Sawing Process Research Articles

Research on the reliability of wire web in diamond multi-wire saw slicing photovoltaic monocrystalline silicon wafer

Diamond multi-wire slicing technology is the main method for producing the solar cell substrate based on monocrystalline silicon. To reduce the production cost and increase the production efficiency during the sawing process, the diameter of the diamond saw wire is becoming thinner, and the sawing speed is getting faster, which leads to an increasingly prominent problem of saw wire breakage during the slicing process. To understand the breaking characteristics of diamond saw wire and evaluate the reliability of the saw wire during the sawing process, the tensile testing of saw wires was carried out in this paper. And based on the Weibull function, the breaking force was analyzed statistically. A maximum tension force model for the saw wire during the sawing process was established. And based on the maximum tension force model and Weibull reliability function, the influence of various process parameters on the reliability of the wire web was analyzed. The results indicated that as the usage time of the saw wire increases, the breaking force gradually decreases and stabilizes. Compared to the fresh saw wire, the reliability of the used saw wires is significantly reduced. As the abrasive distribution density and the wire speed increases, the reliability of the wire web gradually increases. Conversely, as the feed speed and the pretension of the saw wire increase, the reliability of the wire web gradually decrease. The results of this paper provide a theoretical approach for assessing the reliability of diamond saw wire web during the sawing process. It also provides guidance for optimizing process parameters to enhance the reliability of the wire web.

Analysis of contact length and temperature effect in rocking mode diamond wire sawing of monocrystalline silicon carbide wafer

Diamond wire sawing (DWS) is a primary and fundamental stage for slicing large-diameter ingots into multiple wafers, enabling high-volume production in a single process. However, the extended contact length between the diamond wire and work material generates heat, which detrimentally impacts the surface quality of the sliced wafers and accelerates the diamond wire wear rate. This study implemented a rocking mode sawing strategy to investigate the effect of contact length on the surface quality of as-sawn wafer and diamond wire wear rate. Experiments have been conducted on monocrystalline silicon carbide (4H-SiC) with and without a rocking-mode multi-DWS machine. The experimental sawing temperature has been validated using Fourier’s law of thermal conduction, a finite element model, and a linear time series regression model. Results indicated that the minimal sawing temperature had been observed with the rocking mode sawing strategy, attributed to its shorter contact length compared to the process without rocking mode. Additionally, the finite element and regression models closely matched the experimental data, achieving accuracies of 93.57 % and 99.96 %, respectively. Fourier’s law of thermal conduction proved significant for precisely determining the sawing temperature. Notably, the rocking mode sawing strategy significantly affected the sawing temperature, surface quality, and diamond wire wear rate compared with the sawing process without the rocking mode.

Effect of anisotropy on 4H-SiC cracking behavior during diamond wire sawing

Cracking behavior caused by the anisotropy of single-crystal silicon carbide (SiC) brings challenges to the quality of the diamond wire sawing and grinding process. In this study, the effects of SiC anisotropy on machanical properties is analyzed based on Griffith’s theory. The results indicate that the fracture toughness and the fracture strength exhibit anisotropy. At the same time, an analytical model for the initiation and deflection of the surface radial crack is proposed based on the scratching stress field. On the basis of these results, the anisotropic machanism of the surface radial crack initiation, deflection, the surface radial crack initiation (SRCI) depth, and the residual scratching depth are investigated in combination with the single abrasive scratching experiment. The shear stress and the maximum principal stress are the primary driving forces for the initiation and deflection of surface radial crack, respectively. The direction of the minimum shear strength and the fracture strength determines the anisotropy of cracking behavior. Meanwhile, the anisotropy of the SRCI depth and the residual scratching depth is caused by the fracture strength anisotropy. This research offers fundamental insights into the anisotropic cracking behavior of SiC, thereby contributing to the precise control of crack damage and improve the quality of the SiC diamond wire sawing and the as-cut wafers grinding process.

