A study on chatter boundaries of cylindrical plunge grinding with process condition-dependent dynamics

This paper presents a systematic study on the chatter characteristics of cylindrical plunge grinding processes. Chatter occurrence under a wide range of operating conditions is experimentally identified. The unique transient chatter behaviors during spark-in and spark-out of plunge grinding are also studied; and the transient chatter occurrence is separated from the steady-state chatter occurrence, which is used to define the chatter boundaries.It is shown that the measured structure dynamics of the wheel/workpiece exhibit strong dependency on grinding conditions. The dynamic/chatter model of cylindrical plunge grinding [H. Li, Y.C. Shin, A time-domain dynamic model for chatter prediction of cylindrical plunge grinding processes, ASME Journal of Manufacturing Science and Engineering 128(2) (2006) 404–415] is improved to handle the grinding force-dependent structure dynamics, and the modified model is validated by comparing the predicted chatter boundaries with experimental chatter conditions.     

Analysis of the different forms of application and types of cutting fluid used in plunge cylindrical grinding using conventional and superabrasive CBN grinding wheels

The work reported here involved an investigation into the grinding process, one of the last finishing processes carried out on a production line. Although several input parameters are involved in this process, attention today focuses strongly on the form and amount of cutting fluid employed, since these substances may be seriously pernicious to human health and to the environment, and involve high purchasing and maintenance costs when utilized and stored incorrectly. The type and amount of cutting fluid used directly affect some of the main output variables of the grinding process which are analyzed here, such as tangential cutting force, specific grinding energy, acoustic emission, diametrical wear, roughness, residual stress and scanning electron microscopy. To analyze the influence of these variables, an optimised fluid application methodology was developed (involving rounded 5, 4 and 3 mm diameter nozzles and high fluid application pressures) to reduce the amount of fluid used in the grinding process and improve its performance in comparison with the conventional fluid application method (of diffuser nozzles and lower fluid application pressure). To this end, two types of cutting fluid (a 5% synthetic emulsion and neat oil) and two abrasive tools (an aluminium oxide and a superabrasive CBN grinding wheel) were used. The results revealed that, in every situation, the optimised application of cutting fluid significantly improved the efficiency of the process, particularly the combined use of neat oil and CBN grinding wheel.     

An analysis of grinding power and surface roughness in external cylindrical grinding of hardened SCM440 steel using the response surface method

The aim of this study was to analyze effectively the grinding power spent during the process and the surface roughness of the ground workpiece in the external cylindrical grinding of hardened SCM440 steel using the response surface method. A Hall effect sensor was used for measuring the grinding power of the spindle driving motor. The surface roughness was also measured and evaluated according to the change of the grinding conditions. Response surface models were developed to predict the grinding power and the surface roughness using the experimental results. From adding simply material removal rate to the contour plot of these mathematical models, it was seen that useful grinding conditions for industrial application could be easily determined.     

A fundamental study on the mechanism of electrolytic in-process dressing (ELID) grinding

Demands for high quality surface finish, dimensional and form accuracy are required for optical surfaces and it is very difficult to achieve these using conventional grinding methods. Electrolytic in-process dressing (ELID) grinding is one new and efficient method that uses a metal-bonded diamond grinding wheel in order to achieve a mirror surface finish especially on hard and brittle materials. However, studies reported so for have not explained the fundamental mechanism of ELID grinding and so it has been studied here by conducting experiments to establish optimal grinding parameters to obtain better surface finish under various in-process dressing conditions. In this research the results show that the cutting forces are unstable throughout the grinding process due to the breakage of an insulating layer formed on the surface of the grinding wheel; however, a smoother surface can be obtained using a high dressing current duty ratio at the cost of high tool wear. ELID grinding is efficient for feed rates of less than 400 mm/min, and surface cracks are observed when it exceeds this limit.