Removal Mode Research Articles

An analytical force and energy model for ductile-brittle transition in ultra-precision grinding of brittle materials

The critical grinding depth of ductile-brittle transition is an important processing parameter to guarantee brittle materials machining in ductile mode. Nevertheless, it is a difficult task to predict the critical grinding depth considering multiple grain interactions due to the random grain distribution on the wheel. In our paper, a novel grinding force and energy model is established to predict the critical grinding depth with considering the random interactions between multiple grains, and experimental validations are carried out on single crystal silicon. In this process, the grain-workpiece interactions are explored by the actual grain protrusion heights and random grain distribution. The surface generation mechanisms of the ductile-brittle transition are comprehensively investigated by applying the numerical and experimental methods. It shows that the plastic ploughing and brittle fracture are the dominant material removal modes when grinding brittle materials. Moreover, validation experiment results indicate that the proposed model could accurately predict the realistic critical grinding depth with an average deviation of less than 9.2%. Finally, based on the proposed model, the influence of grinding conditions on the critical grinding depth are investigated in detail. The critical grinding depth increases with increasing grinding speed, while decreases with increasing feed speed. Hence, this research not only provides a new method for predicting the critical grinding depth, but also enhances the understanding of the ductile-brittle transition mechanism in brittle materials machining.

Modeling and experimental study on tool-particle interaction and surface integrity in milling SiCp/Al metal matrix composites

High-efficient machining of SiC particles reinforced composites is always challenging mainly due to their poor surface integrity. In this study, a two-phase finite element model including the Al alloy matrix with Johnson-Cook model and SiC particle with elastic-brittle failure model were developed. The main purpose is to comprehensively investigate particle removal mechanisms and surface integrity following simulation and experimental studies on milling SiCp/Al composites. Specifically, the distributions of residual stress along the depth direction were predicted using finite element model. Results indicated that compressive residual stress mainly appeared on the machined surface, while tensile residual stress distributed at deeper depth down to 0.02 mm. Besides, different relative positions between tool and particle induced specific particle removal modes, which eventually led to various surface defects. Higher level of cutting speed (180 m/min) and feed rate (0.09 mm/tooth) aggravated surface defects and increased the thickness of broken-SiC layer in subsurface. The simulated machined surface defects and surface residual stress correlated well with the experimental observation, and the maximum error value of cutting force was less than 15%. The proposed finite element model was efficient to predict cutting force and distribution of residual stress along the depth direction.

Understanding the machining characteristic of plain weave ceramic matrix composite in ultrasonic-assisted grinding

The machining of silicon carbide (SiC) ceramic matrix composites is a significant challenge because of the severe material damage that may occur during material removal, which might shorten the service life of the composite parts. In this study, the effects of different fibre orientations of two-dimensional woven carbon-fibre-reinforced silicon carbide matrix composites (2D-C f /SiC) on the grinding force, surface roughness, and surface/subsurface micromorphology were investigated to clarify the material removal and breakage mechanism in ultrasonic-assisted grinding of ceramic matrix composites. The results show that the predominant material removal mode in ultrasonic-assisted grinding is brittle fracture. The forms of material breakage are matrix cracking, fibre fracture, fibre pull-out, interfacial debonding, and interfacial fracture. Compared with conventional grinding, the normal force, tangential force, and surface roughness in ultrasonic-assisted grinding decreased by approximately 20%, 18%, and 9%, respectively. The machining parameters significantly impacted the grinding force and surface roughness. The material removal modes varied for different fibre orientations. Ultrasonic-assisted grinding can effectively decrease the grinding force and improve the surface integrity. The findings of this study can be applied to predict the grinding force and surface integrity of 2D-C f /SiC and contribute to the design and manufacturing of this type of material.

A promising approach to assessing anthropogenic impact on natural ecosystems for the sustainable functioning of cyber-physical systems

The article deals with the problem of controlling the emission of gases and suspended particles of thermal power plants. It is a closed system with mutual influence of physical processes (fuel preparation, fuel combustion, flue gases and particulate matter removal) on computational processes (fuel quality control, fuel combustion completeness control, control of permissible emissions into the atmosphere) and the reverse influence of computational processes on physical ones (fuel preparation modes change, fuel combustion modes change, flue gases and suspended particles removal modes change). The fault tolerance and predictability improvement of such a cyber-physical system is associated with an increase of the data reliability from existing feedback loops and the multimodality of physical process control systems.

