Manufacturing Practices A Hands-On Course in Metalworking for Engineering Undergraduates

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1 Manufacturing Practices A Hands-On Curse in Metalwrking fr Engineering Undergraduates Richard Kunz 1 Abstract It is a recurring bservatin amng industry stakehlders that graduating engineers are well-versed in engineering sciences, but lack certain fundamental skills needed t make immediate cntributins in the wrkplace: ability t functin in teams, aptitude fr creative synthesis and design, cmmunicatin skills, and an understanding f the realities f manufacturing. At Mercer University, a curse in Manufacturing Practices prvides students with the pprtunity t gain significant hands-n fabricatin experience in a machine shp envirnment while develping teaming, design, and cmmunicatin skills. The curse has prven valuable in preparing students fr the senir-year capstne design experience as well as fr the realities f the wrkplace. Keywrds: Manufacturing practice; machine shp; welding; teaming. INTRODUCTION Emplyers f engineering graduates inevitably have certain expectatins f their new emplyees. It will always be a struggle fr engineering schls t deliver graduates that meet all f these expectatins. In particular, as technlgy advances, the demands n the graduate, and therefre n the clleges, increase. Breadth versus depth and fundamentals versus applicatins are cnstant surces f debate amng thse charged with establishing and refining engineering curricula. It is clearly nt pssible t be all things t all emplyers. A cmmn thread amng engineering emplyers is that graduates lack fundamental skills needed t make immediate cntributins: understanding realities f manufacturing practices, ability t functin in teams, aptitude fr creative synthesis and design, and cmmunicatin skills. The fllwing bservatins are typical ver a wide range f firms emplying engineers. The head f a small cmputer systems engineering cmpany wrte [Galvan, 1]: We expect recent cllege graduates t arrive at the wrk place fully armed and ready t cntribute t the bttm line.... Additinally, it appears that recent cllege graduates generally lack practical, immediate skills; skills demanded by current market frces; skills such as being able t wrk in teams, being familiar with current technlgies, and a fundamental understanding f systems engineering are glaring examples.... The currency f detailed technical skills is imprtant, but graduates als lack fundamental skills. Skills with the written and spken language are deterirating. In fact, it has becme a cliché that scientists and engineers can nt write. A representative f a large dmestic aerspace cntractr made the fllwing bservatin [McMasters, 2]: We see t many new graduates with an inadequate grasp f what engineering (as cntrasted with engineering science) is and hw ne practices it, particularly in the currently evlving industry envirnment. T few f ur engineering graduates seem t have any idea f hw t wrk in teams r hw t manufacture anything. The reasns fr this situatin are many and cmplex, as are the ptential appraches t addressing it. At Mercer University, a curse in Manufacturing Practices, required f students specializing in Mechanical Engineering, Industrial Engineering, and Engineering Management and typically taken in the junir year, prvides students with 1 Assciate Prfessr, Department f Mechanical Engineering, Mercer University, Macn, GA 31207, kunz_rk@mercer.edu

