Abrasive Grit Size Research Articles

Probing the effect of abrasive grit size on rail grinding behaviors

Three grinding wheels were developed via regulating the abrasive grit size (F10, F16, F30), and their performances are evaluated by a self-designed grinding device. The surface integrity of grinded rails and material removal mechanism were discussed. The results illustrate that the abrasive grit size has a significant effect on the residual stress, surface topography, oxidation and crystal structure of grinded rail surfaces. With the decrease of abrasive grit size, the grinding mechanism gradually changes from rubbing and ploughing to cutting operation. Better surface integrity can be acquired using finer abrasives because of the lower roughness, lower magnitude of residual stress and thinner white etching layers (WELs). And the WELs with nanocrystalline structure could yield the pre-fatigue and abridge the RCF life of rail.

Eksperimentalno istraživanje kriogeno potpomognute obrade čelika za kalupe abrazivnim vodenim mlazom

This paper reports the investigation on parametric optimization of the abrasive aqua jet (AAJ) and cryogenic assisted abrasive aqua jet (CAAAJ) processes for cutting AISI D2 steel using multi objective TOPSIS approach. The input parameters considered were aqua jet pressure, abrasive grit size and jet impingement angle. In this study, depth of penetration, metal removal rate, kerf taper ratio and average roughness were taken as the performance characteristics. The results showed that the CAAAJ process exhibited better performance characteristics than the AAJ process. The AAJ machining process with an inclined jet impact angle influences the output responses, which is evident from an optimal selection of parameters. Besides, the influencing process variables were determined by using the analysis of variance. The overall machining performance of the AAJ and CAAAJ processes were improved by using the optimum process variables through the TOPSIS method.

Effect of rare earth on microstructure and wear behaviour of Ni based microwave clad

In the present investigation microwave energy has been utilized to develop wear resistant Ni-based clad without Nd2O3(unmodified coating) and with addition of Nd2O3 (modified coatings) in varying wt. % of 1-3. The clads have beendeveloped using domestic microwave oven at frequency of 2.45 GHz and power 900 W for duration of 360 s. Theunmodified and modified clads have been characterized in terms of microstructure, XRD, microhardness and two bodyabrasive wear. The average thickness of developed clads has been measured as 1.0 mm approximately. A two body abrasivewear behaviour of unmodified and modified coatings at sliding speed of 36 m/min & 72 m/min with abrasive grit size of 220& 600 has been investigated. The results revealed a better abrasive wear resistance at lower sliding speed and fine grit size.Further, the best results of microstructure, formation of hard phases, improved microhardness and wear resistance have beenshown by the samples having coating composition as 3 wt. % of Nd2O3.

Experimental study on micro-abrasion behavior of hard coatings: the role of load, sliding distance and abrasive particle size

In this study, the micro abrasion wear behavior of the TiN, TiAlN, TiAlN/TiSiN and AlCrN coated WC materials was investigated. The coating process was carried out using the Physical Vapor Deposition (PVD) method. All coatings have a dense and homogeneous microstructure without delamination or crack formation. Wear tests were performed by fixed ball micro abrasion wear device. Micro abrasion wear test were carried out at different loads, abrasive sizes and sliding distances. As a result of the experiments, the best wear performance was obtained with AlCrN coated WC materials at all loads and abrasive grit sizes, followed by TiAlN/TiSiN coated and TiAlN coated samples. Depending on the increase in load, volume losses were increased in all samples under all conditions. Higher wear losses were determined in the tests performed with larger SiC abrasive particles. In the tests performed with SiC F800, the wear mechanism was micro-grooving wear mechanism, while in SiC F1200 tests the wear mechanism was micro-rolling mechanism. The increased number of cycles increased the volume loss of the samples. In the tests conducted with the SiC F800, the micro-grooves were more pronounced in short-range tests, whereas the groove steps in the long-range tests were reduced.