Assessment of the Heat Transfer Conditions in the Cavity of a Rotating Circular Saw

To improve machining processes concerning the usage of lubricants, knowledge of the thermo-mechanical and thermo-fluid interactions at the cutting zone is of great importance. This study focuses on the description of the convective heat transfer which occurs during circular sawing when the lubricant is provided via an internal coolant supply. The highly complex flow field inside the cavity of the sawing process is separated into two distinct flow forms, an impingement and a channel flow. With the aid of experimental and numerical studies, the heat transfer characteristics of these two flow forms have been examined for water and a lubricant used in the circular sawing process. Studies have been conducted over a wide range of Reynolds numbers (impingement flow: 2×103<Re<17×103, channel flow: 1×103<Re<30×103). Additionally, the variation in the inlet temperature of the fluid, as well as the variation in heating power, has been studied. Overall, the impingement flow yields a significantly higher heat transfer than the channel flow with Nußelt-numbers ranging from 120 to 230, whereas the Nußelt-numbers in the case of the channel flow range from 20 to 160. For both flow forms, the use of the lubricant results in a better heat transfer compared with the usage of water. With the aid of these studies, correlations to describe the heat transfer have been derived. The provided correlations are to be used in a coupled numerical model of the chip formation process which also includes the effects of the heat transfer to the coolant lubricant.

Analysis and Testing of Pre-Cut Sugarcane Seed Stalk Sawing Performance Parameters

Sugarcane is an important economic crop in tropical and subtropical regions. Presawing planting is an important method for achieving automated and precise planting with sugarcane planting machines. The sawing process is a key stage in planting management, affecting not only the germination and survival rates of sugarcane, but also reflecting the mechanical performance of sawing. To reduce the peak sawing force and enhance the sawing surface quality of sugarcane seedlings, this study utilized a central composite experimental design method. Single-factor and multi-factor experiments were conducted with a specially designed sugarcane stalk sawing experimental rig to investigate the impact of factors such as the stalk diameter feeding speed, and sawing speed on the peak sawing force and sawing surface quality. Upon being developed and validated, multivariate mathematical regression models elucidated the relationships among these factors. The experimental results showed that the order of influence of each factor on the peak sawing force was the stalk diameter, feed speed, and sawing speed, while for the sawing surface quality, the sequence was the sawing speed, stalk diameter, and feed speed. Correspondingly, the determination coefficients for the peak sawing force and sawing surface quality prediction models were 0.9708 and 0.9675. With a maximum error of 7.6% for the peak sawing force and an average relative error of 7.1%, and a maximum error of 3.5% for the sawing surface quality and an average relative error of 2.83%, the calculated results from the regression models were in good agreement with the experimental findings. This indicates that the models are capable of quickly and accurately predicting the peak sawing force and sawing surface quality of sugarcane stalks under different conditions. The research findings provide valuable insights for the development and optimization of sugarcane stalk presawing equipment and related experimental studies.

Study on the Temperature Distribution and Natural Frequency of a Circular Saw Blade during Three Types of Wood Sawing Processes

Abstract The stability of a circular saw blade during the cutting process affects the knife life and the material utilization rate. In this article, continuous sawing experiments were carried out on medium-density fiberboard, Pterocarpus soyauxii board, and reconstituted bamboo lumber board. The temperature distribution of the saw blade surface was measured. The natural frequency of the saw blade under thermal stress was analyzed by the finite element method. The results show that the material density is positively correlated with the edge temperature of the saw blade. Greater temperature differences within the saw blade lead to worsening dynamic stability. When cutting the reconstituted bamboo lumber board, the saw blade will suddenly lose stability, and the surface temperature will rise rapidly, which greatly shortens the life of the saw blade.