Material removal behavior and crack-inhibiting effect in ultrasonic vibration-assisted scratching of silicon nitride ceramics

To investigate the material removal mechanism and crack-inhibiting effect of ultrasonic vibration-assisted grinding of ceramic materials, a series of double-scratch tests with variable scratching depths and interval distances was conducted. Ultrasonic vibration-assisted scratching (UVS) and conventional scratching (CS) were compared in terms of cutting force, scratch morphology, crack system, and material removal mode, and the effects of ultrasonic vibration and scratch interval distance on the material removal mode and crack-inhibiting effect were analyzed. The results indicate that the crack-inhibiting effect between scratches gradually decreases with an increase in the scratch interval distance. In comparison with CS, UVS can increase the critical load of the brittle-ductile transition and promote the propagation of shallow lateral cracks to the surface. Meanwhile, ultrasonic vibration increases the critical scratch interval distance of the crack-inhibiting effect. The research results also reveal that the material is mostly removed by the interlacing of shallow lateral cracks in UVS; however, this is due to the combined action of deep lateral cracks and radial cracks in CS.

In vitro and in silico approaches to investigate antimicrobial and biofilm removal efficacies of combined ultrasonic and mild thermal treatment against Pseudomonas fluorescens

A combined ultrasonic and thermal (US-TM) treatment was developed in this study to achieve a high efficacy of P. fluorescens biofilm control. The present study demonstrated that combined a moderate ultrasound treatment (power ≥ 80 W) and a mild heat (up to 50 °C) largely destroyed biofilm structure in 15 min and removed>65.63% of biofilm from a glass slide where cultivated the P. fluorescens biofilm. Meanwhile, the viable cell count was decreased from 10.72 to 6.48 log10CUF/mL. Differences in biofilm removal and lethal modes of US-TM treatment were confirmed through microscopies analysis in vitro. The ultrasound first contributed to releasing the bacteria in the biofilm to the environment and simultaneously exposing inner bacteria at the deep layer of biofilm depending on shear force, shock waves, acoustic streaming, etc. When the biofilm structure was destroyed, US-TM treatment would synergistically inactivate P. fluorescens cells. In silico studies adopted COMSOL to simulate acoustic pressure and temperature distribution in the bioreactor; both of them were significantly influenced by various factors, such as input power, sonotrode position, materials and volume of container, etc. Facing the biofilm issue existing on the surface of container, boundary conditions were exported and thereby pointing out potential “dead ends” where the ultrasound may not be effectively transduced. Both in vitro and in silico results may inspire the food industry to adopt US-TM treatment to achieve biofilm control.

Meso-scale numerical simulation and experimental verification of single grain grinding TiC–Fe composites

Grinding process of particle reinforced metal matrix composites (PRMMCs) is extremely challenging due to the addition of hard particles. To reveal the material removal mechanism, a meso-scale numerical model for single grain grinding of TiC–Fe composites was established, considering the random particle distribution model and cohesive zone model. The simulated grinding forces and machined surface topography based on the proposed model show a similar trend and were consistent with the experimental results. The transition stage of ductile-brittle removal of TiC–Fe composites was explored. Results indicated that the grinding forces increase abruptly due to the obstruction of high-strength TiC particles and fluctuate periodically in the Fe matrix. The grinding forces decrease with the elevated grinding speed. Additionally, the material removal processes at different stages were studied and the removal modes mainly include: matrix plastic removal, particles wear, particles debonding, particles fracture, particles pull out. This paper provides significant guidance for the digitization and information construction of PRMMCs machining in enterprises and increases the economic benefits for the manufacturing industry.

Development of Integrated Electrocoagulation-Sedimentation (IECS) in Continuous Mode for Turbidity and Color Removal