Wear of Biopolymers under Reciprocating Sliding Conditions against Different Counterfaces

The objective of this study was to investigate the wear resistance of ultrahigh‐molecular weight polyethylene (UHMWPE) and crosslinked polyethylene (XLPE) against different counterfaces. Friction and wear studies were evaluated under dry reciprocating sliding conditions at room temperature. Ti6Al4V discs finished in polished, lapped, and ground conditions were reciprocated against polymer cylinders. In addition, abrasive wear studies were conducted using different abrasive grit sizes. The friction and wear properties of the two polyethylenes were strongly affected by the different counterfaces. XLPE showed important friction and wear sensitivity with the change of surface roughness of the Ti6Al4V disc, as well as with the change in abrasive grit size. Scanning electron microscopy and energy‐dispersive X‐ray (EDX) analysis of the worn disc surfaces and the polymer pins indicated the wear mechanisms affecting the polyethylenes. POLYM. ENG. SCI., 59:2356–2366, 2019. © 2019 Society of Plastics Engineers

Analysis and modeling of surface characteristics in electrophoretic deposition–assisted internal polishing of AISI 304 steel

This article reports inner surface characteristics of AISI 304 steel pipe by electrophoretic deposition–assisted polishing (EPDAP). Electrophoretic deposition is based on the principle of electrophoresis in combination with deposition of abrasives on tool electrode. The screening experiments were planned using one factor at a time approach and main experiments were conducted using Taguchi L9 orthogonal array design. The process parameters selected were grit size, polishing time, and polishing tool rotational speed. The response variables selected were percentage reduction in surface roughness (PRSR-Ra) and percentage increase in reflectivity (PIRL). The optimum polishing performance for PRSR-Ra obtained is 87.93% at abrasive grit size of 3000, polishing time of 30 min, and polishing tool rotational speed of 200 rpm. The optimum reflectivity performance for the PIRL obtained is 69.07% at abrasive grit size of 3000, polishing time of 30 min, and polishing tool rotational speed of 300 rpm. The surface roughness (Ra) achieved is 0.035 μm (35 nm).

Rigid aspheric smoothing tool for mid-spatial frequency errors on aspheric or freeform optical surfaces

In order to remove mid-spatial frequency errors on aspheric and freeform surfaces, we have developed an aspheric smoothing tool which, unusually, is rigid. This has been proved feasible in the special case where the abrasive grit size exceeds the aspheric misfit, providing a cushion. Firstly, experimental parameters were derived from simulation of Influence Functions regarding misfit between the tool and the surface, which leads to dynamic Influence functions. Then the experimental part was polished into an aspheric surface from generated spherical surface. Thirdly, the choice of tool’s shape parameters was completed with optimisation of conic constant and tilt angle. The tool was machined into aspheric shape with a single-point cutter. Finally, experiments were carried out to compare this tool with a standard spherical smoothing tool. The results showed that this aspheric smoothing tool can removal mid-spatial errors effectively on aspheric surfaces.

Two body abrasive wear characteristics of Al7068/Si3N4/BN hybrid composite

The present study emphasises the mechanical and tribological characteristics of stir cast Al7068/Si3N4/BN hybrid metal matrix composite. The composites were prepared at various weight percentages of Si3N4 and BN and their mechanical properties were evaluated. The composite with maximum tensile strength of 238.7 MPa was obtained for 10% Si3N4 and 5%BN. The abrasive wear test was conducted to evaluate wear rate of composites using pin-on-disc apparatus by varying abrasive grit size, load, sliding velocity and sliding distance. The Taguchi L27 orthogonal array was used to design the experiments and analyse the effect of process parameters. The ANOVA test revealed that the wear rate is highly influenced by mass fraction of Si3N4 and grit size of abrasives. The worn out surface of wear test specimen was analysed using SEM to understand the mechanism of wear.

Machinability and characterisation of machined hole on quartz using developed µ-AJM set-up

ABSTRACTMicro-abrasive jet machining (µ-AJM) is one of the novel machining processes used for machining brittle materials wherein the mechanism of erosion is brittle fracture and for ductile materials wherein the mechanism of erosion is due to shear fracture on the materials. In the current work, an attempt has been made to find the material removal rate (MRR) and characterisation of micro-holes produced on quartz using silicon carbide abrasives of various grit sizes. The process parameters selected are air pressure, stand of distance (SOD) and abrasive grit size and output responses measured for the experiments are MRR, radial over cut (ROC) and taper angle. Taguchi L16 orthogonal array has been selected to conduct the experiments. Grey relation analysis (GRA) was utilised to optimise the process parameters to increase the MRR and at the same time reduce the taper angle and ROC. From the GRA, the obtained optimum parameters are 4 bar air pressure, 0.5 mm SOD and Mix 1 (50% of 320+ 50% of 220) for maximum MRR of 3.96 mg/min, minimum ROC of 85 µm and minimum taper angle of 5°. An improvement method has been adopted to overcome the chipping at the bottom edge of the workpiece.

