Waviness Profile Research Articles

INFLUENCIA DE UNA VIBRACIÓN SIMPLE EN EL PERFIL DE ONDULACIÓN DE PIEZAS TORNEADAS

The generation of the surface topography in machining is a complex process whereby the dynamics of the machine-tool and the kinematics of the cutting process are combined. The purpose of developing a surface topography simulation model in turning is to predict the combined effect of the tool geometry, process parameters, and relative tool-workpiece vibration. The simulations demonstrate that a single vibration frequency can generate multiple wavelengths on the workpiece profile. The correlation between machine-tool vibrations and surface topography is applied to accurately diagnose the machine defect that results in poor surface quality in a cylindrical turning process. Key words: surface topography, tool-workpiece vibration, waviness profile

Influences of fiber orientation and process parameters on diamond wire sawn surface characteristics of 2.5D Cf/SiC composites

2.5D Cf/SiC composite materials are widely used in aerospace high-temperature components, optical system structural components and other fields due to their excellent performance. For the cutting of 2.5D Cf/SiC composites, diamond wire saw cutting process has great potential for application. In this study, experiments were conducted on cutting 2.5D Cf/SiC composites with diamond wire saw along different fiber orientations (P0°, P90°, V90°) and different process parameters. The effects of fiber orientation, feed speed, and wire speed on the surface morphology, surface waviness profile, and roughness of the as-sawn surface were analyzed. The results show that fiber orientation significantly affects the fiber damage mode and surface quality of the as-sawn surface, with the surface quality of the slices ranked as V90°>P0°>P0°. The surface morphology and surface roughness improves with decreasing feed speed and increasing wire speed. However, surface waviness profile peak-valley (PV) values increases with increasing the feed speed and wire speed. The study provides experimental references for process optimization and quality improvement in diamond wire saw cutting of 2.5D Cf/SiC composite materials.

On the Biotribological Surfaces of Dental Implants: Investigation in the Framework of Osseointegration

In the last decades, the use of dental implants has been growing exponentially, but some clinical issues such as inflammations, infections or mechanical complications like fractures or implant loosening, are still open, leading to a failure and implants' revision surgery. Many researchers state that one of the main reasons is certainly due to a not complete or stable implant osseointegration respect the surrounding bone. As stated in literature the formation and the growth of the bone in contact with the implant is strictly correlated with the micro topography of the implant contact surfaces, because of the biotribological, biological and chemical interactions occurring on the surface. To date, however, only arithmetical roughness is reported in the most part of investigations as a valid surfaces' topographical parameter which could be correlated with osseointegration. Moreover, a consolidated and standardized procedure for dental implant surface measurements is not established. Hence, the aim of this investigation was to propose an advanced methodology for analyzing dental implant surfaces based on optical measurements and accurate data processing, and to discuss the results obtained on a real implant, in the framework of osseointegration and biotribological contact literature findings. With reference to a commercial dental implant, the topography was accurately achieved by an optical confocal and interferometric apparatus and then post processed to obtain all the quantities necessary for the contact surface accurate description discussing the role of the topographical quantities on the influence of bone/implant contact/osseointegration phenomena. Height, spatial, hybrid and functional parameters were presented for both waviness and roughness profiles providing significant discrepancies in most of the roughness values. On the other hand, the additional specific investigations such as surface isotropy or particle analysis may yield the basis for a novel protocol of surfaces topographical characterization procedure in dentistry.

