Final Finishing Research Articles

Polydopamine-Lysophosphatidate-Functionalised Titanium: A Novel Hybrid Surface Finish for Bone Regenerative Applications.

Aseptic loosening of total joint replacements (TJRs) continues to be the main cause of implant failures. The socioeconomic impact of surgical revisions is hugely significant; in the United Kingdom alone, it is estimated that £135m is spent annually on revision arthroplasties. Enhancing the longevity of titanium implants will help reduce the incidence and overall cost of failed devices. In realising the development of a superior titanium (Ti) technology, we took inspiration from the growing interest in reactive polydopamine thin films for biomaterial surface functionalisations. Adopting a “one-pot” approach, we exposed medical-grade titanium to a mildly alkaline solution of dopamine hydrochloride (DHC) supplemented with (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), a phosphatase-resistant analogue of lysophosphatidic acid (LPA). Importantly, LPA and selected LPA analogues like FHBP synergistically cooperate with calcitriol to promote human osteoblast formation and maturation. Herein, we provide evidence that simply immersing Ti in aqueous solutions of DHC-FHBP afforded a surface that was superior to FHBP-Ti at enhancing osteoblast maturation. The facile step we have taken to modify Ti and the biological performance of the final surface finish are appealing properties that may attract the attention of implant manufacturers in the future.

Características de carcaça e qualidade de carne de fêmeas suínas alimentadas com ou sem ractopamina

O objetivo foi avaliar o efeito da suplementação ou não de 10 ppm de ractopamina em dietas para fêmeas suínas em fase final de terminação, sobre características de carcaça e qualidade de carne, foram utilizados 54 animais, com peso médio inicial de 98 kg (± 0,9 kg), distribuídos em delineamento inteiramente casualizado composto de dois tratamentos, 27 repetições e um animal por unidade experimental. Os tratamentos usados foram dietas sem ou com suplementação de 10 ppm de ractopamina, por 21 dias. A suplementação de ractopamina em dietas para fêmeas suínas na fase final de terminação influenciaram os parâmetros de características de carcaça e qualidade de carne dos animais. Foram observados efeito significativo (P<0,05) para todas as características de carcaça avaliadas, exceto para rendimento de carcaça e de qualidade de carne: carcaça direita quente e resfriada, perda de carcaça no resfriamento, carne magra na carcaça, perda de água por gotejamento, força de cisalhamento no dia 7 e perda de água por cocção no dia 14, não observou-se efeito (P>0,05) para perda de água por cocção nos dias 1 e 7 e força de cisalhamento no dia 14. Com a adição de 10 ppm de ractopamina na dieta das fêmeas suínas em fase de terminação por 21 dias, obteve influência na qualidade de carne, proporcionando melhores parâmetros de características de carcaça, com maior rendimento de carne magra na carcaça.

Development and Rheological Characterisation of Abrasive Flow Finishing Medium for Finishing Macro to Micro Features

Technological advancement demands the manufacturing of components with a fine surface finish at a minimal cost. This scenario acts as the driving force for the research communities to develop economic finishing processes. Abrasive flow finishing (AFF) is one of the advanced finishing processes employed for finishing, deburring, radiusing and recast layer removal from the workpiece surfaces. AFF process uses a finishing medium that acts as a deformable tool during the finishing process. It is the rheological properties of the medium that profoundly influences the end surface finish obtained on the workpiece after the AFF process. In the current work, an attempt is made to develop an economic AFF medium by using viscoelastic polymers i.e., soft styrene and soft silicone polymer. Detailed static and dynamic characterisation of the medium is carried out. Later, to study the finishing performance of the developed medium, AFF experiments are performed for the finishing of macro and micro feature components. The experimental study showed that the nano surface finish could be achieved by varying the viscosity of the developed medium. Developed medium achieved 89.06 per cent improvement in surface roughness during finishing of tubes (macro feature component), while 92.13 per cent and 88.11 per cent surface roughness improvement is achieved during finishing of microslots and microholes (micro feature component), respectively.