Microstructure and Tribological Performance of Alumina–Aluminum Matrix Composites Manufactured by Enhanced Stir Casting Method

Al–Zn–Mg–Cu matrix composites reinforced with (0–20 wt %) Al2O3 particles have been manufactured by enhanced stir casting technique. Microstructural characterization of cast composites by optical, field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDS) and X-ray diffraction (XRD) reveals homogeneous distribution of reinforcements in Al-alloy matrix with MgZn2 plus Al2CuMg intermetallics. With increasing particle content, hardness of composite rises considerably in spite of marginal rise in porosity. Tribological performance under two-body abrasion has been studied considering central composite design (CCD) apart from identification of mechanisms of wear via characterizations of abraded surfaces and debris. Composites exhibit significantly reduced wear rate and coefficient of friction (COF) irrespective of test conditions, since mechanisms of abrasion are observed to change from microplowing and microcutting in unreinforced alloy to mainly delamination with limited microplowing in composites. Effects of four independent factors (reinforcement content, load, abrasive grit size, and sliding distance) on wear behavior have been evaluated using response surface-based analysis of variance (ANOVA) technique. Dominant factors on both wear rate and COF are identified as reinforcement content followed by grit size and load. Combined optimization of wear rate and COF employing multiresponse optimization technique with desirability approach as well as regression models of individual responses have been developed, and their adequacies are validated by confirmatory tests. The developed mathematical models provide further insight on the complex interactions among wear performances of the selected materials and variables of abrasive system. The optimum amount of reinforcement is identified at around 15 wt % for achieving the lowest values of both wear rate and COF.

Two-body abrasive wear behaviour of AA6061-2SiC-2Gr hybrid nanocomposite fabricated through ultrasonically assisted stir casting

Two-body abrasion wear rate of AA6061 aluminium alloy, AA6061-2SiC nanocomposite, and AA6061-2SiC-2Gr hybrid nanocomposites were studied using a pin on disc machine at various applied normal loads 5-20 N and 50-150 µm abrasive grit size by maintaining a constant sliding distance of 120 m. Morphology of fabricated materials, worn surfaces of tested specimens, and abrasive grit papers were analysed under a scanning electron microscope. The wear rate of the AA6061-2SiC-2Gr hybrid nanocomposite was found to be less than that of AA6061 alloy and AA6061-2SiC nanocomposite. The wear rate decreased by 19% for 50 µm, 28.2% for 100 µm, and 22.5% for 150 µm at an applied normal load of 20 N and 120 m sliding distance for Al 6061-2SiC-2Gr hybrid nanocomposite compared to base alloy.

Fabrication and polishing of chalcogenide glass optical fiber connectors

In this paper, we described the fabrication and polishing characteristics of the end-faces of highly stable physical contact type chalcogenide optical fiber connectors. The effects of downforce pressure, polishing duration, and polishing fluid on the polishing process with abrasive grit size of 0.02 μm were investigated, and the final polishing parameters were determined. The surface roughness Ra was approximately 20 nm in the fiber area, and the average fiber roughness of the core region (10 μm × 10 μm) was about 3 nm, which were measured by the profilometry and atomic force microscope. Finally, the optical performance was analyzed in terms of the insertion loss of 1 dB and return loss of -18 dB.

High stress abrasive wear characteristics of Al 7075 alloy and 7075/Al2O3 composite

This paper focuses on the tribo-responses of as-cast Al 7075/Al2O3 composite and its unreinforced base alloy under two-body abrasion. Composite prepared by stir casting route shows near uniform distribution of 20 wt.% Al2O3 particles in the matrix of Al-alloy. The effects of four control factors i.e., load, SiC abrasive grit size, sliding distance and sliding velocity on three tribo-responses i.e., wear rate, coefficient of friction and roughness of worn surface have been investigated separately for base alloy and composite using pin-on-disc tribometer. Design of test conditions and analyses of output responses have been performed following standard statistical tools of Taguchi orthogonal array, analysis of variance (ANOVA) and regression methods. Composite demonstrates reduced wear rate and lower coefficient of friction, but higher surface roughness as compared to base alloy under all investigated test conditions. The predominant control factor is found to be abrasive grit size followed by load for all tribo-responses except roughness of worn composite surfaces wherein the load plays major role. The optimal combination of control factors of different tribo-responses have been identified considering smaller-is-better approach. Confirmatory tests carried out to validate the developed models yield low errors (8.1–2.6%) exhibiting excellent correlations. Enhanced tribological properties of composite over base alloy has been explained by identification of wear mechanisms through characterizations of worn surface, wear debris and abraded abrasive medium.

