Composite Grinding Research Articles

Preparation and Performance Study of SiC-Reinforced Fe-Based Wear-Resistant Composite Grinding Media.

During industrial and laboratory processes involving material grinding, the grinding media endure prolonged high-collision and friction environments, resulting in substantial wear. Consequently, this study adopts the hot-pressing sintering technique in powder metallurgy to prepare SiC-reinforced Fe-based wear-resistant composite grinding media, aiming to increase wear performance. For this purpose, Fe with 10 wt% SiC powders were milled for the fabrication of the composite. Then, sintering was performed by hot press at 1100 °C in a furnace. Scanning electron microscopy (SEM) and X-ray diffraction were employed to investigate the microstructures and phase of SiC-reinforced Fe-based matrix composite. Subsequently, comparative performance evaluations of the newly developed grinding media and traditional chromium-based media were conducted in terms of wear rate and grinding efficiency. The wear resistance tests revealed that the SiC-reinforced composite media displayed significantly superior wear resistance across various abrasives compared to the chromium-containing alternatives. Specifically, the composite media achieved a wear rate reduction of 2.9 times against standard sand over 1 h, and 2.3 and 2.4 times against sandstone and iron slag, respectively. Moreover, extended grinding for 3 hours further enhanced these reductions to 3.1, 2.4, and 2.7 times, respectively. Additionally, efficiency assessments indicated that at a 1:1 material ratio, the composite media outperformed the chromium-containing media in grinding efficiency by 7.5%, 12.5%, and 10.3% for standard sand, sandstone, and iron slag, respectively. Further increasing the material ratio to 3:1 resulted in efficiency improvements of 7.4%, 17.5%, and 11.3%, correspondingly.

An Investigation Into the Grinding Characteristics and Wear Evolution of Micro-Elastic Composite Grinding Pads

Abstract This paper introduces a novel micro-elastic composite grinding pad for material removal. The study also developed a new grinding wear formula grounded in microcontact mechanics, which is crucial in examining the evolution of interface characteristics under optimal parameter combinations. The results showed that the material removal rate (MRR), reduction of roughness height (σ), and peak curvature radius (ρ) increase were the highest in the initial stage, followed by a slight increase in the real-contact area in the second stage. This research suggests that abrasive particles primarily detach from the elastic pad in the second stage. The plasticity index (ψ) decreases during grinding, which suggests a transition from an elastic–plastic mixed contact interface to a predominantly elastic contact interface. This shift in the interface mechanics explains the gradual reduction in wear at the grinding interface. Both the plasticity index and the MRR are consistent throughout the grinding process. However, the plasticity index is a more effective index of interface wear than the conventional H/E ratio because it considers the surface roughness’s shape and size, which is essential in mild grinding operations. The findings of this study can be used to improve the design and performance of micro-elastic composite grinding pads and to optimize the grinding process for improved efficiency and sustainability.

A new strategy for highly wear-resistant ball using carbon nanotube composites: Study on the impact wear resistance and interfacial bonding mechanism

Traditional low-alloy wear-resistant steel balls have a complex and costly manufacturing process, resulting in poor wear resistance. Fortunately, carbon nanotubes offer a promising solution due to their elastic modulus, lightweight nature and good wear resistance properties. To obtain exceptional impact wear resistance, novel carbon nanotubes/Fe matrix grinding balls were developed, the impact wear resistance was explored, and the carbon nanotube/Fe matrix interfacial bonding mechanism was revealed. The results showed a 30% increase in wear resistance after 2 h of impact-abrasive wear tests, as compared to traditional wear-resistant steel balls (B3). In the composite wear-resistant balls, carbon nanotubes are distributed along the prior austenite grain boundaries and within the grains, hindering the growth of austenite grains and increasing the dislocation density, resulting in fine grain strengthening and dislocation strengthening. At the carbon nanotubes/Fe interface, chemical reactions occurred at the nanotube defects, forming Fe3C, and the presence of Fe3C strengthened the interfacial bonding effect through pinning. During the process of impact-abrasive wear, the carbon nanotubes within the composite grinding ball acted as a bridge and formed a lubricating film, exhibiting exceptional wear resistance.

