Contact Stylus Research Articles

Some of the parameters influencing surface roughness of particleboard

The objective of this study is to evaluate the effects of raw material type, pressure, shelling ratio and density on the surface characteristics of particleboard. The surface roughness was measured using contact stylus method. Mean peak-to-valley height ( R z) was used to evaluate surface characteristics of the specimens. Measurements were taken from both sides of the specimens along and across the sand marks. The results showed that raw material type, shelling ratio, density and pressure affected the surface roughness of particleboard, statistically ( p ⩽ 0.01 ). Increasing the shelling ratio, board density and pressure improved the surface roughness of particleboard, significantly. Boards consisting of a greater amount of pine particles had lower surface roughness values than those of panels consisting of more beech particles.

Surface texture characterization of injection‐molded pigmented plastics

AbstractAn appropriate description of the surface textures deliberately created on injection‐molded plastic parts of interior car components is presented. A spatial wavelength‐dependent analysis is used as an interesting alternative to the traditional roughness parameters. Auto‐correlation functions and power spectral densities are examples of such spectral functions that include parameters both in amplitude and profile directions. Even fractal concepts can be useful descriptors. As an illustration, it is also shown how the effects on the surface topography of the plastic part of after‐etching the mold can be assessed by suitable descriptors. An experimental evaluation of injection‐molded plaques containing three different surface patterns was carried out using an optical profilometer, supplemented by contact stylus measurements. The ability to assess the topography of these plaques by means of a new fast photometric stereo‐technique, denoted OptiTopo, was also evaluated. In its present form, however, this technique does not provide a detailed description of the topography of a pigmented plastic. Reasons for this and possible improvements are discussed. Polym. Eng. Sci. 44:1615–1626, 2004. © 2004 Society of Plastics Engineers.

Enamel loss associated with orthodontic adhesive removal on teeth with white spot lesions: an in vitro study

Teeth with white spot lesions (WSL) might be more prone to enamel loss during bracket debonding. This in vitro study compared enamel loss from teeth with (n = 14) and without (n = 14) WSL after polishing with low-speed finishing burs or disks (Sof-Lex, 3M ESPE, St Paul, Minn). Debonded surfaces were analyzed with a contact stylus profilometer, and digitized data were compared with baseline readings by using AnSur NT software (Regents, University of Minnesota, Minneapolis, Minn). Specimen surfaces were also examined with a scanning electron microscope. Two-way analysis of variance was performed to analyze the data. In teeth without WSL, the volume losses were 0.16 mm 3 for the bur group and 0.10 mm 3 for the disk group; the mean maximum depths were 47.7 μm for the bur group and 54.3 μm for the disk group. In teeth with WSL, the volume losses were 0.06 and 0.17 mm 3, and the mean maximum depths were 35.1 and 48.7 μm for the bur and disk groups, respectively. There were no significant differences in enamel loss between the 2 groups of teeth without WSL ( P = .12). However, in teeth with WSL, the burs removed less enamel than the disks ( P = 0.006). Scanning electron microscope examination showed that any damage on the enamel surface was usually located in the cervical third of the teeth. On most specimens, even though tooth surfaces appeared resin-free to the naked eye, there were remnants of it. The differences between groups were so small that they might be clinically insignificant.

Roughness induced dynamic changes of wettability of acid etched titanium implant modifications

Dynamic contact angle analysis (DCA) was used to investigate time-dependent wettability changes of sandblasted and acid-etched commercially pure (cp) titanium (Ti) implant modifications during their initial contact with aqueous systems compared to a macrostructured reference surface. Surface topography was analyzed by scanning electron microscopy and by contact stylus profilometry. The microstructured Ti surfaces were found to be initially extremely hydrophobic. This hydrophobic configuration can shift to a completely wettable surface behavior with water contact angles of 0° after the first emersion loop during DCA experiments. It is suggested that a hierarchically structured surface topography could be responsible for this unexpected wetting phenomenon. Roughness spatial and hybrid parameters could describe topographical features interfering with dynamic wettability significantly better than roughness height parameters. The Ti modifications which shift very sudden from a hydrophobic to a hydrophilic state adsorbed the highest amount of immunologically assayed fibronectin. The results suggest that microstructuring greatly influences both the dynamic wettability of Ti implant surfaces during the initial host contact and the initial biological response of plasma protein adsorption. The microstructured surfaces, once in the totally wettable configuration, may improve the initial contact with host tissue after implantation, due to the drastically increased hydrophilicity.

