Mill Performance Research Articles

Research on the Flatness Control Performance and Parameter Influence Law of Four-High Skin Pass Rolling Mill

Research on the Flatness Control Performance and Parameter Influence Law of Four-High Skin Pass Rolling Mill

Stakeholder Engagement: Issues to Resolve for Sustainable Performance of Sugar Mills in Western Region, Kenya

Stakeholder Engagement: Issues to Resolve for Sustainable Performance of Sugar Mills in Western Region, Kenya

Implementation of a first-mill cane-feeding control strategy based on a cane-harvest system

The analysis of the extraction performance of three Colombian sugarcane factories revealed large variations in milling operations. Because more than 70% of the extraction occurs in the first mill, the chute level behavior was evaluated, and the coefficient of variation (CV) values were greater than 55%. This was mainly caused by the control strategy not being capable of mitigating the effect of processing different densities of sugarcane. This variability resulted from the frequent change between manual and mechanically harvested sugarcane. An in-line indicator was designed to determine the type of sugarcane; this was based on the electric current drawn by the cane leveller. In collaboration with factory A, a control strategy was designed that changes the velocity relationship of the conveyor belts depending on the sugarcane harvest type. The control strategy was also applied in the second factory (B), with only a 1.5 m high first-mill chute, which affects feeding stability, but dynamic current protection was added. This was based on PID controllers that manipulate conveyor velocity proportionally, reducing the chance that it would come to a halt, protecting the cane knives and shredder from electrical overload, and providing a more constant mill feed. The evaluation of the new control strategy was compared with the old control loops, increasing the overall extraction of 0.40 and 0.68% for factories A and B, respectively. Better stability was achieved in the first mill chute with a CV of approximately 30%, which was also reflected in the chute levels of the following mills. The new control strategy used the instruments and actuators already installed without any additional investments and can greatly improve the milling performance and, as a result, profitability.

Research on the Milling Performance of Micro-Groove Ball End Mills for Titanium Alloys

Titanium alloys are widely used in various fields, but milling titanium alloy materials often leads to problems such as high milling forces, increased milling temperatures, and chip adhesion. Thus, the machinability of titanium alloys faces challenges. To improve the milling performance of titanium alloy materials, this study analyzes the effective working area on the surface of the milling cutter through mathematical calculations. We design micro-grooves in this area to utilize their friction-reducing and wear-resisting properties to alleviate the aforementioned issues. The effective working area of the ball end milling cutter’s cutting edge is calculated based on the amount of milling and the installation position between the milling cutter and the workpiece. By observing the surface structure of seashells, micro-grooves are proposed and designed to be applied in the working area of the milling cutter surface. The impact of the micro-groove area on the milling cutter surface and spindle speed on milling performance is discussed based on milling simulation and experimental tests. Experimental results show that the cutting force, milling temperature, and chip resistance to adhesion produced by micro-groove milling cutters are superior to conventional milling cutters. Milling cutters with three micro-grooves perform best at different spindle speeds. This is because the presence of micro-grooves on the surface of the milling cutter improves the friction state, promoting a reduction in milling force, while the micro-grooves also serve as storage containers for chips, alleviating the phenomenon of chip softening and adhesion to the cutter. When conducting cutting tests with a milling cutter that has three micro-grooves, the milling force is reduced by 10% to 30%, the milling temperature drops by 10% to 20%, and the surface roughness decreases by 8% to 12%.

An Integrated SCOR-AHP Framework for Evaluating Sustainable Supply Chain Performance of Palm Oil Mills

An Integrated SCOR-AHP Framework for Evaluating Sustainable Supply Chain Performance of Palm Oil Mills

On-line measurement of particle size in high-concentration limestone slurry pipeline by Monte-Carlo based ultrasonic attenuation model

Limestone-gypsum wet flue gas desulfurization (WLG-FGD) technology is wildly used to diminish sulfur dioxide emissions in coal-fired power plants, where the particle size of the limestone slurry is a crucial factor closely related to the desulfurization efficiency. The high-concentration Monte Carlo model (HC-MCM) was developed for attenuation spectrum prediction. In numerical simulations with a particle diameter range of 10–70 μm, the differential evolutionary (DE) algorithm was used for retrieving particle sizes with relative deviations that do not exceed 2 % in terms of a given diameter and distribution width. A through-transmission/pulse-echo dual-mode ultrasonic system has been established. The results indicate that the root mean square relative error (RMSRE) of the two modes’ attenuation spectra was 7.03 %. The relative deviations of DV90 are less than 8 % compared to the results obtained through the laser particle analyzer. Moreover, the fineness is within the specifications required for limestone slurry, indicating proper mill performance.

