Citation: Mohankumar, V.; Kapilan, S.; Karthik, A.; Bhuvaneshwaran, M.; Santulli, C.; Kumar, D.T.; Palanisamy, S.; Fragassa, C. A Hybrid Design of Experiment Approach in Analyzing the Electrical Discharge Machining Influence on Stir Cast Al7075/B 4 C Metal Matrix Composites. Metals 2024, 14, 205. https://doi.org/10.3390/ met14020205 Academic Editors: Jorge Salguero and Shili Shu Received: 14 November 2023 Revised: 8 December 2023 Accepted: 24 January 2024 Published: 7 February 2024 Copyright: © 2024 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/). metals Article A Hybrid Design of Experiment Approach in Analyzing the Electrical Discharge Machining Influence on Stir Cast Al7075/B 4 C Metal Matrix Composites Velusamy Mohankumar 1 , Sunderraj Kapilan 2 , Aruchamy Karthik 1 , Mylsamy Bhuvaneshwaran 3 , Carlo Santulli 4 , Durairaj Thresh Kumar 5 , Sivasubramanian Palanisamy 5, * and Cristiano Fragassa 6, * 1 Department of Mechatronics Engineering, Akshaya College of Engineering and Technology, Coimbatore 642109, India; mohankumar@acetcbe.edu.in (V.M.); akarthik@acetcbe.edu.in (A.K.) 2 Department of Civil Engineering, Akshaya College of Engineering and Technology, Coimbatore 642109, India; kapilan@acetcbe.edu.in 3 Department of Mechanical Engineering, K.S.R. College of Engineering, Tiruchengode 637215, India; bhuvaneshwaran@ksrce.ac.in 4 School of Science and Technology, University of Camerino, 62032 Camerino, Italy; carlo.santulli@unicam.it 5 Department of Mechanical Engineering, PTR College of Engineering and Technology, Madurai 625008, India; threshkumar_1234@yahoo.co.in 6 Department of Industrial Engineering, University of Bologna, 40136 Bologna, Italy * Correspondence: sivaresearch948@gmail.com (S.P.); cristiano.fragassa@unibo.it (C.F.) Abstract: The present work centers on aluminum-based metal matrix composites (AMCs), synthe- sized via stir casting and then processed by electrical discharge machining (EDM) in the case of Al7075 as a matrix and 6 wt.% boron carbide (B 4 C) as reinforcement. A design of experiment (DoE) approach, powered by hybrid optimization techniques (such as the entropy weight method (EWM), grey relational analysis (GRA) incorporated Taguchi method) was used to investigate the relationship between current (I), pulse ON time (Ton), pulse OFF time (Toff), and electrode gap (Gap) as input parameters and the material removal rate (MRR), tool wear rate (TWR), and surface roughness (SR) as response parameters. The results showed that an I = 140 A, Ton = 120 ms, Toff = 50 ms, and Gap = 0.4 mm combination gives the best response parameters of MRR = 0.5628 mm 3 /min, TWR = 0.0048 mm 3 /min, and SR = 4.4034 µs. Keywords: aluminum matrix composites (AMCs); aluminum 7075; boron carbide (B 4 C); electrical discharge machining (EDM); design of experiment (DoE); grey relational analysis (GRA) 1. Introduction 1.1. Metal Matrix Composites The metal matrix composites (MMCs) represent an advanced class of materials, capable of amalgamating the desirable properties of metals with the enhanced performance offered by reinforcements [1]. MMCs typically consist of two phases: a metal alloy serving as the matrix phase, with ceramic particles dispersed within it. The objective behind developing MMCs is to achieve a blend of properties unattainable by either the metal matrix or the reinforcement phase alone. Consequently, MMCs often exhibit superior mechanical, thermal, and physical characteristics compared to conventional metal. The selection of the reinforcement material for MMCs is contingent upon the desired properties of the resulting composite material. Various types of reinforcements are commonly used, including ceramic, metal-based, and polymer reinforcements. On the other hand, MMCs employ several major matrix phases, such as aluminum, magnesium, titanium, and copper matrix composites. These matrix phases serve as the foundation into which the reinforcements are incorporated, contributing to the diverse range of properties exhibited by MMCs. Metals 2024, 14, 205. https://doi.org/10.3390/met14020205 https://www.mdpi.com/journal/metals