Surface Finishing Process Research Articles

Development and verification of a cure-dependent visco-thermo-elastic simulation model for predicting the process-induced surface waviness of continuous fiber reinforced thermosets

Process-induced surface waviness effects represent a major concern for series production of high-quality lightweight structures based on fiber reinforced plastics (FRP). This paper suggests a method for the numerical prediction of these effects by using the example of processing glass fiber reinforced plastics (GFRP) in a resin transfer molding (RTM) process. The influence of reaction kinetics, chemical shrinkage and cure-dependent viscoelastic properties of the resin are taken into account. Furthermore, the dependence of surface quality on curing cycle, consolidation pressure, textile architecture and thickness of neat resin layer (NRL) at the part surface are investigated. The work is based on published material data and a visco-thermo-elastic simulation approach which has been previously presented and validated. All numerical results are compared to the surfaces of FRP plates that were manufactured with the corresponding parameter variations. Based on a literature survey, different surface waviness values have been identified for comparison of experimental and numerical results. Satisfactory agreement between experiments and simulations is found. Furthermore, it is shown that the analyzed NRL thickness has no relevant influence on the surface waviness while the curing temperature significantly affects the surface waviness. The role of relaxation-induced change of the surface waviness is highlighted by performing long-term measurements and corresponding time-dependent simulations. It is concluded that relaxation plays a decisive role in the appropriate selection of the subsequent surface finishing process. The suggested simulation approach provides a basis for optimization strategies to improve surface quality and reduce post-processing effort.

Managing the powder coat waste stream: an industrial experimentation approach

Despite acceptance as a functionally and economically competitive alternative to conventional liquid coating, waste generated during powder coating or powder coat waste (PCW) is a notable yet under-examined industrial waste stream. Globally, a large volume of PCW generated during surface finishing processes is landfilled as a fine powder containing microplastics, thereby impacting the environment adversely. In this paper, a step-by-step industrial experimentation methodology based on the principles of the Shainin Design of Experiment was proposed for exploratory experimentation. The proposed methodology offers a convergent approach for diagnostically reducing the process parameters to a controllable number by following a progressive search. A cluster of sanitary ware manufacturing units involved in the surface finishing process was selected as a case study for evaluating the proposed methodology. The results show conveyor hanger pitch, conveyor speed and spray gun pressure as the critical process parameter for dry film thickness (DFT) defect and resulting PCW.

On the Development of an Automated Adaptive Polishing System

The emerge of Industrial 4.0 revolution and influences to production, information, and communication technologies have made manufacturers capable of reaching higher performance in the last decade. Making smart operations has been set as a top strategy of manufacturing societies, and machinery industry as an integral part of production has been highlighted develop. Aerospace, automotive, metals, glass, and plastics industries have been pioneers to improve, optimize, and develop automated polishing as a final operation of surface finishing process considering of KPIs: quality, time, cost, and safety. In this review, after mentioning the state of the art of last relevant papers, some clues for future research will be presented.

Contact Analysis and Friction Prediction of Non-Gaussian Random Surfaces

Engineering surfaces exhibit asymmetrical height distributions due to certain types of surface finishing and running-in process. This non-Gaussian surface reflects different contact performances and tribological properties. In this paper, the influence of non-Gaussian surface parameters on contact performance and friction is investigated. First, the computer program for generating rough surfaces with given parameters is developed; then, contact analysis for rough surfaces are conducted through a deterministic contact model; finally, friction coefficient can be derived from friction model using the results of the contact model. The simulation analyses indicate that the skewness and amplitude of non-Gaussian surface have significant effects on contact performance and friction. The contact characteristic parameters and friction coefficient become slightly changed when kurtosis becomes relatively large.