Modeling of material removal in magnetic abrasive finishing process with spherical magnetic abrasive powder

This study describes the application of a magnetic abrasive finishing (MAF) process to yield a fine finish on planar workpiece (SS304). The grinding tool is a flexible abrasive brush using diamond particles embedded in a spherical iron matrix. This bonded type of spherical MAPs was developed via an atomization technology to solve the problem that hard particles were easily thrown from the magnetic field at high rotational speed. Theoretical model of the material removal was composed of the mechanical properties of work material and four applied process parameters such as working gap, rotational speed of magnetic pole, feed rate of workpiece, and size of magnetic abrasive powder (MAP). The magnitude and distribution of generated magnetic flux was simulated by finite element analysis to evaluate the normal pressure of MAP. The single factor experiment was conduct to analyze the relationship between surface roughness reduction and material removal. Scanning electron microscopy was used to understand the effect of different abrasive material on the finished surface of workpiece. Under the same optimum processing condition, diamond MAPs produced a better surface roughness and more material removal than CBN MAPs and alumina MAPs did. The established theoretical model brought out that high material removal corresponds to a fine surface roughness in the MAF process with atomized spherical MAPs.

Development of a facile fluorophosphonate-functionalised titanium surface for potential orthopaedic applications

sBackgroundAseptic loosening of total joint replacements (TJRs) continues to be the main cause of implant failures. The socioeconomic impact of surgical revisions is hugely significant; in the United Kingdom alone, it is estimated that £137 m is spent annually on revision arthroplasties. Enhancing the longevity of titanium implants will help reduce the incidence and overall cost of failed devices.MethodsIn realising the development of a superior titanium technology, we exploited the natural affinity of titanium for phosphonic acids and developed a facile means of coating the metal with (3S)1-fluoro-3-hydroxy-4-(oleoyloxy)butyl-1-phosphonate (FHBP), a phosphatase-resistant analogue of lysophosphatidic acid (LPA). Importantly LPA and selected LPA analogues like FHBP synergistically cooperate with calcitriol to promote human osteoblast formation and maturation.ResultsHerein, we provide evidence that simply immersing titanium in aqueous solutions of FHBP afforded a surface that was superior to unmodified metal at enhancing osteoblast maturation. Importantly, FHBP-functionalised titanium remained stable to 2 years of ambient storage, resisted ∼35 kGy of gamma irradiation and survived implantation into a bone substitute (Sawbone™) and irrigation.ConclusionThe facile step we have taken to modify titanium and the robustness of the final surface finish are appealing properties that are likely to attract the attention of implant manufacturers in the future.The translational potential of this articleWe have generated a functionalised titanium (Ti) surface by simply immersing Ti in aqueous solutions of a bioactive lipid. As a facile procedure it will have greater appeal to implant manufacturers compared to onerous and costly developmental processes.

TEXTURIZADO POR RECTIFICADO PARA LA MEJORA DE PROPIEDADES DE FRICCIÓN EN COMPONENTES INDUSTRIALES

The economic and environmental cost of friction in machinery and transport is significantly remarkable being the machine tool one of the most affected. In this sector, the movements are totally affected by the friction originated in the displacements between the guideways and the carriages, which results in terms of precision, energy consumption and component wear. In this line, texturing has proved to be a useful tool to reduce friction. Texturing techniques include frosting and scraping, both manual and costly processes in which the final finish of the workpiece depends on the operator. Other techniques such as laser texturing represent an effective and precise procedure which is at the same time expensive and not applicable in large workpieces. One of the main challenges is to develop techniques capable of producing these textures in a repetitive and economically viable way. In this work, a new assisted dressing technique that allows generating different textures by grinding, controlling the geometry and distribution of these, is presented. This technique allows to create textures in large workpieces, such as the guides of the machine tools and to do it in a repetitive way and in the same machine in which the guide has been ground previously, which entails a reduction in time and costs. This technique has been validated through tribological tests obtaining lower friction coefficients than with manual techniques. Keywords: Friction, grinding, texturing, dimples, machine-tool, guideways.

