes of frictional force enabled the determination of critical load (the load at which partial coating loss starts to develop: Lc1, and the overall loss load: Lc2). Lc1 and Lc2 depended on the substrate hardness, while the widths of channels Wc1, Wc2 were almost same regardless of the substrate hardness. (3) Lc1 depended on coating thickness, while the critical contact angle θci, was almost same regardless of coating thickness. Furthermore, Lc1 depended on stylus tip radius R and was proportional to R1.4, while the critical contact angle θci was almost same.

Comparison of some instruments for measuring mirrorlike surfaces

Surface roughness measurements of pitch-polished surfaces by surface profilometers that have nanometer-order resolution are reported. The specimens used are made of fused quartz or silicon wafer. Two different polishing conditions are adopted. The four specimens obtained are measured by means of surface profilometers employing four stylus methods and four optical methods. In addition, the effects of stylus tip radius, measuring pressure and so on are examined. The specimens are adequate for surface roughness standards because of their flatness and their insensitivity to stylus tip radius or measuring pressure. In the eight measurements, the values of the surface roughness are scattered. The values obtained by optical methods are apt to be bigger than those obtained by stylus methods. The optical methods are inappropriate for measurements on transparent specimens. Ra or RRMS are more suitable for representing the surface roughness of ultraprecision machined surfaces than Rmax. The estimate that the value of Rmax is 10 times Ra applies well.

Importance of checking the stylus radius in the measurement of surface roughness

All national and international standards on the assessment of surface roughness are based on the profile of a surface traced by a suitable stylus. The accuracy of this measurement and its numerical evaluation for determining the surface parameters depend on the fidelity of the representation of the trace to the cross-sectional profile of the part. However, for a perfect reproduction of the traced surface, the stylus tip radius should be as small as possible. Different styli or worn styli present different results. The difference lies in the determination of the trajectory drawn through the surface profile, to which the surface roughness height is referred. The extent of this difference due to a worn stylus is not known. In this paper results obtained using two different styli are compared: one is up to the standard and the second deviates slightly from it. Comparison between the results is included, confirming the existence of a large discrepancy between the two cases.

Closure to “Discussion of ‘Assessing the Effect of Stylus Tip Radius and Flight on Surface Topography Measurements’” (1984, ASME J. Tribol., 106, p. 209)

Closure to “Discussion of ‘Assessing the Effect of Stylus Tip Radius and Flight on Surface Topography Measurements’” (1984, ASME J. Tribol., 106, p. 209)

Assessing the Effect of Stylus Tip Radius and Flight on Surface Topography Measurements

The mean square height, slope, and curvature are characteristics of roughness microgeometry that govern the performance of real surfaces in elastic contact. The values of these quantities deduced from stylus profile traces are distorted by the nonlinear filtering effect of the finite stylus tip and by the failure, at high enough tracing speeds of the stylus to maintain contact with the profile being traced. This paper describes the development of a simulation model for assessing the magnitude of this distortion as well as the effect of record length and sampling frequency with tracing profiles that are realizations of a random process having a specified spectrum. Illustrative parametric runs of the model are discussed.

The deformation and twinning of graphite crystals under a point load

Abstract The deformation produced by point loading on the cleaved basal surfaces of graphite crystals has been studied in the scanning electron microscope. The experiments were of two types, viz. sliding and static contact. In the first a small tungsten stylus (tip radius ∼ 1 μm) was slid on the graphite surface inside the scanning electron microscope and the resulting damage observed as it occurred. The marked anisotropy and the limited number of slip systems of the graphite structure result in a characteristic deformation mode which involves the cleavage of thin flakes followed by folding of the partially separated layers. In the second type of experiment the deformation produced by a diamond indenter was studied. These experiments showed that the hardness value of c. 4.8 × 107 N/m2 for naturally-occurring graphite and 22 × 107 N/m2 for neutron-irradiated graphite are determined by a cleavage and folding process and are not related to the basal plane shear strength. It is suggested that the mechanism of folding in both types of experiment is one of mechanical twinning. An important feature of the deformation process is that the dislocation walls forming the twin boundaries are mobile under the applied stress and are free to run in the newly formed chips and flakes in a direction parallel to the basal plane. The greatly increased hardness of neutron-irradiated graphite is explained by the reduction in mobility of the twin boundaries due to the high point defect concentration.