A novel synchronous electrochemical grinding–polishing (SECG-P) in ethylene-glycol electrolyte: Mechanism, modeling and prediction

ABSTRACT Quartz, ceramics, and other insulating brittle materials exhibit outstanding physical and chemical properties, playing an indispensable role in the fields of aerospace and weaponry equipment. Due to their high hardness, brittleness, and non-conductive characteristics, conventional grinding cannot achieve efficient and damage-free machining of these materials. In this research, an electrochemical discharge assisted grinding (ECDAG) process is proposed by utilizing the localized high temperature generated by the discharges to soften the material, thereby facilitating plastic domain grinding to improve machining performance. The influence mechanism of key factors was analyzed, including the localization of electrochemical discharges, the abrasive grain rate of grinding wheels, and the energy matching between electrochemical discharges and grinding. Furthermore, an experimental system was developed for the ECDAG process, and comparative experiments between ECDAG and conventional grinding (CG) were conducted on quartz glass workpieces by machining grooves. The results demonstrate the feasibility and capability of ECDAG for machining insulating brittle materials. Compared with CG, ECDAG with plastic grinding characteristics can achieve superior surface and subsurface quality, greater groove depth, and lower grinding force.

Force model of ultrasonic electrochemical composite grinding of GCr15 steel

The paper examines various schemes for grinding flat surfaces of magnetic alloy products with the application of an electric field: schemes for electrochemical and electroabrasive grinding. Based on the analysis of the features of electrochemical grinding (ECG) of planes of cast magnets, it was established that the most preferable process is the simultaneous ECG of planes with current supply through the end surface of the tool electrode (TE) with simultaneous metal removal from the entire surface in the direction of the maintained size with rotation of the grinding part. This method is characterized by the following advantages: the surface being processed is subjected to simultaneous anodic dissolution; the magnets being processed rotate around an axis parallel and eccentrically located relative to the axis of the EI; current supply to the working area is carried out through the end surface of the EI; the feed of the magnets being processed is performed in the direction of the maintained size. Due to such relative movements of the electrodes, a circular washing of non-metallic inclusions with electrolyte occurs, ensuring a circular dissolution of the metal and their removal from the working area, as well as the removal of metal in the direction of the allowance, which is practically equal to the movement of the workpiece. It has been established that it is advisable to perform the shaping of high-precision permanent magnet planes by electroabrasive grinding (EAG) with separation of electrochemical and abrasive processing zones. The EAG process allows increasing productivity, accuracy and quality of processed surfaces in comparison with ECG and can be implemented on a modernized surface grinding machine model 3G71. For various processing schemes, the work specifies achievable indicators and operational features.

The technological process of galvanic nickel plating using electrochemical grinding and subsequent re-coating is considered. A comparative analysis of the roughness of coatings on detachable electrical contact connectors manufactured at the enterprise and those treated using electrochemical grinding and re-nickel plating technology is performed. Three-dimensional models and profile diagrams of the studied samples of both the manufacturer's production and contact electrical connectors treated using this technology are presented. The problems that arise when applying coatings at the manufacturing plant are shown, as well as the advantages of the galvanic nickel plating using electrolysis, while applying electrochemical surface grinding, which is the reverse process of electroplating metals. It includes partial electrochemical surface grinding followed by re-nickel plating, which helps to increase the actual contact area between electrical connectors, improve electrical conductivity and increase the coefficient of friction at rest, and also increases the service life of vibration-prone all-in-one connectors and detachable connectors in general. The analysis of the obtained values of the arithmetic mean deviation of the profile, the maximum distance between the line of protrusions and the line of profile depressions, the parameter of asymmetry, the average step of the irregularities and the average step of the local protrusions of the profile was also carried out. The presented surface, according to the studied roughness parameters shows the least number of cracks, deep scratches and dents on the product. This, in turn, helps to increase electrical conductivity, improve the surface connection of electrical contact connectors, reduce the resistance when connecting contacts and smooth out micro-dimensions.