Failure analysis of an axle shaft in an airport ground support vehicle

In this study, failure analysis of an axle shaft in an airport ground support vehicle was carried out to determine failure mechanism, failure root causes and preventive actions. Macroscopic observation, numerical analysis, metallographic analysis, chemical composition analysis, hardness measurement and tensile test methods were used in failure analysis. In numerical fatigue analyses, axle shaft was modelled as a functionally graded material due to mechanical properties changing in the material radial section as a result of induction surface hardening. The analysis results showed that the failure mechanism of fractured axle shaft was torsional fatigue. High surface roughness and insufficient mechanical properties were found as failure root causes. Making finish cut with low depth and even grinding in surface finishing process were proposed as a prevention to increase surface quality, reduce surface roughness and stress concentrations in machining of axle shaft. In addition, using another material with higher yield strength (EN 37Cr4) was proposed instead of EN 34Cr4 alloy steel as the axle shaft material.

Surface properties and biocompatibility studies on bone plate by magnetorheological finishing

ABSTRACT Bone plates are essential for providing mechanical support during the healing of bone fractures by adapting to the biochemical environment. The surface quality of bone plates plays a vital role in their sustainability under adverse conditions. Magnetorheological Finishing (MRF) is an advanced surface finishing process that provides high surface finishing without disturbing the polished surface topography. However, while mapping to the workspace has a hole or pocket feature, the Magnetorheological (MR) fluid is not stable and gets trapped inside. Hence, a Feature-based hybrid MRF planning system is developed to overcome the challenge during MRF. The final average surface roughness (Ra) value of 21.56 nm from its initial roughness value of 324.12 nm is achieved on the polished surface bone plate made of Ti–6Al–4V. The enhancement in the surface characteristics of the MRF polished surface leads to the biomaterial's enhanced wear and corrosion resistance.

Hypothesis tests with functional data for surface quality change detection in surface finishing processes

This work is concerned with providing a principled decision process for stopping or tool-changing in a surface finishing process. The decision process is supposed to work for products of non-flat geometry. The solution is based on conducting hypothesis testing on the bearing area curves from two consecutive stages of a surface finishing process. In each stage, the bearing area curves, which are in fact the nonparametric quantile curves representing the surface roughness, are extracted from surface profile measurements at a number of sampling locations on the surface of the products. The hypothesis test of these curves informs the decision makers whether there is a change in surface quality induced by the current finishing action. When such change is detected, the current action is deemed effective and should thus continue, while when no change is detected, the effectiveness of the current action is then called into question, signaling possibly some change in the course of action. Application of the hypothesis testing-based decision procedure to both spherical and flat surfaces demonstrates the effectiveness and benefit of the proposed method and confirms its geometry-agnostic nature.

Inherent Magnetic Sensor for Estimation of Fatigue Damage in Type 304 Stainless Steel

Abstract In this study, the fatigue damage in type 304 stainless steel was estimated using an inherent magnetic sensor via plane-bending fatigue tests and the electromagnetic impedance method. The sensor was a magnetic composite material incorporating a ferromagnetic martensite phase generated in type 304 stainless steel by a surface finish process during the production stage. The output properties of this sensor as a function of the number of cycles were evaluated under various conditions. It was demonstrated that this sensor could detect fatigue damage starting from the zeroth cycle. The sensor output repeatability was evaluated, and the variation in the output between the inherent magnetic sensors was approximately 10% regardless of the sensor type and total strain amplitude. By using the two proposed estimation methods, the specific fatigue level and the number of cycles could be estimated with errors of 3–27%. These results indicated that the inherent magnetic sensor was suitable for use for fatigue damage estimation.

Distortion analysis of generatively designed hinge bracket using meso-scaled thermomechanical simulation with experimental validation

ABSTRACT The accuracy of meso-scaled thermomechanical method (TMM) in analysing distortion of hinge bracket additively manufactured using selective laser melting (SLM) is investigated with SS316L as material and optimised design using Generative Design (GD) approach in which loads, boundaries, and constraints are considered as parametric inputs and stress goal as output. Prior to 3D printing, process simulation for predicting distortion was conducted including a geometrical model with hexahedral mesh type, temperature dependent material and flow curve referred from specialised software. To reduce computational time, a lumping approach with volume fraction was implemented considering heat flux parameters. For validation purposes, a series of experiments was accomplished using SLM, manual support structure removal, and surface finishing process by sandblasting. Furthermore, the finished bracket was measured using an optical scanner and compared with the simulation result. In conclusion, TMM can predict the distortion accurately with percentage point-by-point and mean error of less than 3% and 1.5%, respectively.