Tribological Properties of Al 7075 Alloy and 7075/Al2O3 Composite Under Two-Body Abrasion: A Statistical Approach

Tribological properties, i.e., wear rate, coefficient of friction (COF), and roughness of worn surfaces of an Al-Mg-Zn-Cu alloy and its composite reinforced with 20 wt % Al2O3 particles developed by stir-casting method have been studied and compared under two-body abrasion considering four independent control factors, i.e., load, abrasive grit size, sliding distance, and velocity each at three different levels. Design of test conditions and analyses of output responses have been performed employing standard Taguchi L27 orthogonal array, signal-to-noise ratio, analysis of variance technique, and regression method. Irrespective of wear conditions, composite exhibits lower wear rate and reduced COF with reference to base alloy owing to the load bearing ability and better wear resistance capability of Al2O3 particles. Roughness of worn surfaces of composite is, however, found to be higher over base alloy due to nonuniform abrasion in case of composite that generates the protruded Al2O3 particles on contact surfaces as the surrounding soft matrix is easily removed. For all three tribo-responses of both materials, the most influential factor is identified as grit size followed by load and then, grit size-load interaction except for the roughness of worn surfaces where the influence of sliding distance is also considerable. Linear regression models with excellent predictability have been developed for all tribo-characteristics separately for base alloy and composite. The predominant mechanisms of abrasion are identified as plowing and microcutting for base alloy, but delamination for composite.

Multi-response optimization of machining characteristics in ultrasonic machining of WC-Co composite through Taguchi method and grey-fuzzy logic

This article addresses the application of grey based fuzzy logic coupled with Taguchi’s approach for optimization of multi performance characteristics in ultrasonic machining of WC-Co composite material. The Taguchi’s L-36 array has been employed to conduct the experimentation and also to observe the influence of different process variables (power rating, cobalt content, tool geometry, thickness of work piece, tool material, abrasive grit size) on machining characteristics. Grey relational fuzzy grade has been computed by converting the multiple responses, i.e., material removal rate and tool wear rate obtained from Taguchi’s approach into a single performance characteristic using grey based fuzzy logic. In addition, analysis of variance (ANOVA) has also been attempted in a view to identify the significant parameters. Results revealed grit size and power rating as leading parameters for optimization of multi performance characteristics. From the microstructure analysis, the mode of material deformation has been observed and the critical parameters (i.e., work material properties, grit size, and power rating) for the deformation mode have been established.

Experimental study on micromachining of CFRP/Ti stacks using micro ultrasonic machining process

Carbon fiber-reinforced plastic (CFRP) composite is one of the most sought after material owing to its superior physical and mechanical properties such as high durability and high strength-to-weight ratio. CFRP composites are often used by stacking up with titanium (Ti) to form multi-layered material stacks for applications involving extreme mechanical loads such as in aerospace and automotive industries. However, the machining of CFRP/Ti multi stacks is quite complex and challenging task since both materials are difficult-to-machine materials and show completely different machinability properties. The challenge is further escalated when there is a need to machine the CFRP/Ti stacks at micron level. Several problems arise during the machining process due to the non-homogeneous structure and anisotropic and abrasive properties of composites. Traditional methods of micromachining the CFRP/Ti stacks result in several issues including high cutting force and high tool wear, composite delamination, large groove depth in composites, and poor surface quality. Ultrasonic machining (USM) process has been successfully used to machine titanium, CFRP, and CFRP/Ti stacks at macro scale. Micro ultrasonic machining is a downsized version of macro USM process that is developed to machine hard and brittle materials such as quartz, glass, and ceramics at micron scale. This research explores the possibility of using the micro USM process to conduct micromachining of CFRP/Ti multi stacks. The effects of various process parameters including abrasive grit size, tool material and type on the material removal rate and surface quality are studied. The study found that micro ultrasonic machining process is capable of successfully micromachining CFRP/Ti stacks. In comparison with conventional processes, micromachining of CFRP/Ti stacks using micro ultrasonic machining process resulted almost zero CFRP delamination, minimal variation in CFRP and Ti hole sizes, and longer tool life.