Pitting corrosion inhibition of honeycomb seal using glycerol‐water electrolyte in electrochemical grinding

Atomized-electrolyte jet electrochemical grinding for high-precision green machining of hard-to-machine alloys

Study on grinding force model for improving machining quality in electrochemical grinding of thin-walled honeycomb seal

Research on machining performance for electrochemical grinding of high-speed steel roll material based on interval type-2 fuzzy control

Effects of ultrasonic vibration on the machining mechanism of internal cylindrical ultrasonic-assisted electrochemical hybridized grinding of bearing ring: Experimental study

The results of experimental studies on the combined process of electrochemical grinding, including anodic dissolution of the material being processed and mechanical cutting processes, are presented. The electrochemical effect on the surface layer of the part has a significant impact on the microcutting conditions and the electrochemical grinding process itself. Samples made of corrosion-resistant and heat-resistant steel and titanium deformable alloy were subjected to experimental studies on the designed and manufactured model of a surface grinding machine. 15% aqueous solutions of sodium chloride (NaCl), sodium nitrate (NaNO3), and sodium sulfate (Na2SO4) were used as working media. The research methodology consisted of measuring the forces arising during micro-cutting a surface drawn mechanically to Ra = 0,16 μm and a surface subjected to anodic etching. The study of the electrochemical component has proven that grain boundaries undergo the most intense anodic dissolution; the dependences of grain boundary depth etching on the electrolyte composition and current density are presented. Studies have shown that in an electrolyte containing NaCl, the process of anodic dissolution of steel occurs without the formation of any oxides on the surface of the samples, and in electrolytes based on NaNO3 and Na2SO4 it is accompanied by the formation of oxide films. When processing the titanium alloy in an electrolyte containing NaCl, the maximum etching depth was 7 μm, and in an electrolyte based on NaNO3 it was only 3.8 μm. An increase in current density to 25-40 A/cm2 when processing steel and to 15-20 A/cm2 when processing titanium alloy is accompanied by an increase in the depth of etching; a further increase in the current density in most cases leads to a decrease in the depth of etching. The influence of electrolyte temperature on the depth of etching along grain boundaries is very significant. It was found that due to anodic dissolution, cutting forces were reduced, which extended the service life of abrasive tools and improved the quality of processing.

Abstract Honeycomb seal is an important sealing component in aviation engines, which ensures the gas tightness between the rotor and stator, and it has been widely put into effect for the output efficiency of aero engines. Electrochemical grinding (ECG) is one of its efficient manufacturing methods. However, due to the small wall thickness of its structure, it is susceptible to corrosion and dissolution by electrolysis during the processing. Therefore, sodium lignosulfonate (SL), a green corrosion inhibitor, is added to the electrolyte of ECG to inhibit the corrosion of honeycomb seal and reduce environmental pollution during the machining process. Electrochemical tests and experimental machining with different concentrations of SL are conducted, and surface composition analysis is performed. The ECG experiments show that the efficiency of corrosion inhibition can reach 84.67% and the excessive corrosion can be reduced by 44.8% by adding 0.06 wt.% SL in 2 wt.% NaCl solution. The study provides an efficient and eco-friendly means for restraining the corrosion of honeycomb seal during ECG.

Galvanic coating of electrical connectors is viewed. It was established that the existing electroplating technologies ensure the surface quality that was obtained on the support material. Using the example of galvanic nickel plating on a copper support plate, a method for improving the quality of the nickel-plated surface layer is proposed. It is proposed to use electrochemical grinding as an additional technological operation. Alternating electrochemical grinding and galvanic nickel plating will make it possible to obtain a higher-quality nickel surface layer, which will allow for a larger area of actual contact in the connection. This, in turn, will increase the static coefficient of friction and the reliability of the electrical connection during vibrations. The presented surface will provide a minimum number of cracks, deep scratches and dents on the product, which in turn increases electrical conductivity, surface compound of the contact electrical connectors, and also reduces the electrical resistance that occurs when interconnection.

ABSTRACT 9Cr18Mo bearing steel is widely used in bearing manufacturing due to its high hardness, excellent wear resistance, and superior corrosion resistance. However, traditional grinding often causes defects like grinding burns, limiting its applications. This study investigates electrochemical grinding (ECG) for machining 9Cr18Mo bearings. Electrochemical tests identified the basic ECG electrolyte components suitable for 9Cr18Mo, followed by uniform design, stepwise linear regression, and a whale-genetic algorithm (WOA-GA) to optimize the electrolyte composition to be 14.356 wt.% NaNO3 + 7.841 wt.% Na2SO4. Under these conditions, the material removal rate (MRR) reached 0.118 g/min, with a surface roughness (Ra) of 1.124 µm, indicating high efficiency and excellent surface quality. Scanning electron microscopy (SEM) and nanoindentation tests showed the oxide film’s hardness decreased by 97.52% and elastic modulus by 91.79%, easing grinding challenges. This study establishes a foundation for ECG of 9Cr18Mo and offers insights for machining other difficult materials.