Waviness Affects Friction and Abrasive Wear

Abrasive wear can have a detrimental effect on machinery, especially in the mining and construction industries. To prolong machinery lifetime and cut down energy consumption, a thorough understanding of abrasive wear is essential: surface topography measurement and interpretation (including form, waviness, and roughness) are vitally important. However, the potentially crucial influence of surface topography intricacies on tribological behavior has been obscured since roughness and waviness are considered simple scalar quantities in most cases (e.g., roughness Ra and waviness Wt). In this work, the complete waviness profile of the sliding track was used to shed light on the influence of surface topography on abrasive wear. Bearing steel (100Cr6, AISI 52100) pins and disks were tribologically tested in a flat-on-flat contact with Al2O3-based slurries as interfacial medium. Using slurries with two different particle sizes, 5 and 13 μm, we found that friction fluctuates only with small abrasive particles (5-µm slurry) and relatively low waviness disks. It was found that even small surface deviations (albeit minimized and controlled for) can significantly increase the friction coefficient—up to 91%. Remarkably, not only are frictional fluctuations strongly correlated with the disk’s initial waviness profile, but these small fluctuations correlate with unevenly distributed high wear. These findings enhance our understanding of the friction wear structure and provide the basis for exploring how surfaces can be optimized for better tribological performance.Graphical

Sawing Force Prediction Model and Experimental Study on Vibration-Assisted Diamond Wire Sawing.

Diamond wire sawing is the main machining technology for slicing various brittle materials, such as crystalline silicon, SiC, and NdFeB. Due to their high hardness and high brittleness, as well as the ease with which the surfaces of machined materials are damaged, it is difficult to further improve the sawing efficiency and the surface quality based on research conducted on the original machining method. In this paper, a vibration-assisted diamond wire sawing method is proposed. We analyzed the impact of load on the ingot, motion trajectory, and sawing depth of the abrasive particles, and a macroscopic sawing force prediction model for the vibration-assisted sawing method was established and verified via experiments. Based on the single-wire-sawing experiment and prediction model, the influences of the vibration parameters and sawing parameters on the sawing force were determined. The influences of vibration assistance on the surface quality, including the roughness profile, waviness profile, thickness profile, Ra, and Rz, were explored through single-wire-sawing experiments, and the influences of vibration assistance on the geometric parameters of slices, such as the total thickness variation (TTV) and warp, were explored through multi-wire-sawing experiments. It was found that vibration-assisted sawing can reduce sawing force and improve surface quality.

Modelling of multiple surface roughness parameters during hard turning: A comparative study between the kinematical-geometrical copying approach and the design of experiments method (DOE)

This paper proposes and applies two different methodologies for modelling the roughness parameters in hard turning. The first method is based on the kinematical-geometrical copying of the cutting tool geometry onto the machined surface including a feedback loop through the parameter of statistic equality of sampling lengths in surface roughness measurements (SE). The other method employs the Design of Experiments (DOE) principles expressing the roughness parameters as first order nonlinear function of the input variables: cutting speed v, feed f, depth of cut ap, and tool nose radius rε. The research includes the Ra and Rz roughness parameters which are commonly modelled throughout the research works, and additionally develops models for the Rp, Rv and Rmr(c) roughness parameters which are more challenging to model compared to Ra and Rz as they depend more on the shape of the roughness profile and position of its mean line. Both methodologies for all roughness parameters were verified using a CNC lathe and special rings made of steel EN C55 with hardness of 53±1 HRC. Considering that the roughness profile is just a part of the total geometric deviations of the processed surfaces, and it is obtained from the total profile using software filtration, the research also considers the Wa parameter (waviness profile), as well as the deviations from the circularity (out-off-roundness) of the processed rings as indicators for the stability of the machining process.

Surface quality parameters for structural components manufactured by DED-arc processes

Additive manufacturing of structural metallic components is an emerging technology. The DED-arc (direct energy deposition) process combines efficiency with high degrees of freedom and predictable quality. Compared to powder-based processes, the surface is relatively coarse as a result of high heat input and larger molten zones. In industrial applications, the post-treatment of surfaces of DED-arc components cannot be guaranteed for economic reasons or due to geometric constraints. Hence, the surface topography must be evaluated and quality levels need to be defined. Unfortunately, established surface parameters and their determination cannot be directly transferred to DED-arc components and further research on this topic is needed. This article demonstrates surface topography features of representative DED-arc components. Furthermore, waviness profiles were established by applying an alternative cutoff wavelength to better represent the DED-arc surface characteristics. Based on these waviness profiles, 2-dimensional height parameters were calculated. The waviness parameters were determined for four DED-arc specimens made from high strength wire electrodes. The manufacturing parameters were varied in terms of different energy input and interpass temperature, resulting in varying deposition rates and surface qualities. The waviness parameters correlated with manufacturing parameters. A mixed deterministic and random nature of the surface topography was verified.