On the issue of designing and creation of a composite grinding wheels of increased productivity for rails treatment

The article discusses the technological aspects of the development and design of composite modified wheels used in the mechanical treatment of railway rails. It allows to increase the productivity of treatment and tool durability. An increase in the physical and mechanical features of the shard of abrasive wheels can be achieved by modifying the binder component in the composition of the ceramic charge mixture with a nanomodifier such as carbon tubes. As a result of the modification of the abrasive composition of the charge mixture, it was possible to achieve an effective performance of railway rails treatment without a significant loss in the durability of the composite grinding wheel.

SiO2f/SiO2 composite grinding characteristics based on maximum undistorted chip thickness

ABSTRACT The thickness of the maximum undistorted chip (a gmax ) is a crucial component of the machining arguments and significantly affects the quality of the grind. For the purpose of investigating the impact of the a gmax on the grinding removal properties of SiO2f/SiO2 composites, grinding experiments of SiO2f/SiO2 composites were conducted. The findings indicate that crack propagation, fiber cracking, matrix breaking, and interface debonding are the primary removal modes of SiO2f/SiO2 composites. Grinding force, surface roughness, and chip size all have a positive correlation with the maximum undeformed chip thickness. Surface brittle fracture brought on by SiO2 fiber microcrack results in little surface roughness. The surface quality degrades when bending fracture and compression fracture take place. Controlling the a gmax can enhance the grinding surface quality of SiO2f/SiO2 composites.

Study on the Effect of ELID Grinding on corrosion wear properties of Co-Cr Alloy

Contemporary Co-Cr alloys used in artificial joints can cause health complications in long-term applications. A pin-on-disc friction and wear testing instrument was used to evaluate the corrosion and abrasion of two types of Co-Cr alloys for artificial joints under simulated body fluid conditions after surface electrolytic composite grinding. Co-materials with lower carbon content displayed superior corrosion resistance than those materials with higher carbon content. Moreover, surface processing with electrolytic composite grinding produced a stable surface modification layer, which improved the surface hardness and formed an oxide film that inhibited metal ionization. The formation of precipitates in the corrosive environment is likely to improve the friction and wear properties of the material. As such, a variety of hardness was observed for the artificial joint friction disc and pin, especially when the hardness of the disc was higher than that of the pin, which can improve the friction and wear behavior of joints.

Quality Assurance of Composite Grinding

Quality Assurance of Composite Grinding

Research on procedure optimisation for composite grinding based on Digital Twin technology

The complexity of composite grinding movement, the variety of machining features and available grinding wheels, and the changing working conditions pose a challenge to the rapid programming of safe and efficient composite grinding procedure. The procedure optimisation plays an important role in solving this difficult problem. Therefore, a procedure optimisation method is proposed for composite grinding based on a Digital Twin (DT) system, which takes procedure time as optimisation objective to achieve high efficiency and ensures process rationality and safety by constructing corresponding constraint conditions. Moreover, the actual working conditions mapped into the DT system, such as workpiece parameters, machining requirements, grinding wheel parameters and status, machine tool motion position, and so on, are obtained to update the parameters involved in the optimisation model. And thus, the proposed method has the ability to timely find the optimal procedure under changing working conditions. In addition, a combination algorithm based on genetic algorithm (GA) and dynamic programming is proposed, which greatly reduces the search space of GA and realises the two-class co-optimisation of grinding wheel selection and procedure. Finally, the case study verifies the effectiveness of the proposed method to reduce procedure time and the dynamic response ability to changing working conditions.

Design of a CBN composite abrasive to improve the performance of HSG rail maintenance grinding wheel

A heavy-load resin grinding wheel with zirconia alumina abrasives plays a vital role in rail high-speed grinding (HSG) maintenance. However, the grinding wheel has the defect of short service life. Abrasives are the central performers in the cutting behavior of grinding wheels. A cubic boron nitride (CBN) composite abrasive was developed to enhance the performance of grinding wheels. The results showed composite abrasives bonded more tightly with the resin matrix, strengthening the structure of the wheel. The grinding efficiency and ratio of the composite grinding wheel were improved by 99.8% and 102% respectively, and the rail morphology was optimized.

