10weldnjoin_6f - Today 2.008 Design & Manufacturing II...

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1 2.008-spring-2004 S.Kim 1 2.008 Design & Manufacturing II Spring 2004 Welding & Joining 2.008-spring-2004 S.Kim 2 Today ± Ask “Dave and Pat” ± Joining & Welding ± PP 771-861, Kalpakjian ± Quiz 1 on March 17 th , 12:30 PM ± Closed book, calculator ± Lecture notes, HWs ± Q&A session? March 15 th , Monday, 5-6PM ? ± HW# 4, due next Monday 2.008-spring-2004 S.Kim 3 Joining ± Cost: ± Cheap, but expensive labor ± Quality: ± Wide range ± Flexibility: ± Manual vs automated ± Rate: ± Slow in general '& & Very Large Crude Carrier (VLCC) 2.008-spring-2004 S.Kim 4 Joining processes non Laser welding engine emission controller ECUs fasteners door Body muffler windshield plastic fans door hinges 2.008-spring-2004 S.Kim Figures, B. Benhabib 5 Mechanical Fastening ± Any shape and material almost ± Disassemblable (except Rivets, etc.) ± Least expensive for low volume (standardized) ± Problems: strength, seal, insertion, loosening Threaded Bolted Rivets Snap fit 2.008-spring-2004 S.Kim 6 Rivets ± Cheap, light weight, don’t get loose ± Permanent, less strong than bolts ± Rule of thumb ± Minimum spacing = 3 x d ± Maximum spacing = 16 x thickness of the outer plate Rivets
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2 2.008-spring-2004 S.Kim M. Culpepper, MIT 7 Mechanical fastening ± Crimping ± Embossed protrusions ± Plastic deformation / interference ± Appliance ± Automotive Lego assembly, elastic averaging 2.008-spring-2004 S.Kim 8 Mechanical Joining ± Hemming, seaming ± Bend edge of one component over another ± Automobile door stampings and trunk lids 2.008-spring-2004 S.Kim 9 Adhesive Bonding ± Quick and non-invasive ± Most materials with high surface to volume ratio ± Insulation (thermal, electrical), conducting adhesives available ± Good damping ± Clean surface preparation ± Long curing, hold time, low service T ± Reliability, quality? ± Disassembly? 2.008-spring-2004 S.Kim 10 Stefan Equation u y r a h/2 h/2 F = 2 2 4 1 1 4 3 i f h h a Ft µπ ± Squeeze a drop of liquid ± h f goes down, and ± Viscosity goes up (curing) ± Ft goes up (to separate) When pullin apart? = 2 i 2 f 4 h 1 h 1 4 3μμ π Ft ( ) 2 2 3 3 a r dt dh h p = µ 2.008-spring-2004 S.Kim 11 DFA for bonding Do Do Do not Do not ± Weak to tensile loading, strong to shear and compressive ± Organic ± Epoxy, acrylic, etc. . ± Inorganic ± solder, cement, etc. . 2.008-spring-2004 S.Kim B. Benhabib 12 Solid-Liquid: Brazing and Soldering ± In brazing, the filler material (silver, brass, bronze) has a melting point above 425 ºC; and, in soldering, the filler material (lead, tin) has a melting point well below 425 ºC.
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10weldnjoin_6f - Today 2.008 Design & Manufacturing II...

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