Key structure design and vibration reduction performance analysis of four-tooth unequal pitch end mill based on spectral characteristics

The unequal pitch end mill can effectively suppress the vibration in the cutting process, and it is widely used in the processing of key parts. In this article, the four-tooth unequal pitch end mill is taken as the research object. Combined with the actual working conditions, the key structural parameters and process parameters are optimized from the perspective of spectrum energy distribution and processing efficiency, and the vibration reduction performance of the tool is analyzed and verified. First, the influence of process parameters, inter-tooth angle and helix angle of unequal pitch milling cutter on spectrum amplitude is analyzed. Second, for the milling aluminum alloy AL7075-T6, the most significant parameters affecting the vibration reduction performance of the milling cutter-tooth angle and helix angle and the matching process parameters were optimized. Finally, in order to explore the milling performance of unequal pitch end mills, experiments were carried out on equal pitch and unequal pitch end mills under the same process parameters. The gap between the two tools in milling force and milling vibration was analyzed, and the superiority of unequal pitch end mills in improving milling stability was verified.

ANALISIS KINERJA PENGGILINGAN PADI PADA BERBAGAI SKALA USAHA STUDI KASUS DI KECAMATAN BUAY MADANG TIMUR KABUPATEN OKU TIMUR PROVINSI SUMATERA SELATAN

This research aims to analyze the process of procuring raw materials and the performance of rice mills at different business scales in East Buay Madang District. This research used a case study method on rice mills with different business scales in East Buay Madang District, East OKU Regency, South Sumatra. The rice mill owner was the respondent in this research. Data collection was carried out from March to April 2021. The data analysis method used was descriptive qualitative and quantitative analysis. The results showed that the procurement of raw materials for rice mills at different business scales was not appropriate because there were several components that are not optimal. The performance of rice mills in East Buay Madang District is not yet optimum, because one the four production performance indicators, which is indicator of capacity at small scale rice mills, still needs to be enhanced to be more optimum. .Key words: business scale, performance, procurement, rice mill

Effect of liquid nitrogen assisted milling on AZ91 magnesium alloy

The objective of the present work is to study the effect of liquid nitrogen (LN2) cryogenic on the performance of face milling for producing quality surface in AZ91 magnesium alloy. Machining AZ91 alloy has been a challenging domain due to the risk of ignition or spark during machining, which affects surface finish. In this study, face milling is carried using uncoated carbide inserts in cryogenic condition, and the performance is compared with dry condition based on the surface integrity (SI) characteristics. The findings of this study reveal that use of LN2 results in enhanced surface integrity. Observations showed no harm to alloy microstructure in both conditions, with no alterations to grain integrity in the near machined area. Cryogenic machining resulted in reduction in machining temperature ranging from 146.7 °C to 178.5 °C, when compared to dry condition temperature ranging from 219.4 °C to 251.2 °C. Cryogenic machining considerably generated smoother (Ra = 0.0606 μm) and harder (HV = 116.5) surfaces, and also resulted in compressive residual stresses. This study concludes that cryogenic-assisted milling is an excellent alternative for the production of superior-quality surface in AZ91 alloy.

