3D Surface Topography Research Articles

Analysis of Anisotropy in Turned Surfaces Using Vision Based 3D Surface Topography

Abstract Anisotropy in machined surfaces has a significant effect on the functional performance of an engineering surface. Complexity in surface topography directly affects a component’s functional performance, such as load bearing, friction, wear, surface roughness, and fluid retention properties. The anisotropic and isotropic nature of surfaces could be disregarded for 2D surface characterization, but they are of fundamental importance to 3D surfaces for characterization, which is a result of cutting motion; thus, the machined surfaces consist of fluctuations, peaks, and valleys. The surface topography of the workpiece can be viewed more precisely by viewing it under micro scale magnification. In the present work, an attempt has been made to investigate the effect of the tool condition in machining processes on different workpiece surfaces and to investigate the resulting 3D surface topography on friction and wear properties of machined components. The 3D surface topography parameters, such as Sa, Sq, Ssk, Sku, and Sdr, are extracted by using commercial software (TalySurf10). Subsequently these parameters are used to compare and analyze the specific-functional performances of the tool. The encouraging results of this work pave the way for the analysis of the machined surface and the development of real-time and reliable tool-condition monitoring systems.

Model for the prediction of 3D surface topography and surface roughness in micro-milling Inconel 718

Nickel-based superalloy Inconel 718 retains high strength at high temperature, which meets the requirements of micro-parts in the fields of aerospace, energy, and power. However, Inconel 718 is a kind of difficult-to-machine material. During the micro-milling process, scale effect, multiple regenerative effect, and dynamic response all affect its surface roughness, causing the prediction of surface roughness of micro-milled parts difficult. To solve this problem, we study the predictive modeling of surface roughness of micro-milled Inconel 718. Based on the previously built instantaneous cutting thickness model, cutting force model, and the dynamic characteristics of micro-milling system, the authors establish a flexible deformation model of micro-milling cutter generated by cutting force. Since the machined surface is generated by duplicating the tool profile on the workpiece surface, and based on the actual cutting trajectory as well as flexible deformation of micro-milling cutter, the authors build the surface topography simulation model to predict surface roughness and conduct experiments to verify the accuracy of the model. The research realizes the prediction of surface roughness of micro-milled Inconel 718 parts and partially reveals the machining mechanism of micro-milling.

Calcite dissolution rate spectra measured by in situ digital holographic microscopy

Digital holographic microscopy in reflection mode is used to track in situ, real-time nanoscale topography evolution of cleaved (104) calcite surfaces exposed to flowing or static deionized water. The method captures full-field holograms of the surface at frame rates of up to 12.5s−1. Numerical reconstruction provides 3D surface topography with vertical resolution of a few nanometers and enables measurement of time-dependent local dissolution fluxes. A statistical distribution, or spectrum, of dissolution rates is generated by sampling multiple area domains on multiple crystals. The data show, as has been demonstrated by Fischer et al. (2012), that dissolution is most fully described by a rate spectrum, although the modal dissolution rate agrees well with published mean dissolution rates (e.g., 0.1μmolm−2s−1 to 0.3μmolm−2s−1). Rhombohedral etch pits and other morphological features resulting from rapid local dissolution appear at different times and are heterogeneously distributed across the surface and through the depth. This makes the distribution in rates measured on a single crystal dependent both on the sample observation field size and on time, even at nominally constant undersaturation. Statistical analysis of the inherent noise in the DHM measurements indicates that the technique is robust and that it likely can be applied to quantify and interpret rate spectra for the dissolution or growth of other minerals.

Research about modeling of grinding workpiece surface topography based on real topography of grinding wheel

Modeling of grinding workpiece surface topography is the foundational research about the service performance of the workpiece surface. In this paper, we focus on the real surface topography modeling of the grinding wheel and the digital generation method of the grinding workpiece surface based on the real surface of the grinding wheel. First of all, the grinding wheel surface is restructured based on the measured grinding wheel surface data after completing the filtering process and getting the characteristic parameters from the moving-average model to solve inaccuracy problem. According to the grinding kinematics, the motion trajectory equations of the abrasive grains are established. The surface topography of the workpiece is generated by the Boolean operation, and the optimization algorithm is used to solve the problem of large amounts of calculation and long operation time in the numerical modeling of 3D surface topography. Finally, the accuracy of the model is verified by comparing with the characteristic parameters of the groove and the roughness parameters of the experimental surface, which are the most important parameters in the surface topography.

