Ranking of vitrified grinding wheel parameters by using analytical hierarchical process (AHP) for surface roughness of work piece in grinding operation

Objective of grinding process is to generate high quality surface finish on work piece. There are many parameters which influence on the work piece roughness. Work piece material and characteristics, grinding wheel specification, grinding conditions and dressing conditions influence on the surface quality of the work piece. Selection of grinding wheel is important aspect for producing good quality of surface finish on the work piece. The main components of grinding wheel are the abrasive grains, bond material and porosity. Selection of correct grinding wheel is necessary for generating better surface finish on the work piece. Analytical Hierarchical Process (AHP) is used for ranking of vitrified bond grinding wheel parameters on surface roughness on the work piece in sub sequent grinding operation. The grit, grade, (Hardness of wheel) structure and type of abrasive are critically assisted in terms of the surface finish produced on work piece in the subsequent grinding operation. Analytic Hierarchy Process (AHP) shows that the abrasive grit of grinding wheel has first rank and grade (hardness) of the wheel has Second rank for the producing surface finish on the work piece after grinding operation. Structure and type of abrasive of wheel have a third and fourth rank respectively. Thus, AHP gives qualitative way of controlling work piece surface roughness in sub-sequent grinding operation by selecting proper grinding wheel of vitrified bond which helps the user to select the correct grinding wheel

A progress report on the evaluation of metal cutting coolants

An intensive investigation into the grinding process was carried out in The College of Aeronautics Machine Tools Laboratory during 1955-6. The outcome of this work was a method of evaluating the efficiency of grinding wheel specifications. Briefly, this consists of holding all other conditions constant and changing the grinding wheel specification from the grinding tests made then the rate of grinding wheel wear and the maximum metal removal rate is ascertained. This data may be used to compare one specification to another. The method has been used to select the best wheel specification for a wide range of materials, especially the more difficult machinable alloys examples being the stainless steel and the alloys intended for use at high temperatures. During the ten years since 1956 the method has been further developed by retaining the grinding wheel specification constant and varying the work piece material to determine the grinding machinability of alloys, and also a much more valuable criteria of the grinding process - the efficiency of coolants when used in the grinding process. This work on coolant evaluation has received detailed and extensive attention. The results of tests carried out on more than 300 coolant samples ranging from oil based and water soluble coolants with varying percentages of addative has revealed that the coolant can increase the life of the grinding wheel face by 10 times. All results found from the method of evaluation are expressed in terms of maximum metal removal rate and volume of metal which may be removed at maximum rate

Grinding arrangement for ball nose milling cutters

A grinding arrangement for spiral fluted ball nose end mills and like tools includes a tool holder for positioning the tool relative to a grinding wheel. The tool is mounted in a spindle within the tool holder for rotation about its centerline and the tool holder is pivotably mounted for angular movement about an axis which intersects that centerline. A follower arm of a cam follower secured to the spindle cooperates with a specially shaped cam to provide rotation of the tool during the angular movement of the tool holder during the grinding cycle, by an amount determined by the cam profile. In this way the surface of the cutting edge in contact with the grinding wheel is maintained at the same height on the grinding wheel throughout the angular movement of the tool holder during the grinding cycle

Effect of grinding wheel on the dynamic performance of high-speed spindle system with an improved FE model

The grinding wheel is a key factor which should be considered in the process of predicting the dynamic performance of the high-speed spindle system. Currently, most research is mainly focuses on shaft and bearing using Timoshenko’s beam and Jones’ bearing model. In this research, considering the effect of grinding wheel on the dynamic behavior of the high-speed motorized spindle system, a dynamic model of spindle system has been established by utilizing the finite element method (FEM). The model is improved by optimizing the relevant parameters of spindle system and validated by measuring FRF using impact hammer test. The reported results are well matched (maximum error is 5 %). Using the improved model, the effect of grinding wheel on the critical speeds, mode shapes, centrifugal force and gyroscopic effects of spindle system are analyzed. In addition, the impact of different diameters, materials and fixed methods of grinding wheel on the dynamic property of spindle system are also carried out. The result shows the affect of grinding wheel and design guideline of the spindle and grinding wheel

