Grinding Process Research Articles

Predictive models for the surface roughness and subsurface damage depth of semiconductor materials in precision grinding

Abstract Workpiece rotational grinding is widely used in the ultra-precision machining of hard and brittle semiconductor materials, including single-crystal silicon, silicon carbide, and gallium arsenide. Surface roughness and subsurface damage depth (SDD) are crucial indicators for evaluating the surface quality of these materials after grinding. Existing prediction models lack general applicability and do not accurately account for the complex material behavior under grinding conditions. This paper introduces novel models for predicting both surface roughness and SDD in hard and brittle semiconductor materials. The surface roughness model uniquely incorporates the material’s elastic recovery properties, revealing the significant impact of these properties on prediction accuracy. The SDD model is distinguished by its analysis of the interactions between abrasive grits and the workpiece, as well as the mechanisms governing stress-induced damage evolution. The surface roughness model and SDD model both establish a stable relationship with the grit depth of cut (GDC). Additionally, we have developed an analytical relationship between the GDC and grinding process parameters. This, in turn, enables the establishment of an analytical framework for predicting surface roughness and SDD based on grinding process parameters, which cannot be achieved by previous models. The models were validated through systematic experiments on three different semiconductor materials, demonstrating excellent agreement with experimental data, with prediction errors of 6.3% for surface roughness and 6.9% for SDD. Additionally, this study identifies variations in elastic recovery and material plasticity as critical factors influencing surface roughness and SDD across different materials. These findings significantly advance the accuracy of predictive models and broaden their applicability for grinding hard and brittle semiconductor materials.

Freeform surfaces manufactured with a combination of ultra-fine grinding and plasma jet polishing

In order to meet the increasing requirements of freeform production, a new process chain is presented that combines grinding with thermally induced plasma jet polishing. This is demonstrated by an example of a self-designed Alvarez lens geometry made of fused silica glass. A three-stage grinding process is applied, comprising coarse pre-shaping, fine freeform shape generation, and ultra-fine first surface smoothing. Grinding is performed using a 5-axis CNC machining process with spherical diamond grinding tools. After grinding, the surface quality is sufficient for subsequent plasma jet polishing, in terms of shape accuracy, mid-spatial frequency errors, and roughness. The surface shape is retained during polishing while simultaneously achieving a high surface quality and meeting the roughness requirements for optical applications. The requisite improvements to the grinding processes, as well as a parameter optimization for plasma jet polishing are presented. Moreover, the application of a convolution function, which describes plasma jet polishing theoretically, helps to reduce the number of samples necessary to optimize the process chain with respect to favorable transfer points, thereby perfectly linking the processes. The novel process chain offers a versatile and efficient approach for the fabrication of optical freeform surfaces with a final roughness of less than 0.5 nm.

Innovative EMD-Based Technique for Preventing Coffee Grinder Damage from Stones with FPGA Implementation

Coffee is one of the most widely consumed beverages globally, with Americans averaging 3.1 cups per day. However, before coffee beans can be brewed into a drinkable form, they undergo several critical stages, including harvesting, processing, roasting, grinding, and extraction. During the processing and roasting phases, a significant challenge arises: stones that are similar in size and shape to coffee beans can inadvertently mix into the batch. These stones are difficult to detect using conventional methods, and their presence can have severe consequences. When stones are ground alongside coffee beans, they can cause significant damage to the grinder’s burrs. Commercial coffee grinders typically employ conical or flat burrs, which consist of two circular discs or an inner blade and a disc. These burrs undergo specialized heat treatment and surface processing to ensure durability and precision, making them highly expensive components. Replacing damaged burrs is not only costly but also requires meticulous calibration of the parallelism between the inner blade and the disc to maintain grinding quality. The introduction of stones into the grinding process can lead to equipment damage, resulting in operational downtime and financial losses. To address this issue, this paper proposes a novel method based on Empirical Mode Decomposition (EMD) for detecting stones in coffee beans. The approach analyzes the acoustic wave patterns generated when stones impact or rotate within the grinder.