AFM tip-based mechanical nanomachining of 3D micro and nano-structures via the control of the scratching trajectory

This paper presents a novel mechanical material removal method to produce nanostructures with a precise control of their three dimensional (3D) surface topography. The method employs the tip of an atomic force microscope (AFM) probe as the cutting tool and a closed-loop high precision stage to control the machining path of the tip. In this approach, the tip only describes vertical motions while the stage is actuated along lateral directions in a raster scan strategy. The machining of features with 3D nanoscale topography in this way is the combined result of the tip applying a constant normal load on the sample while varying the distance (i.e. the feed) between two parallel lines of cut. More specifically, an increased feed leads to a reduced machining depth and vice-versa. Thus, the main difference with mechanical milling or turning at such small scale is that this method relies on the control of the feed to determine the machined depth. To support the interpretation of the process outcomes, an analytical model is developed. This model expresses the relationship between the feed and the machined depth as a function of the contact area between the tip and the material. The critical achievable slope of produced nanostructures was derived from this model and validated using experimental tests. This parameter corresponds to the maximum inclination of the surface of a nanostructure that can be machined with the proposed method. From the knowledge of the critical slope, the machining of periodic nanostructures was demonstrated on a single crystal copper workpiece. In principle, the method reported here could be implemented to any instrument with micro- and nano-indentation capabilities by exploiting their load-control feedback mechanism.

Influence of heating parameters on properties of the Al-Si coating applied to hot stamping

The Al-Si coating of ultra-high strength steel has been applied to hot stamping more and more widely, owing to solving the problem of oxidation and decarburization. However, the evolution of Al-Si coating during the heating process was rarely studied in the previous study. The tests about the influence of heating parameters, such as heating temperature, heating rates and dwell time, on properties of the Al-Si coating were carried out on the Gleeble-3500 thermal simulator. The properties of the Al-Si coating, for instance, volume fraction of FeAl intermetallics, α-Fe layer as well as porosity and 3D surface topography, were explored in the study. Results showed that more and more Kirkendall voids and cracks appeared in the Al-Si coating when the heating temperature exceeded 600°C. The heating rates almost had no influence on properties of the Al-Si coating when the temperature was equal to or lower than 500°C. The volume fraction of FeAl intermetallics in the coating with dwell time from 3 s to 8 min at 930°C was 0, 6.19%, 17.03% and 20.65%, separately. The volume fraction of the α-Fe layer in the coating changed from zero to 31.52% with the prolonged dwell time. The porosity of the coating ranged from 0.51% to 4.98% with the extension of dwell time. The unsmooth degree of the surface of the coating rose gradually with the increasing of heating rates and the extension of dwell time. The 3D surface topography of the coating was determined by the comprehensive effect of atoms diffusion, new formed phases, surface tension and the degree of oxidation of the coating surface. Experiments indicated that rapid heating was not suitable for the coating when the temperature exceeded 500°C. Experiments also demonstrated that enough dwell time was essential to obtain the superior properties of the coating.

Effect of textured surface on the frictional noise under line contact and sliding–rolling conditions

Line contact and sliding–rolling movements exist widely in gears and bearings. In order to investigate the influence of surface microstructure on the frictional noise, a numerical study on the frictional noise generated by textured surfaces under line contact and sliding–rolling conditions by the use of finite element method is presented. The finite element model is established based on real surface topography. To improve the analysis reliability, friction coefficients used in the simulation are measured for different textured surfaces under various loads and speeds. The relationship between the 3D surface topography parameters and the frictional noise are analyzed. Results show that the frictional noise under line contact sliding–rolling conditions increases with load and speed, which can be explained from an energy dissipation perspective. Moreover, the 3D surface topography parameters of mean peak curvature and peak density influence the frictional noise during sliding–rolling under line contact significantly.

Assessment of Breast Asymmetry in Adolescent Idiopathic Scoliosis Using an Automated 3D Body Surface Measurement Technique