Evaluation of surface smoothness by laser displacement sensor 1: effect of wood species

The best methods for determining surface roughness in an industrial environment are of the noncontact variety, with reproduction of the profile. The objective of this work was to compare the roughness profile obtained by a contact stylus with a commercial laser displacement sensor (LDS). Measurements were done using 15 wood species with different densities and colors, based on which special triangle profiles were prepared. The accuracy of the laser sensor was examined by statistical analysis of roughness parameters measured from the profiles. Experimental results show that LDS profiles were imitated correctly. However, LDS accuracy depends on the scanned wood properties (density and color), installation position of the sensor, and profile shape. It was found that evaluation of dark and high-density wooden surfaces was imperfect.

Difficulties In Characterising Roll Surfaces

Mill rolls finished by electrical discharge texturing (EDT) are widely used in the manufacture of steel and aluminium alloy sheet / strip. Appropriate selection of process operating parameter levels: peak current, onloff time, polarity, etc., allows a limited degree of independence in specifying roll surface topography in t e r n of surface roughness (Ra), peak count (Pc) and skewness (Rsk), in order to meet specific functional requirements. Experimental work aimed at determining the effect these operating parameters has been carried out and comprehensive surface topography measurements made using a variety of non contact (white light interferometer and laser units) and stylus contact systems. The paper details the significant differences, which occurred in results for Pc and Rsk values between the various measuring devices. In contrast, Ra measurements were fairly consistent. Replicated Rsk readings taken on a Wyko machme 6 months apart typically varied by 300%, and in one case changed from -1.1 to +0.65. Similarly, when comparing results from two apparently identical Wyko units, significant differences were found in Pc, by up to 200%. 3D Talysurf stylus measurement of the same workpiece surfaces gave wildly different Pc values fiom those obtained on the Wyko units, despite use of the same slice levels and analysis software.

Fibroblast growth on surface-modified dental implants: an in vitro study.

A major consideration in designing dental implants is the creation of a surface that provides strong attachment between the implant and bone, connective tissue, or epithelium. In addition, it is important to inhibit the adherence of oral bacteria on titanium surfaces exposed to the oral cavity to maintain plaque-free implants. Previous in vitro studies have shown that titanium implant surfaces coated with titanium nitride (TiN) reduced bacterial colonization compared to other clinically used implant surfaces. The aim of the present study was to examine the support of fibroblast growth by a TiN surface that has antimicrobial characteristics. Mouse fibroblasts were cultured on smooth titanium discs that were either magnetron-sputtered with a thin layer of titanium nitride, thermal oxidized, or modified with laser radiation (using a Nd-YAG laser). The resulting surface topography was examined by scanning electron microscopy (SEM), and surface roughness was estimated using a two-dimensional contact stylus profilometer. A protein assay (BCA assay) and a colorimetric assay to examine fibroblast metabolism (MTT) were used. Cellular morphology and cell spreading were analyzed using SEM and fluorescence microscopy. Fibroblasts on oxidized titanium surfaces showed a more spherical shape, whereas cells on laser-treated titanium and on TiN appeared intimately adherent to the surface. The MTT activity and total protein were significantly increased in fibroblasts cultured on titanium surfaces coated with TiN compared to all other surface modifications tested. This study suggests that a titanium nitride coating might be suitable to support tissue growth on implant surfaces.

Plaque formation on surface modified dental implants. An in vitro study.

Bacterial adhesion on titanium implant surfaces has a strong influence on healing and long-term outcome of dental implants. Parameters like surface roughness and chemical composition of the implant surface were found to have a significant impact on plaque formation. The purpose of this study was to evaluate the influence of two physical hard coatings on bacterial adhesion in comparison with control surfaces of equivalent roughness. Two members of the oral microflora, Streptococcus mutans and Streptococcus sanguis were used. Commercially pure titanium discs were modified using four different surface treatments: physical vapour deposition (PVD) with either titanium nitride (TiN) or zirconium nitride (ZrN), thermal oxidation and structuring with laser radiation. Polished titanium surfaces were used as controls. Surface topography was examined by SEM and estimation of surface roughness was done using a contact stylus profilometer. Contact angle measurements were carried out to calculate surface energy. Titanium discs were incubated in the respective bacterial cell suspension for one hour and single colonies formed by adhering bacteria were counted by fluorescence microscopy. Contact angle measurements showed no significant differences between the surface modifications. The surface roughness (Ra) of all surfaces examined was between 0.14 and 1.00 microm. A significant reduction of the number of adherent bacteria was observed on inherently stable titanium hard materials such as TiN and ZrN and thermically oxidated titanium surfaces compared to polished titanium. In conclusion, physical modification of titanium implant surfaces such as coating with TiN or ZrN may reduce bacterial adherence and hence improve clinical results.