Introduction. When manufacturing critical parts from high-strength and difficult-to-process steels in various industries, the final quality is usually formed during finishing operations. The efficiency of the process is significantly higher when using combined, hybrid methods of influencing the surface being processed. When processing some complex-shaped parts, more attention in finishing operations is usually paid to reducing roughness while maintaining previously achieved dimensional accuracy indicators. For this purpose, abrasive tools on a rigid base are often used, placing it in a less rigid technological system. To increase the efficiency of the process, it is necessary to establish optimal modes of mechanical and electrochemical processing of parts. In the absence of the possibility of using industrial equipment for hybrid technologies at the initial stage, taking into account the need to modernize existing technological equipment for the implementation of the electrochemical grinding process, it is advisable to study this process by simulating it on simulator devices. The purpose of the work is to develop a device for studying and simulating the process of electrochemical grinding of conductive parts with abrasive heads on a metal bond. Research methodology. To simulate the process of electrochemical grinding of conductive parts using abrasive heads on a metal bond, we have developed a special device. It allows for the basing of the workpiece and the tool, implementation the electrochemical grinding process, its kinematic and electrical conditions: main motion, linear displacement of working bodies, mechanical and electrical modes, ensuring the necessary conditions for the implementation of the technology, and implementing a control system. Results and discussion. To determine the influence of mechanical cutting modes on the roughness of the machined surface of a part made of corrosion-resistant steel 0.12 C-18Cr-10 Ni-Ti, empirical studies were carried out on the designed device. Planning and processing of experimental results were carried out using standard methodology for preparing and conducting a full factorial experiment. The resulting model makes it possible to determine rational mechanical cutting conditions and evaluate its influence on the quality of the surface being processed.

Enhancing honeycomb surface quality by harnessing vortex effect in electrochemical grinding

ABSTRACT To fill the gap for the impact of electrochemical machining parameters on the electrochemical grinding process, solitary abrasive grinding was introduced to investigate the impact of electrochemical machining parameters on grinding material removal and abrasive wear during grinding. The results indicate that under identical grinding profundity, the grinding material removal volume after high-voltage electrochemical machining in the incipient grinding process was slightly higher than that after low-voltage electrochemical machining. In the subsequent grinding process, the abrasive granule materialize as macro-fractures after low-voltage electrochemical machining, causing the grinding material removal competence to diminish. After high-voltage electrochemical machining, the wear degree of the abrasive granule is alleviated, thereby persisting a higher grinding material removal competence. A grinding model was built to interpret the impact of electrochemical machining parameters on the grinding process. The study provides a theoretical guidance for the selection of electrochemical machining parameters for electrochemical grinding.

Experimental study on electrochemical grinding of superalloy honeycomb material

Electrochemical grinding (ECG) offers advantages such as burr-free and stress-free material removal. Despite its proven potential, limited research has addressed the comprehensive effects of key process parameters on the surface integrity of AISI 304 stainless steel, particularly for applications requiring high-quality finishes, such as medical components. This study bridges this gap by systematically investigating the influence of ECG key parameters including voltage, rotational speed, and electrolyte concentration on main surface integrity parameters including current density, surface roughness, microhardness, and surface texture. Total of 20 experiments were carried out following a Response Surface Methodology (RSM) design, incorporating five levels of variation for the parameters of electrolyte concentration, voltage, and grinding wheel speed. Results revealed that voltage and electrolyte concentration were the dominant factors affecting current density, increasing it by 368 % and 241 %, respectively, while higher rotational speeds decreased it by 44.5 % due to reduced contact time and electrolyte removal. Surface roughness decreased by up to 65 % in the perpendicular direction as concentration and voltage increased, but higher voltages led to over-etching, increased the surface roughness. Electrolyte concentration and voltage also reduced surface microhardness by 10–14 % through intensified corrosion, while higher wheel speeds increased microhardness due to enhanced mechanical removal. The maximum variation for in-depth microhardness extended up to a depth of 40 μm below the surface. Surface texture analysis also revealed more uniform pitting across the surface at higher concentrations, indicating more consistent material dissolution. However, at higher voltages, deep pitting emerged, raising surface roughness.

This article considers the development of a mathematical model of electrochemical grinding for processing precision components operating at varying loads. The combination of processes (for example, the mechanical and electrochemical material removal processes) significantly improves operation control capabilities by increasing the number of control inputs and selected input variables. The results of the research are presented as evaluated based on the capacity of products manufactured using this grinding method. The conducted qualitative and quantitative assessments demonstrate the adequacy of mathematical models. The difference between experimental and calculated values made up 5-10%. The electrochemical grinding helps improve the operability of components operating at varying loads compared to mechanical grinding.