A vibration model of a rotor system with the sinusoidal waviness by using the non-Hertzian solution

The nonlinear contact forces and deformations between the balls and raceways can cause very complex vibration behaviours of rotor systems with the waviness in the support bearings. However, almost all previous works that used sinusoidal waviness took the Hertzian solution as the calculation method, which is not an accurate method based on Johnson’s formulation since the changes in the curvature at the sinusoidal contact surfaces. To overcome this issue, a new dynamic model of a rigid rotor system with the waviness in the support bearings is proposed. To provide a more accurate nonlinear contact force formulation for the sinusoidal waviness profile, the model used the Johnson’s extended Hertzian contact model to replace Hertzian contact model. This model can consider the time-varying curvature between the mating sinusoidal surfaces. The lubricating condition in the support bearing is also considered. A comparative study on the effects of Hertzian contact model, simplified Hertzian contact model, and Johnson's extended Hertzian contact model on the nonlinear vibrations of the rotor system is developed. The effects of the waviness amplitude and orders on the vibrations of the rotor system are discussed. The comparative simulations show that the proposed model can provide a more reasonable approach for predicting the vibrations of the rigid rotor system. Moreover, the simulations give that the nonlinear contact forces in the support bearings can greatly affect the system vibrations.

Information technology for quality assesment of the processing of metal surfaces by the method of wavelet analysis

Purpose. Analyze the effectiveness of using wavelet analysis to assess the quality of metal surfaces. Develop information technology information technology to automate the process of assessing the quality of metal surfaces by wavelet analysis.
 Methodology. The main parameters for assessing the processing of metal surfaces are considered. A multilevel decomposition of the profile using wavelets was performed.
 Findings. The developed software allows to calculate parameters of an assesment of processing of metal surfaces that will help to minimize number of routine operations and difficult mathematical calculations, and also gives illustrative graphs of waviness and roughness.
 The advantage of this software product is that it is focused and developed specifically for the analysis of signals-profilograms of metal surfaces and is free.
 In further development, this software product can be used in the mechanical engineering industry (milling) and will help reduce the cost of software.
 Originality. The method of optimal decomposition of a complex signal is considered, using the criterion of minimizing the total entropy of wavelet coefficients of both its components in determining the optimal level of decomposition, reconstruction of the signal by approximating wavelet coefficients of the optimal signal. Convenient software has been developed.
 Practical value. The developed information technology of the software product for estimating the parameters of non-stationary signals can be used in the analysis and diagnosis of objects of different nature, in the mechanical engineering (milling) industry, in particular obtaining of waviness and roughness profiles.

A Novel Laser-Aided Machining and Polishing Process for Additive Manufacturing Materials with Multiple Endmill Emulating Scan Patterns

In additive manufacturing (AM), the surface roughness of the deposited parts remains significantly higher than the admissible range for most applications. Additionally, the surface topography of AM parts exhibits waviness profiles between tracks and layers. Therefore, post-processing is indispensable to improve surface quality. Laser-aided machining and polishing can be effective surface improvement processes that can be used due to their availability as the primary energy sources in many metal AM processes. While the initial roughness and waviness of the surface of most AM parts are very high, to achieve dimensional accuracy and minimize roughness, a high input energy density is required during machining and polishing processes although such high energy density may induce process defects and escalate the phenomenon of wavelength asperities. In this paper, we propose a systematic approach to eliminate waviness and reduce surface roughness with the combination of laser-aided machining, macro-polishing, and micro-polishing processes. While machining reduces the initial waviness, low energy density during polishing can minimize this further. The average roughness (Ra=1.11μm) achieved in this study with optimized process parameters for both machining and polishing demonstrates a greater than 97% reduction in roughness when compared to the as-built part.