Application of the lifting wavelet to rough surfaces

This paper proposes a lifting wavelet model for enhancement of accuracy of surface roughness characterisation. In this work, the theory and fast algorithm of the lifting wavelet are briefly introduced and a lifting wavelet model for extraction of roughness of surfaces has been developed. The rough surface recovered has good refinement accuracy in contrast to the least squares polynomial fitting. Applications are conducted by using a series of typical surfaces, planes and curves, measured by contact (stylus) and non-contact (phase-shifting interferometry) instruments, to demonstrate the feasibility and applicability of using the lifting wavelet model in the analysis of these surfaces.

The Many Faces of Turbine Surface Roughness

Results are presented for contact stylus measurements of surface roughness on in-service turbine blades and vanes. Nearly 100 turbine components were assembled from four land-based turbine manufacturers. Both coated and uncoated, cooled and uncooled components were measured, with part sizes varying from 2 to 20 cm. Spanwise and chordwise two-dimensional roughness profiles were taken on both pressure and suction surfaces. Statistical computations were performed on each trace to determine centerline averaged roughness, rms roughness, and peak to-valley height. In addition, skewness and kurtosis were calculated; as well as the autocorrelation length and dominant harmonics in each trace. Extensive three-dimensional surface maps made of deposits, pitting, erosion, and coating spallation expose unique features for each roughness type. Significant spatial variations are evidenced and transitions from rough to smooth surface conditions are shown to be remarkably abrupt in some cases. Film cooling sites are shown to be particularly prone to surface degradation.

Development of a lifting wavelet representation for surface characterization

This paper reviews the existing numerical analysis methods and their problems in surface metrology. Based on the requirements of functional analysis of surfaces, this paper proposes a lifting wavelet representation for extraction of different components of a surface. The theory of the lifting wavelet is introduced and a fast algorithm is developed. Different frequency components of the surface can be separated, extracted and then reconstructed according the intended requirements of functional analysis. The surface textures can be highlighted and multi-scalar topographical features can be identified and clearly recovered. In order to verify the behaviour of the new model, a computer simulation based on sinusoidal and triangular waveforms is used. Case studies are conducted using a series of typical surfaces of engineering and bioengineering, such as planes, cylinders and curves, measured by contact (stylus) and non-contact (phase-shifting interferometry) instruments, to demonstrate the feasibility and applicability of using the lifting wavelet model in the analysis of these surfaces.

In vivo evaluation of the surface of posterior resin composite restorations: A pilot study

Statement of Problem. Several methods have been used to determine the surface characteristics of resin composites in vivo and compare composite wear rates with enamel wear rates. Purpose. This pilot study describes the surface characteristics of resin composites and the wear of resin composites and enamel during 1 year of in vivo service. Material and Methods. A single Class II posterior resin composite restoration (Z100) was placed in 10 patients. Restored teeth and unrestored adjacent control teeth were measured for wear 4 times within the first year. A null point contact stylus profiler and fitting software were used to measure epoxy casts. Maximum depth of wear, average depth of wear, and characteristics of the restoration margin were determined. Paired t tests were used to compare the control and restored teeth, and ANOVA was used to assess the progression of wear over time (P<.05). Results. After 1 year, maximum depth of wear over the entire preparation region was on average 204.8 μm (± 129.8), significantly greater than the 36.8 μm (± 10.1) average maximum depth of wear of enamel at occlusal contact areas on control teeth (P=.009). Maximum depth of wear progressed over time (P=.009). Fracture of excess composite, commonly called flash fracture, occurred in 50% of the restored teeth extending over the preparation margin. Conclusion. Composite restorations wore significantly faster than enamel contact areas on control teeth. Also of concern were the marginal flash fractures that could facilitate secondary caries. (J Prosthet Dent 2000;84:353-9.)

Evaluation of the root-mean-square slope of 3D surface topography

Based on the application of fractal geometry theory, a quantitative evaluation method of root-mean-square (RMS) slope of 3D homogeneous and stochastic surface topography is proposed, by means of the concept of surface spectral moments. Through the FFT of discrete data from the profiles measured by a Talysurf-5 contact stylus instrument, the power spectrum and the fractal dimensions of the profiles are obtained. Furthermore, the second order spectral moments of the profiles and the surfaces are found. These parameters are used to define the evaluation measure of RMS slope of the surface. By the experiments for ground and fine turned specimen, the results confirm the correctness of this method.