Investigations on process vibrations and forces and their effects on resulting optical component qualities in a CNC grinding process

Abstract The presented investigations deal with the real-time evaluation and recording of vibrations and forces during a CNC grinding process as well as the analysis and control of process influences on the surface quality of optical components. The experiments were performed on a 5-axis CNC machine and monitored using a laser vibrometer and a dynamometer. The subsequent examination of the component surfaces and topographies is carried out with the aid of two white light interferometry systems (macroscopic and microscopic). The aim of the investigations is to record and analyze correlations between the vibrometry, force and topography measurement data in order to examine their influence on the grinding process and the resulting component quality and to examine whether in-process vibrometry and force measurements can be used to detect and predict component quality during the process. Furthermore, the influence of individual grinding parameters on the grinding forces as well as the resulting component qualities are investigated under consideration of the surface roughness. It is shown that the vibration and force data measured during the grinding process correlate to a high degree with the recorded topography data. In addition, it was possible to determine which parameters have a significant influence on the observed CNC process. The setting parameters feed speed, tool grain size, and infeed depth had the greatest influence on the roughness and also on the forces. For example, the roughness could be reduced by around 47% by using the lowest considered feed speed compared to the highest. Furthermore, the forces were significantly influenced by the ultrasonic and could be reduced by around 53% by switching it on. The results underline the importance of real-time measurement technologies for improving CNC grinding processes, as they provide critical insights into the dynamic behavior of the system and its impact on the surface quality of optical components. This research demonstrates that by understanding the correlation between process forces, vibrations, and resulting surface topographies, it is possible to develop predictive models for in-process quality assurance. Consequently, the findings pave the way for more efficient and reliable grinding processes, reducing rework rates, and production costs. The presented approach can be directly applied in high-precision manufacturing environments, contributing to advancements in the fabrication of high-quality optical systems.

Determination of Best Input Parameters for Internal Grinding SKD11 Tool Steel using MCDM

This article presents the results of an optimization study on the determination of the best input parameters for the internal grinding process when processing cylindrical-shaped parts of SKD11 tool steel. For this purpose, three Multi-Criteria Decision Making (MCDM) methods including the Evaluation based on Distance from Average Solution (EDAS), Multi-Attributive Border Approximation Area Comparison (MABAC), and Multi Attribute Utility Theory (MAUT) were used to solve the MCDM problem, while the entropy method was applied to find the criteria weights. Three objectives, namely the Surface Roughness (SR), Material Removal Rate (MRR), and wheel life (Tw), were also investigated. Six input factors, involving the coarse dressing depth (ar), coarse dressing times (nr), fine dressing depth (af), fine dressing times (nf), non-feeding dressing (n0), and dressing feed rate (Sd), were examined. Additionally, the Taguchi method with the L16 (44+22) design and the Minitab R19 program were deployed to design this study’s experiment and investigate its outcomes. The MCDM work was successfully solved and the best process factors are proposed.

Optimization of edge grinding process based on stress-strength induced boundary effect

Optimization of edge grinding process based on stress-strength induced boundary effect

The Modularized Development of a Wheel-Side Electric Drive System Using the Process of Hobbing and Form Grinding

The wheel-side electric drive system is a melding of a vehicle powertrain and suspension system, which saves chassis space and can adapt to different models. To achieve the goal of highly modularized development, the system is supposed to meet the requirements of various working conditions without changing the interface state. The electric motor drives the wheel through two-stage fixed axis helical gears, so the transmission is short in path and acts as the suspension arm at the same time. As a result, the gears are critical to output robustness and NVH performance. The modeling accuracy is decisive for simulations and tests, so it is necessary to build a precise geometric model instead of the data-fitting estimation. The gears are manufactured by a hobbing and form grinding process, which is described functionally along with the relationship between the tooling parameters and tooth profile curves. Based on the rain flow methodology and extrapolation theory, a comprehensive load spectrum with nine stages is formulated, which can cover the working conditions of a basic version, a NVH version, and a durability version. According to the Miner cumulative damage hypothesis, the equivalent durability mileage of 150,000 km is converted. The prototype machine is simulated and verified on the test bench, and the test results show that the wheel-side electric drive system has a reliable output performance. The equivalent damage of the comprehensive load spectrum is 63.27%, where the 2# stage driving gear is the most vulnerable component of the whole system. The research in this paper can provide data support for damage calculation and lightweight optimization with modularized development and applications in the future.

