Search Results (11)

Poor surface quality is one of the drawbacks of metal parts made by additive manufacturing (AM)—they normally possess relatively high surface roughness and different types of surface irregularities. Post-processing operations are usually needed to reduce the surface roughness to have ready-to-use parts. Among all the surface treatment techniques, electrochemical polishing has the highest finishing efficiency and flexibility. However, although the average surface roughness can be reduced effectively (more than 80% roughness reduction), large-scale surface waviness still remains an issue when finishing metal AM parts. To maintain the finishing efficiency while reducing the surface waviness, a novel hybrid surface finishing technique is designed, which involves the combination of electropolishing, ultrasonic vibration, and abrasion. Preliminary experiments to prove the feasibility of novel hybrid finishing methods were conducted on Ti6Al4V coupons manufactured via laser powder bed fusion (LPBF). Electropolishing, a combination of ultrasound and abrasion, and hybrid finishing were conducted for process optimization and comparison purposes. The effects of the voltage, inter-electrode gap, temperature, ultrasonic amplitude, abrasive concentration, and processing time were studied and optimized. When similar optimal arithmetic mean height values (Sa ≈ 1 μm) are achieved for both processes, the arithmetic mean waviness values (Wa) obtained from hybrid finishing are much less than those from sole electropolishing after the same processing time, with the amount being 61.7% less after 30 min and 40.0% after 45 min. Full article

A lack of dimensional stability of worsted fabrics when laundering leads to a rapid increase in wool textile waste. Dry cleaning is thus highly recommended; however, it requires solvent(s), which are not eco-friendly. The aim of this study was to produce a machine-washable, 100% worsted wool woven as an outer fabric for men’s suit jacket that is also water-repellent in order to reduce the number of washes required during use. Chemical treatments were applied through successive paddings, using a blend of aqueous dispersion of polyurethane and polysiloxane (PUPX) for shrink-proofing/dimensional stability, followed by a second blend of an aqueous emulsion of fluorotelomer methacrylate and paraffin/hydrocarbon waxes (C6PW) polymers for water-repellency. The dimensional change of the finished fabric did not exceed 2%, meeting Woolmark requirements AW-1. Zeta potential measurements confirm that the fabric coated with PUPX has an overall anionic nature, which allows the good adhesion of the successive cationic C6PW polymer blend used in the second padding. Additionally, Scanning Electron Microscopy (SEM) analysis confirmed the good adhesion of the first blend (PUPX) to the wool fiber surface and inter-fiber bonding. After the application of (C6PW) resin, the fabric exhibited durable water repellency with a 5/5 spray test rating after 10 washes and dimensional stability, as well as high resistance to wear and abrasion, while retaining a soft feel and good flexibility. Full article

Polyester fibers are widely employed in a multitude of sectors and applications from the technical textiles to everyday life thanks to their durability, strength, and flexibility. Despite these advantages, polyester lacks in dyeability, adhesion of coating, hydrophilicity, and it is characterized by a low wettability respect to natural fibers. On this regard, beyond the harmful hydrophobic textile finishings of polyester fabrics containing fluorine-compounds, and in order to avoid pre-treatments, such as laser irradiation to improve their surface properties, research is moving towards the development of fluorine-free and safer coatings. In this work, the (3-glycidyloxypropyl)trimethoxysilane (GPTMS) and various long alkyl-chain alkoxysilanes were employed for the fabrication in the presence of a catalyst of a water-based superhydrophobic finishing for polyester fabrics with a simple sol-gel, non-fluorinated, sustainable approach and the dip-pad-dry-cure method. The finished polyester fabrics surface properties were investigated by static and dynamic water repellency tests. Additionally, the resistance to common water-based liquids, abrasion resistance, moisture adsorption, and air permeability measurements were performed. Scanning electron microscopy was employed to examine the micro- and nano-morphology of the functionalized polyester fabrics surfaces. The obtained superhydrophobic finishings displayed high water-based stain resistance as well as good hydrophobicity after different cycles of abrasion. Full article

This work uses the solvent casting method to fabricate an elastomeric tool with polyurethane as the base material and silicon carbide (SiC) as embedded abrasive particles. The distribution of abrasive particles and the pore structure in the fabricated tools are analyzed. The fabricated tools are porous in nature and have self-replenishing as well as self-lubrication properties. Aluminum 6061 alloy and electroless nickel-phosphorus plating having different initial roughness are selected as workpieces to study the wear mechanisms and loading of the flexible abrasive tool. The rotational speed of the tool, tool compression, and feed rate are fixed input process parameters. Total finishing time, sliding distance, and roughness are varied to obtain output responses. The workpiece material is also taken into account as a variable parameter in this study. These materials are classified as different counter surfaces as their surface roughness and mechanical properties vary. The finishing time and sliding distance for these counter surfaces differ in order to relate their effects on tool wear and loading. The nickel-plated surface shows a higher percentage reduction in surface roughness of 92% as compared to the aluminum surface, with a 62% reduction in surface roughness. The coefficient of friction, wear, and tool condition are analyzed to understand the mechanism of tool wear and tool loading. In this process, both two-body and three-body abrasions occur simultaneously and continuously. Full article

Brushing with bonded abrasives is a flexible finishing process used to reduce the roughness of technical surfaces. Although industrially widespread, especially for the finishing of metallic surfaces, insufficient knowledge of the motion, the material removal, and the wear behavior of the abrasive filaments complicates predictions of the work result. In particular, the reliable finishing of ceramics with bonded diamond grains proves difficult due to increased material removal rates, quickly leading to undesirable changes in the workpiece geometry. Based on technological investigations with abrasive brushing tools, this article provides insights into the surface finishing of zirconium dioxide with a focus on finding compromises between reduction in the surface roughness and alteration of the workpiece shape. Full article