Research on chip flute design of variable pitch variable helix end milling cutter based on manufacturability

In this paper, a design method of chip flute structure of variable pitch variable helix (double variable) end milling cutter based on manufacturability is presented, which aims to improve the dynamic balance and milling performance of the tool. The feasible region for grinding the chip flute of a double variable end milling cutter is obtained by solving the numerical model for the shape of the radial cross-section curve of the chip flute, along with the position and orientation of the grinding wheel. The multiple tool-walking grinding method is proposed to avoid the interference and edge cutting between the grinding wheel profile and the chip flute section, and the chip flute structure design criterion is obtained. The error between the grinding simulation results and the design target parameters is about 1 %, which verifies the effectiveness of the design criteria. With the double variable end milling cutter designed by this criterion, the milling vibration amplitude is reduced by about 21 %, and the average surface roughness of the workpiece is reduced by 9.872 μm. The chip flute structure design method proposed in this paper not only meets the manufacturing feasibility, but also effectively improves the milling performance of the tool. On the premise of considering manufacturability, the design method of chip flute as the optimization objective provides a new idea for tool structure design.

4-way coupling CFD-DEM simulation of particle breakage and classification in a spiral jet mill: A critical analysis

Jet-milling is a particle engineering process widely adopted in industrial manufacturing to reduce the particle size of powders. Computational Fluid Dynamics simulations (CFD) coupled with Discrete Element Modelling (DEM) proved to be a valuable tool to tackle the complexity and the non-linearity of particle breakage and classification occurring in mills. To date however, they have been employed to address only single aspects of process design being unable to reproduce it completely. The coupled CFD-DEM simulations presented in this work are for the first time capable of simultaneously describe particle fragmentation, particle-gas interaction and classification. Through coarse-graining, realistic amounts of powder can be simulated allowing to demonstrate/study how the hold-up mass slows down the milling gas affecting classification and thus the milling performance. Bottlenecks/limitations of model and methodology are critically examined to understand what is currently preventing us from creating a digital twin of the milling process.

Analysis of quinoa roller millstreams: Physical, chemical, and functional properties

The objective of present study is to assess the performance of roller milling on quinoa grains, aiming to produce distinct mill stream fractions from perisperm and evaluate its composition and functionalities. During the roller milling process, quinoa yielded three break and three reduction flour streams, as well as coarse bran, fine bran, and germ. Among flour streams, C1 accounted for 49.61% while C2 represented 23.62% of total straight run flour (SRF). Notably, quinoa flour streams exhibited brighter colour and finer granulation similar to wheat flour. Content of ash, protein, and fat increased with successive break flour streams (B1 to B3), displaying a similar trend for reduction flour streams (C1 to C3). Starch damage was higher for last reduction flour streams. Roller milling of quinoa resulted in distinct flour streams from the perisperm, showing physical properties similar to wheat flour. These mill streams varied in yield, nutritional properties, and flour functionalities.

Understanding the effects of machinability properties of Incoloy 800 superalloy under different machining conditions using artificial intelligence methods

Incoloy 800 is frequently used in high-temperature applications as it has the ability to retain good metallurgical stability at elevated temperatures. Due to the nature of the applications used for, parts made from Incoloy 800 usually require different machining processes such as milling and turning. Therefore, the current study aims to investigate the milling performance of Incoloy 800 under different cutting parameters (75–150 m/min and 0.075–0.15 mm/rev) and cooling conditions namely dry, flood, Minimum Quantity Lubrication (MQL) and Cryogenic (Cryo)+MQL. It was observed that all machinability metrics improved in the MQL+Cryo C/L environment. It is noticeable that the surface roughness value improved by 30% in this environment. In addition, a model based on artificial neural networks (ANN) and particle swarm optimization (PSO) was proposed to analyze the results and predict optimum cutting parameters. It appears that Cryo+MQL strategies are the best option for all cutting parameters. It was found that the estimations for surface roughness, flank wear, and cutting temperature with the proposed ANN architecture are achieved with overall relative error of 6.08%, 12.38%, and 8.32%, respectively. The proposed model resulted in good performance between the experimental test data and the predicted values. The developed model made the most efficient predictions for the MQL+Cryo cutting environment. It was observed that the estimations of the different input parameters in the MQL+Cryo cutting environment present a relative error of 8.36%, 1.46%, and 2.38% for surface roughness, flank wear, and cutting temperature, respectively. By utilizing the predictive capability of the trained ANN model, the optimization of the input parameters was carried out with the PSO technique. Thus, with the developed PSO-ANN model, promising findings were obtained in overcoming important handicaps such as time and cost in experimental studies.