Experimental Analysis for the Use of Sodium Dodecyl Sulfate as a Soluble Metal Cutting Fluid for Micromachining with Electroless-Plated Micropencil Grinding Tools

Microgrinding with micropencil grinding tools (MPGTs) is a flexible and economic process to machine microstructures in hard and brittle materials. In macrogrinding, cooling and lubrication are done with metal cutting fluids; their application and influence is well researched. Although it can be expected that metal cutting fluids also play a decisive role in microgrinding, systematic investigations can hardly be found. A metal cutting fluid capable of wetting the machining process, containing quantities as small as 0.02% of the water-soluble fluid sodium dodecyl sulfate was tested in microgrinding experiments with MPGTs (diameter ~50 µm; abrasive grit size 2–4 µm). The workpiece material was hardened 16MnCr5.

Experimental investigation of tool wear and machining rate in rotary ultrasonic machining of nickel alloy

ABSTRACTNickel alloys possess the excellent potential at high temperature and resistance to oxidation/corrosion owing to its high nickel content. These materials necessitate non-traditional machining methods. The rotary ultrasonic machining (RUM) process comes into existence as a superior alternative to the conventional machining of nickel alloys. The processing of these alloys using RUM needs attention. This article details the multi-response optimization in RUM of nickel alloy using the desirability concept. The present work is carried out with two shapes of the tool: (i) Plain tool and (ii) lateral slotted tool. During RUM, the process parameters—power rating tool rotation, abrasive diamond grit size and feed rate are varied. Compared with the plain tool, the lateral slotted tool shows the more efficient machining rate (MR) with less tool wear (TW). The micro-graphs disclose the mechanism of MR and TW during RUM.

Optimization of material removal rate in ultrasonic machining of polycarbonate bulletproof glass and acrylic heat-resistant glass by Taguchi method

PurposeThe purpose of this paper, an original research paper, is to study the optimization of material removal rate (MRR) in ultrasonic machining of polycarbonate bulletproof glass and acrylic heat-resistant glass. The machining of these materials is a very tough job. There are so many constraints which need to be taken into account while machining, but without proper knowledge of material properties and machining parameters, machining is not possible. This paper gives basic knowledge about polycarbonate bulletproof and acrylic heat-resistant glass and provides ways as to how these types of materials are processed or machined.Design/methodology/approachThe Taguchi method was utilized to optimize the ultrasonic machining parameters for drilling these advanced materials. The relationship between MRR and other controllable process parameters such as concentration of slurry, type of abrasive, abrasive grit size, power rating, concentration of HF acid and type of tool material has been analyzed by using the Taguchi approach.FindingsThrough the Taguchi analysis, it is concluded that types of abrasive and HF acid concentrations have a significant role to play in MRR for both materials; in which, type of abrasive have 72.91 and 72.96 percent contribution in MRR for polycarbonate bulletproof and acrylic heat-resistant glass, respectively. Similarly, HF acid concentration has 14.70 and 14.65 percent contribution in MRR for polycarbonate bulletproof and acrylic heat-resistant glass, respectively. The MRR was improved by 34.44 percent in polycarbonate bulletproof glass and 29.25 percent in acrylic heat-resistant glass.Originality/valueAfter experimental investigation, the results of the Taguchi modal are validated.

Experimental study and optimization of cutting parameters in machining of super alloy with hybrid ultrasonic method

Super alloys are intensively used in various industries, especially in the aerospace industry, because of their special characteristics. A number of holes are sometimes required to be drilled into super alloys for aircraft at their final stage assembly. In the present study, a hybrid ultrasonic machining method, called rotary ultrasonic machining (RUM), was successfully used in super alloy drilling. The empirical modeling of the process parameters of RUM was performed for the super alloy (Inconel 718) using an experimental design approach, called response surface methodology (RSM). Parameters, namely tool rotation, feed rate, ultrasonic power, and abrasive grit size, were selected as input variables. The others were kept constant. The performance was measured in terms of the machining rate and the surface roughness. The developed models were found to be reliable representatives of the experimental results with prediction errors less than ±5%. Moreover, the feed rate for the quality and productivity aspect was found to be the most critical factor. The optimized values of the machining rate and the surface roughness achieved through a multi-response optimization were 0.9 825 mm3/s and 0.951 μm, respectively.