Wear mechanisms of diamond segmenta in cutting of carbon fiber reinforced cement-based composite and optimizing in parameters

Carbon fiber reinforced cement-based composite material (CFRC) is a novel type of composite material that involves the incorporation of carbon fibers into ordinary concrete. This addition effectively enhances the tensile strength, deformation performance, and dynamic load resistance of reinforced concrete structures. Consequently, CFRC has found increasing applications in the construction industry. The objective of this research is to investigate the wear mechanisms of diamond tools during the sawing process of CFRC and offer guidance on cost reduction through the optimization of processing parameters. The wear analysis of diamond segments can be divided into two categories: matrix wear and diamond particle wear. The diamond particles can exist in different states, and the formation of voids resulting from the detachment of diamond particles is considered as a reference point. The analysis reveals that abrasive wear is the main mechanisms of matrix wear in CFRC sawing. The wear resistance is strongly influenced by the proportion of diamond particles in favorable states, which is determined by the applied loads and operating parameters. The proportion of diamond particles exhibits a clear variation with adjustments made to the feeding speed. Notably, an increase in feeding rate results in a significant decrease in the percentage of blunt particles, reducing it from 28% to 6%. To achieve a lower wear rate, a predictive model was established using Design Expert software based on the experimental results. The model demonstrated that a wear rate as low as 268.5 mm/m2 can be achieved with a flywheel speed of 78 r/min and a feeding speed of 90 mm/h. The optimization process, aimed at minimizing wear rate, was successfully carried out without compromising productivity.

Granulometric characterization of Arctic driftwood sawdust from frame sawing process

Arctic driftwood can be used as an alternative source of wood as construction timber and furniture material, especially in Iceland and Greenland. The use of Arctic driftwood can help in the fight against climate change, by developing land reforestation processes and reducing the volume harvested wood from forests and sustainability of harvesting processes. In this paper the results of an analysis of the effect of long-term residence of pine (Pinus sylvestris L.) and larch wood (Larix sibirica L.) stay in Arctic ice and seawater on the granulation of wood sawdust and the distribution of fine wood dust particles during the frame sawing process are presented. The distribution of wood chips and dust was analysed using sieve and laser diffraction methods. The results confirmed that Arctic driftwood, compared to normal wood for both analysed species, generate slightly more fine wood dust particles during the frame sawing process, which can be harmful to human health. However, these differences are not significant, indicating that the same dust extraction systems can be used for both sawing processes.

Investigating damage mechanisms of honeycomb cores machined with PCD circular saw blades

Aluminum honeycomb core (AHC) is extensively applied in aerospace and transportation industries for its exceptional strength-to-weight ratio. However, the unique structure of AHCs limits their manufacture. In this research, the damage mechanism of AHCs is firstly studied with polycrystalline diamond (PCD) circular saw blades to provide high-quality AHCs for wide-format honeycomb composites. The study meticulously examines the various forms of sawing damage incurred by AHCs at different material removal rates (MRR) and categorizes them accordingly. The results show that burrs of AHCs change from tiny blocks to larger strips with the MRR. At high MRR, the predominant failure modes include collapse, deformation, and hot cracking, while at low MRR, AHCs mainly suffer from cracking, micro-collapse, and oxidation by SEM and EDS analysis. A dynamic analytical model of the sawing angle is proposed based on the sawing trajectory to elucidate vibration scratching and burr formation. The effect of the sawing angle is quantified by the deformation displacement and damage area by the optical measurement. The microscopic reciprocating vibration scratching of AHCs is interpreted by the blade’s vibration state. The causes of sawing damage at different MRRs are investigated, indicating that at high MRR, the increased impact of the sawtooth leads to severe vibration scratches, collapses, and strip burrs, whereas, at low MRR, the high-frequency scratching of the sawtooth tends to result in tearing and micro-collapses. A comprehensive description of burr formation is presented by a 3D finite element model. Additionally, the cutting heat is the main cause of the oxidation of sawing surfaces by EDS. This systematic investigation analyzes and explores the sawing damage mechanisms of AHCs, offering in-depth insights for optimizing the sawing process to eliminate surface quality problems and improve the sawing efficiency and accuracy of wide-format AHCs.

