Integrating Rp Technology Into Tennessee Tech’s Design And Manufacturing Curriculum

The rapid advances in computer technology opened new horizons for the faculty who are teaching in CAD/CAM technologies and will continue to do so in the future. Tennessee Tech University (TTU) took the advantage of this opportunity provided by NSF-CCLI-A&I program grant to adapt and implement successful Rapid Prototyping (RP) experiences, and educational practices that have been developed and tested at various engineering schools. RP capabilities affect the pedagogy in the core design and manufacturing curriculum. RP adds excitement and realism to the curriculum by enabling the students to build physical models directly from CAD data. The prototype communicates important information about parts, including engineering data such as fit and limited functional testing, labeling, highlighting, and appearance simulation. Undoubtedly, students who have an understanding of the realities of the relationship between CAD tools and design principles will be much more attune to the realities of the industrial standard in RP. TTU RP objectives have been implemented by integrating new hands-on laboratory experiments into two current junior level required courses; CAD for Technology and CNC Machining Practices. This paper will report the current RP curriculum enhancements accomplished in both courses. The State of the Art The mission for all instructors is to educate their students the best way possible. Their teaching techniques should challenge, educate, and promote the students' innovative thinking 1 . The lecture-based format of teaching, which predominates in engineering education, may not be best to achieve these goals 2 . Through the lecture method, an instructor introduces students to course work by producing notes on a chalkboard or overhead. The instructor then hopes that students can regurgitate this collected information on their homework or exams. Some classes, if students are lucky, have accompanying laboratory practices where they can gain hands-on experience. There have been several attempts to revise engineering curriculum to improve understanding and foster creative thinking 3 . “Proceedings of the 2004 American Society for Engineering Education Conference & Exposition Copyright©2004, American Society for Engineering Education” P ge 967.1 The Manufacturing and Industrial Technology (MIT) Department of the College of Engineering at TTU currently has four courses in the CAD/CAM/CNC areas. In order to eliminate the paperbased submissions and automate the delivery of the MIT courses, WebCT distance learning course materials were prepared for some MIT courses and implemented starting Fall 2002 4 . Program changes are being structured to support the advanced technological education and increase the students’ marketability. The guiding philosophy behind the creation of this structure is to graduate students who have a firm and realistic knowledge of how the manufacturing world functions and the problems to be faced. Many schools worldwide are committed to providing their students with the innovative tools they need to be successful leaders in their future careers. Now a significant focus of the MIT curriculum has become the incorporation of these new tools into MIT’s CAD, CAM, and CNC courses. One of the primary instrumentations to support this purpose is adapting and implementing the RP used by the nation’s technological schools into MIT curriculum 5-7 . In July 1999, TTU’s Technology Access Fund provided a computer laboratory to support many of the software needs for CAD, CAM and CNC practices. Fifteen DELL OptiPlex GX1, Pentium III computers currently run programs such as: AutoCAD, Mechanical Desktop, Pro/E Wildfire, MasterCAM, and CNCez. In December 2002, this computer lab was upgraded to include 22 Pentium IV computers and multimedia teaching capabilities. Although students gain excellent experience with industrial – level CAD/CAM/CNC software tools, compatible advanced manufacturing hardware is limited for producing parts in a real environment. Since the hands-on labs are very important to concrete the CAD/CAM/CNC concepts, lack of adequate CAM and CAD application hardware is the “weak link” in the current enhancement effort. MIT students’ lab practices were limited to conventional CNC turning and milling projects. There was no high technology equipment beyond a couple of CNC machines. Therefore, implementing RP filled the gap between CAD/CAM and provided MIT students with the opportunity to practice high tech prototyping assignments. A Generic Overview on RP RP consists of various manufacturing processes by which a solid physical model of a part is made directly from 3D model data, without any special tooling. CAD data may be generated by 3D CAD modelers or model data created by 3D digitizing systems 8 . Charles Hull is given credit with bringing the first commercial RP machine to market in 1987 with SLA-1 5,9 . His machine, like