Surface Finish In Grinding Research Articles

Discussion of Effect of Disk Grinding Surface Finish on Fatigue Strength of the Nuclear Component Material

Disk grinding is often used to repair the scratches of the surface of the component and also used to weld toe finish to mitigate undesirable stress concentration. This study investigates the effect of disk grinding surface finish on fatigue strength of the nuclear component materials. In order to achieve this objective, fully reversed tension-compression strain-controlled fatigue tests of disk grinding finished austenitic stainless steel SUS316L plate are conducted at RT in air. Two types of disk grinding directions, which are parallel and perpendicular to the cyclic loading direction, are considered in this study, and fatigue test results are compared to S-N curves obtained by emery polishing and lathe machining finished specimens. It is found that the disk grinding surface finish decreases fatigue strength of materials and, in some cases, the fatigue strength of disk grinding finished materials is lower than that of lathe machining finished specimens with maximum height roughness Rz over 100 μm. In order to find out the mechanism of fatigue strength reduction due to the disk grinding, metallographic observations and some measurements such as roughness, hardness and residual stress of the surface are carried out. In addition, the effect of stress concentration and texture of the micro grooves introduced to the surface of the material by disk grinding are discussed.

Surface Reversal Method for Cylindrical Tool Characterization

Cutting edges protrusion properties for cutting tools have significant effect of grinding surface finish and its characterization is crucial in understanding tool-work interaction. Existing definition of reference datum in surface topography analysis is not suitable for abrasive tool cutting edges protrusion characterization in relation to tool-work interaction. This paper proposed Surface Reversal Method for the reference datum determination in the characterization of cutting edge protrusion on flat end face of cylindrical cutting tool meant for vertical grinding. Fabricated cylindrical artefact is used to test the theory, accompanied with a specially made fixture. Performance of the proposed method is evaluated based on the repeatability of step height measurement on the topography component and inclination of the reference datum which extracted from primary surface measured by laser confocal scanning microscope. The proposed method provides better datum definition than conventional method for height measurement of the abrasive tool topography in relation to the tool-work interaction.

3D metal removal simulation to determine uncut chip thickness, contact length, and surface finish in grinding

The two most important geometric parameters that describe the mechanics of grinding are the uncut chip thickness and the contact length. Currently, analytical approaches are used to estimate these parameters. The accuracy of these approaches, however, is limited because they do not take into account the random shape, size, and protrusion height and placement of the abrasive grains around the circumference of the grinding wheel. In this paper, a simulation technique was used to gain new insight into the effect of the stochastic nature of grinding wheels on the geometric properties of the grinding process. The simulator was used to calculate the number of active grains, uncut chip thickness, and contact length for a stochastic wheel model of Radiac Abrasive’s WRA-60-J5-V1 grinding wheel. These values were then mapped to every grain on the grinding wheel and used to determine the instantaneous material removal rate of the wheel and workpiece surface finish. There was excellent agreement between the predicted and experimentally measured surface topology of the workpiece. The results suggest that only 10–25 % of the grains on the grinding wheel are active and that the average grinding chip may be as much as ten times thicker and ten times shorter than would be produced by a grinding wheel with a regular arrangement of cutting edges as assumed by existing analytical approaches.

Specific energy in grinding of tungsten carbides of various grain sizes

The objective of this study is to investigate specific energy in grinding of tungsten carbides of various grain sizes. Through the construction of a mathematical model, the study demonstrates the correlation of specific energy with the grinding process parameters and the material property parameters for the tungsten carbides. The study also examines material-removal mechanisms and surface finish in grinding of such materials using scanning electron microscopy, X-ray diffractometry and energy dispersive spectrometry techniques, etc. The study concludes that specific energy is related not only to grinding process parameters, but also to the physical–mechanical properties of the workpiece material.

A geometric method for three-dimensional modelling of surface finish in grinding

In this paper, a geometric method is presented for predictive modelling of surface finish in grinding. The chip removal process by successive grains is modelled as a three dimensional Boolean operation, from which the surface roughness is predicted. A solid modeller is used to model an individual chip as a partial ellipsoid. The measured topography of the grinding wheel, together with kinematic relationship in surface grinding, is used to determine the geometrical characteristics of the proposed ellipsoid. The surface roughness predicted by the model is compared with experimental results. The results show good consistency between the model and the actual surface properties.

Some observations in grinding unidirectional carbon fibre-reinforced plastics

This paper investigates the grinding performance of epoxy matrix composites reinforced by unidirectional carbon fibres, using an alumina grinding wheel. Emphasis was placed on understanding the effect of fibre orientations and grinding depths on the grinding force and surface integrity, and on understanding the grinding mechanisms, with a comparison to orthogonal cutting. It was found that greater grinding forces occurred at a fibre orientation between 60° and 90°, but poorer grinding surface finish took place between 120° and 180°. The surface integrity was highly dependent on the fibre orientation and the depth of grinding, which is very similar to the results of orthogonal cutting.

Automatic design of fuzzy logic controller using a genetic algorithm—to predict power requirement and surface finish in grinding

We have developed a method for automatic design of fuzzy logic controller (FLC) using a genetic algorithm (GA). The performance of an FLC depends on its knowledge base (KB), which consists of membership function distributions (also known as data base) and rule base. To design a proper KB of the FLC, the designer should have a thorough knowledge of the process to be controlled. Sometimes, it becomes difficult to gather knowledge of the process beforehand. Thus, designing the proper KB of an FLC is not an easy task. In this paper, a new approach for designing the KB of an FLC (using a GA) is proposed and its effectiveness is compared to a previous approach based on GA-fuzzy combination for making predictions of power requirement and surface finish in grinding (a machining process to obtain smooth surface on the work).