Grinding Disc Research Articles

Sustainability Versus Efficiency of Manufacturing Process: Structured Comparison of Two High Precision Fine Grinding Processes

The efficient and ecological handling of resources becomes more and more important in today’s manufacturing processes since the global demand for energy as well as raw materials is increasing consistently in the modern world. On the other hand, customers’ demands need to be satisfied. Therefore, the optimisation of production processes regarding efficient and ecological aspects as well as market demands is very important, especially in case of the manufacturing of high precision products, where the market environment is highly turbulent. In this paper two high precision fine grinding processes are compared concerning their efficiency and ecological friendliness. Therefore, Life Cycle Assessment (LCA) as well as Data Envelopment Analysis (DEA) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) is used for comparison purposes. In case of Life Cycle Assessment (LCA) material flows like grinding disc degradation, the consumption of cutting fluid and the material loss during the grinding process are taken into account such that the exposure for human and environment can be compared and analysed. Considering DEA and TOPSIS, the efficiency of the production process as well as demands of the market are evaluated. Therefore, the surface topography characterised by the target variables roughness (Ra, Rz) and gloss as well as the production time is analysed. In this study, two grinding processes are analysed using three different methods enabling an evaluation from different points of view. The comparison between the two high precision fine grinding processes is carried out within the case study "fine grinding of cutlery".

Assessment of water-based fluids with additives in grinding disc cutting process

Application of cutting fluids in grinding disc cutting process (GDCP) plays a significant role in minimizing production cost and energy. However, GDCP is significantly different from the grinding wheel grinding process (GWGP) with its very thin disc (3.5 mm), large diameter (400 mm), large cutting depth (several and even ten of millimeters) and no cutting fluids, which lead to a lot of environmental pollution such as sparking, chips splashing, smoke, dust and so on. In this regard, atomization application of water-based cutting fluids is good choice due to less environmental threat in addition to high thermal conductivity and supreme cooling/lubricating efficiency. Besides some eco-friendly properties of additives such as surfactant and graphene, application of such additives eliminates the need for toxic additives used frequently in the industry. Hence, in this study, four types of environmentally friendly water-based cutting fluids (W, W-S, W-G, W-G-S) are prepared by ultrasonic stirring of water, surfactant (sodium alcohol ether sulfate, SAES) and graphene, then their atomization applications are assessed in GDCP of AISI 1045, as one of the most common and representative material in industry application. To optimize these cutting fluids, G-ratio, Fx-Fy and cutting tilt are compared with those of dry cutting using joint analysis of specific heat, viscosity, wettability, permeability and two-direction force. Also, agglomeration of graphene is proposed to reveal the unexpected reduction in lubrication performance and finally a cutting fluid is developed for minimizing the loss of grinding disc. The obtained results of four types of cutting fluids manifest that the proposed W-S can maximally improve G-ratio by amount of 77.6%, reduce line span by amount of 34.5% and cutting tilt by amount of 14.8% compared with conventional dry cutting.

Experimental comparison of abrasive and erosive wear characteristics of four wear-resistant steels

In the current research, the wear behavior of four steel wear resistant plates was investigated. In order to compare the wear-related characteristics of the candidate steels, tests of hardness, slurry erosion and two-body abrasive wear experiments were conducted. In addition, the microstructural evolutions were analyzed using optical microscopy. To identify the changes in samples’ characteristics along the depth, the aforementioned tests were conducted at different depths of the plates. The microstructural evolutions regarding the changes in the phases, including their types, their shapes and their sizes, were studied. To study the erosion behavior, an experimental rig was developed that allows samples to move inside a slurry environment. Regarding the abrasive wear, the pin-on-disk method was used in which the sample plays the role of a pin moving on a circular abrasive grinding disk. The tests were carried out under different amounts of the normal force that pushes the sample on the disk. Finally, the samples were compared regarding their microstructures, hardness, erosive and abrasive behavior. The results showed that the steel that exhibited the highest hardness did not necessarily show the highest wear resistance. Furthermore, it was observed that the steel that had the highest erosive resistance did not show the abrasive resistance accordingly.

Examination of different grain hardness varieties of the grinding technology properties of wheat

In the mill industry, the purpose of the grinding technology is to separate wheat endospermium and shell and to recover grists. The most important and the highest energy requirement operation is shredding. Flour quantity and quality produced from wheat depends on the variety of wheat that will be shredded, the type of grinding equipment and the condition used before the grinding. For this reason, during my experiments, I ground two grain structured varieties of wheat in laboratory conditions using a disk grinder, stone grinder and roll grinder in air-dry and conditioned states. We measured the equipment’s performance and the produced grist’s particle size distribution, followed by the calculation of the energy requirements of the grinders. In the grinding experiments we compared the ash contents of the different particle sized grist’s fractions to map the wheat’s particular properties.