Removing grid artifacts from a two-dimensional crisscrossed grid in cone-beam computed tomography to enhance image quality

One-dimensional linear X-ray grids are typically used in clinical practice to reduce the number of scattered X-rays reaching the detector surface, thus improving image contrast in radiography. However, such grids can only remove scattered X-rays in one direction. Additionally, the primary challenge in using X-ray grids in digital radiography is the presence of grid artifacts, such as grid strip shadows and moiré, which can reduce image quality. To overcome these difficulties, in this study, we developed a prototype two-dimensional (2D) crisscrossed grid with a strip density of 1.724 lines/mm by adopting a high-precision sawing process to further improve its scatter radiation removal ability and implemented it in a cone-beam computed tomography (CBCT) system to enhance image quality. We propose a new software-based method called the grid artifact reduction (GAR) algorithm to efficiently eliminate grid artifacts of a 2D grid in CBCT. The GAR algorithm involves three main steps: 1) preprocessing for flat-field compensation, 2) postprocessing for GAR, and 3) CBCT reconstruction. To verify the efficacy of the proposed approach, we conducted an experiment on a CT quality control phantom (Pro-CT MK II™) and quantitatively evaluated the CBCT image quality using the contrast-to-noise ratio (CNR) and Hounsfield unit (HU) accuracy error. The CNR value measured in the CBCT image obtained using the 2D grid and proposed GAR algorithm was 3.22, which is approximately 4.4 times of the value obtained without GAR. Furthermore, the corresponding HU accuracy error was 30.47, an improvement of approximately 1.3 times. These results indicate that the proposed approach is highly efficient in eliminating scattered X-rays, thereby improving the quality of CBCT images. Consequently, high-quality CBCT images were obtained using the proposed approach (i.e., using a 2D crisscrossed grid in CBCT and the proposed GAR algorithm).

Peeler core and slabwood fibre properties for Pinus radiata D.Don pulp production

Background: Pulp production based on Pinus radiata D.Don is constantly improving the value recovery of logs. One example is using the peeler cores and slabwood derived from sawing and peeling processes to produce pulp. However, these two raw materials have not been characterised for their fibre properties. Methods: We report on four wood fibre quality attributes derived from peeler cores and slabwood, directly influencing pulp quality and pulping process: fibre length (mm), fibre width (µm), fines content (%), and coarseness (µg/m). This pilot study sampled two P. radiata stands grown on different sites and early silvicultural regimes in the Araucanía Region of Chile. Analysis of wood fibre consisted of three trees per stand, and six discs per tree: two at the bottom, two at breast height (1.3 m), and the last two at 5.23 m height. Results: The trajectory of mean annual increment in diameter at breast height (MAI) and periodic annual increment in diameter at breast height (PAI) for trees in the two stands aligned with their respective site qualities and silvicultural regimes. In Stand 1, with a site index of 36, and Stand 2, with a site index of 31, the average proportions of juvenile wood (measured at 1.3 m) were 50% and 53%, respectively. Thus, despite weed control and fertiliser application in Stand 1, there was no increase observed in the proportion of juvenile wood. There were significant differences in fibre properties between peeler core and slabwood, and these differences were present across the range of tree heights and diameters (p<0.05). While there were no statistically significant differences among disc positions, significant distinctions emerged between stands and wood types. The interaction between these factors was also found to be statistically significant (p<0.05). Conclusions: Our study suggests that adding these two materials into the mix for producing pulp would have positive implications due to pulp from peeler core is more suitable for printing and writing grades and addition of mature wood from slabwood, could improve strength properties of paper manufacture. However, it is necessary to test the optimal proportion for the final mix.