Experimental study on the interface between low cement recycled aggregates concrete and ultra-high durability concrete

Increasing the durability of concrete structures and reducing the environmental consequences associated with their production is essential to contribute to the sustainability of this industry. Bearing this concern in mind, a concept was developed that consists of considering an eco-friendly concrete only in the core of the structural members, combining a concrete with reduced cement dosage (LCC) with a recycled aggregate concrete (RAC) from construction and demolition waste and, in the outer layer, an ultra-high-durability concrete (UHDC) to significantly improve their durability. The structural behavior and durability of these composite reinforced concrete members are greatly dependent on their connection. Thus, the main objective of the present study is to evaluate the shear strength at the interface between the considered UHDC and two concrete mixtures, one to be used as reference (CC) and the other with low cement dosage and with recycled aggregates (LCRAC). To achieve that goal, an experimental program was carried out based on the slant shear test, where the type of concrete, the roughness of the substrate, and the way how the UHDC is applied are the main variables. The results were compared with the predictions of the main codes, Eurocode 2 and fib Model Code 2010. The used technique to place the UHDC proved to have a major influence on the shear strength at the interface, reaching differences around 60%. It was also concluded that the strength and the porosity of the binder matrix, the waviness profile of the indented interface, and the characteristics of the aggregates have a great influence on the shear strength at the interface.

Comparative Surface Quality of Larch (Larix decidua Mill.) Fretwork Patterns Cut through by CNC Routing and by Laser

Fretwork, as a decorating technique, can today be performed with modern means by laser or CNC routing, but the tool influence on the surface quality must be well understood for further optimization of the cutting parameters. The paper presents an experimental work for the determination of the influence of the cutting angle with respect to the grain on the surface quality of larch wood (Larix decidua Mill.) cut through by laser and CNC routing at different feed speeds. The research considered geometric fretwork patterns derived from triangle, where the cutting angles with respect to the wood grain were 0°, 15°, 30°, 45°, 60°, 75° and 90°. The feed speeds of the CNC routing were set for 2, 2.5, 3, 3.5 and 4 m/min. The surface quality was analyzed by a range of roughness, waviness and primary profile parameters combined with stereomicroscopic images. Although the principle of cutting and interaction with wood of the two processing tools, laser and CNC, is very different, the analysis with roughness parameters has revealed that the cutting angle with respect to the grain has an essential influence, whatever the cutting tool. The surface quality decreases with an increase in the feed speed of the CNC router and processing at 15° and 60° appears to be the worst option from all angle variants for both types of processing. Cutting by laser is melting wood in latewood areas resulting in a smoothing effect.

Surface Texture after Turning for Various Workpiece Rigidities

In the paper, we present an analysis of the surface texture of turned parts with L/D (length/diameter) ratios of 6 and 12 and various rigidity values. The studies were carried out on samples made of S355JR steel and AISI 304 stainless steel. A detailed analysis of 2D surface profiles was carried out by using a large number of parameters that allowed us to distinguish significant differences in the surface microgeometry, which confirmed that determining surface characteristics from one height parameter (Ra—arithmetical mean height) is far from sufficient. The obtained results indicate significantly better roughness and waviness values of the AISI 304 steel surfaces in terms of its size, periodicity, and regularity. Therefore, the turning process of AISI 304 shafts with low rigidity allows one to be able to achieve better quality texture and have a positive effect on the general properties of a workpiece. In all tested samples, surface irregularities decreased along with the distance from the tailstock. The shafts with an L/D ratio of 12 had worse surfaces in the first two sections due to lower rigidity. The results received close to the three-jaw chuck, regardless of the L/D ratio and material type, demonstrated similar waviness and roughness parameters and profiles.

