Concurrent Engineering Concepts Applied to Concurrent ... - CiteSeerX

The paper will be published on the Proceedings of Third ISPE International Conference on Concurrent Engineering, Research and Applications (CE96/ISPE) in the University of Toronto, Ontario, Canada, August 26-28, 1996

Concurrent Engineering Concepts Applied to Concurrent Education and Research Jack Zhou, Shlomo Carmi, Alan Lau, and Spiros Koulas Department of Mechanical Engineering and Mechanics Drexel University Philadelphia, PA

Abstract Concurrent Engineering (CE) has attracted more attention in recent years regarding its reducing the time to market, cutting down the total cost, and improving quality. As a new concept and methodology, CE has not been widely implemented in industry, research and engineering education yet. This paper describes a newly developed CE course which employs the method of concurrent education. Similar to concurrent engineering, concurrent education aims to break the barriers of traditional sequential, or step-by-step, isolated curricula. Concurrent education integrates multistages of curricula and brings interdiscipline teachings into classroom. In this course, a specific research project, Design and Manufacturing of a Rear Wheel Spindle and its Assembly for the FSAE Race Car, was used as an example to illustrate application of CE . A recent survey conducted by ASME council on education has identified the top 20 “Best Practices” in product realization process. It also found that most new engineering graduates lack the fundamental knowledge and skills of the "Best Practices". Concurrent engineering is one of the top 10 best practices. In the newly developed courses of CE using the research project and concurrent education method described in this paper, students not only can learn about concurrent engineering, but also can learn new technologies faster, more efficiently and practically. In this course, the main components of CE: Advanced Tools in CE, Tele-Communication, TeleManufacturing, Team Spirit and Leadership are all emphasized.

1

Introduction

Concurrent Engineering has received substantial attention in the last three or four years. The essence of concurrent engineering is simultaneous or parallel consideration of all facets of the product development process (including design, analysis, manufacturing, testing, quality control and marketing) for the purpose of reducing the time to market, cutting down cost, and improving quality. The implementation of the methodology of CE in product design and manufacturing processes is still in its infancy [1]. Some progressive industries in the United States have applied CE technology into their product development processes and achieved significant benefits: 55% less time to market, 70% higher return on assets , and 350% higher overall quality on average [ 2, 3]. Concurrent Education in our study means concurrently introducing the latest science and technology into the new curriculum development of our high education system, breaking the barriers of traditional sequential (i.e. step by step) and isolated curricula, but integrating multi-stages of curricula and interdisciplinary teachings into classroom. The motivation of proposing and implementing concurrent education can be explained by a Curriculum Development Project of the


ASME Council on Education entitled “Integrating the Product Realization Process (PRP) into the Undergraduate Curriculum [4].” This project was sponsored by the National Science Foundation and conducted by an ASME Project Team of industry and academic experts. This study defines the “Best Practices” widely used by leading companies in PRP, and determines the “Best Practices” for which knowledge and skills are needed by new BS-level engineers and by experienced mechanical engineers. In the study, sixty-six senior managers from thirty three leading companies were surveyed to validate the importance of each “Best Practice” for both new and experienced mechanical engineers. After the survey, industry’s top 20 “Best Practices” were identified from 56 industrial listed “Best Practices” for new BS graduates (see Table 1). Similar survey sent to all accredited mechanical engineering departments in the U. S. revealed that academic respondents agreed strongly with the industry respondents in their ranking of the “Best Practices” by importance. Among the industry’s top 20 “Best Practices” for new graduates , 16 elements were also on academia's top 20 list (Table 1). It is apparent form these results that to better prepare our engineers and to enhance global competitiveness of U.S. industry, the industry’s top 20 “Best Practices” skills should be taught at U.S. universities. From Table 1, it can be seen that Concurrent Engineering was ranked as top 10 in the industry’s “Best Practices,” but it was not even included in academia's top 20 list. Most universities either lack knowledge and understanding of the CE technology, or lack experience in applying the concept of CE in education. Table 1 . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Be st practice s for bach e lor’s-le ve l e n gine e rs INDUS TRY Teams/teamwork Communication Design for manufacture CAD systems Professional ethics Creative thinking Design for performance Design for reliability Design for safety Concurrent engineering Sketching/drawing Design for cost Application of statistics Reliability Geometric tolerancing Value engineering Design reviews Manufacturing processes Systems perspective Design for assembly

