Micro-finishing Process Research Articles

Evaluation of Surface Finishing Efficiency of Titanium Alloy Grade 5 (Ti–6Al–4V) After Superfinishing Using Abrasive Films

Ti–6Al–4V is the most commonly used alpha–beta titanium alloy, making it the most prevalent among all titanium alloys. The processed material is widely employed in aerospace, medical, and other industries requiring moderate strength, a good strength-to-weight ratio, and favorable corrosion resistance. A microfinishing process on the titanium alloy surface was conducted using abrasive films with grain sizes of 30, 12, and 9 μm. Superfinishing with abrasive films is a sequential process, where finishing operations are performed with tools of progressively smaller grains. The surface topography measurements of the workpiece were taken after each operation. The experiment was in the direction of developing a new surface smoothness coefficient considering the number and distribution of contact points so as to properly evaluate the quality of the surface finishing. The results showed that the finest-grain films gave the most uniform contact points, thus offering the best tribological characteristics; the 9 LF (micron lapping film) tools gave the smoothest surfaces (Sz = 2 µm), while the biggest-grain films, such as the 30 FF (micron microfinishing film), were less effective since large protrusions formed. This is a suitable study to explore the optimization paths for the superfinishing of titanium alloys, with implications for improving the performance and longevity of components in critical industrial applications.

Comparative Analysis of Microabrasive Film Finishing Effects across Various Process Variants.

The paper investigates various methods of microfinishing and arrives at the best technique to produce a very smooth surface. Various setups, with and without oscillation, were developed, together with a microfinishing attachment used on conventional lathes and milling machines. The workpiece material used was an amorphous nickel-phosphorus Ni-P alloy. The surface roughness parameters, such as Sa, Sv, and Sp, were measured with the TalySurf CCI6000 instrument. For the measurement of the surface protrusions, an "analysis of islands" technique was used at various levels of cut-off. The 2BA method-machining below the workpiece axis with oscillation-turned out to be the most effective method applied because it had the highest density of protrusions while having the smallest value of surface roughness. Non-oscillation with the machining zone below the axis also becomes effective, indicating that repositioning can compensate for a lack of oscillation. Already, the very compact surface structure achieved with minimized depths in the valleys by the 2BA method supported the improvement in tribological performance and increase in load-carrying capacity, together with lubricant retention enhancement. These results show that the microfinishing process can be optimized by parameter tuning, and also, non-oscillating methods could come to be a practical alternative, probably reducing the complexity of equipment and cutting costs. Further studies need to be aimed at the scalability of these methods and their application to other materials and fields.

MAF process for aluminum 6060: An analytical temperature modelling and chemo-mechanical analysis

The magnetic abrasive finishing process is a sophisticated micro-finishing process that enhances the surface quality of superalloys, ceramics, and composites. Surface temperature plays a pivotal role in facilitating chemo-mechanical reactions between the processed surface and abrasive particles. In triggering the chemo-mechanical response of the micro-finished surface of Aluminum 6060 (Al-6060), an analytical thermal model derived using Jaeger moving heat formulation to find the flash temperature (FT) and flash time duration (FTD) at the micro-finishing interface of the processed workpiece and the abrasive particles of the magnetic abrasive brush. Furthermore, the present work performed an RSM-based Box Behnken design experiment to analyse and explain the crucial role of machining gap, abrasive weight, Voltage, and rotational speed on surface temperature, machining surface, and hardness. ANOVA highlighted key factors in machining responses. Surface roughness and temperature were notably influenced by voltage (58.42 % and 57.62 %, respectively), while surface hardness primarily depended on abrasive weight (60.65 %). Using the developed model, extreme FT of 880 °C and 810 °C were calculated under specific conditions, along with corresponding FTD required for quasi-steady-state conditions. FT and FTD were identified as sufficient for initiating chemo-mechanical action in the MAF micro-finishing process, depending on contact pressure, the number of abrasive particles, and sliding velocity, which in turn are influenced by magnetic intensity, abrasive ratio, and rotational speed. Furthermore, a detailed examination of the finished surface was carried out using the SEM, EDS and XRD of Al-6060 which shows that the SiC does participate on the finishing surface. Chemical substrates such as Kaolinite (Al2O9Si2), Iron silicide (FeSi), and Cristobalite (O2Si) had formed on the finished surface of Al-6060 due to the chemo-mechanical action between the SiC and workpiece material.