Comparison of Approaches to Predict Grinding in An Industrial Rod Mill Operating at Low Fillings

ABSTRACT Several approaches have been proposed over the years that may be used to predict the performance of industrial rod mills. Unfortunately, studies that allow comparing the accuracy in their predictions are very scarce. The work compares four methods for predicting size reduction in an industrial rod mill. These were the Bond work index method (BW) and the Callcott–Lynch (CL) model, both originally proposed for rod mills, besides the Herbst–Fuerstenau (HF) and the Austin–Klimpel–Luckie (AKL) models, first proposed for ball mills, but here adapted and applied to rod milling. A total of 10 industrial surveys were conducted of the industrial mill in dry grinding of coke breeze, covering operation under a variety of conditions, all of which at lower fillings than commonly used in industry (<15%). Since most conditions surveyed were not within the typical operating range for rod mills, simulations using the Discrete Element Method were used to predict the mill power, used as input in both BW and HF models. At first, the fidelity of methods that allow predicting full-scale mill performance solely from bench-scale information, namely BW, HF, and AKL, is compared. Results showed that they all presented high biases in their estimates of product fineness, with AKL predicting finer products whereas BW and HF predicting coarser products. Using then data from a single industrial survey for model calibration (base case), in addition to the bench-scale test results, a comparison of the four approaches became possible. Taking the absolute deviations between measured and predicted P 80 values, it became evident that the HF provided the highest fidelity in the predictions, with mean deviations of 12.8%, AKL with 15.3%, with both BW and CL presenting deviations above 18%. The work thus shows that size-mass balance models that rely on fitting most model parameters from bench-scale tests (HF and AKL) can provide predictions with good confidence when data from an industrial base case are additionally used in fine-tuning the model, even when applied to describing rod milling under unusually low fillings.

Effects of shear thickening fluid preparation on tool performance in the milling of Ti6Al4V titanium alloy

The performance and quality of tools can directly affect the efficiency and quality of machining, and preparation methods of the cutting edge have an important impact on the machining performance and tool life. As a method that can adapt to the unique and complex geometry of the cutting edge, shear thickening passivation is an innovative application of shear thickening fluid. In this study, the effects of shear thickening passivation methods on the milling performance and tool life of cemented carbide milling cutters were investigated. The cutting force, tool wear, tool life and surface morphology were analyzed by side milling Ti6Al4V titanium alloy with cemented carbide milling cutters that were unprepared, drag finished and shear thickening passivated, respectively. The results demonstrate that shear thickening passivation can remove the micro-defects of the tool after grinding. After shear thickening passivation, the cutting edge is rounded, and the rake and flank surfaces are flat, and the defects of the cutting edge are removed. Compared with the unprepared tool, the life of the shear thickening passivated tool is improved by 50 %. Therefore, the shear thickening passivation can effectively improve the tool life and tool performance and significantly reduce the economic cost in practical machining.

Application of Chaotic Signals for Improving the Performance of New Generation Ball Mills

Application of Chaotic Signals for Improving the Performance of New Generation Ball Mills

Investigating the room- and cryo-milling impact in lignocellulosic biomass and its consequence over pyrolysis and oxidative treatments

The lignocellulosic biomass recalcitrance is the uppermost factor for the utilization of this renewable resource. The development of new pre-treatments, addressed to enhance performance in lignocellulosic biomass conversion into biofuels, fine chemicals, and as potential sources of building blocks for materials, must be focus in two main areas: effectiveness (cost-effective and chemical effective) and green chemistry. In this research, a set of different biomass sources (farmer, harvested wild trees and secondary products) were studied to evaluate the high efficiency of the non-liquid nitrogen (LN) and LN-treated biomass samples’ planetary ball milling performance. The samples have been characterized by particle size distribution, thermogravimetric, FT-IR, statistical chemometric and chemical oxidation analysis. The results have shown a high level on the rupture of the crystallinity and depolymerization degrees of the cellulose and the lignin, for both, non-LN and LN-treated samples. The thermogravimetric analysis showed a clear diminishing in temperature degradation, and a larger amount of biomass degraded at lower temperature, as well as, a high chemical oxidation degree than not milled samples. Finally, the LN-treated samples even exhibited a lower degradation temperature, a larger amount of biomass degraded at lower temperature and a higher oxidation degree, than those non-LN milled.