The present work focused on the development and evaluation of a compact electrocoagulation (EC) reactor, combined between EC and clarifier processes in continuous modes for decolorization and turbidity removal, named the integrated electrocoagulation-sedimentation reactor (IECS). The experiments were firstly conducted in the four-liter batch column in order to optimize the EC configuration and operation condition. The removal kinetics were also investigated and predicted for kinetic correlations. After various optimization steps, the IECS reactor was conducted, consisting of EC and clarifier compartments. Liquid flow pattern in EC compartment was examined through resident time distribution technique for defining the number of EC units and divided baffles. In summary, four units of EC were placed in the EC compartment of the IECS reactor with 90% in the width of three baffles. Each EC unit had two pairs of aluminum electrode plats in monopolar arrangement with a 1.5 cm gap and required a current density of 13.5 mA/cm2. For the clarifier compartment, it was mainly designed based on the batch settling test for separating the precipitated particles. The treatment performance of the IECS reactor was tested at different liquid flows in order to reduce the pollutant to a certain level. For the individual condition, liquid flow rates of 3 and 1 L/min were defined for turbidity and color, respectively. If both pollutants are presented simultaneously, a liquid flow rate of 1–2 L/min can be used for decreasing turbidity from 250 to <20 NTU and color from 6000 to <300 ADMI.

Functionally graded AZ91/WC nanocomposite fabricated via friction stir processing using a novel way

In this work, functionally graded AZ91/WC nanocomposites were prepared by a novel multi-step chamber diameter reduction method. The WC nanoparticles were packed into chambers with graded diameters and processed by friction stirring using a tool with four-sided grooved probe. The functionally graded nanocomposites were fabricated at different tool rotational speeds (830, 960 and 1160 rpm) at a constant traverse speed and plunge depth of 40 mm/min and 0.1 mm, respectively. The properties of the functionally graded samples and AZ91 Mg alloy were evaluated by optical and scanning electron microscopy, energy dispersive spectroscopy, and other tests such as hardness, pin on disc wear and potentiodynamic polarization tests. The results showed that ?-Mg and graded distribution of WC nanoparticles improved as the tool rotational speed increased. The hardness increased slightly with increasing the rotational speed of the tool. The results also revealed that the wear rate was decreased and corrosion resistance was improved by adding WC nanoparticles. Abrasive wear mode was the main mode of material removal during dry sliding, while cracks and pits were the main features of the corroded surface.

Characteristics of cryogenic abrasive air-jet direct-write machining: A comparison with abrasive air-jet direct-write machining at oblique angles

• The velocity model of abrasive particles in the radial direction is modified. • Abrasive air-jet (AAJ) direct-writing of PDMS at 15° is presented. • Cryogenic abrasive air-jet (CAAJ) direct-writing of PDMS is presented. • CFD models of AAJ and CAAJ direct-writing are established. • "U"-shaped micro-channels are obtained by CAAJ and compared against AAJ at 15°. Cryogenic abrasive air-jet (CAAJ) machining technology is performed simultaneously with the occurrence of the glass transition for PDMS material. However, the mask material is also cooled with cryogenic PDMS cooling. Then, they both show significant brittle characteristics. Therefore, this leads to very poor selectivity between the mask and the PDMS. To solve this problem, CAAJ direct-write machining under unmasking conditions are proposed based on the modified velocity model of abrasive particles in the radial direction. This technique was used to direct-write machined the PDMS materials under small SOD. Then, the effect of cryogenic conditions on machining characteristics of PDMS micro-channels was studied by comparing the abrasive air-jet direct-write machining at oblique angles and CAAJ direct-write machining technologies through a series of experimental studies and CFD simulations. The results show that the material removal mode is transformed to a semi-brittle one, which greatly improves erosion removal efficiency, aspect ratio and bottom surface roughness of the micro-channel. On the other hand, the change in the viscosity of the jet medium has a crucial influence on the geometry of the micro-channel. The rebound direction of abrasive particles changes, and the sidewall of micro-channels is secondarily eroded due to an increase in jet medium viscosity in CAAJ. This, in turn, leads to a micro-channel with "U"-shaped profile. In addition, during CAAJ direct-write machining, sliding, scratching, and rolling of abrasive particles caused by bubble bursting can effectively reduce the bottom surface roughness of the micro-channel.

Experimental investigations on micro-EDM milling of niobium carbide-nickel based cermet using statistical and empirical techniques

