Design For Manufacturing - Cornell University

Design For ManufacturingMAE 2250

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Phases Phase 0: PlanningPhase 1: Conceptual designPhase 2: System designPhase 3: Detail designPhase 4: Testing and refinementPhase 5: Production ramp-upIterate

Over The Wall

Two things hppened Manufacturing people were put on the designteam– “Concurrent engineering” Manufacturing requirements were made veryspecific and became ‘needs’ themselves– The ‘new customers’

DFX The service people are customers: Design forservicability The environment is a customer, ‘Design forenvironment’ Design for manufacturing (DFM) Design for Assembly (DFA) Design for X (DFX)

DFMDFM is a means of addressingproducibility issues early in the designcycle, and integrating manufacturingconcerns and considerations into adesign to obtain a more producibleproduct

DFM ProcessEstimate themanufacturing costsReduce cost ofcomponentsReduce cost ofassemblyConsider effects onother factorsReduce cost ofsupporting production

FixedPertimePerproduct

CategoriesQA, shippingCustom approximates standard for high enoughquantities (e.g. electric motor, 100,000/yearSecurityguard, AirconditioningAssembly is usually done by humans evenfor mass produced products, unless veryvery high quantities ( 100,000)

Reducing cost of components Understand the limitations of the fabricationprocesses; do not exceed normal capabilitiesunless you really have to– Geometry (Making a square hole is hard)– Accuracy and tolerances of machining– Surface finish of casting

Understand cost drivers Welding cost is proportional to weldinglength, fixturing Machining cost is proportional to materialremoved, fixturing Injection molding? Thickness of part. Workwith experts to find out details E.g. produce an tall open box by bending andwelding. Where would you put bends andwhere welds?

Redesign to eliminate process steps Use net-shape processes. Forging, casting andmolding provide close to final shapes andeliminate machining steps E.g. Stamped piece: U shape with two holes. Ifholes are on base, can be stamped in one go.If holes are on flanges, needs two steps

Chose process with economy of scale Injection molding Machining Additive Manufacturing

Jeff Hanson, RedEye RPM

g-your-production-bets-with-3d-printing

Reducing Assembly costs DFA index: Theoretical minimum number ofcomponents x 3 seconds, divided by actualassembly time– Shorter actual assembly time higher index Theoretical minimum– Do parts need to move with respect to each other?(ignore compliant mechanisms)– Must the parts be made of different materials?– Do the parts need to be separate froaccess/maintenance reasons?

Integrate parts Fewer assembly steps (higher DFA)Reduced cost of tooling (e.g. fewer dies)More control over relative positioningConflicts with modularity!

Integrate parts Fewer assembly steps (higher DFA)Reduced cost of tooling (e.g. fewer dies)More control over relative positioningConflicts with modularity!

Consider customer assembly Assemble-it-yourself furniture Good also for packing and shipping Requires very careful and intuitive assemblyplan

Reduce cost of supporting production Less equipment – flexible equipment “Just in time” production Frequent error proofing. Design your productso critical errors are self-evident.– E.g. design some notches and protrusions so thatif parts are not assembled correctly, next partwont fit

Guidelines Heuristics (rules that are generally true)– have been developed for various manufacturingtechnologies. Some DFM guidelines–––––––Guidelines for machiningGuidelines for assemblyGuidelines for injection moldingGuidelines for sheet metal processingGuidelines for sheet die formingGuidelines for castingGuidelines for welding

DFA Goals Reducing costs Reducing time Reducing errorsIn some projects (e.g. aerospace, cost is lessimportant than time and error. In others, e.g.toys, cost is more important than error)

Guidelinesforassembly

Guidelinesforassembly

Design for robotic assembly

Guidelinesforassembly

Guidelinesformachining

Guidelinesformachining

Guidelinesforinjectionmolding

Guidelinesfor sheetforming

Guidelinesfor sheetforming

Guidelinesfor casting

Are you still here?A.B.C.D.E.YesNoOnly physically (but not spiritually)Spiritually (only my clicker is here)What-e-ver

Guidelines Heuristics (rules that are generally true) –have been developed for various manufacturing technologies. Some DFM guidelines –Guidelines for machining –Guidelines for assembly –Guidelines for injection molding –Guidelines for sheet metal processing –Guidelines for sheet die forming –Guidelines for casting