Evaluation Performance of the Asphalt Concrete with Crumb Rubber

Many researchers have been researching alternative materials to be used as modifiers in asphalt mixtures to improve their properties. This study presents a study of laboratory evaluation of the performance of hot-mixed asphalt (HMA) using crumb rubber as an additive. It is noted that crumb rubber was identified to have potency as a modifier in HMA due to the elastic behavior exposed by the rubber particles, especially in reducing the rutting potential. This research used fine crumb rubber Shred (2.36-0.85 mm) obtained by an ambient-temperature grinding process from discarded truck tires to modify asphalt concrete. The fine crumb rubber with different contents, i.e. 2.5%, 5%, 7.5%, and 10%, was incorporated into the mixture using the dry process method.

Grinding process, surface characteristics, and machining performance of α/β‐SiAlON ceramic double‐circular‐arc end mill

Grinding process, surface characteristics, and machining performance of α/β‐SiAlON ceramic double‐circular‐arc end mill

Built-in electric field in the Mn/C60 heterojunction promotes electrocatalytic nitrogen reduction to ammonia.

The electrochemical nitrogen reduction reaction (NRR) has been regarded as a green and promising alternative to the traditional Haber-Bosch process. However, the high bond energy (940.95 kJ mol-1) of the NN triple bond hinders the adsorption and activation of N2 molecules, which is a critical factor restricting the catalytic performance of catalysts and their large-scale applications. Herein, an Mn/C60 heterostructure is constructed via a simple grinding and calcination process and achieves an extraordinary faradaic efficiency of 42.18% and an NH3 yield rate of 14.52 μg h-1 mgcat-1 at -0.4 V vs. RHE in 0.08 M Na2HPO4. Our experimental and theoretical results solidly confirm that the spontaneous charge transfer at the Mn/C60 heterointerface promotes the formation of a built-in electric field, which facilitates the electron transfer from Mn towards C60 and creates localized electrophilic and nucleophilic regions. The formation of the space-charge region effectively optimized the adsorption energy of the key intermediate *NH-*NH2 and also reduced the free energy barrier for the hydrogenation step of *NH-*NH to *NH-*NH2. Furthermore, the calculated lower limiting potential (UL(NRR)) in Mn/C60 relative to the HER (UL(HER)) demonstrates its enhanced selectivity toward the NRR. This work provided new insights into enhancing the activity and performance of electrocatalysts for the NRR by constructing heterojunctions to improve nitrogen adsorption.

Improving measurement system fidelity through the optimization of preventive maintenance and operating conditions: a comparative study of measurement system analysis approaches

Abstract This study focused on measurement system analysis MSA through gage of Repeatability and Reproducibility R&R methods (Average and Range Xbar/R, Analysis Of Variance ANOVA, Evaluating Measurement Process EMP III) to verify the accuracy and precision of a laser diffraction particle size analyser used to monitor particles’ size in wet grinding process, this device gained great faith in many researches without checking its fidelity. The initial evaluation demonstrates the measurement system’s unacceptability, driving to establish an improvement plan including preventive maintenance scheduling for the instrument to maintain it in good working conditions and anticipate futures anomalies that could affect the measurement system fidelity, standardization of measuring process by the instrument to reduce repeatability, which was found to be the largest source of variation in the gage R&R analysis affecting measurement accuracy and precision, along with unifying the method of calculating solid rate percentage of samples before measurements because it is a significant factor that can affect the measurement results, finally, operators training to conduct measurements in the same way and following unified procedures in the purpose of minimizing reproducibility and increasing the measurement system fidelity, which is proven by the final results. Along this evaluation, a critical comparison between these techniques is conducted in terms of calculations, result’s interpretation and acceptability requirements to evaluate the efficiency of each method. Xbar/R and ANOVA demonstrate a similarities in interpretation and acceptability criteria but ANOVA surpassed Xbar/R by adding new factors in the calculations, while EMP III, which is not widely addressed in the literature, shows a great difference with a distinguished methodology, distinct metrics and acceptability guidelines. Therefore, a combination of ANOVA and EMP III in measurement system analysis would be very effective by extracting comprehensive informations about the studied instrument. 

Stability of Ternary Drug-Drug-Drug Coamorphous Systems Obtained Through Mechanochemistry.

