What is it about?

This study investigated the effects of process parameters on acceleration amplitude in the drilling of AISI D2 and AISI D3 cold work tool steels using HSS twist drills of two different lengths. Workpiece hardness, drill length/tool overhang, cutting speed, feed rate, and number of holes drilled were chosen as the process parameters. In the tests made by using the full factorial (FF) design technique, the values of induced machining vibrations occurring on the workpiece during drilling were specified as the acceleration amplitude.

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Why is it important?

From a survey of the literature, it can be seen that the effect on vibrations of factors such as drill size and geometry (causing tool bit wear, an indication of tool life), cutting speed, feedrate, spindle speed, power, moment, force, machining time, and thrust force have been examined both experimentally and theoretically, and mathematical models have been developed. The theoretical values obtained from these developed models and experimental results are consistent. In this present study, full factorial (FF) design was selected by reason of the advantages offered by this experimental design and modeling technique. The purpose of the present work was to employ experimental, graphical, and statistical methods to examine the effects of process parameters on the vibration (acceleration amplitude) created in the drilling of AISI D2 and AISI D3 cold work tool steels using HSS twist drills of different sizes. The relationship between acceleration amplitude and tool wear was also investigated in this study. This is very important for determining theoptimum levels of the process parameters and affects cutting tool cost, productivity, the quality of drilled parts, and machining time. The information can also be used to identify and select the components necessary for the prevention of vibration.

Perspectives

Measurement results were evaluated by linear regression analysis, and a second-order equation was developed for the prediction of the acceleration amplitude. The correlation coefficient of the predictive equation at a 95 % confidence level was calculated as R 2 = 0.703. The main and interaction effects of the process parameters on the acceleration amplitude were evaluated, and the percentage contributions of the process parameters to the acceleration amplitude were determined by variance analysis. In addition, scanning electron microscope (SEM) and optical microscope images of the drill wear were taken, and the wear characteristics and acceleration amplitude were correlated. The most effective parameters on acceleration amplitude were determined as the number of holes drilled, workpiece hardness, cutting speed, and feed rate. No significant effect of drill length/tool overhang was observed. With increasing cutting speed, number of holes drilled and the drill length/tool overhang, the acceleration amplitude values increased, although they decreased with increasing workpiece hardness.

Prof.Dr. Ali Riza Motorcu
Canakkale Onsekiz Mart Universitesi

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This page is a summary of: The effects of process parameters on acceleration amplitude in the drilling of cold work tool steels, The International Journal of Advanced Manufacturing Technology, April 2015, Springer Science + Business Media, DOI: 10.1007/s00170-015-7097-z.
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