Niobium Carbide (NbC) based cermet is a relatively less explored wear resistant material which has potential applications in moulds for ceramic injection moulding as well as cutting tool inserts. The NbC-Ni based cermets exhibit similar hardness as WC-Co cemented carbide but show better wear resistance and chemical stability against iron or steel. The demand for Ni bonded NbC cermets is forecasted to increase due to the rising cost of Co in conventional WC-Co cemented carbides. This poses additional challenges for existing mechanical micromachining processes such as frequent tool failure, higher tool wear and poor surface quality. Therefore, electrically conductive sintered NbC matrix cermets with a Ni binder have been developed which makes it suitable to machine them using electro discharge machining (EDM) and electrochemical machining (ECM) operations.This work presents experimental investigations using micro-EDM milling operation on NbC-Ni workpieces. A combination of empirical and statistical studies is employed to determine the suitable processing window for this material. The empirical study involves microstructural analysis and surface topography characterization using scanning electron microscopy (SEM) and confocal microscopy, respectively. The microstructural features such as micro-cracks, micro-cavities, micro-voids and micro-globules are identified and related to the major material removal mode of melting/vaporization. The statistical study involves parameter optimization and process monitoring. Material removal rate (MRR) of 0.091 mm3/min and tool wear rate (TWR) of 0.048 mm3/min can be achieved to its optimality and tracking the change in sparks frequency, shorts frequency and feed-rate enables to detect the suddenly accumulated debris. In this way, this holistic approach has been demonstrated to achieve an improvement in understanding and optimizing the machining process for novel NbC matrix cermet using micro-EDM technology.

Analysis of the crack propagation mechanism of multiple scratched glass-ceramics by an interference stress field prediction model and experiment

The crack propagation mechanism of glass-ceramics is the theoretical basis for the improvement of surface quality after grinding. The unclear mechanism of the multi-scratch interference effect on the crack propagation of glass-ceramics makes it difficult to propose methods to suppress crack propagation and control strategies to improve the surface quality. This research is aimed at understanding the influence of interference between scratches on lateral crack propagation, material removal mode, and surface quality during the grinding of glass-ceramics. In this study, the stress field model of the interference effect is established to reveal the influence mechanism of the interference effect on crack propagation in glass-ceramics. The amplitude and orientation distribution of the characteristic stress for the lateral crack are analysed. The results show that an increase in amplitude and the influence range of tensile stress and expansion merging under interference promote the further propagation of lateral cracks and brittle removal of glass-ceramics. Multiple scratches experiments produced by single grit were conducted, emulating the interference caused by multiple grits, and they were analysed by an interference stress field prediction model. For glass-ceramics, lateral crack/brittle fracture phenomena are predominant in the case of multi-scratch/double-scratch, whereas major plastic deformations are dominated in the case of a single scratch. A significant reduction in the critical cut depth is noted with an increase in the interference intensity which corresponds to the number of scratches. This preliminary work enables the understanding of the implications of the interference effect on lateral crack propagation in grinding glass-ceramics and provides a scientific basis for the establishment of a control method to suppress crack propagation and improve grinding quality.

Experimental research on micro hole drilling of polycrystalline Nd:YAG

Polycrystalline Nd:YAG materials have wide applications in solid-state lasers. In this study, micro hole drilling experiments were performed on polycrystalline Nd:YAG using a polycrystalline diamond micro drill. The hole diameter, edge chipping, and hole wall surface quality were examined in detail. The results showed that the hole diameter was slightly larger than tool diameter. A diameter error of less than 5.5% was achieved. The edge chipping at the entry hole was formed by the encircled petal shape exfoliations, which were produced by the indentation and rotation movement in the drilling entry stage. Edge chipping at the exit hole was generated by an entire piece of exfoliation, which was produced by a circle of microcracks around the tool tip propagating to the bottom surface in the drilling exit stage. The edge chipping width at the entry hole was smaller than that at the exit hole. Based on different material removal modes, the hole surface morphology was classified into three types: ductile removal, coexisting ductile and brittle removal, and brittle removal. The hole surface quality mainly depended on the proportion of the brittle fracture to ductile removal surface.

Effect of Graphene Nanoplatelets Reinforcement on Grindability of Zirconium Diboride Ceramics

Abstract The effect of graphene nanoplatelets (GNPS) on the grindability of GNP reinforced ZrB2 was studied using a resin bonded diamond grinding wheel under dry and wet conditions. A comparative study of grinding forces was performed at selected wheel surface speeds and depths of cut for surface grinding. ZrB2-GNP showed lower normal grinding forces due to the improved fracture toughness and reduced hardness. The presence of GNP reinforcement in ZrB2 resulted in lower tangential forces and reduced specific grinding energy due to the role of GNP as a solid lubricant. The measured forces showed a good correlation with the micro cutting model for ZrB2 and ZrB2-GNP under dry conditions. The tangential forces showed the same trend as normal forces at different depths of cut and wheel surface speeds for ZrB2 and ZrB2-GNP with average force ratios of 0.3 and 0.35, respectively. The presence of porosity in ZrB2 increased the normal grinding forces during wet grinding. Scanning electron microscope (SEM) images of the grinding chips indicated a mixture of both the ductile mode and the brittle mode of material removal with predominantly brittle fractured chips. Energy-dispersive spectroscopy (EDS) confirmed the presence of GNPs in ZrB2-GNP grinding chips. The topography of the grinding wheel showed higher wheel loading after the dry grinding than that of wet grinding. The wet grinding resulted in relatively lower surface roughness (Ra values) than dry grinding.