Evaluation of the root-mean-square wavelength of machined 3D surface topography

Based on the application of fractal geometry theory, a quantitative evaluation method of root-mean-square wavelength of 3D stochastic surface topography is proposed, by means of the surface spectral moments. Through the FFT of the discrete data of the profile measured by a Talysurf-5 contact stylus instrument, we obtained the power spectrum and the fractal dimension of the profile. Furthermore, the zero and 2nd order spectral moments of the profile and the surface are found. Using these parameters, the evaluation of RMS wavelength may be processed. By the experiments for ground samples, the results confirm the correctness of this method.

The influence of CarisolvTM on enamel and dentine surface topography

The purpose of the present study was to investigate the surface topography of healthy enamel and dentine before and after application of a new chemomechanical system for caries removal, Carisolv. The same surfaces were investigated with respect to the influence of phosphoric acid, plus carious dentine after removal with either Carisolv or burrs. One-hundred freshly extracted teeth were used. Surface topography was measured in two different ways in order to characterize the surfaces at different levels of resolution, atomic force microscopy (AFM) and a contact stylus profilometer. Somewhat conflicting data were obtained with the two measuring techniques. When surfaces were investigated over a small area (AFM), healthy enamel seemed unaffected by Carisolv, while healthy dentine became smoother. Etching enamel with phosphoric acid resulted in a rougher surface, while no effect was detected on etched healthy dentine. Caries removal using Carisolv resulted in a smoother surface compared with conventional caries removal. When the surfaces were monitored with the contact profilometer, no effect of Carisolv could be detected on healthy enamel or dentine. Phosphoric acid etching, in contrast, increased the surface roughness of both enamel and dentine. When compared with conventional caries removal technique, caries removal with Carisolv did increase the surface roughness.

Stylus contact method for surface metrology in the ascendancy

Stylus contact method for surface metrology in the ascendancy

Comparison of two stylus methods for measuring surface texture

Objectives: The purpose of this study was to evaluate and compare two “stylus” methods for measuring surface texture of dental tissues and materials Methods: The two styli chosen were a contact diamond stylus and a non-contact focussed laser stylus attached to the same measuring apparatus. Results: These indicate that there are significant differences between those obtained from surface texture measurements using a non-contact laser stylus and a diamond contact stylus method despite being mounted in the same profilometer. This is valid for both the test specimens of known surface texture, provided by the manufacturers, and for a “real world” simulation using contoured and finished Dicor ceramic blocks. The only significant agreement between the two styli was found for the R a parameter. This should not be used alone to describe the roughness of a surface because the parameter is not sensitive to profile shape. Owing to the properties of the stylus used it is essential that the limitations of surface profilometry be recognised. Significance: Caution should be exercised when comparing the results of surface texture studies of dental hard tissues and restorative materials using varying types of stylus attached to a surface profilometer.

Dimensional changes during veneering procedures on discoloured teeth

Objectives: The aim of the study was to determine the dimensional changes of teeth when veneering procedures are involved. Methods: Fifteen discoloured central incisors were selected from a group of 180 veneer restorations (VRs) composed of three different types of materials (direct resin composite, indirect resin composite and porcelain). Impressions and dies were made before treatment, after preparation and after placement and finishing the restoration. Contact stylus profilometry and subsequent analysis of the 3-D surface images provided quantitative data of the differences between the various treatment phases. Results: The preparation reduction was the most for indirect resin composite VRs and the least for direct resin composite VRs. All veneer restorations showed nearly the same thickness and dimensional change after treatment, except one, which resulted in an additional increase of volume of the tooth. Conclusion: From the results of this study it is concluded that the dimensions of a discoloured tooth treated with a veneer restoration unintentionally increased, resulting in overcontour.

Stylus Contact Method for Surface Metrology in the Ascendancy

Stylus Contact Method for Surface Metrology in the Ascendancy

共焦点光学系の走査型レーザ顕微鏡による表面凹凸形状測定と機能的ディジタルフィルタ処理

By using a confocal scanning laser microscope (SLM) which is commercially available, the topography data of surface texture can be easily obtained in a short time. However, unreasonable short-wavelength components tend to be included in the raw data, when compared with the data obtained through a contact stylus instrument. In order to eliminate such noisy components, a digital filtering process was proposed and its design procedure in the spatial frequency domain was developed. The functional performance of the digital filtering was discussed with regard to the surface texturescreated by several machining methods. A fairly good agreement was reached between the corrected SLM data and the reference data in respect of perspective 3-D plots and some conventional roughness parameters. On the other hand, this filtering process showed unsatisfactory effects on certain local geometry parameters of surface texture.