Study on the influence of the brazing sheet placement angle on the rotation strength of composite grinding wheel

• The rotation stress formula of the composite grinding wheel is deduced and analyzed. • Cutting off effect of the brazing sheet in the composite grinding wheel is analyzed. • The finite element simulation analysis was used for the wheel rotation performance. • Carried out the grinding wheel rotation test to verify the correctness of the study. A high performance composite grinding wheel with brazed diamond sheets was developed for rail grinding. The rotation stress formula of the composite grinding wheel is deduced and analyzed, and the cutting off effect of the brazing sheet on the resin in the composite grinding wheel is analyzed. The finite element simulation analysis of the rotation performance of the composite grinding wheel is carried out when the brazing sheet is in the middle of the grinding wheel or one end of the brazing sheet is flush with the grinding end of the grinding wheel. The corresponding composite grinding wheel is made to carry on the rotation test, which is compared with the simulation analysis results. The results show that for the Ø260-size rail grinding composite grinding wheel, when using 15 mm wide and 55 mm long brazing sheets, the optimal placement angle is 55°, followed by 60° and 45°. The analysis of the noise detection results of the rotary testing machine shows that the resonance speed of the rail grinding wheel is between 4600–4800 rpm, and the rotary noise of the composite grinding wheel with brazing sheet is lower than that of the resin grinding wheel.

A parameterized automatic programming solution for composite grinding based on digital image processing

In this paper, a parameterized automatic programming solution whose advantage depends on the automatic feature recognition of digital image is proposed and applied to the development of automatic programming software for composite grinding. This solution can overcome the difficulty of recognizing intersecting feature of complicated rotational part. And a 7-layer CNN classifier is utilized to decide whether the part has the internal features or not, which makes the proposed feature recognition method more intelligent than retrieving the unknown objects blindly. The emphasis of the research is the geometric data extraction algorithm which is the synthesis of border following algorithm, corner detection algorithm and a variety of morphological processing. Under the condition of 12000 × 12000 pixel dimension and 200-dpi resolution of input image, the relative errors between the extracted and actual values of various geometric data are all less than 0.05% for the rotational parts of maximum diameter 500 mm and maximum length of 1500 mm. And all the extracted values of geometric data rounded to integers can fully meet the requirements of NC programming. The automatic programming software based on the proposed solution has excellent portability and practicability, which is independent of any CAD tools or data exchange standards. After the programs generated by the automatic programming software are validated in simulation software NCSIMUL, the software is integrated into HNC-848 CNC system and applied in the prototype of H377 composite grinding center.

Filtration efficiency of surgical and FFP3 masks against composite dust.

The aim of this study was to investigate the protection efficiency of two types of face masks against composite dust and to characterize the particles that penetrated through the masks. Composite dust was created by grinding a commercial nano-filled composite in a plexiglass box without using water cooling or high vacuum evacuation, in order to obtain a worst-case exposure. Dust particles were collected using a personal inhalable aerosol sampler (IOM) fixed inside a custom-made phantom head. Surgical and filtering facepiece (FFP3) masks were tested, and the situation without a mask served as control. The IOM sampler contained a cassette with two filters to collect large inhalable (4-100µm) and respirable dust particles (<4µm). The amount of particles was determined gravimetrically by weighing filters before and after composite grinding, and further characterized by electron microscopy. Particle collection for both inhalable and respirable dust was the highest when no mask was used, and the lowest with the use of a FFP3 mask. Different sizes and shapes of particles were observed, with the largest particles (>1µm) being seen when no mask was applied, whereas only nanoparticles could be detected when either type of face mask was applied. Even though FFP3 masks showed a higher filtration efficacy than surgical masks of the inhalable dust fraction, penetration of a small respirable particle fraction was inevitable for both masks.

