Single Grain Scratch Tests to Determine Elastic and Plastic Material Behavior in Grinding

Abstract

This paper presents an overview of kinematic simulations in grinding. Up to now the simulations are carried out under the assumption of an ideal cutting process. Therefore, the simulation results are not exactly identical to the experimental results. For this reason, the simulation needs to be enhanced with the plastic material flow during cutting. To explain this behavior, single grain scratch experiments were conducted to detect the different sources of influence on the plastic deformation and on the pile-up. First, in the experiments the grain shapes as well as the cutting speeds were varied. To take the effect of different grain shapes into account, three different grains were used. The effect of the cutting speed was investigated at cutting speeds ranging from 60 to 120 m/s. The results were evaluated with a confocal microscope. To quantify the results of the efficiency of the cutting process, the relative chip volume parameter was used.

Modelling of specific grinding energy for Inconel 718 superalloy

“…It could be attributed to insufficient material strain rate eventually resulting in more material being displaced and therefore more material pile-up. 23 Here, the share of U Plo in U Total has been found to be nearly 50%, 30%, and 20% at the infeed of 5, 10, and 15 μm, respectively. Therefore, U Plo for 5, 10, and 15 μm has been calculated incorporating modified f ( t , p ) as 50%, 30%, and 20%, respectively, of f t as obtained in single grit grinding.…”

“…It could be attributed to insufficient material strain rate eventually resulting in more material being displaced and therefore more material pile-up. 23 Here, the share of U Plo in U Total has been found to be nearly Table 5. Details of specific primary rubbing energy calculations.…”

“…According to them, slopes of the cutting edges are more influential than the number of cutting edges for grinding force simulation. Aurich and Steffes 23 conducted single grit scratch tests using cBN grit on AISI 4140H heat treated steel. They used an indexable insert onto which the single grain was galvanically bonded.…”

Analysis of the grain shape influence on the chip formation in grinding

“…In addition, the orientation of the abrasive grain respectively the grain shape orthogonal to the feed direction has an influence on chip formation. This has been demonstrated by several authors in relation to the position of the cutting edge (Deng et al, 2014) and the edge angle (Aurich and Steffes, 2011) without deriving a general statement. Nguyen and Butler (2005) determined depending on the rake angle which grains cause elastic or plastic material deformation or chips when engaging.…”

“…Depending on a predefined grain orientation, the grain shape char- acteristics rake angle and wedge angle ı (in scratching direction), apex angle ␤ (transversal to the scratching direction) and opening angle ␣ (horizontal in scratching direction) were determined for each grain. Instead of the direct evaluation of the grain shape other authors evaluated the grain shape by analysing the resulting scratch groove geometry (Aurich and Steffes, 2011). Due to the elastic and plastic material deformation in the scratch groove, the angles would probably not be represented correctly and only information about the grain shape transversal to the scratching direction could be obtained.…”