Finite element simulation of sintering of metal-bonded grinding wheels

The grinding wheel properties porosity, particle distribution and the grain holding force influence the surface roughness of the machined workpiece and the performance of the grinding process. These properties of a grinding wheel are in turn defined during tool production. However, the adaptation of the properties of a grinding wheel to the specific grinding task is currently based on empirical knowledge and experience. Understanding the interdependencies from the initial manufacturing to the final grinding results is the key to achieve the target-oriented generation of the grinding wheel properties for the grinding task at hand. With regard to the large number of powder particles for the manufacturing of metal-bonded grinding wheels, an analytical investigation of the powder metallurgical processes is not suitable. Numerical simulations offer a cost and time saving alternative to provide information on the sintering behavior and gain knowledge on the acting mechanism. In this article the sintering of a metal-bonded diamond grinding wheel is modelled and the obtained results are connected to material properties of the resulting grinding layer

Study on Hydrodynamic Pressure in Grinding Contact Zone Considering Grinding Parameters and Grinding Wheel Specifications

AbstractIn the grinding process, coolant lubricant is used to lubricate and mainly to transmit the heat generated in the contact zone. Grinding wheel accelerates a portion of the coolant lubricant into the contact zone. As e resault of the wedge effect between grinding wheel and workpiece in the contact zone a hydrodynamic pressure is generated, which influences the grinding results. In this paper, a new model for the hydrodynamic pressure of the coolant in the contact zone is presented. The simulation results show that the hydrodynamic pressure is proportion to grinding wheel velocity, and in inverse proportion to the minimum gap between wheel and workpiece. Furthermore, it could be investigated that the specification of the grinding wheel can affect the value of this pressure. The experimental results correspond to the simulation results, which show the validity of the simulation

Effects of Abrasive Grit Shape on Grinding Performance

The quality of grit in grinding wheel has predominate influence on the grinding wheel performance, such as wheel sharpness and wheel wear. This paper presents an investigation on the effect of difference grit shapes on grinding force and grit holding capacity. Some critical grinding behaviours are analysed in relation to grit shapes to establish a foundation for grit quality assessment. A desirable grit shape is identified for better cutting efficiency and grinding wheel life

Optimization of discontinued grinding wheel geometrical parameters

Розроблена і досліджена математична модель для визначення температури переривчастого шліфування з урахуванням геометричних параметрів переривчастих шліфувальних кругів (ПШК). Встановлено, що температура переривчастого шліфування містить дві складові: що безперервно зростає і періодичну імпульсну. Досліджений перехідний процес зміни температури, встановлена залежність для визначення часу перехідного процесу. Сформульований критерій оптимізації процесу – мінімальна температура переривчастого шліфування і встановлені закономірності її зміни. Розроблені рекомендації по вибору геометричних параметрів ПШК.Purpose. Because in known techniques entry parameters characterizing not only grinding wheel geometry, but also grinding modes, it is necessary to work out the techniques with entry parameters which invariant to the modes of grinding. Design/methodology/approach. The superposition method created a mathematical model for determination of discontinued grinding wheel temperature. As a result a possibility was to compare the model with the known one. It gave the condition to find time constant and evaluate transient time after which the both models will be identical to the temperature calculated. The benefits of this study are a new presentation of the grinding temperature consisting of a periodic part superposed on the rising temperature due to the average surface flux. The values of both parts are given and analyzed and then used to find the minimum grinding temperature by changing the discontinued grinding wheel geometry parameters: the number of cutting ledges and their fill factor on the discontinued wheel circuitous step. The more the parameters mentioned the less the discontinued grinding temperature will be. The study allows choosing the optimal geometrical parameters of the discontinued grinding wheel on the bases of conformities to law of influence of discontinued grinding wheel geometrical parameters on the grinding temperature. Corresponding recommendations on the choice of discontinued grinding wheel geometrical parameters are presented in some detail as thoroughly as possible. Findings. The each optimal geometrical parameter intervals of discontinued grinding wheel that does not depend on the grinding modes are found. Originality/value. The change intervals of the each optimal parameters of discontinued grinding wheel were chosen depending on the minimum discontinued grinding temperature.Разработана и исследована математическая модель для определения температуры прерывистого шлифования с учетом геометрических параметров прерывистых шлифовальных кругов (ПШК). Установлено, что температура прерывистого шлифования содержит две составляющие: непрерывно возрастающую и периодическую импульсную. Исследован переходный процесс изменения температуры, установлена зависимость для определения времени переходного процесса. Сформулирован критерий оптимизации процесса: минимальная температура прерывистого шлифования и установлены закономерности ее изменения. Разработаны рекомендации по выбору геометрических параметров ПШК