% 94 89 88 86 85 85 85 82 80 74 74 74 73 73 71 70 68 68 67 67

ACADEMIA Teams/teamwork Communication Creative thinking Design reviews CAD systems Sketching/drawing Professional ethics Design for performance Design for safety Manufacturing processes Design for manufacture Design for cost Finite-element analysis Design for reliability Physical testing Design of experiments Test equipment Systems perspective Application of statistics Design for assembly Information processing

% 92 92 87 86 86 83 82 82 80 79 74 74 71 70 70 69 68 67 67 65 65

It is not surprising that due to curricula rash in the existing paradigm of mechanical engineering curricula, there is little room for new course in CE. To address this unfortunate situation, an initiative of applying concepts of CE in academia is necessary. A new teaching paradigm, which we label as Concurrent Education, must be developed. In the Concurrent Education paradigm, one can develop integrated curriculum that encourages multi-stage, inter-disciplinary and parallel learning by using the latest technology. In the following sections, we present germane features of a recent study


to apply CE concepts in the Concurrent Education paradigm and to develop research projects and CE course. 2. Advanced Tools in Concurrent Engineering The big advantage, today, for implementing CE is the extensive development of computer aided engineering. By using computer aided engineering all facets of the product development process can access a same design and can innovate and improve the design from the different disciplines by using a common computer aided engineering database. In implementing CE there must be a convenient platform on which different divisions for a new product development can work and communicate simultaneously. For mechanical engineering, this platform should be an advanced CAD/CAM/CAE software which has solid and parametric modeling capabilities. In this study, the CAD/CAM/CAE software used was SDRC’s I-DEAS. The capabilities and major functions of I-DEAS is illustrated in Figure 1. There are three main categories in I-DEAS: CAD, Analysis and Simulation, and CAM. Under the three categories there are many software packages which cover most of mechanical engineering applications. This integrated software can be simultaneously used by different teams such as design, analysis, simulation, testing, manufacturing, quality control and marketing. Besides the software, a manufacturing system integration hardware is indispensable. Figure 2 shows our integrated manufacturing system for CE application and education. In the system, not only software and hardware have been combined as a complete system, but also information feedback flows are constructed to enable application of CE methodology. 3. Concurrent Education In this section we describe the practice of concurrent education in our concurrent engineering course teaching, in which multi-discipline technologies such as CAD, finite element analysis, CAM and CNC machining, automatic control, computer communication and networking, computer aided inspection, and engineering economics are integrated to assist CE methodology and applications. A sequence of courses on concurrent engineering has been developed for the upper level undergraduate students, graduate students and selected engineers from industry on back-to-school retraining. The sequence consists of three three-credit courses; each one is formulated for one academic quarter of learning. The proposed courses are designed to enhance the competitiveness of engineering graduates to


I-DEAS Integrated Design Engineering Analysis Software

CAD C

ANALYSIS & SIMULATION

CAM Manufacturing Process Simulation

3-D Solid Modeling

Finite Element Analys is

Detailed Drafting

S ys tem Dynamics Analys is

Tolerancing

Thermal Modeling Analys is

Assembly Modeling

Optimization

Mechanism Animation

Integrated Data Tes ting. . .

Rapid Prototyping, CNC Machining Plastic Injection Mold Filling and Cooling, Thermoset Molding

Figure 1 A typical CAD/CAM/CAE software for CE applications

C omputer

A ided

D esign

C omputer

A ided

M anufacturing

C omputer and

A ided Q uality

I nspection C ontrol

Sun or HP Workstation

I-DEAS Pro-Engineer Smart CAM

Micromeasure & Contour Software

I-DEAS Pro Engineer AutoCad

Rapid Prototyping CNC Machine

Automatic Inspection (using CMM)

Redesign

Quality Control / Reverse Engineering

Process Modification

Figure 2. An integrated manufacturing system for the CE applications and education