Design of Grinding Machine Spindle

Abstract When grinding high demands are usually placed on the geometrical tolerances of the workpiece surface. For this reason, the spindles of the grinding machines are normally designed with requirements for a minimum position change of the grinding disks due to external forces and bending moments. The design theory of these spindles is relatively well elaborated, as it represents the most frequently used solution in practice. However, there are also cases where it is necessary to grind some hard-to-reach areas, using a great ejection of the spindle. In these cases, it is necessary to reassess the required geometrical tolerances with regard to its necessity to comply with the minimal changes in the position of the grinding discs due to the great ejection. Where it is necessary to maintain high geometrical tolerances, it is necessary to ensure a greater rigidity of the spindle. This rigidity is usually improved by increasing its diameter. By doing this we also increase the weight of the spindle that is heavily ejected, and thus its deformation can occur due to gravity forces. That is why it is necessary to analyse the deflection of the spindle depending on its ejection in the course of its design. In the case we increase the diameter of the grinder spindle the possible applicable grinding disc diameter decreases, due to the growing size of its housing. Any grinding of hard-to-reach surfaces is therefore done in particular to improve the quality of the surface with low requirements on the geometrical tolerances. This article deals with the design patterns for a spindle used in axial grinding for inner rotating surfaces. The article contains a spindle design solution and an analysis of its deflections, depending on its ejection, and the size of the passive forces.

Modelling, design and analysis of offset, non-orthogonal and profile-shifted face gear drives

This article proposes the application of a profile-shifted grinding disc to generate an offset, non-orthogonal and profile-shifted face gear. A detailed investigation of the modelling, tooth geometry and contact characteristics of the offset, non-orthogonal and profile-shifted face gear has been conducted. The mathematical models of the profile-shifted shaper cutter, profile-shifted pinion, profile-shifted grinding disc and offset, non-orthogonal and profile-shifted face gear are established. Considering the topological modification, the tooth surface equation of the offset, non-orthogonal and profile-shifted face gear is deduced. Based on the undercutting and pointing of the tooth surface, the limiting tooth width of the offset, non-orthogonal and profile-shifted face gear is determined, and a mathematical model of tooth contact analysis of the offset, non-orthogonal and profile-shifted face gear drive is established with the alignment errors. Using the approach presented in this article, an example of an offset, non-orthogonal and profile-shifted face gear drive and analytical results are presented.

Study of Breakage Tendencies of Palm Kernel, Coconut and Periwinkle Shells using Ball-Milling Process

The needs for eco-friendly composites have initiated the use of agricultural wastes as possible replacements for expensive synthetic carbon and glass fillers for metal and polymer strengthening. In this study, degree of refinement of palm kernel shells, coconut shells and periwinkle shells has been investigated through ball-milling approach. Palm kernel, coconut and periwinkle shells were pulverised using disc grinder and refined using top-down approach under the same milling conditions. The particles of palm kernel, coconut and periwinkle shells obtained were analysed and their sizes were determined. Energy dispersive X-ray spectroscopic and X-ray Diffractometric analyses indicated different compositions of the examined agricultural wastes particles. Imaging sizing of the particles indicated attainment of nanoparticles when milling for 74 hours at 10 charge ratios for both carbonized and uncarbonized palm kernel, coconut and periwinkle shells. Comparison of sizes showed that uncarbonized palm kernel shell has a least grain size among other uncarbonized agricultural waste particles. Therefore, uncarbonised palm kernel shells have highest breakage tendency among others. KEYWORDS : Degree, Refinement, Agricultural wastes, Fillers, Milling.

Study on Precision Polishing of Alumina Ceramics

The research is mainly to investigate the surface roughness by the mechanical polishing for the processing of alumina ceramic materials. In the experiment, the ceramic test piece was placed between the ceramic work ring and the grinding disc and then grinded firstly with an alumina grinding slurry with a particle size of 10 μm to make the original roughness of the test piece reach Ra value of 1.49 μm. Then the silicon carbide slurry polishing was employed to conduct the experiments by changing the concentration of the polishing, particle size, load, rotation and time to observe the polishing effect of ceramic materials under different parameters. The results showed that the silicon carbide particle size of 2μm, with the polishing time of 50 min, the disc speed of 90 rpm, the concentration of 35%, the original surface roughness of alumina ceramic Ra 1.49μm could be downed to 0.22 μm. The improvement rate could reach 94%. And the greater the specimen load with the better grinding efficiency, the smaller the load caused worse cutting force between alumina and the specimen surface. However, the better the surface roughness when the time kept going. Furthermore, alumina ceramic test piece after precision mechanical polishing by 3D surface roughness profiler and scanning electron microscope (SEM) analysis, the observation found that the wave of the original test piece rugged, after grinding and polishing wave front and grinding scratches had been removed, and a smooth surface was obtained.