2 an pprtunity t gain significant hands-n fabricatin experience, while develping teaming, design, and cmmunicatin skills. This curse, in cmbinatin with a freshman design curse and the senir capstne design experience, gives students valuable experience in putting int practice knwledge gained in mre traditinal lecture and labratry curses while bringing t bear certain critical aspects f life n the utside. COURSE OVERVIEW A majr fcus f the curse is t prvide each student with a hands-n familiarity with machines and tls used in typical fabricatin prcesses. At the first class meeting, each student is assigned t a team f tw t three members. The members f each team wrk tgether n all grup activities during the term. Curse activities cnsist f three majr parts, each cmprising apprximately ne-third f the semester: Machine shp familiarizatin Welding technique familiarizatin Design prject The class meets twice a week fr three hurs each meeting. A typical class sessin begins with a presentatin by the instructr, explaining the bjectives fr the class and demnstrating the tls and equipment being used. The demnstratin is generally fllwed by an exercise in which each team takes a turn n the machines t accmplish a specific task, such as drilling a specified hle pattern, r cutting and bending sheet metal t specificatins. Each member f the team is required t take a turn n the machines t ensure that all students have a nearly equal handsn experience. Grades in the curse are based n the fllwing: Take-hme quizzes cvering material frm the assigned reading in the texts and in-class presentatins In-class written tests at the end f the machine shp and welding mdules Practical exams at the end f each blck f instructin in shp skills. Each student makes an article t specificatins using machines and techniques learned during the exercises The design prject, in which each team designs and builds a fixture fr the prductin, n a vertical milling machine, f a specified part. During the curse f the prject, each team prduces a preliminary design reprt, a final design reprt, and fabricates and demnstrates the fixture. Perfrmance, which is a subjective measure f the students attitude, attentiveness, safety cnsciusness, and team cntributins. COURSE COVERAGE Students gain expsure t a variety f machine tls, hand tls, and welding equipment during the first eight t nine weeks f the semester divided between the machine shp and the welding shp. Safety prcedures and equipment are cvered in detail during the first class meeting and re-emphasized thrughut the term. A particular pint is made that students are respnsible nt nly fr their wn safety but fr the safety f their classmates as well. Students are encuraged t ask questins whenever they are unsure abut a prcedure r if they feel uncmfrtable abut a prcess. Mst imprtantly, n pressure is put n the students t finish a particular exercise befre the end f the scheduled class meeting. Machine Shp Mdule During the machine shp mdule, students gain familiarity with capabilities, peratins, and prcesses invlving a number f typical machine shp tls and machines, Figure 1. Exercises and presentatins include: Measurement using rules, micrmeters, and vernier calipers

3 Threads, thread classes, fits, tapping and drilling Dimensining, tlerancing, and manufacturing drawings Drilling with a drill press, grinding, sawing with a band saw, and use f hand tls Use f a lathe fr turning, cutting threads, and knurling Precisin milling using a vertical milling machine Sheet metal cutting with a shear brake, riveting Figure 1. Students wrk at a lathe, milling machine, and press brake Fr the practical exams, each student makes a meat tenderizer and a chimney cap (Figure 2). The meat tenderizer uses lathe techniques including turning, tapering, knurling, and cutting threads, as well as milling peratins t cut the pattern n the head. The chimney cap invlves layut, use f the press brake fr cutting and bending, and riveting. Teams wrk tgether n the practical exams, but each student must prduce a finished article. Figure 2. Machine shp practical exam: meat tenderizer; chimney caps

4 Welding Techniques Mdule During the welding mdule, students gain expsure t: Oxyfuel gas welding Shielded metal arc welding (SMAW) Gas metal arc welding (GMAW) Resistance welding, Plastic welding Sldering Fr the practical exam, each student makes a bt scraper (Figure 3). Figure 3. Welding shp practical exam: bt scraper DESIGN PROJECT The design prject cmprises a majr cmpnent f the curse, bringing int play machine shp techniques, wrking in teams, written and ral cmmunicatin, and design. During the furth week, the teams are given a Request fr Prpsals (RFP) cntaining the specificatins fr a fixture fr mass-prducing a specific part frm blanks n a vertical milling machine. Each team is given three weeks t respnd t the RFP with a preliminary design reprt, fllwed by a detailed design reprt fur weeks later. The teams spend the last fur weeks f the term building their fixture frm the detail design, and demnstrate it during the last class perid. Fixture requirements frm a typical RFP are shwn in Figure 4. The part that the fixture is designed t prduce is shwn in Figure 5. Each team submits a written prpsal which amunts t a preliminary design in respnse t the RFP. As with industry RFPs, prpsals must adhere t specified requirements which are detailed at a brief bidder s cnference. The prpsal is required t include three parts: Prblem Definitin, in which the team cmmunicates its understanding f the prblem and the requirements Design Cncept Descriptin, which cntains an verview (with drawings) f the fixture cnfiguratin and a descriptin f hw the design will meet each f the custmer requirements.