Определение температуры нестационарного и прерывистого шлифования

Виконано аналіз перехідних процесів зміни температури шліфування в рухомої ї нерухомої системах координат відповідно для дво- и одновимірної математичної моделі температурного поля. Розроблена і досліджена математична модель для визначення температури переривчастого шліфування з урахуванням геометричних параметрів переривчастих шліфувальних кругів. Встановлено, що температура переривчастого шліфування містить дві складові: що безперервно зростає і періодичну імпульсну. Досліджений перехідний процес зміни температури, встановлена залежність для визначення часу перехідного процесу.Purpose. Because in known techniques entry parameters characterizing not only grinding wheel geometry, but also grinding modes, it is necessary to work out the techniques with entry parameters which invariant to the modes of grinding. Design/methodology/approach. The superposition method created a mathematical model for determination of discontinued grinding wheel temperature. As a result a possibility was to compare the model with the known one. It gave the condition to find time constant and evaluate transient time after which the both models will be identical to the temperature calculated. The benefits of this study are a new presentation of the grinding temperature consisting of a periodic part superposed on the rising temperature due to the average surface flux. The values of both parts are given and analyzed and then used to find grinding temperature by changing the discontinued grinding wheel geometry parameters: the number of cutting ledges and their fill factor on the discontinued wheel circuitous step. The more the parameters mentioned the less the discontinued grinding temperature will be. The study allows choosing the optimal geometrical parameters of the discontinued grinding wheel on the bases of conformities to law of influence of discontinued grinding wheel geometrical parameters on the grinding temperature. Corresponding recommendations on the choice of discontinued grinding wheel geometrical parameters are presented in some detail as thoroughly as possible. Findings. The each optimal geometrical parameter intervals of discontinued grinding wheel that does not depend on the grinding modes are found. Originality/value. The change intervals of the each optimal parameters of discontinued grinding wheel may be chosen depending on the minimum discontinued grinding temperature.Выполнен анализ переходных процессов изменения температуры шлифования в подвижной и неподвижной системе координат соответственно для дву- и одномерной математической модели температурного поля. Разработана и исследована математическая модель для определения температуры прерывистого шлифования с учетом геометрических параметров прерывистых шлифовальных кругов. Установлено, что температура прерывистого шлифования содержит две составляющие: непрерывно возрастающую и импульсную. Исследован переходный процесс изменения температуры, установлена зависимость для определения времени переходного процесса

Damage evolution assessment and modeling for CBN grinding wheel wear

The wear rate of a grinding wheel directly affects the workpiece surface integrity and tolerances. This paper summarizes a combined experimental-modeling framework for life expectancy of an electroplated Cubic Boron Nitride (CBN) grinding wheel, typically utilized in nickel-based superalloy grinding. The article presents an experimental framework to facilitate the formulation of a micromechanics based modeling framework. The presented study investigates the topological evolution of the grinding wheel surface and mechanisms of grit failure via depth profiling, digital microscopy, and scanning electron microscopy. The results are used to elucidate the statistical evolution of the grinding wheel surface. Different modes of grit failure, including grit attritious wear, fracture, and pull out haven been identified. The analysis of the surface topological features indicates a unique grit activation process, leading to a nonuniform spatial distribution of the grit wear. In addition, single grit pull out experiment has been conducted to assess the residual strength of the grit–wheel interface and the associated state of damage percolation. The experimental results are utilized in developing a life expectancy model for the CBN grinding wheel to assess the grit mean time to failure as well as grit surface topological evolution as a function of the process parameters