Relieving the teeth of hobs for cutting the Wildhaber-Novikov gears

Screw and relieved surfaces with a profile of substantial and variable curvature are often used in machine parts and cutting tools. Among them, a special place is occupied by worm hobs for cutting the teeth of Wildhaber-Novikov gears with the profile of the generating worm, variable not only in radius, but also in sign of curvature. A technique for forming the tooth flanks of these hobs by a disk grinding wheel is developed, which allows the grinding and ground profiles in the axial section of the generating worm to be brought together as close as possible. The method for calculating the settings-up and profile coordinates of the grinding wheel is given for its performance in real production conditions.

Experimental grinding of cubic zirconia with grooved and non-grooved diamond discs

As a cubic crystalline form of zirconium dioxide , cubic zirconia (CZ) is hard, optically flawless, and usually colorless. This interesting mineral crystal has become a popular gem with its low cost, durability, and close visual likeness and the same fashion as diamond , and the cutting techniques for the preparation of cubic zirconia gems have received intensive attentions from diamond gemstone industry in recent years. Among the processes of gem cutting, the grinding process is not only the most time-consuming, but also the key process to determine product quality. However, mechanical characteristics such as the low strength, fracture toughness, and elastic of cubic zirconia make the grinding process much more challenging. In this work, a novel grooved and metal-bonded diamond disc was designed and employed in CZ grinding process to reduce the cutting forces and enhance the material removal rate. Experiments were conducted on an automatic faceting gem machine developed by our group to investigate the influences of intermittent vibro-impact in grinding gemstone. The comparison of some important parameters like the grinding force and the surface roughness obtained by grooved diamond disc and non-grooved diamond disc was carried out. Five rotational speeds of grinding disc, i.e., 1600, 1900, 2200, 2500, and 2800 rpm and five feed rates of 0.3, 0.5, 0.7, 0.9, and 1.1 mm/min were used respectively in this study. From the experimental results, it was observed that the normal grinding force with grooved disc was significantly smaller than that of non-grooved disc, which means under the same grinding force, the feed rate of grooved grinding plate disc is higher than that of non-grooved grinding disc. And the surface roughness of the CZ surface was also decreased with the use of the grooved disc compared with the non-grooved disc. Therefore, the present grooved disc could be a promising tool for cubic zirconia grinding to improve the processing efficiency while also ensures the surface quality.

Theoretical and experimental research of roughness parameters of the lantern wheel profile of gerotor, that are provided by grinding in continuously gear generating conditions

The paper presents the results of the research of roughness parameters of the lantern wheel profile of gerotor, that are provided by grinding in continuously gear generating conditions. The results include the data obtained during the modeling of micro unevennesses forming and the results, that are obtained of measuring parameters of the roughness of the lantern wheels, the processing of which was carried out in the manufacturing. To perform the grinding operation, were used disc grinding wheels, the profile geometry of which provides gear generating continuous of the wheel profile with respect to the grinding wheel profile. To design of the tool profile, were involved a convex and a concave sections of the equidistant to epicycloid. The received theoretical and experimental results testify to advantage using of a profile on the basis of a concave site which provides in 2,5-2,7 times the best roughness at identical parameters of processing. It is established that the application of the tool profile, which has the same sign of curvature with the machined profile, positively influences for the surface roughness and tool durability.

Improving cellulose nanofibrillation of waste wheat straw using the combined methods of prewashing, p-toluenesulfonic acid hydrolysis, disk grinding, and endoglucanase post-treatment

Here we established a new approach for improving the cellulose nanofibrillation of high ash content waste wheat straw (WWS). The results were comprehensively elucidated from the ash removal, delignification, mechanical fibrillation and endoglucanase post-treatment. When water dosage was increased from 50 to 500 times of the WWS weight, the ash content gradually decreased during prewashing process, which facilitated lignin solubilization in subsequent p-toluenesulfonic acid (p-TsOH) hydrolysis. Approximately 80% of lignin in prewashed WWS could be dissolved during acid hydrolysis to result in a relatively higher crystallinity of 59.1%. Compared with the lignocellulosic nanofibrils (LCNF) directly obtained using acid hydrolysis and disk grinding, prewashing-assisted acid hydrolyzed WWS was fibrillated into LCNF with smaller height of 57.0 nm. Mild endoglucanase post-treatment could further produce less entangled LCNF with thinner diameters. In short, this study presented a promising and green pathway to achieve an efficient utilization of agricultural residue wastes to cellulose nanomaterials.