Experimental analysis of magnetorheological finishing of blind hole surfaces using permanent magnet designed tools

Permanent mould dies are used for various plastic injection moulding products. Most of the mould cavity is blind and henceforth difficult to finish. In this study, a novel magnetorheological fluid-based finishing process using permanent magnet tools has been developed for nano-finishing of cylindrical blind hole surfaces. Tools to finish the internal and flat-bottomed surfaces of the cylindrical blind hole are developed. The finishing performance of both tools is evaluated for finishing ferromagnetic material used in dies. The material of the die is P20 tool steel having 41 HRC hardness. Response surface methodology using a central composite design technique has been utilized for the plan of experiments and analysis of significant process parameters on the percentage change in surface roughness using newly developed tools. During finishing the internal cylindrical blind hole surface, the process parameters like rotational speed, reciprocation speed and abrasive mesh size are found to be significant. However, during flat-bottomed surface finishing of cylindrical blind hole workpiece, rotational speed, abrasive mesh size and abrasives volume percentage are found to process significant parameters. Experimentation at optimized parameters results in the final surface finish of 83 nm on internal cylindrical surface and 93 nm on the flat-bottomed surface of cylindrical blind hole workpiece.

Densification, mechanical behaviors, and machining characteristics of 316L stainless steel in hybrid additive/subtractive manufacturing

Directed energy deposition (DED) is capable of manufacturing high-density and complex metal components, whereas traditional machining methods are limited in these regards. Nevertheless, the fabrication of parts with DED that have accurate dimensions and geometries as well as acceptable surface states is a concern, as these factors are inferior to those of traditionally machined components. Therefore, the application of parts fabricated with DED is restricted. Thus, the hybrid additive/subtractive manufacturing (HASM) method has been exploited to comprehensively utilize the advantages of both. In this paper, the HASM method was used to fabricate bulk parts with four different scanning strategies (alternating the orientation of subsequent layers by 0°, 45°, and 90° and island scanning are referred to as an X-scan, a Rot-scan, an XY-scan, and an Island-scan, respectively) followed by subtractive milling to gain a smooth surface with a determined thickness for the next scanning and deposition period until the parts were completely finished. The influence of the scanning strategy on the densification level and mechanical behavior of the specimens fabricated with HASM was studied. The results show that the specimens fabricated with the 7 × 7 mm2 island scan with short scan vector lengths showed a higher densification than the specimens fabricated using long scan vector lengths (the three methods mentioned above). Finally, to obtain a fine surface finish, the influence of the feed per tooth (fz) on the surface quality of a 316L stainless steel during the milling process that occurs during the HASM process was also investigated. The result shows a fz of 0.25 mm yielding the minimum surface roughness value among the samples observed herein, which implies that the surface quality was better than that of the other studied conditions.

Magnetorheological finishing of grooved drum surface and its performance analysis in winding process

The fine level finishing of grooved drum surfaces is an essential requirement for enhancing the performance of the winding machines in today’s textile industries. The fine level of finishing is required as less as possible on the grooved surface of the textile winding drum. With the least possible roughness value over the external grooved surface of the winding drum, the breakage of the yarn and hairiness of the yarn gets reduced. To accomplish the requirement of finishing the grooved surface of the winding drum, a rectangular-rotating magnetorheological (MR) finishing process is utilized. After the MR finishing, the functional performance of the already using ground grooved winding drum in industry and the present MR finished grooved winding drum has been compared and examined their performance. The functional performance of the MR finished grooved drum is found better than the ground grooved winding drum due to the fine level of finishing. After 60 min of MR finishing, the average surface roughness value of the grooved drum surface gets reduced from 200 nm to 10 nm. Scanning electron microscopy and mirror images are also conducted. These results showed better surface characteristics with the MR finished grooved winding drum than the ground grooved winding drum. After the MR finishing operation, the grooved winding drum is taken to the textile industry. In the industry, the effect of surface roughness on the functional life of the grooved drum is investigated in the winding process. The functional performance has been found better with the MR finished grooved drum surface in the winding process than the ground grooved drum surface.

