Engineering and Technology Journal Vol. 38, Part A (2020), No. 02, Pages 226-231 Engineering and Technology Journal Journal homepage: engtechjournal.org 226 Publishing rights belongs to University of Technology’s Press, Baghdad, Iraq Regression and Statistical Analysis of Process Parameters on Heat Affected Zone in Electrical Discharge Machining of Tool Steel Saad K. Shather a , Shukry H. Aghdeab b , Waqass S. Khudier c* a Production Engineering and Metallurgy, Baghdad, Iraq. drengsaad_k_sh@yahoo.com b Production Engineering and Metallurgy, Baghdad, Iraq. shukry_hameed@yahoo.com c Production Engineering and Metallurgy, Baghdad, Iraq. 70127@uotechnology.edu.iq *Corresponding author. Submitted: 16/05/2019 Accepted: 21/06/2019 Published: 25/02/2020 KEYWORDS ABSTRACT Electrical Discharge Machining (EDM), Heat Affected Zone and Response Surface Methodology. The presented study has the aim of finding out the relationships between input variables and process parameters that describe mathematical models, also to estimate the impact of independent parameters on the Heat Affected Zone (HAZ). In the presented paper, A2-Tool Steel material is the utilized workpiece material, whereas copper is the electrode material. RSM, which is the abbreviation of Response Surface Methodology, is used for identifying the impact of controllable parameters; such controllable effects consist of pulse current, pulse on time, and pulse off time on HAZ. It has been noticed that model has been developed by RSM adequacy is suitable since the coefficient related to the determination is considered closest to one for HAZ, whereas the highest percentage of error between experimental and predicted data is (-13.829%). From ANOVA, the pulse current has the most significant factor affected on HAZ with 67.219% contribution. How to cite this article: S. K. Shather, Sh. H. Aghdeab and W. S. Khudier “Regression and statistical analysis of process parameters on heat affected zone in electrical discharge machining of tool steel ,” Engineering and Technology Journal, Vol. 38, No. 02, pp. 226-231, 2020. DOI: https://doi.org/10.30684/etj.v38i2A.304 1. Introduction In EDM, the material is going to be eliminated through melting and vaporizing by all-electric discharges, electrically conductive materials have been machined via accurately sparks at high pressure and temperature between a workpiece and an electrode in the dielectric medium [1]. This is why the machined surface consists of layers that have been thermally damaged that include the white layer and the heat-affected zone. In such different layers, an observation will be conducted on the residual stresses and micro cracks [2].