Direct mechanical production of wood nanofibers from raw wood microparticles with no chemical treatment

Wood nanofibers (WNFs) were directly isolated from raw wood micro-particles (WMP) of Paulownia using disk grinding with no chemical treatments. TEM analysis showed that the average diameter of the WNF is 55 ± 22 nm, which is 4800 fold less than that of WMP (265 ± 45 μm). The production mechanism of WNF was discussed. XRD results confirmed that the crystallinity and crystallite size of WNF were lower than those of WMP. Chemical composition measurements and FTIR results showed that the chemical compositions of WNF and those of WMP were almost the same. A TGA test also demonstrated that the thermal stability of WNF and WMP was the same (250–260 °C), and the char content of WNF was slightly lower than that of WMP. The direct production of WNF from WMPs with no chemical treatments is an environmentally valuable approach and WNF can be regarded as a promising sustainable nanomaterials with abundant potential applications.

The process of interaction between abrasive disk and a workpiece while grinding under ultrasonic vibrations

This research includes the analysis of kinematic relations between abrasive disk grains and the workpiece in the abrading process while applying ultrasonic vibrations (USV) on the workpiece. Supposition, that applying vibrations lied in axes of abrasive disk increases efficiency of disk grinding, has been set. Analytical approach showed dependences for calculating the grinding force. These dependences include changing of disk grains microcutting kinematics and mechanical characteristics of workpieces while applying USV. The technique of pilot studies is given. For imposing on preparation of USV used the device in which it was one of links of oscillatory system that provides the minimum losses of energy USV and high amplitude of fluctuations of preparation. Field researches have shown, that applying USV lied in axes of abrasive disk decreased the grinding force, the wear of disk, and high-level parameters of the processed surface roughness.

A method for grinding face gear of double crowned tooth geometry on a multi-axis CNC machine

The stability requirement of bearing contact and a favorable function of transmission errors motivates the investigation of design and manufacture technology of the face-gear drives. Application of a grinding disc wheel with axial profile modification and a longitudinal ease-off topography design of face gear tooth flanks could be proper utilized to obtain a double crowned tooth geometry, which results in the pre-designed bearing contact and desired transmission errors. With the profile crowned tooth geometry of the gear generated by the modified wheel cutter, finding of the execution motions to generate the tooth geometry with the longitudinal ease-off topography design on a multi-axis Computer Numerical Control (CNC) machine with the same tool is a major issue. Therefore, a universal method on the Design Optimization Techniques is proposed to obtain the execution motions for such problem. The proposed optimization methodology is also applicable for the tooth flank error correction by a worm hob or a grinding cutter on the CNC generator. With the term of additional movement of execution motion is defined, a detailed description of additional movements for the ease-offs of the real crowned tooth geometry is also investigated. The feasibility of proposed method is validated by numerical examples.

Моделирование напряженного состояния режущей поверхности дискретного шлифовального круга

Grinding disks with high frequency discretization of a cutting surface allow not only breaking a cutting process and de-creasing its thermal intensity, but decreasing a vibration level of a technological system which has a positive effect upon quality of a surface worked. But, for realization of intensive grinding modes these tools should possess a mechanical strength not only in the central hole, but that of a discrete cutting surface. In this connection in modern CAE-complex CosmosWorks a computer simulation of a stressed state of a cutting surface and a central hole of the grinding disk subjected to a high-frequency discretization is carried out. On the basis of the simulation results there is developed a durable tool allowing the fulfillment of discrete grinding in intensive modes.