Study designCohort study. ObjectivesTo assess breast asymmetry (BA) directly with 3D surface imaging and to validate it using MRI values from a cohort of 30 patients with significant adolescent idiopathic scoliosis (AIS). Also, to study the influence of posture (prone vs standing) on BA using the automated method on both modalities. Summary of background dataBA is a common concern in young female patients with AIS. In a previous study using MRI, we found that the majority of patients with significant AIS experienced BA of up to 21% in addition to their chest wall deformity. MRI is costly and not always readily available. 3D surface topography, which offers fast and reliable breast acquisitions without radiation or distortion of the body surface, is an alternative method in the clinical setting. MethodsThirty patients with AIS were enrolled in the study on the basis of their thoracic curvature, skeletal and breast maturity, without regard to their perception of their BA. Each patient underwent two imaging studies of their torso: a 3D trunk surface topography and a breast MRI. An automated breast volume measuring method was proposed using a program developed with Matlab programming. ResultsStrong correlations were obtained when comparing the proposed method to the MRI on the left breast volumes (LBV) (r = 0.747), the right breast volumes (RBV) (r = 0.805) and the BA (r = 0.614). Using the same method on both imaging modalities also yielded strong correlation coefficients on the LBV (r = 0.896), the RBV (r = 0.939) and the BA (r = 0.709). ConclusionsThe proposed 3D body surface automated measurement technique is feasible clinically and correlates very well with breast volumes measured using MRI. Additionally, breast volumes remain comparable despite being measured in different body positions (standing and prone) in a young cohort of AIS patients. Level of EvidenceLevel IV.

Three-dimensional Topography Simulation Research of Diamond-wire Sawing Based on Matlab

The influence law of the surface topography and roughness by processing parameters of diamond wire-saw slicing simulation is researched in this paper. At First, the wire saw slicing model is built. The position relation between the wire saw and the machining surface is definite in the model. The motion trajectory of the diamond abrasive on the wire saw is generated. Processing the motion trajectory of the diamond abrasives and the 3D topography of the slicing surface is generated. According to the 3D topography and the roughness formula, the surface roughness can be calculated. Finally, by changing machining parameters, such as wire saw linear velocity and workpiece feed velocity, the corresponding surface roughness will be obtained. Therefore, the influence law of wire saw linear velocity and workpiece feed velocity on the surface roughness is studied. The influence law provides a theoretical basis to improve the quality of wire saw slicing.

Topographical orientation effects on surface stresses influencing on wear in sliding DLC contacts, Part 2: Modelling and simulations

The effects of surface roughness and topographical orientation on surface stresses influencing wear have been investigated for diamond like carbon (DLC) coated steel surfaces with three levels of surface roughness in the range of 0.004–0.11μm Ra values, and with topographical groove orientations of 0°, 45° and 90°. A novel multiscale numerical finite element method (FEM) model was developed to integrate the layered and microstructural material features with the grooved topography. Fractal geometry and a surface voxelisation based approach were utilised to derive 3D surface topography. The surface texture representation includes: fractal signatures, which are sets of fractal dimensions calculated at individual scales in different directions, texture aspect ratio describing surface anisotropy, and texture direction signatures calculated by the variance orientation transform (VOT) method. The simulations show details of the main topographical orientation effects on local stresses affecting wear as they appear at a single scratch test with a spherical diamond ball and in a self-mated sliding situation of two rough surfaces. The 45° sliding direction in relation to grooves resulted in a mixed state of surface loading in the scratch test contact. In the complex state of stress-strain within the roughness peaks the overall tensile stress decreased, leading to greater surface resistance to cracking as compared to 0° and 90° directions. Model based calculations showed that the surface structure was about four times more rigid in the direction of grooves as compared to the more flexible behaviour in the perpendicular direction. This behaviour was empirically confirmed. The numerical calculations of rough vs rough sliding surface include real surface topographical features at various scales, material microstructural features down to nano-scale and topographical-microstructural interaction features. This approximation is thus more comprehensive than the classical approach. The real area of contact was 15–30% of the apparent contact area. The macro-topography dominated the tendency for surface cracking and plastic deformation, which is influencing on both wear and friction, while the micro-topographical features contributed to cracking and deformation by less than 40%.

Multiscale characterisation of 3D surface topography of DLC coated and uncoated surfaces by directional blanket covering (DBC) method

Diamond-like carbon (DLC) coated surfaces exhibit anisotropic and multi-scale characteristics, i.e., their roughness change with both scale and direction. However, most currently used standard surface characterisation parameters and methods work well only with isotropic surfaces at a single scale. This problem can be overcome by variance orientation transform (VOT) and directional blanket covering (DBC) methods. Both methods calculate fractal signatures (FSs) in different directions allowing for detailed measurement of roughness of anisotropic and multiscale surfaces. FS is a set of fractal dimensions (FDs) at individual scales, and FD is a measure of surface roughness. High FD values mean rougher surfaces. Unlike other directional FSs methods, e.g., VOT, the DBC method automatically selects scales of calculations. In this study, the DBC method was used to analyse surface topography images of DLC coated and uncoated bearing steel discs of increasing roughness. Its ability to differentiate between two groups of surfaces is evaluated. The results obtained showed that the DBC method can detect differences in roughness at different scales and directions between the DLC coated and uncoated surfaces. This work could lead to applications of the DBC method in modelling of wear and friction behaviour of DLC coated and uncoated surfaces at different scales.