flexibly and cost-effectively create products for a rapidly changing market. Each course in the threecourse sequence has its own theme and emphasis. The first course entitled “CAD/CAM/CAE in Concurrent Engineering” is to introduce the modern tools needed for implementation of the concurrent engineering technology. The second course "Knowledge-based Design and Flexible Manufacturing in Concurrent Engineering" teaches knowledge needed to enhance the quality of design and manufacturing in concurrent engineering. The third of the sequence is “Concurrent Engineering: Design for Manufacturing”. The course will illustrate how the concurrent engineering concept can be successfully introduced in an integrated and simultaneous way for a specific product. 3. 1. Fundamentals of CE and Our CE Wheel The proposed curriculum is designed to enhance the agility, timeliness and competitiveness of engineering graduates to rapidly realize products in today's changing market. In the new curriculum, students will be taught to abandon the obsolete concept that product realization consists of sequential steps of product concept, design, materials, analysis and manufacturing, with each step being handled by experts or specialists having only sequential and marginal interface with each other. The students will be taught that to be competitive, product realization needs to be an agile concurrent process. The main character of today's production engineering is that the design optimization, materials choice, analysis, simulations, choice of manufacturing processes, prototyping and actual production proceed simultaneously with the "specialist" in the each discipline is fully aware of what the others are doing. Information about modifications and feedback from any of the specialist's activities is immediately accessible to everyone in the entire product realization process. Appropriate redesign and new simulations etc. taking into considerations of the materials and manufacturing processes can be undertaken immediately in a parametric way [5]. To put this agile manufacturing concept to work, our engineering graduates, instead of being a specialist in one area (such as design, finite element analysis, or manufacturing etc.) must also be a generalist having good grasp of each aspect of design, materials, simulation, and manufacturing processes. After students have learned the basic concepts of CE and fundamental CE technologies in Section 2 “Advanced Tools in CE,” our CE wheel was established as in Figure 3. In the CE wheel, each team member will take care of several tasks. They need to communicate, collaborate, and coordinate with each other concurrently. 3.2. Team Spirit and Leadership In CE, Team Spirit and Leadership is crucial to the whole product development processes. Different divisions or departments in a CE wheel need to communicate and collaborate with each other appropriately. Individuals in a CE wheel should know that only when the whole project team reaches its final goals each individual will get one’s success. For doing this, leadership skills are very necessary.


Economics (Eugene)

Concept Design (Spiros, Eugene)

Modeling and Design Updates (Fred & Christina)

CNC Machining (Spiros & Daniel) Product Development Center (Spiros & Daniel) CAM (Fred, Christina)

Rapid Prototyping (Daniel)

Finite Element Analysis (Spiros & Eugene)

Assembly (Spiros)

Figure 3. Our CE wheel used in the concurrent education and research projects For learning and practicing Team Spirit and Leadership, students will be formed as several teams. Each team having five to six people will pick up a comprehensive term project which they are interested in, and elect a team leader. Each team organized by the team leader needs to prepare a detail plan for project and have a regular weekly group meeting to check their schedule and progress. In a team, not only members can communicate, discuss the project and shear their knowledge simultaneously, but also each member needs to be in charge of a major task for the project such as design, analysis, manufacturing, and economic analysis. At the end of the term, each team needs to submit a project report and give a presentation to the whole class and a course evaluation team which consists of the members from curriculum development team and the experts from other disciplines and industry. 3.3. CE Research and Application Projects Some ‘Practice Oriented Research Projects for Students’ have been developed in the CE course. The purpose of developing the projects is to let students to apply the CE methodology and techniques they learned to solve a real engineering problem and build their research ability. In the first CE course, there were four projects developed for the students in the class and they are: Design and Manufacturing of a Rear Wheel Spindle and its Assembly for the FSAE Race Car, Finite Element Analysis for a High Pressure Optical Cell, Dynamic Analysis of a Multi-layer Printed Circuit Board, and Reverse Engineering in a Plastic Pump Re-design. In the following we will use the project “Design and Manufacturing of a Rear Wheel Spindle and its Assembly for the FSAE Race Car” as an example to illustrate application of CE.