Brushing with bonded abrasives is a flexible finishing process used for the deburring and the rounding of workpiece edges as well as for the reduction of the surface roughness. Although industrially widespread, insufficient knowledge about the contact behavior of the abrasive filaments mainly causes applications to be based on experiential values. Therefore, this article aims to increase the applicability of physical process models by introducing a new prediction method, correlating the contact forces of single abrasive filaments, obtained by means of a multi-body simulation, with the experimentally determined process forces of full brushing tools during the surface finishing of ZrO₂. It was concluded that aggressive process parameters may not necessarily lead to maximum productivity due to increased tool wear, whereas less aggressive process parameters might yield equally high contact forces and thus higher productivity. Full article

In this article, we present a numerical model of a magnetic abrasive finishing station, which was analyzed using the finite element method (FEM). The obtained results were compared with the real values measured on an experimental station of our own design. The prepared station had the option of adjusting the magnetic flux density inside the machining gap, the width of which could be changed from 10 to 30 mm. The maximum value of the magnetic flux density inside the air gap was 0.8 T. The real distribution of magnetic flux density in the finishing area was also analyzed. A design of experiment was carried out with the following variables: abrasive grain concentration, width of the machining gap, and process duration. The results are presented in the form of regression equations and characteristics for selected roughness parameters. Full article

In the wood flooring sector, good surface mechanical properties, such as abrasion and scratch resistance, are prerequisite. Surface wood protection is provided by finishing systems. Despite coating improvement, scratches formation on wood flooring is unavoidable. A new approach to increase service life is to confer the self-healing property to the finishing system. The most common coatings used for prefinished wood flooring are acrylate UV curable 100% solids coatings. They usually have good mechanical properties and high cross-linking density. The objective of this study was to develop and evaluate an intrinsic self-healing formulation, which is applicable to wood flooring. For this purpose, acrylate formulations were developed with monomers and oligomers carrying hydroxyl groups. To meet the requirements of wood application, hardness, and polymerization conversion of coatings were evaluated. König pendulum damping tests provide information on coating hardness and flexibility. Results around 80 oscillations is acceptable for UV curable wood sealer. The chemical composition was studied by FT-IR spectroscopy while dynamical mechanical analysis (DMA) was performed to determine glass transition temperature and cross-linking density. The self-healing behavior was evaluated by gloss and scratch depth measurements. The formulation’s composition impacted the hydrogen binding quantity, the conversion, the T_g and the cross-linking density. The (hydroxyethyl)methacrylate (HEMA) monomer provided self-healing and acrylated allophanate oligomer allowed self-healing and cross-linking. This study demonstrated that it is possible to combine high cross-linking density and self-healing property, using components with low steric hindrance. Full article

Titanium alloy wire is characterized by high specific strength, good corrosion resistance, high-temperature resistance and other excellent comprehensive performance. It has been widely used not only in aerospace, shipbuilding and other high-tech fields, but also increasingly in medical equipment, food safety and other fields. Because titanium alloy wire is relatively difficult to process, it has a large deformation resistance, good elasticity, high flexion ratio and more serious rebound. During the processing, adhesion problems may occur, thus reducing the surface quality. The magnetic abrasive finishing (MAF) has good flexible machining characteristics. In this study, the rotating magnetic field was loaded on the titanium alloy wire, and the magnetic abrasive was absorbed by the magnetic field force to form a magnetic abrasive brush, so as to realize the precision processing of the titanium alloy wire. Under the same processing time, when the angle of the magnetic head was 37°, the surface roughness of titanium alloy wire was reduced to 0.28 μm by MAF, which improved the processing quality and efficiency of the titanium alloy wire. Full article

Ultraviolet-curable resin was introduced as a bonding agent into the fabrication process of precision abrasive machining tools in this study, aiming to deliver a rapid, flexible, economical, and environment-friendly additive manufacturing process to replace the hot press and sintering process with thermal-curable resin. A laboratory manufacturing process was established to develop an ultraviolet-curable resin bond diamond lapping plate, the machining performance of which on the ceramic workpiece was examined through a series of comparative experiments with slurry-based iron plate lapping. The machined surface roughness and weight loss of the workpieces were periodically recorded to evaluate the surface finish quality and the material removal rate. The promising results in terms of a 12% improvement in surface roughness and 25% reduction in material removal rate were obtained from the ultraviolet-curable resin plate-involved lapping process. A summarized hypothesis was drawn to describe the dynamically-balanced state of the hybrid precision abrasive machining process integrated both the two-body and three-body abrasion mode. Full article

Many manufacturing sectors require high surface finishing. After machining operations such as milling or drilling, undesirable burrs or insufficient edge finishing may be generated. For decades, many finishing processes have been on a handmade basis; this fact is accentuated when dealing with complex geometries especially for high value-added parts. In recent years, there has been a tendency towards trying to automate these kinds of processes as far as possible, with repeatability and time/money savings being the main purposes. Based on this idea, the aim of this work was to check new tools and strategies for finishing aeronautical parts, especially critical engine parts made from Inconel 718, a very ductile nickel alloy. Automating the edge finishing of chamfered holes is a complicated but very important goal. In this paper, flexible abrasive tools were used for this purpose. A complete study of different abrasive possibilities was carried out, mainly focusing on roughness analysis and the final edge results obtained. Full article