Universal submerged arc welding (USAW): high weaving amplitudes as a new possibilities to SAW process

Universal submerged arc welding (USAW): high weaving amplitudes as a new possibilities to SAW process

Occupational Health and Safety Analysis Using Job Safety Analysis and Hazard Identification Risk Assessment and Risk Control Methods

Occupational Safety and Health is an important factor in the smooth production of a company that has a relationship with machinery, work tools, work environment, raw materials and processing. The purpose of this research is to minimize the number of work accidents in the company by identifying hazards, risk assessment and risk control. The research method used is the Job Safety Analysis method to classify work activities and identify hazards descriptively while the Hazard Identification Risk Assessment and Risk Control method is used to conduct risk assessment and risk control in each sequence of work processes. The results of the research conducted showed 57 potential hazards with 17 potential hazards in the unloading process, 3 potential hazards in the measurement process, 11 types of hazards in the sawing process and 26 potential hazards in the sorting process. Based on the results obtained, the risk categories can be classified as 16 (28%) potential hazards in the lowrisk category, 28 (49%) potential hazards in the medium risk category, 13 (23%) potential hazards in the highrisk category and 0 (0%) potential hazards in the extreme risk category. The risk control carried out is by using elimination, substitution, administrative and PPE.

现代苹果园修剪机械的设计与试验

In response to the problems of low efficiency and difficulty of pruning operations in modern dwarf dense orchards, an adjustable position saw blade pruning machine was designed, mainly consisting of a pruning device, a regulating device and a hydraulic system. Through the mechanical and modal analysis of the circular saw blade, the limit speed of the circular saw blade was derived. A finite element model of the sawing process was established, and a single-factor simulation analysis was conducted for three important parameters: feed rate, circular saw blade speed and branch diameter, and a three-factor, three-level quadratic regression orthogonal test was designed to derive the best matching sawing parameters, which was verified in field tests. The test results showed that the average passing rate was 92.8% at the feed rate of 4 km/h under the circular saw blade speed of 2800 rpm, which was higher than 88.8% at 3 km/h and 88.9% at 5 km/h. The optimum sawing parameters were: the circular saw blade speed of 2800 rpm and feed rate of 4 km/h, which were consistent with the simulation results, and the passing rate of the cut was high at this time, meeting the technical requirements of orchard pruning.

Operational determination of current-voltage characteristics welding power sources in nuclear engineering

Welding equipment is everywhere equipped with modern digital welding arc power systems based on microprocessor and other logical element bases. At the same time, there is a tendency to minimize information not only for Chinese, but also for equipment of well-known brands, so it is important to quickly monitor the accuracy of the accompanying documentation in order to avoid deterioration in the quality of products and waste of time re-equipment. Modern recorders of welding processes allow several times to reduce the time for checking the declared characteristics of all power sources certified for use in the nuclear power industry. Among the characteristics and service functions analyzed by the recorder, it should be noted static current-voltage characteristics, oscillograms of «hot start», «afterburner» and «anti-sticking». The paper presents the data of selective tests for compliance with the declared passport data of inverter power supplies INEM-200T (MMA process), Artsen CM-500 (MAG process) and ION 48-900 (SAW process). Based on the results of the research, conclusions were drawn about the benefits of using the proposed model of the welding process recorder at enterprises of heavy nuclear engineering.

Feasibility evaluation of the use of mud residue from marble shop as soil remineralizer

Brazil is a major producer of dimension/ornamental stones, with a great diversity of raw materials. The sawing process transforms 20 to 30% of the extracted block into powder, with the generation of fine waste around 800,000 t/year. An alternative to reusing this waste is its application as a source of nutrients for the soil. This study evaluated the potential use of mud residue from a marble shop located in João Monlevade, Minas Gerais, as a remineralizer, based on fertility, mineralogical and chemical analysis performed by X-ray diffraction and X-ray fluorescence. For fertility, pH in CaCl2 0.01 mol L-1, organic matter, aluminum saturation, potential acidity, sum of bases, cation-exchange capacity, base saturation, macro and micronutrients were determined. The studied residue has free silica, the sum of basis, and K2O content in the range established by MAPA to be certified as a remineralizer. The sample contains 6.7% phyllosilicates, a source of faster K availability, and 19.4% K-feldspar, a slow-release source. Results described in this study indicate that residue can be a promising, efficient, and low-cost alternative to improve soil fertility.