Preparation, microstructure analysis and performance evaluation of bonded magnetic abrasives

The traditional edged tool for machining is uneconomical for harder and difficult to machine materials. In view of the seriousness of this issue, the newly unconventional fine finishing process i.e., magnetic abrasive flow machining (MAFM) has been developed. However, the major constraint in wide spread adoption of this technology is the exorbitant cost of magnetic abrasives, which acts as a cutting tool in MAFM. In this paper, to improve the finishing performance, iron (Fe) powder mixed with diamond abrasives were prepared as bonded magnetic abrasives. These magnetic abrasives were prepared by mechanical alloying followed by annealing of diamond abrasives of 52 μm grit size and Fe powder of 49 μm grit size. These abrasives were micro-structurally analysed. The results indicate that densification increases and porosity decreases with increasing temperature. Further it was clarified that the prepared bonded magnetic abrasives has potential performance as the new magnetic abrasives for fine finishing.

Implementation of SMED in a cutting line

The present work was carried out on a cork company that is dedicated to the production of floating floors and its aim was to reduce by 15% the time it takes to perform series changes in one cutting line. The research methodology used in this work was the action research methodology. The methodology consisted of 5 phases, as follows: 1st - historical data collection and setup filming, 2nd - footage analysis and conduction of informal interviews with workers, 3rd - flow, Gantt, and spaghetti charts creation and making of an action plan based on the waste and improvement opportunities identified in video analysis, 4th - validation with the line workers of the new operating mode created with the Single Minute Exchange of Dies (SMED) tool and communication to the Maintenance department about their role in this project, 5th - making and placement of plasticized cards on the cutting lines to ensure that new operating mode is followed and carrying out the actions identified in the action plan. The obtained results are very positive in the cutting line: after the implementation of the new guidelines in the Final Finishes 2 (AF2), there was a 2 minutes increase in the changeover compared to the time initially observed, but being now performed by only two workers and not by three, as initially occurred.

A study in turning of AISI D2 steel with textured and non-textured coated carbide tool at the flank face

Surface texturing of a cutting tool is a new technique which can enhance the cutting performance during machining. In the present work micro-EDM is applied to produce texture at the tool flank face. Two types of texture, i.e. groove and dot are made at the flank face of a coated carbide tool for machining AISI D2 steel. For comparison purpose, machining is performed using non-textured tool also. Cutting speed, feed and depth of cut are selected as the cutting parameters, each having two levels. The cutting force and feed force are considered as main performance parameters beside surface roughness and flank wear. From the experimental study, it is noticed that textured tool gives low values of cutting and feed forces during machining as compared to a non-textured tool. In comparison to groove-texturing tool, dot-texturing tool generates less cutting and feed forces. Both the texturing tool gives fine surface finish and less flank wears in comparison to non-textured tool.

Experimental investigations into magnetic abrasive flow finishing process on aluminium 6061-T6

The magnetic abrasive flow finishing (MAFF) process has been developed and investigated as an advanced fine finishing process. It is used for a surface finish (SF) of the straight and complex intricate profile using the ferromagnetic nature of abrasive media. This article presents an experimental investigation on the newly developed MAFF attachment, which was mounted on a shaper machine. A custom design workpiece fixture was used in MAFF attachment for the finishing of a straight hollow cylinder shape workpiece, which can easily modify based on workpiece shapes. A curved workpiece seat was prepared and fasting with two brass plates by nut and bolts arrangement. Taguchi design of experiment approach applied for experimentation on aluminium 6061-T6 workpiece material by MAFF setup. The main process parameters considered for experimentation are magnetic flux density (MFD), number of cycles, abrasive concentration, and piston speed while responses are material removal (MR) and surface finish (SF). The results found after finishing by MAFF were also compared with the AFF. It was identified that remarkable enhancements observed in MAFF responses. The finished surfaces were also observed by scanning electron microscope (SEM) and X-ray diffraction (X-RD).

