New Inexpensive 3-D Printers Open Doors to Novel Experiential Learning Practices in Engineering Education

This work describes a set of new inexpensive 3D printers and their applications in experiential learning as part of engineering education encompassing two multidisciplinary undergraduate engineering programs, Mechatronics and Industrial Engineering. The work addresses applications of inexpensive 3D printers in support of many engineering and nonengineering courses and activities at our university. Challenges of running a successful 3Dprinter lab are addressed. A number of student projects are described. Based on the shear amount of 3D prints and their quality it can be concluded that the acceptance of this technology is high within the undergraduate engineering student population. Introduction Early laboratory demonstrations of additive rapid prototyping systems were conducted thirty years ago (1984). However, the acceptance of these systems in undergraduate engineering curricula was relatively slow due to the high cost of the equipment, the high cost of the materials used, and the high maintenance costs. Only a few engineering departments could afford such machines. Even then, 3D printers were mostly used for demonstrations or a limited number of student projects. However, recently this changed. Namely, a new breed of rapid prototyping machines, the inexpensive 3D printers, based on the fused deposition modeling (FDM) process emerged. Such 3D printers “build” three-dimensional objects by depositing multiple layers of molten plastic, one on top of the other. Instead of paying $100,000 for a single rapid prototyping machine as of a couple of years ago, an engineering department can now equip a whole rapid prototyping laboratory with ten 3D printers for under $20,000. For example, Afinia H-Series and UP Plus 3D Printers cost $1,599, MakerBot Replicator 2’s cost $2,199 while Replicator 2X’s cost $2,799. Also, the plastic filament, acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA), costs between $23/kg and $48/kg, dissolvable filament costs $65/kg, while translucent plastic and flexible filament cost $130/kg. This affordability creates a number of new possibilities for 3D printers’ use in engineering education. Benefits of using 3D Printers in Engineering Education The benefits of using 3D printers in engineering education are many. Now, students can create inexpensive functional plastic parts early in their studies. Even before learning how to create 3D solid models in any of the computer-aided design (CAD) programs (usually taught in the freshmen year) students can download object files from the Web and create 3D objects from them. At the beginning stages of students’ development of 3D visualization skills through CAD programming, an instructor can 3D print some of the parts that are hard to visualize. Then, as soon as the students become proficient with CAD programming they can verify their designs by creating 3D printed parts without having to machine them. Machining skills are usually not emphasized in many engineering curricula. Students are exposed to machining processes such as turning, drilling, milling, grinding, welding, casting, molding, etc. in their second or third year of study in mechanical, industrial, or mechatronics engineering curricula. In other engineering disciplines students may only receive a rudimentary P ge 24932.2 exposure to manufacturing methods. Now, by using 3D printers, students don’t have to wait to their junior year to create something. They don’t have to be proficient as machinists whether using manual or CNC machines. Even when students are capable machinists, the availability of lathes, milling machines, welding stations, CNC machining stations, or other manufacturing equipment is often limited. Machining of many complicated parts requires a number of steps (setups, jigs, fixtures, etc.) that are rather time consuming. Unless a part must be made of metal and requires high precision, it is much faster to design and 3D print such part in plastic – at least at the initial design stages. Supervision and safety of students in a machine shop are always high priority for machine shop coordinators. At most institutions, students are not allowed to work alone in machine shops due to safety concerns. In 3D printing, except for the high temperatures of the extruder assembly and the build platform (for ABS plastic only), there are very few safety concerns. The 3D printing process is mostly a hands-off process. During printing, there are no forces that can propel plastic parts and cause injuries. During the 3D printing process, except for the recommendation to 3D print in a well-ventilated area when printing with ABS plastic due to unpleasant fumes, and not to touch the hot nozzle, there are no other safety concerns. When removing parts from the printer, there are no sharp metal chips or metal edges that can cause serious injuries to students. However, one must be careful when releasing a part (mostly PLA) from the build