Background/Objectives: This study investigates the preparation of coamorphous systems composed entirely of active pharmaceutical ingredients (APIs), namely praziquantel, niclosamide, and mebendazole. The objective was to formulate and characterize binary and ternary coamorphous systems to evaluate their structural, thermal, and stability properties. Methods: Ten different mixtures (binary and ternary) were designed through a mixture design approach and prepared using a sustainable, one-step neat grinding process in a lab-scale vibrational mill. The systems were prepared reproducibly within 4 h across the entire experimental domain. Structural characterization was performed using PXRD and FTIR to confirm the absence of crystalline domains and the presence of molecular interactions. The glass transition temperature (Tg) was theoretically calculated using the Gordon-Taylor equation for three-component systems and determined experimentally via DSC. Stability studies were conducted on seven systems under different storage conditions (-30 °C, 5 °C, 25 °C, and 40 °C) for six months. Results: PXRD analysis confirmed the formation of coamorphous systems with no crystalline phases. DSC revealed a single Tg for most systems, indicating homogeneity. Stability studies demonstrated that five out of seven systems adhered to the "Tg-50 °C" stability rule, remaining physically stable over six months. Recrystallization studies indicated diverse pathways: some systems reverted to their original crystalline phases, while others formed new entities such as cocrystals. Conclusions: This study highlights the feasibility of coamorphous systems composed of multiple APIs using a simple, solvent-free grinding approach. The findings underscore the importance of molecular interactions in determining stability and recrystallization behavior, offering insights for designing robust coamorphous formulations.

Review of advanced sensor system applications in grinding operations.

Today, in a wide variety of industries, grinding operations are an extremely important finishing process for obtaining precise dimensions and meeting strict requirements for roughness and shape accuracy. However, the constant wear of abrasive tools during grinding negatively affects the dimensional and surface conditions of the workpiece. Therefore, effective monitoring of the wear process during grinding operations helps to predict tool life, plan maintenance and ensure consistent product quality. The objective of this review is to examine current tool condition monitoring techniques, both direct and indirect, in various sensor systems and their application in both traditional and AI-driven grinding processes. By examining these techniques, the review provides insight into how different monitoring techniques can improve process efficiency, reduce downtime, and improve finished product quality, as well as the application of intelligent and adaptive processes to traditional grinding operations. Key Scientific Concepts of Review: The review discusses the critical role of sensor systems in monitoring tool condition, including technologies such as imaging, vibration analysis, acoustic emission, and force measurement. These systems are vital for detecting wear and predicting failures, allowing for timely interventions and preventing unplanned downtimes. The integration of artificial intelligence into these monitoring systems greatly enhances their capabilities, as they enable more proactive strategies and adapt to changing conditions during the grinding process.

Optimizing Sustainable High-performance Green-concrete Characteristics with Minimum Cement Content: Experimental Program

With the increasing cement demand for concrete production, this study aims to optimize the compressive strength and rapid chloride permeability (RCP) of highperformance green concrete (HPGC) with minimum cement content using an experimental and analytical Response Surface Method (RSM). Waste palm oil fuel ash (POFA) was treated by heating and grinding processes to produce ultrafine POFA (UPOFA), which was employed by 0%, 30%, and 60% as a replacement binder with cement in HPGC production. Silica Fume (SF) was replaced by 0%, 10%, 15%, and 20% of the remaining mass of cement. The RSM with a central composite design (CCD) approach was utilized to optimize the mix design parameters. The experimental results showed that HPGC containing 30% UPOFA and 20% SF achieved superior compressive strength at ages of 28 days and 90 days. The combination of 60% UPOFA and 20% SF demonstrated the lowest permeability to chloride. The developed models had statistical significance and demonstrated satisfactory correlation values (R2) of 99.43 and 99.9; 99.46 and 99.67 for compressive strength and RCP at 28 days and 90 days, respectively. Thus, RSM could be an effective strategy for optimizing the mix design and reducing the harmful environment by minimizing waste volume and intensive energy for cement production, thereby harnessing concrete sustainability. Keywords: Concrete sustainability, Green concrete, RSM, UPOFA, Silica fume.

Ultrasonic strengthening grinding process induces α-Al2O3 adhesion to improve high temperature oxidation resistance of TA15 alloy

Ultrasonic strengthening grinding process induces α-Al2O3 adhesion to improve high temperature oxidation resistance of TA15 alloy

Active compliance control of grinding process for stripping enameled copper wire

Active compliance control of grinding process for stripping enameled copper wire

Enhanced grinding process of a cement ball mill through a generalised predictive controller integrated with a CARIMA model

Cement ball mills in the finishing stage of the cement industries consume the highest energy in the cement manufacturing stage. Therefore, suitable controllers that result in good productivity and product quality with reduced energy consumption are required for the cement ball mill grinding process to increase the profit margins. In this study, generalised predictive controllers (GPC)have been designed for the cement ball mill grinding operation using the model obtained from the step response data taken from the industrially recognized simulator. The servo and regulatory responses are analysed with and without constraints by implementing the designed GPC under the closed loop. The error metrics for GPC and conventional controllers are also analysed. The designed GPC for the cement ball mill grinding process outperforms the traditional controller in error metrics.

