Design for Assembly Time estimation Design Rules RedesignTime Estimation for AssemblyHandling pick up orientInsertion location (obstructed view? Self locating?) hold down and resistance securing methodSymmetryHandling Issues36001809000β360360901801800αSize Fragile/SharpNest/TangleSlippery/FlexibleB-D Manual handling chartInsertion IssuesObstructed Access/ViewAlignmentInsertion ForceB/D chart 2-2 first &secondB-D Manual insertion chart1 – screw(2) (steel)not easy to align2 – cover(steel) not easy toalign – assembly worker’sfingers must be used toalign edges3 – spring(steel) (closed ends)subject to continuous cycling andmust be spring steel4 – piston stop(plastic)edge is chamfered for easeof alignment5 – piston(aluminum) obstructedaccess for insertion of spindle intobottom of bore6 – main block(plastic)depth of bore is 28mmwith small through hole forpiston spindlePneumatic PistonSub-AssemblyB-D Manual handling chartpistonscrews coverspringB-D Manual insertion chart AcoverpistonspringB-D Manual insertion chart BscrewsPneumatic Piston Sub-Assembly1 2 3 4 5 6 7 8 9Name of AssemblyPart I.D. No.number of times the operation is carried out consecutivelytwo-digit manual handling codemanual handling time per parttwo-digit manual insertion codemanual insertion time per partoperation time, seconds (2)*[(4)+(6)]operation cost, cents 0.4*(7)figures for estimation of theoretical minimum partsPNEUMATIC PISTON6 1 30 1.95 00 1.50 3.45 1.38 1MAIN BLOCK5 1 10 1.50 10 4.00 5.50 2.20 1PISTON4 1 10 1.50 00 1.50 3.00 1.20 1PISTON STOP3 1 05 1.84 00 1.50 3.34 1.34 1SPRING2 1 23 2.36 08 6.50 8.86 3.54 0COVER1 2 11 1.80 39 8.00 19.60 7.84 0SCREW43.75 17.50 4 design efficiency 0.27TM CM NM = (3*NM)/TMBoothroyd/Dewhurst Design RulesReduce part count and part typesStrive to eliminate adjustmentsDesign parts to be self-aligning and self-locatingEnsure adequate access and unrestricted visionEnsure the ease of handling of parts from bulkMinimize the need for reorientations duringassemblyDesign parts that cannot be installed incorrectlyMaximize part symmetry if possible or make partsobviously asymmetricalRules to reduce part countDuring operation of the product, does the partmove relative to all other parts already assembled?Only gross motion should be considered – small motionsthat can be accommodated by elastic hinges, for example,are not sufficient for a positive answerMust the part be of a different material than or beisolated from all other parts already assembled?Only fundamental reasons concerned with materialproperties are acceptableMust the part be separate from all other partsalready assembled because otherwise necessaryassembly or disassembly of other separate partswould be impossible?1 – snap on cover andstop (plastic)2 – spring(steel)3 – piston(aluminum)4 – main block(plastic)Redesign:Pneumatic PistonSub-AssemblyRe-design1 2 3 4 5 6 7 8 9Name of AssemblyPart I.D. No.number of times the operation is carried out consecutivelytwo-digit manual handling codemanual handling time per parttwo-digit manual insertion codemanual insertion time per partoperation time, seconds (2)*[(4)+(6)]operation cost, cents 0.4*(7)figures for estimation of theoretical minimum partsPNEUMATIC PISTON (re-design)4 1 30 1.95 00 1.50 3.45 1.38 1MAIN BLOCK3 1 10 1.50 00 1.50 3.00 1.20 1PISTON1 1 05 1.84 00 1.50 3.34 1.34 1SPRING2 1 10 1.50 30 2.00 3.50 1.40 1COVER & STOP13.29 5.32 4 design efficiency 0.90TM CM NM = (3*NM)/TMSee master mechanic electric screw
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