Effects of Pressure Rollers with Variable Compliance in the Microfinishing Process Utilizing Abrasive Films.

This article presents a comprehensive investigation into pressure rollers utilized in the microfinishing process, covering aspects such as design, experimental properties, compliance, and finite element simulation. Prototype pressure rollers with unconventional elastomer configurations were designed and analyzed to explore their effectiveness in achieving superior surface finishes. Experimental analysis and finite element simulations were conducted to gain insights into the performance and behavior of these pressure rollers under various loading conditions. This study addresses the validation of constitutive material models used in finite element simulations to ensure accuracy and reliability. The results indicate that the applied material model, validated through experimental analysis, accurately predicts pressure roller behavior. Finite element simulations reveal distinct contact zone patterns and stress distributions across the contact surfaces, highlighting the importance of considering deflection-induced variations in contact behavior. Additionally, the investigation evaluates the effectiveness of different pressure rollers in removing surface irregularities during the microfinishing process. Roller R3 demonstrates the highest efficacy in removing surface peaks, suggesting its potential for achieving superior surface finishes. Overall, this research contributes to the advancement of microfinishing techniques by providing insights into pressure roller design, performance, and behavior, thereby optimizing microfinishing processes to produce high-quality components. The urgency of this study arises from the growing need for exceptional surface finishes in various industrial sectors. With manufacturing industries increasingly pursuing high-precision components boasting flawless surface quality, the significance of microfinishing processes is highlighted.

Challenges and Opportunities in ECH of Gears

Electrochemical honing (ECH) is an encouraging technique of gear finishing because of its micro-removal characteristic. In ECH, material removes by combined effect of anodic dissolution and mechanical abrasion. It is a hybrid micro-finishing process. ECH is a productive technique of gear finishing with high accuracy and long tool life. However, the lack of comprehensive research and complex setup design prevents it from being commercialized. This paper discusses the emphatic features of electrochemical honing of gears; its prospective features and capabilities. A comparative study is executed to explore the improvement in process capability and advantages of it. The shortcomings of the process are also discussed. Some guidelines are also mentioned for future research. It helps research community to mature this process further.

Określanie zdolności diamentowych folii ściernych do mikrowygładzania

In order to determine the micro-finishing abilities of diamond abrasive films, surface topography was analyzed using confocal microscopy OLS 4000 Olympus. In the analysis of stereometric features of the abrasive surface, it was considered that during the micro-finishing process the abrasive surface is pressed against the workpiece. The procedure for determining the changes in topography of the film surface in the treatment area was developed as a result of elastic deformations of the film carrier, the grain binding binder and the pressure roller. New parameters for the activity of abrasive grains were developed and the values of grain hollows, depending on the pressure value in the machining zone and the nominal size of the grain (3, 9, 15, 30 μm) were determined.

Modeling and simulative analysis of the micro-finishing process

Honing operations are primarily applied to enhance tribologically loaded surfaces. In order to reduce the experimental effort during process design and optimization, a prediction of the specific surface topography resulting from a particular honing operation is necessary. Therefore, a high-resolution geometric process model for force-controlled honing operations was developed, which utilizes numerical data of tools and workpieces from topographic scans. In this paper, the modeling approach is presented and applied to a micro-finishing process with different process parameter values. The simulation results are also compared to surface topographies generated in experiments in order to validate the simulation model.

Optimization of guide pads for the BTA deep hole drilling of high alloyed steels by microfinishing

The boring and trepanning association deep hole drilling of materials with a high tendency to adhesion, such as high alloyed-steels, is characterized by a poor surface quality of the bore hole. Material particles adhere to the guide pads that are positioned on the circumference of the drill head and that are normally responsible for the outstanding workpiece quality. In order to prevent this mechanism the guide pads were coated with an innovative amorphous and tetrahedral bonded (ta-C)-coating. This coating has a reduced friction coefficient of 0.1 against steel and a hardness coefficient of about 7,000 HV. To use the benefits of this ta-C-coating the pre- and the after-treatment of the uncoated carbide substrate and ta-C-coated guide pads are essential. For these process steps a microfinishing process was carried out as an alternative to the conventional treatment by polishing and brushing. The microfinishing of the uncoated guide pads effects a smooth surface that is necessary for an optimum bonding strength of the ta-C-coating at the carbide substrate. Furthermore the chamfer edge in the lead-in-area is rounded which reduces the mechanical load at this specific area during the process. The finishing process of the coated guide pads reduces the coating defects and improves the friction coefficient. Thus, the wear behavior of the guide pads is improved because of the better friction conditions during the drilling process of high alloyed steels.