INCREASING THE EFFICIENCY OF MECHANICAL PROCESSING OF PARTS VEHICLES

The work theoretically substantiates the conditions for reducing the conditional cutting stress (energy intensity of processing) during grinding and blade processing of parts of transport machines, taking into account the angle of entry of the cutting tool into the processed material. It is shown that under the conditions of grinding, they consist in the change of the shape of microsections by cutting grains: the transition from counter grinding by the periphery of the wheel to the kinematic schemes of end and parallel grinding by the periphery of the wheel, the reduction of the intensity of friction of the cutting grain with the processed material and the negative front angle of the cutting material. In terms of blade processing, they consist in the application of tangential turning, parallel milling, especially with an end mill. The existence of the extremum (maximum) of the conditional cutting stress from the sum of the conditional friction angle of the cutting grain with the processed material and the negative front angle of the cutting grain has been proved. The ranges of change of this amount are determined, at which the conditional cutting stress becomes the smallest. It is shown that the nature of the change in the conditional cutting stress is determined by the change in the conditional shear angle of the processed material. It was established that infinite values of conditional cutting stress are achieved under the condition of equality of the conditional shear angle of the processed material and the angle of entry of the cutting tool into the processed material. Therefore, it is necessary to increase the conditional shear angle of the processed material by reducing the intensity of friction in the cutting zone and the negative front angle of the cutting tool. The conditions for increasing the efficiency of blade processing by increasing the ratio of the tangential and radial components of the cutting force, as well as the ratio of the slice thickness to the radius of rounding of the cutting tool tip, which consist in reducing the friction in the cutting zone and the front angle of the cutting tool, have been theoretically determined. The introduction at the machine-building enterprise of high-speed cutting technologies with progressive cutting carbide tools with wear-resistant coatings of the TaeguTec company with the use of high-speed CNC metal cutting machines of the "machining center" type made it possible to increase the efficiency of processing the complex profile surfaces of the "Cup of the wheel differential".

Study on the Relationship Between Vibration Signals in CFRP Grinding and Grinding Mechanism

AbstractIn the process of grinding carbon fiber reinforced polymer (CFRP), the changing state of acceleration vibration signal is closely related to the grinding surface quality. Therefore, the time domain and frequency domain signal changes in acceleration can be used to monitor and control the grinding process to improve machining quality and efficiency. In this paper, changes in acceleration frequency domain signals under different grinding angles are studied, and the relationship between the vibration forms of acceleration frequency domain signals at the beginning, middle and end of grinding as well as the surface morphology and quality of the corresponding grinding position is studied. Combined with the micro-morphology of the grinding area, it can be seen that, a high frequency and low amplitude vibration can improve the grinding surface quality, but a high amplitude will have a negative impact on the grinding quality. The acceleration vibration during grinding is more stable and the corresponding surface quality is better. With an increase in grinding angle, the maximum amplitude of acceleration first increases and then decreases. The length of the surface fiber also initially decreases and then increases. Lastly, the resin residue first increases and then decreases. The purpose of this study is to provide a theoretical basis for the subsequent grinding state adjustment.

Анализ технологических и энергетических параметров шаровых мельниц

The paper considers issues related to the analysis of the most important process parameters of ball mills, such as changes in productivity, power consumption, amount of water entering the mill, oil pressure in the mill hydraulic system, pulp density during mill unloading. It was found that the power consumed by the mills varies within 836–1260 kW. The energy characteristics of the mills, as well as specific power consumption, correlation coefficients and regression equations are presented. The values of the coefficients of variation, asymmetry and excess show good agreement with the normal distribution law of random variables. Specific power consumption for mills varies within 6.71–9.94 kWh/t. In the future, it is planned to carry out a verification calculation of the drive electric motors of the mills in order to establish that the actual power of the electric motor corresponds to the calculated one. Such a check allows to objectively assess whether the actual power consumption corresponds to the adopted technology of the grinding process in the autogenous grinding body of the mining and processing plant.