Surface finishing of Nitinol for implantable medical devices: A review.

Nitinol (NiTi), a nickel-titanium alloy, has been used for various cardiovascular, orthopedic, fracture fixation, and orthodontic devices. As with most other metallic biomaterials, the corrosion resistance and biocompatibility of NiTi are primarily determined by the properties of the surface oxide layer such as thickness, chemical composition, structure, uniformity, and stability. Currently, a number of finishing methods are used to improve the properties of surface oxide of NiTi with an ultimate goal to produce a defect-free, impurity-free, thin homogeneous oxide layer that is stable and composed of only titanium dioxide (TiO2 ) with negligible amount of Ni species. This review discusses the effects of various surface finishing methods such as mechanical polishing, electropolishing, magnetoelectropolishing, heat treatments at different temperatures, passivation, chemical etching, boiling in water, hydrogen peroxide treatment, and sterilization techniques (steam autoclave, ethylene oxide, dry heat, peracetic acid, and plasma-based treatments) on the properties of a surface oxide layer and how it impacts the corrosion resistance of NiTi. Considering the findings of the literature review, a checklist has been provided to assist with choosing finishing/sterilization methods and relevant rationale and recommendations to consider when selecting a surface finishing process for NiTi used in implantable medical devices.

Investigations on the Potential of 5G for the Detection of Wear in Industrial Roller-Burnishing Processes

Roller burnishing represents an economical alternative to conventional surface-finishing processes, such as fine turning or honing. In contrast to the well-known wear mechanisms of chip-forming processes, the wear behavior in roller-burnishing is strongly based on the experience of the machine operators. The nature of the finishing process makes roller-burnishing very sensitive to surface defects, as it is often not possible to rework the last step in a process chain. In the present work, a prototype for a smart roller-burnishing tool with 5G communication is presented, which serves as an inline-monitoring tool to detect tool wear. A suitable metric to monitor the tool wear of the manufacturing roll is suggested, and the potentials of 5G communication for the described use-case are evaluated. Based on the signal-to-noise ratio of the process-force, a metric is found that distinguishes new rolls from worn rolls with very small defects on the micrometer scale. Using the presented approach, it was possible to distinguish the signal-to-noise ratio of a roll with very small wear marks by 3.8% on average. In the case of stronger wear marks, on the order of 20 µm, the difference increased to up to 15.6%.

Study on the Motion Characteristics of Abrasive Media in Vibratory Finishing

In order to investigate the motion characteristics of the abrasive media in the vibratory finishing, the RecurDyn and EDEM coupled simulation method is employed. The simulation results show that the trajectories of the abrasive media are annular spiral motions in general, including a circular motion about the central axis of the vibratory finishing machine and an elliptical motion around the center of the media flow. The reliability of the RecurDyn-EDEM coupled simulation for the vibratory surface finishing process is validated by X-ray real-time detection, which has significance in better understanding of the motion characteristics of abrasive media and the optimal design of the vibratory surface finishing processes.

Mechanical evaluation of WC-Co materials with varying microstructures

Tungsten carbide‑cobalt materials are useful in a variety of extreme applications due to a desirable blend of properties, yet the technology has not significantly changed since their initial development in the 1920s. The mechanical properties of this class of materials is highly dependent on two variables, the size of the tungsten carbide grains, and the amount of binder phase present in the final body. In this study, the amount of binder phase is isolated across three commercial materials from the same manufacturer with three different grain sizes to investigate the effect on mechanical properties. The mechanical properties investigated are indentation hardness, flexure and tensile strength, as well as fracture toughness. In general, an increase in hardness and tensile strength with decreasing grain size was observed, while the fracture toughness showed the opposite trend with toughness increasing with increasing grain size. The flexure strength results did not show a correlation to grain size. Fractographic analysis identified the dominant strength-limiting flaw for each sample, which largely were in the form of porosity. Other flaws types, such as inclusions from the milling process, clusters of large grains, and machining cracks from the surface finishing process, were also identified. Weibull analysis was performed and deemed appropriate for analysis of these materials, but strength-size scaling was not conducted due to the variability in the strength-limiting feature between the different specimen geometries.