ENHANCING MILLING PERFORMANCE OF 6061 ALUMINUM ALLOY WITH NANOCUTTING FLUID AND MQL

During the machining of aluminum alloys, the adhesion of chips to the tool affects the performance characteristics. Today, different cooling systems are used to eliminate these negativities. In this study, the effects of end milling using HSS and carbide cutting tools of 6061-T6 aluminum alloy on surface roughness, chip thickness ratio and tool wear were examined using different cooling techniques (dry, minimum quantity lubrication (MQL) and nanocutting fluid). Different cutting speeds (180, 200, 220 m/min) and different feed rates (0.05, 0.06, 0.07 mm/rev) were used in the experiments. According to experimental findings, tool wear and surface roughness decreased at low cutting speed and feed rate by using nanocutting fluid with carbide cutting tools. It has been observed that the chip thickness ratio increases with high cutting speeds using nanocutting fluid and decreases with dry machining and high feed rates. The best milling performance of the aluminum alloy was achieved in experiments using carbide cutting tools and nanocutting fluid.

Wear characteristics and performance in side milling of Ti2AlNb intermetallic alloys with coated and uncoated end mills

Ti2AlNb intermetallic alloy is highly suitable for aerospace key component manufacturing due to its low density, exceptional temperature strength, high specific strength, and creep resistance. However, the poor machining quality and severe tool wear appear, because of their poor thermal conductivity and excellent high temperature strength performance. In this paper, the coated and uncoated end mills are performed to investigate the tool wear characteristics during side milling of Ti2AlNb intermetallic alloys. In addition, the milling forces, tool service life, tool wear morphologies and mechanisms are discussed in detail. Results indicate that the coated and uncoated end mills suffered severe tool wear in the side milling process, leading to a rapid increase in milling forces. The coated end mill exhibited a longer service life of tools than the uncoated end mill. The service life of coated end mill reaches 6 min, primarily limited by flank wear and accompanied by chipping, whereas the uncoated end mill had a service life restricted to 2 min due to tool tip breakage. Tool wear morphologies of coated and uncoated end mills include rake face wear and flank face wear. Typical characteristics (e.g., crater wear, built-up edge, chipping and adhesion) are observed on the rake face of the both coated and uncoated end mills. On the flank face of the coated end mill, the chip adhesion, micro-chipping, chipping and coating delamination are found, whereas only chip adhesion and micro-chipping appear for uncoated end mill. Furthermore, the primary mechanisms of wear for both coated and uncoated end mills are adhesive wear and oxidation wear, which occur on both the rake face and flank face.

Evaluating the grinding performance of cutter-type disk mills using DEM-CFD simulations with a breakage model

In the recycling process of plastics, grinding is commonly employed as a pre-treatment method to facilitate molding by increasing the specific surface area. A cutter-type disk mill that mainly causes shear forces is expected to be the most efficient for grinding plastics. However, it is necessary to optimize the geometry and operating conditions of the mill. This study aimed to evaluate the grinding performance of different blade geometries in the cutter-type disk mill. To optimize the blade geometry, the discrete element method (DEM) coupled with the computational fluid dynamics (CFD) and a breakage model was employed to simulate plastic particle breakage. The simulations showed that the highest grinding performance was achieved with a grinding blade angle of 45°. Depending on the angle of the grinding blade, the effects of the power acting on the grinding blade and the force acting on the particles varied. According to these results, an appropriate blade geometry in the cutter-type disk mill can be proposed for grinding plastic. This study demonstrated that the DEM-CFD simulations are effective for evaluating the grinding performance and optimizing the blade geometry of the cutter-type disk mill.