Atmospheric pressure plasma jet and minimum quantity lubrication assisted micro-grinding of quenched GCr15

High-strength alloys have significant application values in aerospace industry due to their excellent mechanical properties. However, grinding of these alloys, which is generally used for precision machining, suffers from problems like high grinding temperature and poor surface quality. Having relatively lower grinding temperature and smaller grinding force, micro-grinding is a high-efficient manufacturing method for precision machining of difficult-to-cut materials. Nevertheless, the side effects induced by current composite grinding methods, such as temperature gradient and chatter marks, tend to be more obvious in the micro-machining process. Atmospheric pressure plasma jet (APPJ) can effectively improve metal surface wettability without changing surface structures. On the other hand, minimum quantity lubrication (MQL) can more efficiently cool and lubricate the grinding area. Here, we propose to induce APPJ and MQL cooling media into the micro-grinding area, and adjust the cooling and lubricating characteristics. Quenched GCr15 workpieces are machined under five different conditions (dry micro-grinding, nitrogen jet assisted micro-grinding, APPJ assisted micro-grinding, MQL assisted micro-grinding, and APPJ+MQL assisted micro-grinding), and grinding temperature, grinding force, surface roughness, and surface morphology of workpieces in each group are investigated and analyzed. The results indicate that APPJ can reduce grinding force and that APPJ+MQL micro-grinding can obtain surfaces with much better surface quality. Tensile experiments demonstrate that APPJ can reduce material elongation rate and promote material fracture, which contributes to its positive effect on the micro-grinding process. The environmentally-friendly method is expected to have promising application potentials in machining of difficult-to-cut materials.

Investigating Minimum Quantity Lubrication in Unidirectional Cf/SiC composite grinding

The influences of minimum quantity lubrication (MQL) on the grinding performance of unidirectional carbon fibre-reinforced ceramic matrix (Cf/SiC) composites were investigated in this paper. The experimental results indicate that MQL can significantly improve surface quality and reduce grinding forces. In addition, MQL has a low cost and does not generate considerable pollution. According to the lubrication mechanism of MQL, the effects of nozzle direction, air pressure, oil flow rate and nozzle distance on the grinding performance of unidirectional Cf/SiC composites were carefully investigated in this research. Excellent surface quality and low grinding forces can be achieved when the nozzle direction, air pressure, oil flow rate and nozzle distance are 15°, 5 bar, 100 ml/h and 80 mm, respectively. The surface topographies show that smooth fibre separation, fibre breaking, fibre outcropping, fibre pullout and matrix cracks are the main failure forms of the ground surface. The histogram reflects that the proportion of fibre pullout is the highest, whereas that of fibre outcropping is lowest. In the MQL grinding process, a large amount of heat is removed by water vapour, which can significantly reduce the grinding temperature. Meanwhile, effective oil films form in the contact areas between the grits and the material surface. The above factors are advantageous for improving the grinding performance of unidirectional Cf/SiC composites. The objective of this research was to investigate the influences of MQL for unidirectional Cf/SiC composites, validate these interpretations with experimental results and provide reasonable recommendations for guaranteeing the machining accuracy of Cf/SiC composites.

Wear characteristics of brazed diamond sheets with different grinding time

In order to expand the application field of tools containing brazed superabrasives, the wear characteristics of brazed diamond sheets, which used in rail-grinding composite grinding wheels, under different grinding time were studied. The brazing sheet’s grinding ratio decreases with time while wear and thermal damage of the diamond abrasive increase. With continuous long-term grinding, the solder shows melt-slip phenomenon, which increases grinding portion of the brazing sheet. Meanwhile, there was partial oxidation of the solder in the wear debris. When the total grinding time is the same, in short-time multiple grinding, the brazing sheet suffers less, higher grinding ratio; the thermal damage of the diamond abrasive is lower and the wear of abrasive is mainly impact crushing, flattening and mechanical shedding.

Correction to: Acoustic emission signal of fiber-reinforced composite grinding: frequency components and damage pattern recognition

The original version of this article contained a mistake. The arrows and lines in Figs. 1(a) and 5 are missing.