Amplitude effect on micro-hole drilling of 3D needled Cf/SiC by ultrasonic vibration

The poor quality of the micro-hole in the conventional drilling (CD) of 3D needled Cf/SiC composites seriously limits its application in modern industry. Ultrasonic assisted drilling (UAD) is a hybrid machining technology that combines CD with ultrasonic vibration. When processing holes in the Cf/SiC composites, the UAD has great advantages of improving hole wall quality and reducing cutting force, and it has been widely applied to Cf/SiC manufacturing. This study mainly focuses on the influence of amplitude in UAD on the manufacturing of micro holes in the Cf/SiC. By analyzing the micro-morphology of the hole wall and outlet edge under different amplitude in UAD, the influence of amplitude on the fiber removal mode and material damage mechanism is studied. Meanwhile, the thrust force in CD and UAD is also obtained. The results show that the defects of the hole are reduced with the alteration of the fiber removal mode in UAD. And with the increase of the amplitude, the hole quality is further improved. However, the excessive amplitude leads to the damage of the matrix. The thrust force curve shows a “multi-peak” shape with a regular interval due to the layered structure of Cf/SiC in CD and UAD. Compared with the CD, the thrust force of UAD is reduced by up to 70.1% as the amplitude increases from 3 μm to 9 μm. Furthermore, the hammering effect caused by ultrasonic vibration alleviates the material damage around the outlet edge in UAD. With the increase of amplitude, the matrix damage and the fracture of the fiber around the outlet are alleviated. The fracture feature of the fiber around the outlet is more regular than the CD. Consequently, UAD is a beneficial method for Cf/SiC composites micro-drilling with better hole quality and it plays an important role in the future of Cf/SiC processing.

Grinding performance oriented experimental evaluation on TiC-Steel cermet with vitrified bond cBN wheel

TiC-Steel cermet is widely used in aerospace and mining machinery owing to its excellent performance. However, the high wear resistance and the heterogeneity make its machining a challenging task. To investigate the grinding performance of TiC-Steel cermet, vitrified bond cBN wheel was customized to conduct dry grinding experiments. Grinding force was measured using a Kistler dynamometer; surface topography and 3D surface roughness parameters were measured by laser microscopy and scanning electron microscopy. Results indicate that plastic removal of steel phase, brittle fracture of ceramic phase, ceramic phase wear, ceramic phase debonding and microcracks are main removal modes of TiC-Steel cermet. 3D surface roughness parameters S a , S q , and S z consistently increase with increasing grinding depths from 25 μm to 125 μm and decrease with increasing spindle rotation speed. Effect of feed rate on the 3D surface roughness parameters is less than that of the grinding depth. The trend of the grinding force and surface topography is similar to that of 3D surface roughness parameters. Hence, the optimal processing parameters ( v w = 1–2 m/min, a p = 25 μm, n s = 5130 rpm) were used to obtain the best surface quality and the lowest grinding force (the minimum F N and F T of 9.2 N and 3.5 N, respectively). This study is devoted to broaden the research on the machinability of carbide-based cermets and promote utilization rate of cermets in industry.

