At the Georgia Institute of Technology (Georgia Tech; Atlanta), there’s both a whole lot of innovation and some major renovations going on at the university’s George W. Woodruff School of Mechanical Engineering.
Long known for turning out some of the best and brightest in engineering fields, Georgia Tech’s school of mechanical engineering is putting the final touches on some major changes to its Design Studio and Invention Studio, located in the university’s Manufacturing Related Disciplines Complex (MRDC) headquarters.
The renovation project, underway for some 15-20 weeks, involved knocking down walls and integrating much of the hands-on manufacturing and machining areas at the Montgomery Machining Mall’s Design Studios and Invention Studios. “We did the Montgomery Machining Mall about a year ago. We’re just finishing the Design Studios, and now we’re starting to take apart the Invention Studio, so we’re doing it in phases,” said SME President Thomas Kurfess, P.E., FSME, a Georgia Tech mechanical engineering professor and HUSCO/Ramirez Distinguished Chair in Fluid Power and Motion Control. “It’s a multimillion-dollar upgrade.”
Immersion in Manufacturing
For Georgia Tech mechanical engineering students, diving right into manufacturing doesn’t take long, with a design/build curriculum that introduces undergraduate freshmen first to design with CAD classes that also make use of 3D printing. The next year, sophomores tackle manufacturing and building things in ME 2110, a course taught by Kurfess that he said is considered the toughest class in the curriculum. The university annually graduates roughly 3-4% of all mechanical engineering undergraduates in the nation, he noted.
The early immersion in building products in the ME 2110 class is a “trial by fire” for students. “It defines our culture,” said Kurfess, who took over the course in 1997 and shifted it to more of a manufacturing focus. “I’m not a design person—I’m a build person, I’m a manufacturing person. We design, and we build in ME 2110!”
In the class, many students who haven’t had any exposure to manufacturing get to learn and see that they can actually build things. “If you ask any student ‘what was your most difficult course,’ almost every one says ‘ME 2110,’ because you’ve got to build stuff,” Kurfess said. “It’s not like they’re solving huge equations, but it is typically the first time they have to design and build a complex system that works reliably.
“It’s great to draw something up, but [you have] to build it and have it work—not only once, but time after time after time, because you’re running in a competition,” Kurfess continued. “It defines the culture of mechanical engineering here, this one particular course. I wouldn’t call this a weed-out course, as most students perform well above expectations; however, we get them in there and tell them, ‘You can do this.’ A lot of them have never had any experience like this; we work with them on it, and when they walk out, their life [has changed].”
The course provides skills for the next step in manufacturing, according to Kurfess. “They’re still far away from designing a new BMW or next-generation combat aircraft but [the course] is where the stake is put in the ground,” he said. The design/build experience is a common thread woven throughout the four-year undergrad program, he added.
Hands-On in the Shop
Out in the Montgomery Machining Mall, students have access to a variety of machining equipment, ranging from basic two-axis Bridgeport and Sharp milling machines to many kinds of lathes, grinders, presses, saws, EDMs, and metrology gear. In the Invention Studio, there’s an entire wall filled with just 3D printers, Kurfess said.
Georgia Tech runs team competitions three times a year—fall, spring and summer—where students put inventions through their paces. “When they get to the second year course, they’re machining things and assembling things, and [they participate in] a competition where they’re actually building and programming an autonomous system,” Kurfess said.
The competitions have had second-year students programming controllers running FPGA (field programmable gate arrays) and ARM processors, Kurfess noted. “To make these systems work, they have to machine [parts for] motors and solenoids and sensors and so forth,” he said. “We give them designs for brackets and couplers and they have to machine and build these systems. This is the next step in their training. It’s one thing to say ‘Oh, I want to print this part on a 3D printer.’ You’ve got to design it to do certain tasks. So now, besides the paper design, they’ve got to be able to build it. And all of a sudden, they learn why it’s important to hold a tolerance.”
In Georgia Tech’s third-year classes, students continue learning a variety of manufacturing processes—3D printing, machining, and basic metrology—before moving into other areas like injection molding, Kurfess said. In their senior year, students have capstone projects that in many instances are sponsored by companies that require students to design and build products.
Expanding the machine shop’s scope gives instructors and students a lot more access and flexibility. “Space was really tight, but in the manufacturing group, [some] very forward-thinking people said ‘we’ve got our manufacturing research labs and we have our machine shops—let’s knock down the walls and create a huge shop area where we have research going on and teaching going on, and students have access to these machines,” Kurfess said. With the expansion, the school now has graduate and undergraduate students who are either paid or volunteer to run the various shop operations seven days a week.
—Senior Editor Patrick Waurzyniak
Tech Papers from SME Journals
and Manufacturing Letters
These summaries, excerpts, and web links are from recent papers published in the SME Journal of Manufacturing Systems, Journal of Manufacturing Processes, and Manufacturing Letters, which are printed by Elsevier Ltd. (www.elsevier.com) and used here with permission.
Special-Purpose Machines for Modular Drilling
In their paper, “Drilling reconfigurable machine tool selection and process parameters optimization as a function of product demand,” authors Ana Vafadar, Kevin Hayward, and Majid Tolouei-Rad of the Edith Cowan University (ECU; Perth, Australia) School of Engineering, describe a new special purpose machine to provide a modular platform for performing drilling operations. The paper, published in the Journal of Manufacturing Systems, Volume 45, is available through ScienceDirect at http://www.sciencedirect.com/science/article/pii/S0278612517301255.