5 Analysis f the Design Cncept, which demnstrates that the blank is accurately and securely held in the fixture during all machining peratins. Prblem: Design and build a fixture fr mass prducing a Lvejy cupling (see Figure 5) frm blanks using a vertical milling machine. The fixture must prvide fr safe, rapid accurate machining f blanks int the required part. Detailed Requirements: The fixture shall prvide adequate supprt fr machining parts withut using a vise. Prper alignment f the blanks shall be accmplished withut the aid f a sine plate. The head f the milling machine shall remain vertical fr all machining steps. The fixture shall be capable f making the parts frm blank runds nminally 2 in diameter x 1.5 in. The lateral edge f the blanks will be either saw cut r rugh milled. Once each blank is clamped in the fixture, prper machining shall nt require any measurement f the blank itself. All finish dimensins shall be btained by mvement f the milling machine table relative t a psitive reference pint in the fixture itself. The machine peratr shall be capable f finding that psitive reference pint accurately and reprducibly if necessary. This shall be pssible withut the use f an edge finder. The fixture shall prvide enugh clamping pints t prevent excessive mvement f the blank while it is being machined. The fixture shall prvide fr accurate, reprducible alignment f the fixture with the lng axis f the table f the milling machine. Tw hles shall be prvided fr securely and accurately munting the fixture t the table f the milling machine. Figure 4. Typical specificatins fr the design prject. Figure 5. Lvejy cupling Teams then receive feedback frm their prpsals and are given detailed requirements fr the Final Reprt. The Final Reprt cntains all the infrmatin required t fabricate and assemble the fixture and t use it t make the part. As such, it cntains the fllwing elements: A Bill f Materials, including estimated csts, fr the raw materials cmprising the fixture.

6 Detail drawings f each part cmprising the fixture, cntaining sufficient infrmatin fr a machinist t fabricate the part A parts list An assembly drawing, shwing hw the fixture is put tgether frm its cmpnent parts Detailed, step-by-step instructins fr using the fixture t make the part, including: Munting, securing and aligning the fixture n the milling machine Munting, securing, and aligning the blank in the fixture Setting the zer psitin Prper cutting tls t be used fr each machining peratin Tl paths fr each machining peratin A key fcus f the Final Reprt is its clarity and cmpleteness. It is emphasized that this reprt cnstitutes the sle enduring dcumentatin fr the fixture. It must be sufficiently self-cntained that, in twenty years, smene culd use it t build and perate the fixture. The ability f engineers in industry t prvide clear, cmplete, and selfcntained dcumentatin f their designs is in many respects just as valuable as their ability t design. The teams spend the last five weeks f the term building and testing their fixture accrding t the final design (Figure 6). The last class perid, each team demnstrates their cmpleted fixture (Figure 7) t the class, discussing its features, any design changes made during the prcess, and lessns learned during its design and cnstructin. Figure 6. Student teams wrk n their fixtures Figure 7. A cmpleted fixture with the fabricated part COURSE OUTCOMES AND STUDENT REACTION It is nt the intentin f the curse t enable students t becme certified machinists. Rather, the fcus is t give them a basic familiarity with machine shp and welding shp tls, practices, and capabilities. This is accmplished in large part via the hands-n nature f the class activities. Students gain a firm appreciatin f what it takes t make a part t specificatins, as well as the effect f dimensining and tlerancing n fit, frm, and functin. It is imprtant that design engineers be able t cmmunicate effectively with manufacturing engineers and technicians, and the experiences gained in this curse are valuable in develping this capability. Pre-requisites fr the curse include Statics and Graphics and Visualizatin. Students use their knwledge f statics in their fixture design t ensure that the blank is adequately restrained during machining peratins. They apply their graphics educatin t prduce detail and assembly drawings in the final design reprt. Thus, this curse is perhaps their first pprtunity t apply what they have learned in previus curses t a cncrete utcme.