Influence Factors on Grinding Force in Surface Grinding of Unidirectional C/SiC Composites

C/SiC has excellent mechanical properties and is extensively utilized in the aerospace field. Meanwhile, it is a typical intractable material in virtue of its special intrinsic structure. To investigate the grinding force and material removal mechanism of fiber reinforced CMC, a unidirectional C/SiC composite material was designed and prepared. A series of particular surface grinding experiments were carried out, and then the grinding force model was established based on multiple-exponential function method. Furthermore, the surface morphology and grinding mechanism of the composites were analyzed. The results show that the grinding parameters (wheel speed, grinding depth, feed speed) have a significant impact on the grinding force, and the order of grinding force is as follows: Normal>Longitudinal>Transverse. The R2 (Goodness of fit) values of the grinding force model are all above 0.9, which demonstrates the models can reliably predict the grinding force of the unidirectional C/SiC composite grinding. Besides, the dominant removal mechanism of C/SiC composites is the brittle fracture, and its failure modes are the combination of matrix cracking, fiber breakage and interface debonding. Then, the factors affecting the grinding force in surface grinding of the composite are revealed. The research results can provide theoretical support for improving grinding efficiency and precision machining of composites.

Acoustic emission signal of fiber-reinforced composite grinding: frequency components and damage pattern recognition

Current researches of acoustic emission (AE) mainly put the focus on fault diagnosis of traditional isotropic materials machining process or analysis of fiber-reinforced composite (FRC) tensile or bending strength, while there are merely studies on AE research of FRC grinding process. Numerous kinds of damage occur during FRC grinding process owing to their complicated structure. The main purpose of this paper is to extract proper index to estimate AE signals of FRC grinding and to recognize damage patterns, thus realizing FRC processing on-line detection. AE signals are obtained by single-grain grinding experiments of quartz fiber–reinforced silicon dioxide matrix composite (SiO2/SiO2). The AE signal features are discussed, and the outstanding character of frequency components is proposed. The frequency of each damage pattern is analyzed and verified. AE effective voltage value (EVV) and event number percentage (ENP) of peak frequency (PF) of AE signals with processing parameters are researched. The results show that for the same kind of FRCs, frequency components of AE signals are only affected by damage patterns rather than processing parameters or grinding directions, thus being a proper estimate index. There are four main frequency bands during SiO2/SiO2 grinding. The frequency 6.4–9.8 KHz corresponds to fiber fracture, 14.8–17.9 KHz is fiber debonding, 23.6–26.4 KHz is debris rubbing with workpiece and tool, and 34–35.5 KHz is matrix crack. EVV has a similar changing trend to grinding force with machining parameters. AE ENP of PF that the maximum peak amplitude (PA) corresponds to could quantitatively confirm the main damage modes under each processing condition.

Study on wear characteristics of brazed diamond sheet for rail’s composite grinding wheel under different pressures

To improve the performance of grinding wheels for rail, a composite grinding wheel was developed by combining brazed diamond sheets and original resin grinding wheel. An experimental methodology for grinding process was established to study the grinding wear characteristics of the brazed sheet. The results indicate that with increasing working load, the wear rate of the brazing sheet increases and the grinding ratio decreases. In addition, the temperature rise becomes faster and the proportion of oxidation products in the grinding debris increases. Brazing alloy shows melt-slip phenomenon when grinding was performed continuously for a long time. When the worn brazing material is mixed with iron debris, the mixture hinders agglomeration and shrinkage of the molten debris.

Simulation of thermal strength of the process of flat grinding of workpieces in intermittent circles

The present article is concerned with numerical schemes of the radial Py and the tangential Pz components of the grinding pressure and with the average contact temperature T, °С. These characteristics give an opportunity to assess the level of the thermal power strain at every path of the operational cycle of the flat pendulum grinding using a standard grinding wheel (SW), an intermittent grinding wheel (IGW) and a composite grinding wheel (CGW). Value forecasting of forces Py,pz and the temperature T will make it possible to manage the grinding process and will give the opportunity to avoid the defects precipitation at the grinding finish of the workpiece.