all RP machines, requires 3D CAD data for its operation. To begin the RP process, the 3D CAD data is sliced into its thin (~.005 in.) cross-sectional planes by a computer. The cross-sections are sent from the computer to the RP machine, which builds the part layer-by-layer. The first layer’s geometry is defined by the shape of the first cross-sectional plane generated by the computer. It is bonded to a platform or starting base and additional layers are bonded on top of the first, shaped according to their respective crosssectional planes. This process is repeated until the prototype part is complete. The advantages of RP are obvious: development of physical models can be accomplished in significantly less time as compared to the traditional machining process. Some other applications “Proceedings of the 2004 American Society for Engineering Education Conference & Exposition Copyrightø2004, American Society for Engineering Education” P ge 967.2 of these technologies include development of molds, patterns for casting, and tooling. The prototype built by RP machines can be put to a number of uses as given in Table 1. Table 1: The Advantages of Rapid Prototyping Systems Check the feasibility of new design concepts Visualization Function/fit test and verification Conduct market tests/evaluation Promote concurrent product development Make Rapid tooling Make many exact copies simultaneously Use as a master for metal mold conversion Manufacturing producibility and supplier quoting Reverse Engineering using RP Three-dimensional prototypes put students and designers on equal footing in evaluating designs. All the interested parties can see, touch, and handle the design, just as the ultimate customers will. Most students can’t see the design changes or final designs in product form until tooling is produced. New concept-stage RP technologies can provide dozens of snapshot views of the final product at a fraction of the time and cost of RP systems. This lets students watch as the product evolves and lets them take more chances and be more creative as less time, effort, and ego are invested in each model. The various existing RP methods can be categorized by the material they use: photopolymer, thermoplastic, and adhesives. Photopolymer systems start with a liquid resin, which is then solidified by discriminating exposure to a specific wavelength of light. Thermoplastic systems begin with a solid material, which is then melted and fuses upon cooling. The adhesive systems use a binder to connect the primary construction material. The typical processes are SLA, LOM, SLS, FDM, and 3D Printing 8 . Rapid Prototyping Technology at TTU Although neither the current TTU curriculum nor any other school in the state of Tennessee had an educational RP laboratory to practice 10 , Middle Tennessee State University, Murfreesboro, TN has recently purchased some rapid prototyping machines for their machine tool technology lab. These machines were planned to be used in industrial projects and senior level capstone courses 11 . At TTU, all the CAD design labs are currently done with AutoCAD2002 in the computer lab, and the CNC production labs cover only Milling and Turning Processes practicing CNCez and MasterCAM. Establishing the RP laboratory and enhancing the current courses with RP help the course instructor to convey the cutting edge technology to current students in these courses. Since the initial introduction of the RP process in 1987, several machines have entered the market, which are now affordable by universities. Project team has searched many sources in order to decide which RP machine will be selected. A low cost per prototyped part is important because of the need to prototype a large number of concepts, and to have many student teams use the machine. Speed is important as well. With a class size ranging from 15-20 students and plans “Proceedings of the 2004 American Society for Engineering Education Conference & Exposition Copyrightø2004, American Society for Engineering Education” P ge 967.3 to increase the class size to 40 students, a machine that takes 1-2 days to produce a part would limit student access. The use of benign printing materials also would make it safer to let students work with the system. Because of the short time allowed in the course schedules for the projects, and large number of student teams, cost and speed are the two main determinants in the decision to purchase the Z406 machine 12 . The speed of the system allows an entire class of students to color print parts out for their projects within a week. Additionally, it is easier to modify parts after they have been printed, just as traditional foam models are reshaped. Safety concerns are negligible with the Z406 machine. After a communal build is completed, students receive the final parts they designed and built. There is also no need to add additional support structure on the CAD part design. This extra work is totally eliminated with the Z406 system.