3.4. A CE Application Example 3.4.1. Introduction The FSAE race car is a small formula style car which is solely designed by university students to compete in an annual competition held by FSAE. Drexel University has participated for many years in this competition and have done better and better each year. For the 1996 competition it has been realized that there is a need for a redesign of the rear wheel spindle. This redesign is necessary because of high cost and difficulty of manufacture of the 1995 spindle design. The 1995 design consisted of many aluminum plates welded together, very inefficient. For the 1996 design it was decided to make the part out of aluminum using CNC machining. 3.4.2. Design Requirements The rear wheel assembly is shown in Figure 4. The following is a list of the requirements that the spindle design has to meet. Functional Requirements: Mounting for upper and lower suspension A-arms; Mounting for tie rod (used for wheel alignment); Mounting for hub and hub mount. Compactness: The entire assembly- spindle, hub, hub mount, A-arms must fit within the inner diameter of the wheel (12.75”) and allow for sufficient wheel travel (1” up, 1” down). Strength: The spindle must be able to withstand extreme driving conditions without permanent deformation, cracking, or excessive bending. Weight and Cost Savings: The spindle must be lightweight (< 2 lb.) and manufacturable for a reasonable cost (approximately $50 to $75 per part when manufacturing 2000 parts.) 3.4.3. Design and Analysis There were four senior students (Spiros Koulas, Christina Arnold, Eugene Kurtz, and Fred Sapp) and a graduate student (Daniel Herscovici) in the race car design team. Dan was the technical coordinator and also a member. Spiros was the team leader. Each member in the team had his/her own tasks and specific responsibility which can be shown in the CE wheel (Figure 3). All the tasks in the CE wheel started simultaneously but with different initial speeds. The tasks with higher initial speeds were those that the running of other tasks were relying on. Considering the functional requirements Spiros and Eugene came up with an initial concept design for the spindle and its assembly. Fred and Christina then built a solid model of the part using I-DEAS. After examining the solid model they were able to make some modifications that improved the fit of the hub unit and reduced the overall size of the spindle. These modifications included moving the widest part of the spindle to match up with the widest part of the hub mount, and radiusing the spindle central to provide a better fit and evenly distributed forces between the hub unit and spindle. Figure 5 shows the updated model. Once they finished the initial modeling the following work can be performed parallelly. After the first modifications Spiros made an assembly modeling to check if the functional requirements were satisfied. These requirements were met as seen in Figure 4. A selected material 6061-T6 aluminum was used for the spindle because of its ease to machine, good strength, and relatively inexpensive. Spiros and Eugene then performed a Finite Element Analysis using loading conditions expected during extreme driving conditions. Meshing and boundary conditions of the FEA can be shown in Figure 6. A 3D solid mesh of element length 0.125 inches was used. The part was constrained in the X, Y, and Z directions through a big central connection hole and three mounting holes on the part. An applied 320 lb. force at the top and bottom mounting holes in opposite directions. Using linear static analysis, the model was solved using the solver in I-DEAS to find the stress distribution and deformation which can be seen in Figure 7. The colored contour plot


represents the stress while the deformed model represents the displacement. The maximum deformation was found to be 1.16E-02 inches, while the maximum stress was found to be 4,000 psi for the given loading conditions. Both of these results are quite adequate, considering the displacement is quite small and the yield stress for 6061-T6 aluminum being 40,000 psi. This gives us a factor of safety of 10. Due to other factors such as road impact, fatigue and alternating stresses which were difficult to analyze, a factor of safety of 10 is not excessive. 3.4.4. Tele-Manufacturing In this project a main research topic is to implement tele-manufacturing in CE. Today’s manufacturing is not only parallel processes, but also a global activity. Taking the advantages of computer networking and tele-communication, a global range tele-manufacturing is possible. In this study two machining processes, rapid prototyping and CNC machining, were achieved using telemanufacturing techniques. In order to check the physical fit and functional requirements it was decided to make a rapid prototype using stereolithography. We contacted AT&T Bell Laboratories at North New Jersey to use their 3D-Systems’ SAL-250 stereolithography machine. Using a SLA postprocessor Dan generated a STL file from the solid model. The size of the compressed STL file for the spindle design was 10 MB containing approximately 40,000 facets. The STL file was transferred to the AT&T Bell Lab through internet using File Transfer Protocol (FTP). With the help of a senior engineer at AT&T Bell Lab, Dan spent 20 hours and

Figure 4. Rear wheel spindle assembly of the FSAE race car


Figure 5. Solid modeling and dimensioning of the spindle


Fig. 6 Boundary conditions used in FEA

Fig. 7 FEA results for the spindle in contour map

brought back a prototype of the spindle. With the rapid prototype we were able to confirm that the part met our form fit and functional requirements. The next step of the process was to actually build the part using CNC machining. We contacted colleagues at SUNY Farmingdale, Long Island, New York, and got their help to use their Cincinnati Milacron 750 machining center. After consulted with CNC instructor/engineer John Bussani at SUNY Farmingdale through many times of e-mail, fax, and phone calls, the project team learned and found out all the information about cutting tools, general layout of the CNC machine, CNC controller, and