Prediction of the Interface Temperature Rise in Tribochemical Polishing of CVD Diamond

Tribochemcial polishing is one of the most efficient methods for polishing CVD (Chemical Vapor Deposition) diamond film due to the use of catalytic metal. However the difficulty to control the interface temperature during polishing process often results in low material removal because of the unstable contact process. So this research investigates the contact process in the tribochemical polishing of CVD diamond film and proposes a dynamic contact model for predicting the actual contact area, the actual contact pressure, and the interface temperature in the polishing process. This model has been verified by characterizing surface metrology of the CVD diamond with Talysurf CLI2000 3D Surface Topography and measuring the polishing temperature. The theoretical and experimental results shows that the height distribution of asperities on diamond film surface in the polishing process is well evaluated by combining the height distribution of original and polished asperities. The modeled surface asperity height distribution of diamond film agrees with the actual surface metrology in polishing process. The actual contact pressure is very large due to the small actual contact area. The predicted interface temperature can reach the catalytic reaction temperature between diamond and polishing plate when the lowest rotation speed and load are 10 000 r/min and 50 N, respectively, and diamond material is significantly removed. The model may provide effective process theory for tribochemcial polishing.

3D surface topography analysis in 5-axis ball-end milling

This article presents a new analytical model to predict the topography and roughness of the machined surface in 5-axis ball-end milling operation for the first time. The model is able to predict the surface topography and profile roughness parameters such as 3D average roughness (Sa) and 3D root mean square roughness (Sq) by considering the process parameters such as the feedrate, number of flutes, step-over and depth of cut as well as the effects of eccentricity and tool runout in 5-axis ball-end milling. This model allows to simulate the effects of the lead and tilt angles on the machined surface quality in the virtual environment prior to the costly 5-axis machining operations. The effectiveness of the introduced surface topography prediction model is validated experimentally by conducting 5-axis ball-end milling tests in various cutting conditions.

Repulsive Interaction of Sulfide Layers on Compressor Impeller Blades Remanufactured Through Plasma Spray Welding

This study investigated the repulsive interaction of sulfide layers on compressor impeller blades remanufactured through plasma spray welding (PSW). Sulfide layers on the blades made of FV(520)B steel were prepared through multifarious corrosion experiments, and PSW was utilized to remanufacture blade specimens. The specimens were evaluated through optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, 3D surface topography, x-ray diffraction, ImageJ software analysis, Vicker’s micro-hardness test and tensile tests. Results showed a large number of sulfide inclusions in the fusion zone generated by sulfide layers embodied into the molten pool during PSW. These sulfide inclusions seriously degraded the mechanical performance of the blades remanufactured through PSW.

Non-contact on-machine measurement using a chromatic confocal probe for an ultra-precision turning machine

On-machine measurement (OMM) involves the interruption of the machining process and the subsequent measurement of the workpiece without its removal from the machining tool. Chromatic confocal sensing is a well-known measurement technique that is able to evaluate the position of a point on an object surface along the optical axis of the system with high accuracy. The present study integrates a chromatic confocal measurement probe with an ultra-precision diamond turning machine to achieve the non-contact OMM of machined components. The procedure for establishing the position of the rotary axis of the spindle based on dual standard spheres is first described in detail, and the relevant OMM procedure for machined components of different surface topographies is explained. Then, a 50-μm quartz step height standard is employed to investigate the linear measurement accuracy of the chromatic confocal probe. Finally, the measurement accuracy of the proposed OMM method is compared experimentally with that of the stylus method. The results show that the estimated form error value of the OMM method agrees well with the value obtained by the stylus method. The proposed OMM method feasibly achieves non-contact OMM with a nanometer-level accuracy for an ultra-precision turning machine and is capable of reconstructing the 3D surface topography of flat, spherical, and aspheric surfaces. After integrating the OMM method, the ultra-precision turning machine can realize the function of processing-measurement integration.

The tribological behavior evolution of TiB2/Al composites from running-in stage to steady stage

The purpose of this study was to investigate the characteristics of a friction and wear transition from the running-in stage to the steady-state stage for an Al-based composite containing TiB2 particles and fabricated by a pressure infiltration technique. The dry sliding friction and wear behavior was investigated using a 3.98mm diameter AISI 52100 steel ball-on-disk geometry under applied loads of 1N and 3N. Microstructural characterization and element distribution were carried out using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). 3D surface topographies and roughness of the wear surfaces were measured using confocal laser scanning microscopy (CLSM). The results indicated that the formation of a transfer film and boric acid (H3BO3) was the main reason for the low friction coefficient of about 0.16 at a load of 1N. An increase of friction coefficient was caused by the abrasion of pulled-out TiB2 particles. In the running-in stage at an applied load of 3N, abrasive wear dominated and resulted in the formation of grooves and pulled-out TiB2 particles. In addition, at a steady-stage friction coefficient of 0.6, severe three-body abrasive wear and oxidative wear were the dominant wear mechanisms. An excellent correlation was found between friction coefficient and surface roughness, as measured by 3D topography.