Stages of technological process of high anisotropy formation of magnetic properties under «dry» pressing of powder products

The article proposes the description of technological production process of anisotropic products from powders of high materials which provides powders preparation and products made of them. It has been shown that the main drawback of «wet» pressing technology is low accuracy at dosing wet charge. To eliminate warping and cracking of briquettes obtained by «wet» pressing during the sintering, they are subjected to air drying at room temperature within 48-72 hours. However, the percentage of product failure due to mechanical and magnetic characteristics remains high. Practically all the drawbacks of «wet» pressing can be eliminated by reverse to dry powder pressing, which allows to obtain low mass magnets without additional final finishing machining, to avoid warping and cracking of the product, and to reduce sintering time. Nevertheless, under the dry powder pressing the magnetic characteristics of products are significantly lower than under the wet pressing. When working with disperse materials, a promising direction is to converse them into fluidized state. To obtain the fluidized state of powder materials, vibrational technologies are used, involving the transfer of a wide range of energy to the powder material, i.e. mechanical, acoustic, electric and magnetic energy.

Manufacturing and performance analysis of mechanically alloyed magnetic abrasives for magneto abrasive flow finishing

The final finishing of precision components possessing a high degree of surface finish has bring about the application of magneto abrasive flow finishing (MAFF) process because of the development of manufacturing technology. In MAFF process, the magnetic abrasives play the role of cutting tool in MAFF process. This investigation highlights a novel technique of manufacturing magnetic abrasives with mechanical alloying followed by heat treatment. The performance of these magnetic abrasives was analysed in terms of percentage surface finish improvement (PSFI) of aluminum tubes. The experiments were planned and conducted according to response surface method (RSM) on aluminum tubes to check the effects of several parameters/limits such as magnetic flux density (MFD), no. of cycles and extrusion pressure (EP) on surface finishing. The experimental results revealed that the best PSFI of 72.7 % has been obtained at optimal processing conditions. The best surface finish (Ra) of 0.27 μm was acquired in this investigation. The scanning electron microscopy (SEM) images have been obtained to show the surface finish improvement after MAFF process.

Analyzing Process Parameters for Finishing of Small Holes Using Magnetically Assisted Abrasive Flow Machining Process

The necessity of fine surface finish on the interior surfaces with no imperfections is a significant thought in various manufacturing components like hydraulic chambers, bearings etc. This analysis presents one of the non-traditional technique of finishing i.e., magnetically assisted abrasive flow machining for finishing the interior surfaces of small holes of aluminum tubes with mechanically alloyed cum sintered magnetic abrasives. These abrasives have been developed in a ball mill i.e., attritor. The central composite design was proposed to perform the experiments to discuss the effects of process parameters like extrusion pressure, magnetic flux density, and no. of processing cycles on percent improvement in surface finish, and a mathematical model of these parameters was established. It was concluded that surface finish is improved up to 72.7% (Ra 0.22 µm) which is in close conformity with optimized value of 72.3% at optimum conditions. Scanning electron microscopy has been carried out to understand the surface texture of the machined surfaces.

A Scenario on Dry-WEDM and WEDM for Industrial Applications

In present day manufacturing industries playing the major role in the machining of new materials with complex shapes, intricate structure and difficult profiles. The improvement of industries and machines is accountable for product quality and accuracy, which are not satisfied in conventional machining techniques. The WEDM is advanced machining process, they are capable to machining the components which are difficult to machine, whereas Dry-WEDM is another method, it utilizes the gas instead of dielectric liquid, it exhibits lower corrosion, fine finish, decrease dielectrics and environment friendly. Development of WEDM is suitable machining option for meeting the demands of modern tool room application and metal cutting industries. The purpose of the article attempts is to highlights the application, improvement and future scope of Dry-WEDM and WEDM in industrial areas.