Edge chipping characteristics in grinding SiCf/SiC composite

Silicon carbide fiber-reinforced silicon carbide ceramic matrix composite (SiCf/SiC) is promising for manufacturing aero-engines because of its high-temperature resistance and lightweight. However, since SiCf/SiC is hard and brittle, the machining of SiCf/SiC has been suffering from uncontrolled machining-induced damages, such as edge chipping, cracks, fiber breakage. This paper studies the edge chipping characteristics of SiCf/SiC in brittle removal mode in single grain grinding. It is found that the edge chipping in grinding SiCf/SiC is complicated. The edge chipping in grinding the SiC matrix is dependent on the pre-existed defects rather than grinding parameters. While the edge chipping in grinding SiC fibers is dependent on both fiber orientation and grinding speed. The edge chipping in the grinding perpendicular to the fiber orientation is larger than that in the grinding along with the fiber orientation. It decreases with increasing grinding speed. Increasing grinding speed from 20 m/s to 50 m/s and 90 m/s, the width of the edge chipping area decreases by 30% and 60% respectively. While in the grinding along with the fiber orientation, edge chipping is minor and insensitive to grinding speed. Therefore, this study represents that increasing grinding speed would not enlarge the edge chipping but greatly increase the material removal rate, which is important for the surface finish and damage control of the machining of SiCf/SiC.

Investigation of material removal mechanisms and ductile-brittle transition zone of zirconia ceramics sintered at various temperatures

Sintering is a comprehensive process that involves the complex evolution of material microstructures and properties, being recognized as a critical factor to improve the machinability of ceramics. The present work aims to address the evolution of the material removal mechanisms of the 3mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) during the sintering process based on the micro scratching tests. The impacts of sintering temperatures on the material removal behaviors, including scratching forces, scratch morphologies, specific scratching energies, and critical transition depths, were rigorously studied. The acquired results indicate that the intergranular bonding strength is a critical factor that determinines the material removal mechanisms of 3Y-TZP, and 1100°C signifies the transition threshold for the material removal mode. After 1100°C, the material removal mechanism has gradually converted into the typical ductile-brittle removal regime. Moreover, the critical depth in ductile regime at 1200°C is about 1.89 times that at 1500°C, and the critical depth of ductile-brittle transition at 1200°C is approximately 2.08 times that at 1500°C.

Theoretical Modeling and Experimental Analysis of Single-Particle Erosion Mechanism of Optical Glass.

The study of the single-particle erosion mechanism is essential to understand the material removal mechanism in the non-contact polishing process and ultimately ensure the high-efficiency, non-damage, and ultra-smooth processing of optical glass. In this study, the theoretical model of smoothed particle hydrodynamics (SPH) is established to reveal the dynamic removal process of a single particle impacting the optical glass. The single-particle erosion mechanisms, which include ductile–brittle transition, crack initiation, and propagation, are discussed in detail through theoretical simulation. A series of particle impact experiments are designed to validate the correctness of the SPH model. The experimental data show good agreement with the simulation results in terms of the depth and width of the eroded craters. Thereafter, the SPH simulation is conducted by studying the effect of various impact parameters, such as impact speed, impact angle, and abrasive diameter, on the material removal process. With the gradual increase of impact velocity and particle size, the material removal mode changes from plastic removal to brittle removal. Although the large impact velocity and particle size increase the material removal rate, they lead to the occurrence of brittle removal and reduce the surface and sub-surface quality. When the impact angle is between 45° and 75°, the material removal rate is the largest, and the increase of the material removal rate does not cause damage to the subsurface layer of the material.

A Quantitative Modeling and Prediction Method for Sustained Rainfall-PM2.5 Removal Modes on a Micro-Temporal Scale

PM2.5 is unanimously considered to be an important indicator of air quality. Sustained rainfall is a kind of typical but complex rainfall process in southern China with an uncertain duration and intervals. During sustained rainfall, the variation of PM2.5 concentrations in hour-level time series is diverse and complex. However, existing analytical methods mainly examine overall removals at the annual/monthly time scale, missing a quantitative analysis mode that applies micro-scale time data to describe the removal phenomenon. In order to further achieve air quality prediction and prevention in the short term, it is necessary to analyze its micro-temporal removal effect for atmospheric environment quality forecasting. This paper proposed a quantitative modeling and prediction method for sustained rainfall-PM2.5 removal modes on a micro-temporal scale. Firstly, a set of quantitative modes for sustained rainfall-PM2.5 removal mode in a micro-temporal scale were constructed. Then, a mode-constrained prediction of the sustained rainfall-PM2.5 removal effect using the factorization machines (FM) was proposed to predict the future sustained rainfall removal effect. Moreover, the historical observation data of Nanjing city at an hourly scale from 2016 to January 2020 were used for mode modeling. Meanwhile, the whole 2020 year observation data were used for the sustained rainfall-PM2.5 removal phenomenon prediction. The experiment shows the reasonableness and effectiveness of the proposed method.