Modeling of oscillating bone sawing forces with instantaneous cutting speed and depth of cut

Oscillating bone sawing is a crucial procedure in orthopedic surgery, but excess sawing forces are often detrimental to implant fixation and postoperative patient recovery. Therefore, understanding and controlling sawing forces are critical. However, the conventional bone cutting model is not applicable to the oscillating sawing process, as it requires variable speed cutting with a negative rake angle, which is affected by the difference in viscoelasticity of the bone at different speeds. In this study, an oscillating sawing force model was developed that considered variations in cutting speeds and depth of cut for each saw tooth. A speed-related cutting force model, including ploughing force in the tool edge and rake face, was developed, considering the effect of speeds on fracture toughness and normal stress based on orthogonal cutting experiments. Moreover, the model accounted for each saw tooth's instantaneous depth of cut by considering the depth of elastic recovery and interference effect of adjacent saw teeth, based on a kinematic model of the saw tooth tip. The impact force in the blind groove cut and the acceleration effect on cutting force were also considered in the model. The proposed model accurately predicts sawing forces, offers insights for reducing them through design parameter modifications, and has potential applications in medical training simulations, robotic-assisted surgery, and the optimization of saw blade shapes or movement to reduce sawing forces.

Experimental study on the formation mechanism of saw marks in wire sawing

Saw marks generated by the wire sawing process significantly deteriorate the flatness and surface quality of wafers. In this paper, the influence of sawing parameters on the geometric of saw marks is systematically studied. Based on the observation results of the saw marks morphology, the formation mechanism of saw marks is analyzed. The experimental results indicate that the cross-sectional shape of the saw marks approximates a triangular wave, and its peak-to-valley value increases with the rise of the feed rate, the wire speed, and the wire reciprocation period. The wavelength of saw marks approximates the feed distance during each wire reciprocation period. The formation of saw marks can be ascribed to the periodic lateral force originating from the twisting of the wire during the wire reciprocating. The lateral force is only about 2.7–6.2 % of the feed force, and its magnitude increases with the increasing feed rate and reciprocation period, and the decreasing wire speed. This study provides new insights for a deeper understanding of the formation mechanism of saw marks.

Simulation analysis of the circular sawing process of medium density fiberboard (MDF) based on the Johnson–Cook model

Simulation analysis of the circular sawing process of medium density fiberboard (MDF) based on the Johnson–Cook model

Measurement and Prediction of Sawing Characteristics Using Dental Reciprocating Saws: A Pilot Study on Fresh Bovine Scapula

Bone sawing is one of the most common operations during traditional dental and cranio-maxillofacial surgery and training systems based on virtual reality technology. It is necessary to predict and update conditions (including the sawing force, temperature and tool wear) in real time during VR surgical training and surgical simulation. All the specimens used in this study were fresh bovine scapula. The forces and temperatures were measured during the sawing process. Additionally, the thermal conductivity was measured via a laser flash instrument. Response surface methodology (RSM) was adopted to analyze and model the sawing force and sawing temperature. Meanwhile, tool wear was observed using a scanning electron microscope. The regression models of the sawing force and temperature rise under different experimental conditions were acquired. To obtain the minimum force within the recommended parameter ranges of commonly used medical reference parameters for bone sawing, a higher rotational speed combined with a lower feed rate were recommended. When considering the sawing force and temperature rise comprehensively, the rotational speed should not be extremely high (about 13,000 rpm is recommended). Meanwhile, abrasive wear is the main wear mode of saw blades. In order to avoid surgery failure, it is necessary to replace the saw blade in time. The experimental data were confirmed to be scientific and accurate for the predicted models of sawing conditions. To minimize the main cutting force, a feed rate of 40 mm/min combined with a rotational speed of 13,700 rpm is recommended. High cutting temperatures have the potential to cause irreversible tissue damage, so surgeons using dental reciprocating saws need to avoid excessively high-speed gears.