Study of Measuring Temperature of Burnishing Process Using Diamond Tip Tool

The surface finishing process has been evaluated in terms of its comprehensive performance as well as it has also been evaluated by its productivity and environmental effect. Burnishing is a surface finishing process for metal products after machining. This process utilizes the plastic deformation of the workpiece surface and yields a smooth surface. In addition, residual stress occurs in the processed workpiece surface. Therefore, the fatigue strength and abrasion resistance of the workpiece are improved. However, friction heating is a severe problem in maintaining the workability of a diamond tip burnishing tool. To estimate the temperature rise caused by burnishing, a new burnishing tool made of boron-doped chemical vapor deposition (CVD) diamond was developed. Its temperature and other characteristics were determined by the tool-workpiece thermocouple method. The thermoelectromotive force was measured and calibrated to temperature using the obtained calibration curve. The tool temperature was found to increase with the rotation speed. The tool temperature obtained under experimental conditions using the highest rotation speed was about 950-960 ℃. Moreover, black scratches as seen in tool wear were observed.

An experimental analysis on surface roughness of the selective laser sintered and unsintered Inconel 718 components using vibratory surface finishing process

The selective laser sintering (SLS) is one among the most fast emerging rapid prototyping processes, primarily due to its capability to produce component using different kind of raw materials. On the other hand, because of stair stepping effect the prototypes produced by SLS technique have moderately high surface roughness. Vibratory finishing is the multifunctional process is utilized in several engineering industries internationally for various applications like fine finishing, brightening, cleaning, and radiusing of components. In the present research work, due to excellent mechanical properties Inconel 718 powder particles were used as raw materials to produce component using SLS technique. The surface roughness of the components (both sintered and unsintered) were analyzed by subjected them to vibratory surface finishing process using different media under constant amplitude of 0.8 mm and frequency of 25 Hz, 50 Hz, and 75 Hz for different processing time in minutes. The surface roughness tester was used to anlyse the surface roughness of the components after vibratory finishing test. The surface morphology was examined using scanning electron microscope and EDAX. The Vicker’s micro hardness tester was used to know the surface roughness of the components, laser sintered samples shows extreme hardness as compared to unsintered samples [17]. The experimental results confirm that, the surface roughness of the laser sintered and unsintered samples was reduced at 75 Hz as compared to lower taken frequencies. However, laser sintered sample performed well as compared to unsintered samples due to high density, less porosity and high surface hardness.

High-efficiency wafer-scale finishing of 4H-SiC (0001) surface using chemical-free electrochemical mechanical method with a solid polymer electrolyte

Silicon carbide (SiC) has been extensively studied for applications in next-generation high-power electronic devices. High-quality and low-cost electronic devices require a surface finishing process that can produce smooth and defect-free 4H-SiC (0001) surfaces. However, SiC surfaces are difficult to remove because of their extremely high mechanical strength and chemical stability. Herein, we present a high-efficiency, wafer-scale, chemical-free finishing process for a 4H-SiC (0001) surface using electrochemical mechanical polishing (ECMP) with a solid polymer electrolyte (SPE). The ECMP method comprises electrochemical oxidation at the SiC/SPE interface and subsequent oxide removal by CeO2 particles. Electrolysis with a SiC (anode)/SPE/cathode electrochemical system demonstrated that the use of SPE as an alternative to liquid electrolytes allows the efficient electrochemical oxidation of highly inert SiC (0001) surfaces without requiring any chemicals. The ECMP process achieved a high material removal rate for SiC (0001) in the range of 1.8–9.2 μm/h, although strongly dependent on a 50 to 450 mA electrolytic current. Moreover, an electrolytic current of 250 mA produced a smooth and defect-free surface with a sub-nanometer-scale roughness (0.68 nm Sa) and excellent uniformity over an entire 2-inch SiC (0001) surface. Atomic force microscopy observations showed that ECMP under a low electrolytic current (30 mA) combined with subsequent CeO2 polishing without electrolysis can help improve microscale surface morphologies. The proposed ECMP, which produces a smooth and uniform surface without requiring chemicals, is a highly efficient and environmentally friendly finishing process for the fabrication of SiC wafers.