Accurate theoretical calculation of the discharge coefficient for sonic nozzle using geometric parameter measurements in Re=(7.33×104–1.26×106)

In order to improve the measurement accuracy and efficiency of sonic nozzles (SNs) in laminar boundary layer, a correlation model for theoretical discharge coefficient of sonic nozzle taking into account the viscous effects on the boundary layer along the nozzle wall (Cd,th,1), and the multi-dimensional characteristic effect of the core region (Cd,th,2) was proposed. The theoretical discharge coefficient is related to the measurement of geometric parameters, such as the throat diameter, d, and curvature radius, Rc. The detailed geometric measurements of sonic nozzle by 3D coordinate measuring machine were conducted. Then, the evaluation procedures of parameters d and Rc including roundness and waviness profile for designed SNs of d = 7.453 mm and d = 1.919 mm were presented in detail. The effect of waviness profile on the discharge coefficient and boundary layer transient was investigated. It indicated that waviness effect is quite complex. Finally, the validation of the theoretical calculation model of discharge coefficient was verified by the experimental data of National Institute of Metrology (NIM) and National Metrology Institute of Japan (NMIJ) based on the accurate measurements of the geometric parameters. The result showed that the consistency between the Cd,exp and the Cd,th is better than 0.11% when the effect of the heat transfer was considered within the range of Re= (7.33 × 104–1.26 × 106).

Contactless System of Measurement of Waviness for Laser Destructuring of Metallic Surfaces

Data on the waviness of a processed part related to the coordinate system associated with the laser treatment bench used with a surface are needed to increase the effectiveness of the technology of laser destructuring. At the present time, there are no contactless topographic measurement instruments that meet all the requirements that are imposed on the system used in measurement of the profile of the surface of parts and that are determined by the parameters of the technological process of laser destructuring. A trial design of a system for measurement of the profile of a surface (waviness) constructed according to the principle of an optical profilometer and modified in accordance with the requirements imposed on measurements performed on a laser treatment bench is created. Through the use of the system measurements of waviness are performed directly on the bench, which significantly reduces the length and difficulty of the technological process. A diagram and operating principle of the waviness measurement system on a laser destructing bench are described. A triangulation method is used in the measurements. Through the use of a trial design of the system the waviness profi le of a surface with spatial wavelength 2 mm may be measured with error 3.78 μm in the vertical direction and 13.8 μm in the lateral direction. Verification of the precision of the trial design of the system is performed by a standard method of stylus profilometry. The waviness profile of a surface obtained with the use of the trial design of the system may be used for modulation of the amplitude of the power of laser radiation in hte technological process of laser destructuring.

Suppression of Surface Waviness Error of Fresnel Micro-Structured Mold by Using Non-Integer Rotation Speed Ratio in Parallel Grinding Process.

Fresnel micro-structured lenses are widely used in the field of modern optoelectronic technology. High-precision Fresnel micro-structured mold is the key technology to achieve its large-scale replication production. Focusing on the surface waviness error of Fresnel micro-structured mold machined by parallel grinding process, this paper conducted theoretical modeling and experiment research. Based on the grinding kinematics theory, the simulation models of the surface waviness topography and the circular waviness profiles of the ground Fresnel micro-structured mold were developed, considering the combined influence of the non-integer rotation speed ratio and other grinding parameters. A series of grinding experiments were carried out to verify the proposed simulation models. The influence of a non-integer rotation speed ratio and a wave-shift value upon the surface waviness error of the ground Fresnel micro-structured molds were analyzed. Both the simulation and experimental results proved that choosing the non-integer rotation speed ratio and a proper wave-shift value could greatly reduce the surface waviness error and improve the surface quality and uniformity.

3D printing and morphological characterisation of polymeric composite scaffolds

3D-printing is an efficient method of designing customised structures and producing synthetic bone grafts appropriate for bone implants. This research aimed to manufacture a new multi-functionalised 3D-printed poly(lactic acid)/carbonated hydroxyapatite (PLA/cHA) scaffolds with mass proportions of 100/0, 95/5 and 90/10 in a bid to verify their potential application in tissue regeneration. The filaments of these hybrid materials were obtained by extrusion technique and subsequently used to manufacture the 3D-printed scaffolds, using a fused deposition modelling (FDM) technique. The scaffolds were characterised based on their thermal properties, microstructure and geometry by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS), respectively, in addition to determination of their apparent porosities. The degradation of the scaffolds and the liberation of degradation products were evaluated in in vitro for different days under simulated physiological conditions. New microanalyses of mechanical behaviour of the materials: tensile and compression stresses, density, frequency analysis and optimisation with DSC were performed. While, evaluation of the surface luminance structure and the profile structure of the nanostructured PLA composite materials was done by SEM, in 3D printed form. The filter profile of cross-sectional view of the specimen was extracted and evaluated with Firestone curve of the Gaussian filter; checking the roughness and waviness profile of the structure. It was observed that the thermal properties of the composites were not affected by the manufacturing process. The microstructural analysis showed the effective incorporation of the ceramic filler in the polymer matrix as well as an acceptable PLA/cHA interaction. The degradation tests showed the presence of calcium and phosphorus in the studied medium, confirming their liberation from the composites during the incubation periods.