Assessment of metallic contaminants in grinded millet using domestic grinding machine

In this study, the quantity of metallic contaminants extracted from grinded millet was evaluated. The millet was grinded in three different forms; wet, paste, and dry forms for up to 3 minutes using locally fabricated grinding machine with cast grinding discs. Separate grinding discs were used for different millet forms, while the same quantity of millet, 1 kg, was used throughout the experiments. The millet was soaked for 24 hours before grinding in order to obtain wet and paste forms of the millet. Metallic contaminants were carefully extracted from the grinded millet using magnetic bed along with sedimentation and decantation. The extracted materials were then quantified to ascertain the food form that produces the highest amount of metallic contaminants. Also, the wear rate of the grinding disc was also determined with respect to the grinding time. The results show that the wet form has the highest amount of metallic contaminants of about 1.397 g followed by the paste form with 1.075 g. The dry form has the least value corresponding to 0.945 g. The grain sizes of the metallic contaminants were calculated to be 12.095 nm for the wet form, 8.056 nm for paste form while the dry form has the smallest grain size of 3.124 nm. The results revealed that metallic contaminants are always contained in grinded food processed with local grinding discs. Thus, materials with better wear resistance should be selected for production of grinding discs to be used for food processing.Keywords: Millet, Metallic contaminants, Quantification, Magnetic extraction, Sedimentation and Health hazards

The Research into the Effect of Conditions of Combined Electric Powered Diamond Processing on Cutting Power

The paper presents results of the investigation into efficiency of high-tensile composite materials grinding with metal bonded diamond abrasive tools, as well as it demonstrates the necessity to stabilize diamond disks cutting properties in order to reduce cutting power, since it is one of important economic indicators of processing. The comparative analysis of preliminary studies of various diamond processing methods reveals that the minimal cutting power is observed when using the combined method of electric powered diamond processing which includes electrochemical grinding and simultaneous continuous electrochemical dressing of the grinding disk surface. Further research into the suggested method reveals relevant mathematical dependences of metal-bonded diamond disks cutting power and electric modes. The analysis of the results shows that combining of hard-alloy surface electrochemical dissolution and electrochemical dressing of the disk surface facilitates mechanical cutting with high effectiveness and little effort. This leads to substantial reduction of cutting power as compared with other methods. The reasonable electric modes are discovered which provide the minimal cutting power without reducing efficiency of the process and quality of finished product.

Estimation of the Levels of Fe in Wheat and Maize Flour Milled using Commercial Milling Machine and A Home Blender

Milling devices are among the most commonly used in our indigenous markets and homes and variety of elements such as Cu, Ni, Zn, Pb, Ti, Co, Cr, Al, Si, and Fe are used in their manufacture and fabrication. Often times they are present as alloys. With prolonged processing, these metals are gradually introduced as contaminants in the food being processed. Wheat and maize were selected for this study due to their wide usage as sources of protein and carbohydrate in Nigeria and Africa in general. The samples were cleaned by picking out sand, stones and other impurities and ground using the commercial milling machine and a home blender and were digested with HNO3 and HClO4 in the ratio of 4:1 and analyzed using AAS. Average Fe concentration values for both wheat and maize samples milled with commercial milling machine is 13.53 mg/kg and 26.79 mg/kg respectively while samples milled with the home blender gave concentration values of 4.00 mg/kg and 2.64 mg/kg for wheat and maize respectively. The high concentration of Fe in ground maize and wheat milled using the commercial milling machine could be attributed to the abrasive friction of the grinding disc as the grains come in contact with it during grinding resulting in its chipping off into the milled sample. It is therefore recommended that the commercial milling machine be redesigned with the incorporation of a permanent magnet to minimize or totally eliminate the introduction of Fe fillings into the ground grains and other foodstuffs. Keywords: Commercial milling machine, wheat, maize, contaminants, home blender, grinding

Nanofibrillation of deep eutectic solvent-treated paper and board cellulose pulps

In this work, several cellulose board grades, including waste board, fluting, and waste milk container board, were pretreated with green choline chloride-urea deep eutectic solvent (DES) and nanofibrillated using a Masuko grinder. DES-treated bleached chemical birch pulp, NaOH-swollen waste board, and bleached chemical birch pulp were used as reference materials. The properties of the nanofibrils after disc grinding were compared with those obtained through microfluidization. Overall, the choline chloride-urea DES pretreatment significantly enhanced the nanofibrillation of the board pulps in both nanofibrillation methods—as compared with NaOH-treated pulps—and resulted in fine and long individual nanofibrils and some larger nanofibril bunches, as determined by field emission scanning electron microscopy and transmission electron microscopy. The nanofibril suspensions obtained from the DES pretreatment had a viscous, gel-like appearance with shear thinning behavior. The nanofibrils maintained their initial crystalline structure with a crystallinity index of 61%–47%. Improved board handsheet properties also showed that DES-treated and Masuko-ground waste board and paper nanocellulose can potentially enhance the strength of the board. Consequently, the DES chemical pretreatment appears to be a promising route to obtain cellulose nanofibrils from waste board and paper.