Investigation on the generation of the medium-frequency waviness error in flycutting based on 3D surface topography

Undesirable medium-frequency waviness error along the cutting direction was often left on the machined surface of KDP crystals adopting ultraprecision single-point diamond flycutting (SPDF), reducing the optical performance of KDP crystals and restricting their capability in the inertial confinement fusion (ICF). In order to reduce such medium-frequency waviness error, an indirect method for investigating the generation of the error was proposed in this paper. The tool-tip vibration was indirectly extracted by combining the intermittent cutting trajectory of the flycutting process and the medium-frequency waviness error, which was extracted from the 3D surface topography using 2D wavelet transform method. The main frequency of the extracted tool-tip vibration was calculated and compared with the modals of the machine tool spindle system, which was obtained by FEM analysis and modal test. Finally, an improved spindle system was proposed based on the FEM analysis, and contrast tests between origin and improved machine tool were carried out. Results show that the tool-tip vibration can be effectively extracted by the proposed method, which deduces that the vibration that produced the medium-frequency waviness error is mainly generated by the sixth-order modal of the spindle system. In addition, the quality of the machined surface has been greatly improved with the improved spindle system.

Prediction of the Functional Performance of Machined Components Based on Surface Topography: State of the Art

This survey overviews the functional performance of manufactured components produced by typical finishing machining operations in terms of their topographical characteristics. Surface topographies were characterized using both profile (2D) and 3D (areal) surface roughness parameters. The prediction of typical functional properties such as fatigue, friction, wear, bonding and corrosion is discussed based on appropriate surface roughness parameters. Some examples of real 3D surface topographies produced with desired functional characteristics are provided. This survey highlights technological possibilities of producing surfaces with enhanced functional properties by machining processes.

Posture and low back pain during pregnancy — 3D study

Back pain is a common complaint of pregnant women. The posture, curvatures of the spine and the center of gravity changes are considered as the mechanisms leading to pain. The study aimed to assess spinal curvatures and static postural characteristics with three-dimensional surface topography and search for relationships with the occurrence of back pain complaints among pregnant women. The study was conducted from December 2012 to February 2014. Patients referred from University Clinic of Gynecology and Obstetrics were examined outpatient at the Posture Study Unit of Department of Orthopaedics and Traumatology. Sixty-five women at 4-39 weeks of pregnancy were assessed and surveyed with Oswestry Disability Index; posture was evaluated using surface topography. The study confirmed that difficulties in sitting and standing are significant in the third trimester of the pregnancy. The overall tendency for significant lumbar curvature changes in pregnant women was not confirmed. Major changes in sagittal trunk inclination in relation to the plumb line were not observed in the study group. The issue regarding how the pregnancy causes changes in spinal curvature and posture remains open for further studies. Presented method of 3D surface topography can reveal postural changes, but that requires several exams of each subject and strict follow-up of the series of cases.

Surface integrity studies on abrasive water jet cutting of AISI D2 steel

ABSTRACTThis article investigates the 3D surface topography and 2D roughness profiles, and micrographs were analyzed in the abrasive water jet (AWJ) cutting of AISI D2 steel kerf wall cut surfaces by varying water jet pressures and jet impact angles. In 3D surface topography, roughness parameters such as Sq, Ssk, Sp, Sv, Sku, Sz, and Sa were improved by various jet impact angles with different water jet pressures. However, the roughness parameters Ssk and Sku strongly depend on the water jet pressure and jet impact angle. This is confirmed by kerf wall cut profile structures. Fine irregularities of peaks and valleys are found on the AWJ cut surfaces, as evident from 2D roughness profiles. The scanning electron microscope micrographs confirm the production of an upper zone not very much damaged and a lower striation free bottom zone, by using the jet impact angle of 70° with a water jet pressure of 200 MPa. Finally, the results indicate a jet impact angle of 70° maintaining the surface integrity of D2 steel better than normal jet impact angle of 90°. The results are useful in mating applications subjected to wear and friction. This has resulted in enhancement of the functionality of the AWJ machined D2 steel components.