Waviness measurement system for implementing in laser destructuring by remelting of metal surfaces

To increase the efficiency of laser destructuring, data on the waviness of the part associated with the coordinate system of the laser processing machine are required. At present, there are no non-contact profile measurement systems on the market that meet all the requirements that apply to a system for measuring the surface profile of parts and are determined by the parameters of the laser destructuring. The developed measurement system will allow to take waviness measurement directly at the laser processing machine, which will significantly reduce the complexity of the process. A prototype of a system for measuring the surface profile (waviness) has been created inaccordance with the measurement requirements for a laser processing machine. The scheme and principle of operation of the system for measuring the waviness of the installation for laser destructuring are described. In measurements, the triangulation method was used. A prototype allows to measure the profile of the of the surface waviness with a spatial wavelength of 2 mm with an accuracy of 3,78 μm in the vertical direction and 13,8 μm in the lateral direction. The accuracy of the prototype was verified using the standard method of stylus profilometry. The waviness profile obtained with a developed system can be used to modulate the amplitude of the laser radiation power in the laser destructuring.

Nano-structures of 4D morphology surface analysis of [formula omitted] (SAE 1045) tool wear

This research aims to present computational nanoparticle surface characterisation analysis of fourth-dimensional wearing tool in a machining process. The effect of hardenability, toughness, heat treatment and feed rate of material removal processes of cutting and machining were investigated. The aim of this research is evaluating the process of nanoparticle in the cutting time, cutting speed, and the wear in the tool part caused by the machining process was observed. It was also possible to watch the flank wear generated in the tool, which can only be seen with a 50 times magnification in microscopes and the observed wear is up to 102.32 μ. The 4D nanostructure composite particle evaluating of the tool, the 3D surface luminance structure, and the profile with cross-sectional views of the atomic force microscope (AFM) are extracted and analysed. The waviness profile, surface roughness and Gaussian filter of the tool are observed and considered in ISO standard parameters. It was found that tool wear nanoparticles are dispersed inside the grains, and spherical nanoparticles grow with an increase in temperature at the 4D. The nanostructure of the wear grain size and the 3D morphology is influenced by motif, furrow segmentation of the grains, and reduced from an average particle of 316grains to an average of 225grains. This allows us to accomplish the goal of identifying the graph the characteristic life curve of the optimum value of the tool life.

Nanostructural computation of 4D printing carboxymethylcellulose (CMC) composite

Additive manufacturing of complex structures with functional and programmable attributes of Fused deposition Method (FDM) of 4D printing enables complex and innovative designs with shape memory properties. However, several challenges still exist in successfully realising FDM of 4D printing due to its high complexity, fragility and control of temperature for a specific change in the shape of specific materials. This study focuses on microstructure, the calculation in the creation of hydrogel, cellulose, and ink that combines sound waves to create shape memory properties of hydrographic cellulose compositions in 4-dimensional printing. The high amounts of hydrocolloid cellulose fibres are used for carboxylic cellulose particles, carboxymethyl cellulose (CMC) and matrix fibre decay compound 5.0% shapes memory. Thermoplastic shapes are also used in composite coagulation processes to create a mophological charaterisation composite of 3D-printing polymer structure based on full-area measurement technology, which is the change of particles. Investigation of the nanostructure of CMC composite particle in 4D surface structure, roughness, waviness profile of the specimens ware extracted and analysed. Typed A complex workshop structure demonstrates the capability of sonication used in 3D printing. The most important property is the content of cellulose in the form of final materials is the volume of cellulose in a sonicated composite.