State-of-art-review of electrochemical honing of internal cylinders and gears

This paper is an attempt to present a state-of-the-art review of two major applications of electrochemical honing (ECH) for internal cylinders and gears, which are the most commonly used parts in numerous engineering applications. ECH is a hybrid process of electrochemical machining (ECM) and mechanical honing, combining the fast material removal capabilities of ECM and controlled functional surface generating capabilities of mechanical honing in a single operation. ECH is a precision micro-finishing process capable of producing excellent surface quality having a cross-hatch lay pattern required for lubricating oil retention, compressive residual stresses required for the components subjected to cyclic loading, and completely stress-free surfaces. Furthermore, it provides these benefits productively. It makes ECH an ideal choice for superfinishing, improving the surface integrity, and increasing the service life of the critical components such as internal cylinders, transmission gears, carbide bushings and sleeves, rollers, petrochemical reactors, moulds and dies, gun barrels, etc., most of which are made of very hard and/or tough, wear-resistant materials generally susceptible to heat distortions. Consequently, ECH finds widespread use in the automobile, avionics, petrochemical, power generation, and fluid power industries. This paper presents a detailed description of the process principle, parameters, capabilities, equipment details, applications, and comprehensive literature review of past research work on the ECH of internal cylinders and gears along with some directions for future research with an objective to revive the interest of the global research community to mature this process further.

Precision microfinishing by electro-chemical honing

Surface condition and shape deviations produced by manufacturing processes have pronounced influence on the functional performance of engineering components. This paper reports a comprehensive study on the influence of several key process parameters of Electro-Chemical Honing (ECH), a precision microfinishing technology, on dominant machining criteria the surface roughness improvement. The current intensity, electrolyte concentration, stick-out pressure and stick grit-size are found to be the major players influencing the response significantly. With distinct coordination of electrolytic dissolution and mechanical scrubbing, ECH can be utilized as a precision microfinishing process for critical components of tribological significance. More than 90% improvement in surface finish with precisely controlled shape deviations can be achieved. Important features of the ECH setup that was designed and developed indigenously are also highlighted.

Stress analysis of a ballised hole

Ballising is a micro-finishing process where an oversized ball is forced through an undersized hole resulting in superior roundness, refined surface quality and increased dimensional precision of the hole. In addition, the internal pressure exerted on the wall of the hole, due to the interference between the diameter of the hole and that of the ball, renders a plastically deformed region from the bore to a radius that forms the elastic-plastic boundary. Beyond the elastic-plastic boundary, only elastic deformation occurs as the material recovers upon the exit of the ball. Stress analysis using the theory of plasticity and von Mises yield criterion predicts a resultant compressive stress state surrounding a ballised hole. The resultant stress state is a function of the radius of the elastic-plastic boundary which in turn is a function of the interference. Experimental investigation with varying interferences into the resultant stress state of a ballised hole in a medium carbon steel concurs with the theoretical predictions.

Bore finishing—The ballizing process

The ballizing process is a relatively new microfinishing process that involves the forcing of a precision-ground metallic ball through a slightly undersized hole. Traditional hole finishing methods such as grinding and honing are seen to be both time- and energy-consuming when compared to the simpler ballizing process. Tungsten carbide balls were used with different lubricants to bring about force reduction. Forces were measured using a strain-gauge dynanometer. Surface deformation was studied by means of scanning electron microscopy. A mathematical model is proposed for the prediction of the final diameters of the ballized hole and good agreement is found with experimental observations. Thus, in the industrial employment of the ballizing process, use of the mathematical model will enable a quick determination of the values of the relevant parameters in order for a specified part-diameter to be achieved.

A Study of the Ballizing Process

The ballizing process which involves the forcing of a precision ground tungsten carbide ball of a prescribed diameter through a slightly undersized hole, is a relatively new microfinishing process. Though ballizing equipment have been commercialised, very few reports on the process have been published; of these is the one by Prokuryakov et al. In the present study of low speed ballizing, tungsten carbide balls of various diameters were used on brass, aluminium and steel specimens. Surface finish, roundness and forces were measured. With the large volume of data collected, multiple linear regression techniques were used and empirical relationships were established. Optical and scanning electron microscopy were used for surface integrity studies.