Papers by Keyword: Dressing

Abstract: Grinding is a widely used process in many industries due to the precise geometric tolerances and excellent surface finishes it can offer, which makes it very useful when high quality parts have to be manufactured. Due to the wear that the grinding wheel suffers, a process known as dressing is periodically carried out to recover the cutting ability of the wheel. Dressing is an extremely important part of the grinding process, as it can alter and improve the cutting conditions of the wheel.During the dressing of vitrified bonded CBN wheels, the real dressing depth of cut is significantly lower than the theoretical depth of cut, leading to dimensional errors in the dressed grinding wheel, which consequently translate into the ground part. However, while deformations during grinding have been widely studied, this phenomenon has not been yet analyzed during dressing. Therefore, the main objective of this work is to determine the influence of the dressing parameters on the real depth of cut. Also, the effect of dresser wear and the deformations has been determined separately.To this end, a new methodology has been developed to measure the real depth of cut using a laser displacement sensor. Moreover, experimental tests have been carried out to characterize the influence that the dressing speed ratio (q_d) and set depth of cut (a_{d_set}) have on the actual depth of cut (a_{d_real}). It has been seen that the use of negative q_d results in a more accurate real depth of cut, and therefore a more efficient dressing process. While the error using negative q_d is about 10 %, using positive q_d is about 25 %.

Abstract: This study has been conducted to optimize the dressing parameters to find the minimum surface roughness for internal grinding of hardened SKD11 steel using the Taguchi method. The input parameters used are coarse dressing depth, number of coarse dressing, fine dressing depth, number of fine dressing, non-feeding dressing, and dressing feed speed. The Analysis of Variance (ANOVA) and an analysis of the signal-to-noise (S/N) response are conducted to estimate the significance of each input parameter on the responses. It shows that the number of coarse dressing has the most decisive impact on Ra (88.28%). Furthermore, the discrepancy of the roughness average from the experiments and that from prediction are minor.

Abstract: In an effort to produce ideal wound dressing, gellan gum/collagen hydrogel films containing different concentrations of gatifloxacin were prepared via evaporative casting method. The films were examined in terms of physical appearances, water uptake and water vapour transmission rate (WVTR). All the films showed good physical appearances. Swelling percentages of the films were decreased, whereas WVTR values were increased as the addition of gatifloxacin was increased. Swelling percentage of gellan gum/collagen film with the lowest percentage of gatifloxacin (GG/C-GAT01) has the highest swelling ratio (2057%). Meanwhile, the WVTR value of GG/C-GAT1 has the highest WVTR value among all films which is 1245 g m^-2 day^-1. The formulation of GG/C films with the addition of gatifloxacin with good water absorbance and acceptable WVTRs value offered promising materials to be applied as wound dressing materials.

Abstract: This article describes an optimization of dressing parameters to improve the wheel life in surface grinding of hardened SKD 11 steel by using the Taguchi method. Dressing parameters including dressing feed rate, coarse dressing depth, coarse dressing times, fine dressing depth, fine dressing times, and non-feeding dressing were investigated to determine their influence on the wheel life. The DOE method developed by G. Taguchi was selected to design the experiments. An analysis of the signal-to-noise (S/N) response and ANOVA were conducted to obtain the optimal values of dressing parameters for maximizing the wheel life. In the results section, the coarse dressing times and the coarse dressing depth are determined to be the most influential factors which give a statistically significant effect on wheel life. Also, a predictive value of the average wheel life is given with a 3.6% deviation from the verification experiment.

Abstract: This paper introduces a study on multi-criteria optimization of the dressing parameters in surface grinding for 90CrSi tool steel. The aim of the study is to minimize the surface roughness, the normal shear force and maximize the grinding wheel life by using Taguchi method and Grey Relational Analysis (GRA). This multi-objective optimization is obtained by optimizing four four-level and two two-level dressing parameters in sixteen experiments based on an orthogonal array L₁₆(4⁴×2²). From the results of the study, the optimum dressing parameters were proposed. Also, to evaluate the optimum dressing model, an experiment was performed. The results of the comparison between the predicted model and the experiment show that the proposed model has been proven and it can be used for further applying of surface grinding.

Abstract: A new antibacterial acellular dermal matrix (AADM) dressing can not only resist infection, but also accelerate wound healing. AADM was prepared by SDS (0.40%), trypsin (0.40%) and keratin (0.30%), and then cross-linked with carboxymethyl chitosan (1%) with glutaraldehyde, whose tensile strength (MPa) is 10.66, thickness (mm), 0.53, the rate of permeable steam (g • m^-2 • 24h^-1), 3640, porosity (%), 81, degradation time in vitro (h), 24.33, pH, 6.5, and the average inhibition rate, more than 70%. At the same time, scanning electron microscopy showed that the structure of AADM was evacuated and the pores were interconnected. On such basis, a conclusion was drawn: the properties of AADM has been sharply increased, compared with acellular dermal matrix, which cannot resist infection, and the new antibacterial acellular dermal matrix completely meets the clinical requirements for burn dressings.

Abstract: Dressing parameters, which directly affect the flatness of the plate, are very important in planetary double-sided grinding dressing process. In this paper, trajectory and velocity equations of grit are studied. By comparing to the trajectory density of different annular regions, this paper puts forward an evaluation method of the shape of the plate and explores the impact of rotation speed on the shape of the plate. Finally, the experiments are performed by adjusting the rotation speed of the sun wheel and the plate. The results show that the flatness of the plate can be dressed below 0.01 mm, which validates the correctness of the theory.

Abstract: Grinding performance can be influenced by various grinding conditions including workpiece materials properties, grinding wheel properties, grinding operational parameters and dressing operational parameters. In order to achieve stable optimal grinding performance, it is important to select the most suitable operational control parameters to match grinding requirement and to minimize the effects of grinding wheel wear and other changes in the process environment. The paper presents a simple adaptive control logic strategy for the selection of dressing and grinding conditions based on available sensing techniques. In this study, desirable grinding behaviour is discussed to demonstrate how to extract useful process information to guide process parameter adjustment for a stable satisfactory grinding performance.

Abstract: One research objective for generating gear grinding is to increase economic efficiency and productivity of the process. Furthermore, the gear quality must be equal or higher compared to the non optimised process. In addition to the grinding process and the grinding tools, the dressing process can be suitable to lead to an increase of efficiency of generating gear grinding. Due to the variety of dressing tool specifications process users have the problem of selecting the best fitting dressing tool for their demands. Therefore, it is necessary to know the interactions of dressing tool specification and dressing tool wear. But the influence of the dressing tool specification onto dressing tool wear has yet not been sufficiently investigated for generating gear grinding.

Abstract: The high hardness of brittle materials always make it hard to machine with traditional grinding wheels. Conventionally a diamond grinding wheels was used to improve the poor processing capability. Usually the specific grinding energy had been used as an indicator of machinability. According to its definition, the specific grinding energy increases with the active contact area of the grinding wheel decreases. In other words, reducing the surface contact area of the grinding wheel can enhance the specific grinding energy effectively. Conditioning grooves on grinding wheels not only enhance the specific grinding energy, but also achieve the effect of reducing the heat dissipated during the grinding processes. With the proper selection parameters, the high cost of diamond grinding wheel may be replaced by less expensive conventional green carbon and aluminum oxide wheel. In this studies, the relationship between the surface topography of grinding wheels and the grinding capability of brittle materials was investigated. The results show that, the traditional grinding wheel dressing properly while the depth of cut less than 20μm with the rhombic pattern and the depth of cut more than 20μm with the groove-like pattern can grind the brittle materials as good as using diamond wheel.