7 This is als perhaps the first curse in which students functin as a member f a team frm the very beginning. Because f the nature f the class activities, class attendance and punctuality are mandatry. It is impressed n the students frm Day One that their individual success and the success f their team are clsely linked. With very few exceptins, students have shuldered their team respnsibilities very well; due t the small class size and small team size, it is difficult fr a nn-functining team member t hide. In general, the atmsphere in the shp is intentinally lw-key and nn-threatening. Fr many students, the shp is a relatively unfamiliar envirnment, and sme are clearly intimidated by the activities. Each student is required t take a turn n the machines; it is gratifying t see their cnfidence increase as the term prgresses. Discussins f safety cnsideratins accmpany each new machine tl being used. Fr safety reasns, students are encuraged t wrk deliberately and t ask questins; the plicy is nt t rush the students t cmplete a prject. Hrseplay is abslutely nt tlerated in the shp, and has rarely been an issue. Standards fr bth the preliminary design prpsal and the final reprt are enfrced fairly rigidly. The requirements fr reprts f this nature in an industrial cntext are emphasized, as are the reasns behind strict frmatting and cntent requirements. In many industries, a design can lng utlive its designers; when mdificatins are required, the dcumentatin prvides the nly link t the riginal design intent and specificatins. Hence, a prime curse bjective is t give students an appreciatin fr the imprtance f clear and standardized dcumentatin. Class enrllment is limited t twelve students per sectin. Tw sectins are typically run each semester. This class size enables fur teams f three students each. Because Mercer s machine shp has fur vertical milling machines and fur lathes, the teams can wrk in parallel. Class demnstratins are typically perfrmed n ne f the machines, with students gathered arund t watch; having mre than twelve students in the grup wuld severely limit visibility and effectiveness f the demnstratins. An engineering technician and a faculty member administer the curse. The technician is fully versed in machine shp peratins, and requires (and exhibits) nearly infinite patience in explaining and demnstrating the necessary skills. The faculty member is respnsible fr the preliminary and final design reprts and fr prviding back-up t ensure that peratins run smthly in the shp. Clearly, a key t making the curse wrk effectively is t have n staff a technician with the necessary machine shp skills as well as the necessary temperament. Student reactin t the curse tends t be very psitive. Undubtedly, this is partly due t the fact that it is a welcme change f pace frm the traditinal lecture and lab curses that dminate the curriculum. But there is als a sense f accmplishment frm learning new skills and having smething tangible t shw fr it at the end. I enjyed actually making things, is typical f the student respnses t the curse evaluatin. They als have a genuine appreciatin fr the effrt put frth by the curse instructr. Mr. Campbell deserves sme majr recgnitin in being an amazing instructr in the lab. He is very calm and understanding when a student has questins r cannt physically perfrm assigned tasks. SUMMARY AND CONCLUSIONS A curse in Manufacturing Practices at Mercer University s Schl f Engineering prvides students with a handsn experience in the machine shp and the welding shp. Students perfrm exercises n a variety f machine tls drill press, band saw, grinder, lathe, milling machine as well as welding equipment t gain cnfidence, if nt prficiency, in using the equipment. Practical exams give the students the pprtunity t apply their new-fund skills t the fabricatin f ptentially useful items. A majr cmpnent f the curse is a prject, in which student teams design, build, and demnstrate a fixture t be used in the machine shp t fabricate a specified small part. Teams respnd t a Request fr Prpsals with a preliminary design, fllwed by a detail design dcumenting fixture fabricatin and use. The teams then build their fixture in the machine shp and demnstrate them t the class at the end f the curse. In additin t the experience f fabricating items t specificatins, curse activities prvide students with the pprtunity t develp teaming, design, and cmmunicatin skills. The curse therefre serves as a useful bridge between the freshman design curse and the senir capstne design experience. Furthermre, it at least partially

8 addresses industry needs fr yung engineers having the requisite skills t cntribute in the mdern industrial envirnment. REFERENCES [1] Galvan, I. J., Math, Science, and Technlgy Undergraduate Educatin in America: One Small Business Perspective, Shaping the Future: Perspectives n Undergraduate Educatin in Science, Mathematics, Engineering and Technlgy, Natinal Science Fundatin, Pub. N , 1998, pg [2] McMasters, J. H, J. D. Lang, Enhancing Engineering and Manufacturing Educatin: Industry Needs, Industry Rles, Prceedings, 1995 ASEE Annual Cnference and Expsitin, Anaheim, CA, June 25-28, Richard Kunz, Ph.D., P.E. Richard Kunz has been Assciate Prfessr f Mechanical Engineering at Mercer University Schl f Engineering since Fall After receiving his dctrate frm Gergia Tech in 1978, he served n the faculty f Tech s Schl f Engineering Science and Mechanics. In 1985, he left academia t wrk in the Advanced Structures Department at Lckheed-Gergia Cmpany, develping methds fr incrprating advanced cmpsite materials in aircraft structures. This was fllwed by 15 years at Thikl Crpratin (nw ATK Launch Systems) investigating case, nzzle, and prpellant structures fr slid rcket mtrs. He als hlds a BS frm Crnell University and a MSME frm Gergia Tech, and is a registered Prfessinal Engineer in the State f Utah.