Special-purpose machines (SPMs) are customized machine tools that perform specific machining operations in a variety of production contexts, including drilling-related operations. This research investigates the effect of optimal process parameters and SPM configuration on the machine tool selection problem versus product demand changes.
A review of previous studies suggests that the application of optimization in the feasibility analysis stage of machine tool selection has received less attention by researchers. In this study, a simulated model using a genetic algorithm is proposed to find the optimal process parameters and machine tool configuration.
During the decision-making phase of machine tool selection, unit profit is targeted as high as possible and is given by the value of the following variables: SPM configuration selection, machining unit assignment to each operation group, and feed and cutting speed of all operations.
The newly developed model generates any random chromosome characterized by feasible values for process parameters. Having shown how the problem is formulated, the research presents a case study which exemplifies the operation of the proposed model. The results show that the optimization results can provide critical information for making logical, accurate, and reliable decisions when selecting SPMs.
Hot Deformation and Processing of Martensitic Stainless Steel
In their paper, “Hot deformation behavior and processing maps of AISI 420 martensitic stainless steel,” authors Facai Ren, Fei Chen, Jun Chen, and Xiaoying Tang, of the Shanghai Institute of Special Equipment Inspection and Technical Research, Key Laboratory of Pressure Systems and Safety, Ministry of Education, East China University of Science and Technology (Shanghai), and Department of Plasticity Technology, Shanghai Jiao Tong University, the authors investigate testing processes for stainless steel used in a wide range of applications.
The hot deformation behavior of AISI 420 martensitic stainless steel is investigated though isothermal compression tests using a Gleeble-1500D thermal-mechanical simulator in a temperature range of 1123–1423 K and strain rate of 0.01–10 s−1. The hot deformation apparent activation energy is calculated about 363 kJ/mol.
Processing maps are conducted on the basis of the experimental data and the dynamic materials model (DMM) to reveal the hot workability. When the strain is no less than 0.5, the optimum hot working condition corresponds to the deformation temperature range of 1280–1360 K and strain rate range of 0.01–0.05 s−1 with a peak power dissipation efficiency of about 0.43 at strain rate of 0.01s−1 and temperature of 1323 K. Two instability regions are detected from the processing maps and should be avoided during hot working.
The paper, published in the Journal of Manufacturing Processes, Volume 31, is available at http://www.sciencedirect.com/science/article/pii/S1526612517303808.
Heat-Affected Zone in Laser-Assisted Milling of Inconel 718
The Journal of Manufacturing Processes, Vol. 30, features a full-length article, “Heat affected zone in the laser-assisted milling of Inconel 718,” describing the processes involved in using lasers to mill Inconel 718, by authors Zhipeng Pan, Yixuan Feng, Tsung-Pin Hung, Yun-Chen Jiang, Fu-Chuan Hsu, Lung-Tien Wu, Chiu-Feng Lin, Ying-Cheng Lu, and Steven Y. Liang, of the Woodruff School of Mechanical Engineering, Georgia Institute of Technology (Atlanta) and the Metal Industries Research and Development Centre (MIRDC; Kaohsiung, Taiwan). The paper is available at http://www.sciencedirect.com/science/article/pii/S1526612517302803.
The melting zone shape is experimentally characterized in the laser-assisted milling process of Inconel 718. A 3D finite element model is proposed for the temperature field distribution prediction. A good agreement is found between the experimentally characterized melting zone shape and predicted melting zone shape. The material absorption ratio is determined by matching the melting zone shape from experimenting with a simulation model. The material absorption ratio is found to be a weak function of laser scanning speed.
With the increase of laser power input, the absorption ratio monotonically decreases. The effects of laser scanning speed and power input on the melting zone shape are investigated. The melting zone depth, width, and cross-section area decrease with the increasing of laser scanning speed and increase with increasing power input.
How Cutting Speeds and Cooling Methods Affect Ti Machinability
In their paper, “Influence of cutting speed and cooling method on the machinability of commercially pure titanium (CP-Ti) grade II,” authors Akhtar Khan and Kalipada Maity of the Department of Mechanical Engineering at the National Institute of Technology (Rourkela, India), discuss how cutting speeds and different chip cooling methods can improve machining of CP-Ti. The paper, published in the Journal of Manufacturing Processes, Volume 31, January 2018, is available at http://www.sciencedirect.com/science/article/pii/S1526612517303869.
The present investigation aims in highlighting the influence of cutting speed and an eco-friendly cooling technique during finish turning of CP-Ti grade 2. Experiments were performed at three distinct machining modes: dry cutting (DC), flood cooling (FC) and minimum quantity lubrication (MQL) using carbide inserts. Water soluble oil and vegetable oil were used as cutting fluids with FC and MQL respectively.
The work material was turned at three different cutting speeds, i.e. 51, 67 and 87 m/min, whereas feed rate and depth of cut were kept as constant at 0.12 mm/rev and 0.5 mm respectively. A comprehensive exploration on the cooling effects of vegetable oil based MQL method on some of the key machinability aspects (such as cutting force, tool wear, friction coefficient, chip morphology, chip reduction coefficient, micro hardness of machined surface, surface roughness and machining temperature) is reported. The aforesaid turning responses were recorded and compared in order to exhibit the feasibility of the MQL approach in comparison with dry and flood cooling approaches. The results obtained during the investigation clearly established the superiority of implementing MQL for achieving improved machinability within a specified range of process parameters.