plate since PLA adheres well to the platform and often a sharp object is used to remove the part. Students’ success in undergraduate engineering programs is attributed to three students’ characteristics: intelligence, intellectual curiosity, and grit. It can be argued that 3D printing increases students’ intellectual curiosity since it provides fewer steps from “imagination to realization.” Also, since students can create real objects in many design phases, they can stay on task longer then before, thus increasing grit. Previous Work The value of experiments, laboratory exercises, and other hands-on experiences in undergraduate engineering education is well established through Kolb’s Experiential Learning Cycle theory. The use of rapid prototyping machines and more expensive 3D printers aiding visualization in engineering graphics courses, teaching additive manufacturing methods in manufacturing courses, and building of prototypes in engineering design courses are well documented in the literature. Kolb’s Experiential Learning Cycle theory 1 claims that regardless of the learning style, a student learns most efficiently if he/she follows a cycle consisting of four steps (axes): experiencing (concrete experience), watching (reflective observation), thinking/modeling (abstract conceptualization), and applying/doing (active experimentation). Kolb’s learning cycle has been used in various engineering education programs such as civil 2-4 , mechanical 4 , chemical 2, 3, 5 , industrial 6 , aeronautical 4 , and manufacturing 2, 3, 7 engineering. Thus, active experimentation like building mechanical objects as visualization aids, building mechanical parts as a new manufacturing process, and building prototypes as steps in the design process or research, is an essential part of the learning process. The success of rapid prototyping projects in engineering education, albeit using expensive 3D printers, has been well reported in the literature. Walsh, Griffin and Crockett 8 use a ZCorporation 3D Printer in biomedical engineering courses. Lai-Yuen and Herrera 9 design a P ge 24932.3 medical device for a surgeon in their manufacturing processes course using an FDM Dimension and a ZCorp 3D printing machine. Leake 10 uses Genisys XS and a Dimensions 3D printer, both from Stratasys, to develop and deliver a new course on Computer-Aided Design, Manufacturing and Engineering (CAD/CAM/CAE). In architecture, Guidera 11 uses a Stratasys 758 BST 3D printer to fabricate a model of an office tower. In his junior-level mechatronics course in a mechanical engineering program Garner 12 prints plastic parts for a printer using a Dimension uPrint FDM 3D printer. Chiou 13 et al. also use a Dimension uPrint 3D printer to fabricate plastic parts for a walking robot in their robotics and mechatronics course. However, the prices of the 3D printers used in the above research as well as the maintenance and material costs are high precluding such 3D printers to be fully integrated into undergraduate engineering education. For example, uPrint 3D printers start at $14,900 which is about an order of magnitude higher than UP Plus 3D printers. While inexpensive, the 3D printers used in our 3D-printing lab are still based on the newest hardware and software developments. MakerBot’s Replicator 2 was introduced in September 2012, while Replicator 2X started shipping in limited quantities on February 25, 2013 14 . The purchase order for our institution was delayed from January to July of 2013 due to manufacturing problems. The Makerware 3D-printing software was upgraded in September of 2013 15 to include dissolving and flexible materials. Engineering students should become familiar with 3D printing technologies because the 3D printing revolution (for product design and manufacture) is in its full swing. Attesting to this is a 3D printing pen 3Doodler, a successful Kickstart project to be released to the public in March of 2014; however, a Chinese company is already selling its clone version. Being proficient with 3Dprinters is in line with ABET General Criterion 3, Student Outcomes 16 (c) “an ability to design a system, component, or process to meet desired needs within realistic constraints such as economic, environmental, social, political, ethical, health and safety, manufacturability, and sustainability” and (k) “an ability to use the techniques, skills, and modern engineering tools necessary for engineering practice.” The Technology: Inexpensive 3D Printers using Fused Deposition Modeling The 3D-printing lab consists of two UP Plus 3D printers, two Replicator 2 printers, three Replicator 2X 3D printers, and one Thing-O-Matic 3D printing kit (not used). The inexpensive 3D printers use FDM rapid prototyping process where a small diameter nozzle deposits heated plastic filament first onto the build surface and then in subsequent passes onto the previous layers thus fusing the layers and creating plastic objects. Even though the 3D printers in the 3Dprinting lab are using the same FDM technology the prin