clamping fixture, and proposed a first trial of CNC machining process. Fred and Christina generated tool paths using I-DEAS Generative Machining. These tool paths were then converted into G-code which is used by the Controller of the CNC machine. The G-code was then FTPed to SUNY Farmingdale to machine the part. From New York side, after John corrected many errors in the transferred G-code file due to our inexperienced setting, we were ready to machine the part. Spiros, Christina, and Eugene went to SUNY Farmingdale to observe and learn the machining. From a partial trial run on a piece of wooden stock, it was soon found out that the designed clamping fixture was inadequate. The first trial was not successful. They returned to Drexel to make a new clamping fixture. Spiros and Eugene then returned to NY with a new fixture to make the second trial. This time the fixture was adequate and they were able to do a complete run on the wooden stock. However from this trial it was found that some of the tool paths were incorrect, the cutting feeds and speeds were too fast, and the machining process was not the most efficient which would have resulted in a lengthy machining operation. At this point they realized that it would be necessary to re-generate the tool paths and G-code using I-DEAS at Drexel. In the third trial the new machining codes were telecommunicated to NY again. Spiros returned to NY once more to machine the parts. While checking the tool paths an error in one of the procedures was noticed. The project was pressed by a deadline of the final presentation. It was impossible to leave and come back again. Spiros called Fred at Drexel and explained what procedure the error was in. Fred regenerated the tool path and the G-codes for this procedure and then FTPed them to NY, all in a matter of a half hour. When Spiros and John received the code file they were able to complete the machining of the aluminum spindle in one and half hours. 3.4.5. Economic Analysis Although the part was made, we still had some problems. The time that it took was really long. We had to cut the machining time down. This is because that the part will be used on the Drexel FSAE car, and cost of manufacture is very important. In order to reduce the machining time, slight changes were made to the tool paths. Since tolerances were not critical for this part and warpage was not a factor, it was decided that only one cutting pass was necessary. In order to allow the use of a 1” end mill for the entire operation, all the dimensions with round transitional curves on the part were changed from 0.25” to 0.5”(see Figure 5). With these changes, the machining time was reduced to less than 30 minutes per part. As mentioned before for this FSAE race car competition, a major criterion is weight and cost savings. The spindle must be lightweight, less than two pounds, and low cost, not more than $75 per part when manufacturing 2000 parts. The weight criterion has been met from the modified design and chosen 6061-T6 aluminum. The cost savings can be compared as following. Economic Analysis for Manufacture of 2000 parts: Aluminum Stock per part is 52.5 cu. in., Price per cu. in. (60% retail --> based on FSAE guidelines) is $0.29, Material Cost per part is $15.31. Machining time and Machining cost for Initial model and Final model, i.e. after final modification: Initial model, machining time: 1.5 hrs, machining cost: $105.00 ($70.00/hr FSAE guidelines) Final model, machining time: 0.5 hrs, machining cost: $35.00 ($70.00/hr FSAE guidelines) Total cost per part, Initial model: $120.31, Final Model: $50.31 (meets ‘less than $75’ criterion) 3.4.6. Final Presentation We have also developed ‘An innovative evaluation and assessment method for the course teaching.’ At the end of the term, each group needs to submit a term project report and give a presentation to the whole class and a course evaluation team which consists of the members from curriculum development team and the experts from other disciplines and industry. The evaluation team


will review and critique the student projects to examine what the students have learned and the students’ ability to communicate solutions of problems in an industrial nature. After the course evaluation, the FSAE race car design and manufacturing team received the best scours in project contents, team work and presentation. By using CE technology, the FSAE race car team took only five weeks to get the final product-rear spindle starting from initial concept design. 4. Conclusion Concurrent Engineering as a new methodology and a new technology has been applied in our teaching and research. The new paradigm of Concurrent Education has been introduced to our curriculum reformation. In the new CE course developed, an illustrative research project entitled “Design and Manufacturing of a Rear Wheel Spindle and its Assembly for the FSAE Race Car” was conducted using CE methods and the concurrent education approach. The results are saved-time (five weeks student’s school time was used), higher quality (a safety factor of ten was obtained), lowered cost (the cost reduced from $120 to $50 per part), and most importantly trained a new group CE literate engineers. Acknowledgment This study was partially funded by the PRIDE project through NSF Grant #EEC 940910. The authors gratefully acknowledge this support. References [1] G. Halevi and R. Weill, Manufacturing in the Era of Concurrent Engineering, IFIP, NorthHolland, 1992. [2] M. Lawson and H.M. Karandikar, “A Survey of Concurrent Engineering,” Concurrent Engineering Research and Applications, Vol. 2, No. 1, 1994. [3] Andrew Kusiak, Concurrent Engineering-Automation, Tools, and Techniques, John Wiley & Sons, 1993. [4] American Society of Mechanical Engineers, Integrating the Product Realization Process (PRP) into the Undergraduate Curriculum, 1995. [5] Biren Prasad, Concurrent Engineering Fundamentals, Volume 1, Prentice Hall, 1996.