Citation: Rypina, L.; Lipi ´ nski, D.; Banaszek, K.; Kacalak, W.; Szafraniec, F. Influence of the Geometrical Features of the Cutting Edges of Abrasive Grains on the Removal Efficiency of the Ti6Al4V Titanium Alloy. Materials 2022, 15, 6189. https://doi.org/10.3390/ma15186189 Academic Editors: Javier Gil and Matthias Bönisch Received: 29 July 2022 Accepted: 2 September 2022 Published: 6 September 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Influence of the Geometrical Features of the Cutting Edges of Abrasive Grains on the Removal Efficiency of the Ti6Al4V Titanium Alloy Lukasz Rypina 1 , Dariusz Lipi ´ nski 1, * , Kamil Banaszek 2, * , Wojciech Kacalak 1 and Filip Szafraniec 1 1 Faculty of Mechanical Engineering, Koszalin University of Technology, Raclawicka 15, 75-620 Koszalin, Poland 2 Doctoral School, Koszalin University of Technology, Raclawicka 15, 75-620 Koszalin, Poland * Correspondence: dariusz.lipinski@tu.koszalin.pl (D.L.); kamil.banaszek@tu.koszalin.pl (K.B.) Abstract: The shape of the cutting blades of the abrasive grains has an influence on the material separation process in the machining zone. The paper analyzes the influence of the geometrical parameters of the abrasive grains (rake angle γ, apex angle ε, opening angle α), as well as width b z and length b b of the cutting zone on the material removal efficiency. The material removal efficiency was determined taking into account the volume of the removed material V G and the volume of lateral piles-up V R . The analyses were carried out on the basis of the results of experimental and simulations using the finite element method. The relationship between the selected geometric parameters characterizing the cutting zone and the coefficient characterizing the efficiency of the material removal process was determined. A strong influence of the opening angle α as well as the width b z and length b b of the cutting zone on the material removal process by abrasive grain was demonstrated. It was observed that the wide cutting edge, and thus the large opening angle α of the grain, reduced the size of the pile-ups and more effectively removed the chip material. Keywords: grinding; abrasive grain; material removal; efficiency; rake angle; opening angle; apex angle; cutting edge; cutting blade; titanium alloy; finite elements methods (FEM) 1. Introduction Increasing requirements for mechanical parts concern their durability, reliability and good surface quality. Hence, the final machining should be performed with appropriately selected parameters and conditions [1,2]. Titanium alloys are difficult to cut. During the machining of titanium alloys, low thermal conductivity is the reason that approximately 15% of the heat can be accumulated in the cutting edge [3]. This requires improved machining potential of the grinding tools, which should also have high productivity and wear resistance, and should allow for the reduction in thermal damages on the ground surfaces [4–6]. To explain the phenomena of material removal processes, the research should be carried out for three different stages: (i) rubbing, (ii) ploughing, (iii) chip formation. During the rubbing stage, the elastic deformation occurs the most frequently. During ploughing, the grain moves deeper into the material and mainly plastic deformation occurs on the rake face of the grain. Furthermore, the material moves to the sides and forms the pile-up. During the third stage, the chip formation occurs as a result of continuous increase in the depth of the cut [7,8]. Early works were based on the assumptions that the single-grain scratch test should be treated similarly to the orthogonal cutting model, developed by Merchant [9,10]. In orthogonal turning, chip formation occurs; simultaneously, the material moves along the shear plane. The separated chip moves almost entirely parallel to the surface of the blade, which has a positive rake angle. Almost all of the energy is used for the chip formation Materials 2022, 15, 6189. https://doi.org/10.3390/ma15186189 https://www.mdpi.com/journal/materials