Speaker：Hongtao Ding, PhD, Assistant Professor, Department of Mechanical & Industrial Engineering, University of Iowa
 
Time: 14：00－16：00
 
Date: Friday, Dec 19, 2014
 
Venue: Room F310, School of Mechanical Engineering
 
Abstract
Laser-Assisted Machining (LAM) is the process of locally preheating a workpiece with a focused laser beam ahead of the material cutting location. By lowering the material strength in the cutting area at a certain elevated temperature, LAM can achieve lower cutting force, slower tool wear progression rate, higher material removal rate and better surface quality for difficult-to-machine materials. The limited adoption of LAM as the final finishing process by industry is basically due to: (1) the lack of the appreciation of its total benefits compared with traditional finish grinding processes, and (2) the lack of knowledge of the effect of the LAM process on the performance of the finished components. The challenge lies in optimizing the laser-assisted micro and macro machining processes so that the temperature required for the large decrease in workpiece strength does not shorten the life of the cutting tool or adversely affect the finished surface quality and part dimensions. In this talk, microstructure and surface integrity is studied experimentally and numerically for difficult-to-machine materials during LAM. One-step laser-assisted machining process is proposed for hardened AISI 4130 steel to replace the hard turning and grinding operations. A heat transfer model is developed to predict the temperature field inside the workpiece of complex geometry undergoing laser-assisted profile turning. Microstructure of 4130 steel workpiece is simulated using the 3D nose turning option in AdvantEdge FEM by considering both phase transformation kinetics and grain refinement. The surface integrity analysis is experimentally studied by changing heating and operating conditions, viz., average material removal temperature, cutting speed and feed.

 
Biography
Dr. Hongtao Ding is an Assistant Professor in the Department of Mechanical and Industrial Engineering at the University of Iowa. His research areas include laser-based material processing, manufacturing process modeling, micro/nano materials processing, hybrid machining and wind turbine manufacturing. Dr. Ding established the Laser Materials Processing Lab (LMPL) at the University of Iowa. Dr. Ding has published 20 archival journal papers. His pioneer work on physics-based modeling of surface integrity and microstructural change has been recognized for its impacts on metal working industry. Dr. Ding has developed innovative technologies of laser-assisted machining (LAM) and micromachining to improve the machinability of difficult-to-machine materials critically needed by the aerospace and automotive industries in the past 10 years. He has received the ASME Best Paper Award (MSEC2011). Dr. Ding has been serving on the editorial board of several journals including as Associate Editor for the International Journal of Materials Forming and Machining Processes. He has actively participated in activities organized by professional societies including ASME and SME. Dr. Ding has organized the symposium of “Laser, Process Innovations and Energy Field Manufacturing Methodology” for the ASME International Manufacturing Science and Engineering Conference from 2013 to 2015. He received his B.S. and M.S. degrees from Shanghai Jiao Tong University, China, M.S. from the University of Michigan at Ann Arbor, and Ph.D. from Purdue University, all in Mechanical Engineering.