On the interest of a semi-empirical model for the tooth friction coefficient in gear transmissions

Accurate modelling of friction coefficient is of primary importance in efficiency, vibration and failure analyses of enclosed gear drives. After showing the influence of surface/lubricant interactions on friction, the authors used a semi-empirical model which can take all these aspects into account. Lubricant is modelled as an Eyring–Reynolds fluid and rough surfaces are described with two parameters via a stochastic approach. A specific two-disc machine is used to perform series of friction measurements on smooth and rough discs. Smooth discs allow to operate under full film lubrication and to measure a reference shear stress of lubricant, whereas rough discs reproduce gear tooth roughness and generate a representative value of friction on asperities. The purpose of this present paper is to describe calculations of this physical-based friction coefficient model and to present the experimental process. On the basis of new results, the impact of a surface finishing process is assessed as well as the consequence of calculating friction coefficient based on oil injection instead of local bulk temperature.

Parameter optimization during single roller burnishing of AA6061-T6 alloy by design of experiments

Roller burnishing is a surface finishing process that involves plastic deformation of the surface without any removal of the material. The level of surface finish that can be attained in roller burnishing operation depends on several process parameters. Processing at the optimum combination of process parameters is critical for achieving a higher yield during manufacturing. Hence, the present study is carried out to obtain the optimized process parameters during roller burnishing of aluminium alloy AA6061-T6, with an objective to produce a high level of surface finish. The Taguchi method has been used to assess the role of burnishing speed, feed rate, and load on the surface finishing of the alloy. Analysis of variance (ANOVA) and signal-to-noise ratio (S/N) have been employed to analyze, obtain significant parameters, and find out optimum combination levels of the process parameters. The results show that the surface quality of the specimens is significantly improved with burnishing parameters. The analysis of the results shows that the burnishing feed rate has the highest impact on the surface roughness with a contribution of 54.51%, followed by load and burnishing speed.

Influence of different wavelet filtering reconstruction techniques applied to bidimensional surface texture characterization

This article develops a preliminary study of the wavelet filtering application in surface finishing, extracting two-dimensional information from the surface microgeometry in a profile. First, the key elements to be considered in the analysis are described, starting with the surface finishing process of measurement. Then, the fundamentals of wavelet-based filtering and the traditional filtration procedure is shown. This procedure eliminates the values of the detail coefficients obtained in the filtering process before the reconstruction of the signal. Other alternatives of filtration, based on the shrinkage wavelet methodology, are also considered. Next, the features of the surface finish characteristic signals are highlighted, and the alternatives considered are applied on three different profiles generated from the result of a Brinell hardness test. Finally, the main conclusions drawn from the study are presented.

Self-Ordering of Porous Anodic Alumina Fabricated by Anodizing in Chromic Acid at High Temperature

Anodizing Al in chromic acid is a very useful surface finishing process for corrosion protection and nanoscale porous structure fabrication, whereas the self-ordering of porous anodic alumina (PAA) in chromic acid has never been found to date. Herein, we provide a self-ordered PAA film possessing numerous sub100-nm-scale characteristic bumps through anodizing in chromic acid at high temperature. Anodizing of high purity Al plates in a 0.3 M chromic acid solution at conventional low temperatures, such as 293 K, leads to the formation of a disordered PAA film, whereas anodizing at a high temperature of 348 K causes the self-ordering behavior of the pore structure. The PAA film grown in the initial stage possessed the highest regularity, and it decreased with anodizing time due to pore branching during anodizing. A highly ordered PAA film measuring approximately 340 nm in interpore distance can be fabricated by short-term, two-step anodizing in chromic acid at 348 K and 120 V. The ordered PAA film possesses a characteristic nanostructure consisting of hexagonally arranged 100-nm-scale pores and sub100-nm-scale disordered bumps on their pore walls without any electrolyte chromate anion.