Preparation, Microstructure Evaluation and Performance Analysis of Diamond-Iron Bonded Magnetic Abrasive Powder

AbstractThe customary edged tool for machining is uneconomical for harder and hard to machine materials and furthermore the level of surface finish accomplished is not that great. As of late, a lot of consideration in mechanical engineering has been centered on finishing tasks. Not many investigations have been accounted for till date on the advancement of substitute magnetic abrasive powder (MAP). In this paper, to improve the finishing performance, the abrasive powder were prepared by mechanical alloying of diamond powder and iron (Fe) powder, compacting these with universal testing machine (UTM) and then sintered at different temperature in a sintering machine in an inert gas (H2) atmosphere. These compacts were crushed and sieved to obtain various sizes of MAP. This abrasive powder were micro-structurally examined. The results indicate that the densification increases and porosity decreases with increasing temperature. Moreover, the prepared bonded MAP has potential performance as a new MAP for fine finishing in Magnetic Abrasive Flow Machining (MAFM) process.

Haptic Hybrid Prototyping (HHP): An AR Application for Texture Evaluation with Semantic Content in Product Design

The manufacture of prototypes is costly in economic and temporal terms and in order to carry this out it is necessary to accept certain deviations with respect to the final finishes. This article proposes haptic hybrid prototyping, a haptic-visual product prototyping method created to help product design teams evaluate and select semantic information conveyed between product and user through texturing and ribs of a product in early stages of conceptualization. For the evaluation of this tool, an experiment was realized in which the haptic experience was compared during the interaction with final products and through the HHP. As a result, it was observed that the answers of the interviewees coincided in both situations in 81% of the cases. It was concluded that the HHP enables us to know the semantic information transmitted through haptic-visual means between product and user as well as being able to quantify the clarity with which this information is transmitted. Therefore, this new tool makes it possible to reduce the manufacturing lead time of prototypes as well as the conceptualization phase of the product, providing information on the future success of the product in the market and its economic return.

Tribological studies of high surface finish ceramic coatings for low friction and adhesive wear resistant applications

Adhesive wear is a significant material loss mechanism that leads to wide scale surface degradation of functional components especially in engineering industries like wind turbine roller bearings. This paper deals with improving the tribological properties of surfaces where adhesive wear is prominent. Adhesive wear is a common problem in gears, bearings, cutting tools, fittings, valves and earth moving equipment. For instance in a planetary gear arrangement, worn out debris from gears cause adhesive wear on the surface of roller bearings. Ceramic coatings are significant for protecting components and to improve the performance of surfaces subjected to adhesive wear over longer periods. Most of the ceramic coatings have high surface roughness owing to which they contribute to further adhesive wear of fine surfaces. In this paper, focus is on studying the performance of ion plated titanium nitride (TiN) and titanium carbide (TiC) PVD coatings against adhesive wear on EN 31 steel (substrate). Surfaces of samples coated with TiN, TiC and uncoated substrate of EN 31 steel are comparatively studied for adhesive wear behavior using wear tests as per ASTM standards. EN 31 steel is composed of 95% Fe, 0.9–1.1% C, 0.35% Mn, and 0.2% Si. Surface morphology and compositional analysis is inferred from Electron Microscopy (SEM and EDS) and surface roughness is estimated using 3-D confocal microscopy and surface profile measurement. The bond strength of coating is analysed from nanoscratch test; the coefficient of friction, material removal rate and hardness of surface is obtained from nano indentation Test. On experimental investigation, it is found that TiN and TiC ceramic coatings have excellent wear resistance, a low coefficient of friction and fine surface finish which are suitable for adhesive wear resistant applications.