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INTRODUCTION TO DESIGN FOR MANUFACTURE AND ASSEMBLY (DFMA)

INTRODUCTION TO DESIGN FOR MANUFACTURE AND ASSEMBLY (DFMA). J.JAYARAMAN CENTRE FOR AEROSPACE SYSTEMS DESIGN ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY , BOMBAY. STRUCTURE OF THE PRESENTATION. WHY AND WHEN:

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INTRODUCTION TO DESIGN FOR MANUFACTURE AND ASSEMBLY (DFMA)

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  1. INTRODUCTION TO DESIGN FOR MANUFACTURE AND ASSEMBLY (DFMA) J.JAYARAMAN CENTRE FOR AEROSPACE SYSTEMS DESIGN ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY , BOMBAY

  2. STRUCTURE OF THE PRESENTATION • WHY AND WHEN: • EARLY MANUFACTURING KNOWLEDGE IMPROVES PRODUCT SUCCESS • EXAMPLES OF BENEFITS • DFMA IN WORLD WAR II • WHAT: • WHAT IS INTEGRATED DESIGN AND MANUFACTURE

  3. STRUCTURE OF THE PRESENTATION (CONTD.) • HOW: • HOW TO ACHIEVE INTEGRATED DESIGN AND MANUFACTURE • -BDI SOFTWARE • -FMECA • EXAMPLES: • - ACCELERATION SENSING UNIT • -WORKED EXAMPLE • -POWER SUPPLY OF LASER Tx HIGH VOLTAGE • CONCLUSION

  4. BEST PRACTICES TO PRODUCT DEVELOPMENT PRODUCT DEVELOPMENT TECHNOLOGY DEVELOPMENT INTEGRATION DEMONSTRATION PRODUCTION KNOWLEDGE POINT3 KNOWLEDGE POINT 1 KNOWLEDGE POINT 2 TECHNOLOGIES ANDRESOURCES MATCH REQUIREMENTS PROGRAM LAUNCH PRODUCTION CAN MEET COST SCHEDULE AND QUALITY TARGETS DESIGN PERFORMS AS EXPECTED

  5. ATTAINMENT OD DESIGN AND MANUFACTURING KNOWLEDGE WEAPON SYSTEM % OF DWGS. COMPLETED % OF CRITICAL MFG. PROGRAM PRIOR TO MFG. PROCESSES IN CONTROL EXPERIENCE AT PRODUCTION MEET COST & SCHEDULE TARGETS AT LEAST 90% DWGS. COMPLETED ALL CRITICAL PROCESSES IN STATISTICAL CONTROL BEST PRACTICE AIM-9X (AIR-AIR MISSILE) 95% 4% UNIT COST INCREASE 1 MONTH PRODUCTION DELAY UNKNOWN 44% 23% UNIT COST INCREASE 18 MONTH PRODUCTION DELAY 26% F-22 FIGHTER

  6. ATTAINMENT OF DESIGN & MFG. KNOWLEDGE (contd.) WEAPON SYSTEM % OF DWGS. COMPLETED % OF CRITICAL PROCESSES PROGRAM PRIOR TO MFG. IN CONTROL AT PRODN. EXPERIENCE F18 E/F FIGHTER 78% NO UNIT COST INCREASE 3 MONTH PRODUCTION DELAY 58% * PATRIOT ADVANCED CAPABILITY (PAC-3) MISSILE 159 % UNIT COST INCREASE 39 MONTH PRODUCTION DELAY 21 % 35 % ADVANCED THREAT INFRARED COUNTER- MEASURES/ COMMON MISSILE WARNING SYSTEM 21% 182 % UNIT COST INCREASE 34 MONTH PRODUCTION DELAY 0 %

  7. BENIFITS OF DFMA THERE IS A MUCH BETTEER OPPORTUNITY TO MEET PREDICTED COST SCHEDULE AND QUALITY TARGETS WHEN THE MANUFACURING PROCESS DATA IS CAPTURED EARLY

  8. BENEFITS OF DFMA (CONTD.) • F 18 E/F HAS 42% FEWER PARTS THAN C/D EVEN THOUGH IT IS 25% LARGER • REDUCED • -PRODUCTION COSTS • -DEFECTS • -REWORK • BY APPLYING DFMA BDI SOFTWARE & SOURCES OF VARIATION IN THE PROCESS

  9. BENEFITS OF DFMA ( CONTD.) TOMOHAWK CRUISE MISSILE STRATEGIC TACTICAL PARTS 11500 7500 FASTENERS 2500 800 CIRCUIT CARDS 45 22 CONNECTORS 160 45 ASSEMBLY/ TEST HOURS 610 195 UNIT PRODUCTION COST $1000,000 $500,000

  10. ASSEMBLYTIME FOR BALL CAGE DEVICE REDUCED TO 15SEC FROM 130 SEC. 8 SCREWS TO NO SCREWS DFMA METHOD OF ELIMINATING FASTENERS ASSEMBLY OPERATIONS FROM 83 TO 54 TOTAL ASSY. TIME 592SEC. TO 277 SEC.

  11. RIBBON BASEPLATE DIABLO PRINTER OLD DESIGN 77 PARTS

  12. NEW DESIGN 36 PARTS

  13. COMPARISON OF ORIGINAL NEW DESIGNS OF RETICLE ASSY. ORIGINAL DESIGN REDESIGN IMPROVEMENT% ASSY. TIME HRS 2.15 0.33 84.7 NO. OF DIFF. PARTS 24 8 66.7 TOTAL NO. OF PARTS 47 12 74.5 METAL FABN. TIME HRS. 12.63 3.65 71.1 WEIGHT LBS. 0.48 .26 45.8

  14. ORIGINAL OPTION 1 PILOTS INSTRUMENT PANEL LONG BOW APACHE AH-64D HELICOPTER BOEING COMPANY OPTION 2

  15. PILOT’S INSTRUMENT PANEL ORIGINAL PANEL NEW PANEL ( OPTION 1 ) PARTS COUNT 74 9 FABRICATION TIME HRS. 305 20 ASSY./INSTALLATION TIME HRS. 149/153 8/153 TOTAL TIME HRS. 697 181 WEIGHT KG. 3.0 2.74 COST $ 56000 15000

  16. Advantages of DFMA • Typical results of DFMA application • Results of 88 published case studies Decreases • 51% parts count reduction • 37% parts cost • 50% time to market • 64% in assembly time • 57% in manufacturing assembly time • 58% in assembly operations • 69% in separate fasteners • 68% in assembly defects • 57% in service calls 68% in improvement in quality and reliability

  17. Benefits of DFMA • Shorter developmental schedules and reduced cycle times. • Better first article quality • Development of robust product designs • Easier transition of designs to production • Better supplier product integration • More effective risk management

  18. McDonnel Douglas experience • Reduce number of parts and fasteners used on aircraft • It means fewer opportunities for defects • For each fastener there is the chance that the hole will be drilled in the wrong place or be the wrong size • By reducing the number of fasteners – numbers of defects reduced, therefore, produce a higher quality product • Weight is critical. Fuel costs approximately $50,000 per pound of aircraft weight over 6000 hrs of the life of the aircraft • There are 179000 on the FA-18 CD fasteners • In previous models several parts were made of sheet metal because machined parts were unable to reach minimum gage limits • With high speed machining – thinner gauge limits have become possible

  19. ACCELERATION SENSING ASSEMBLY OPTION-I OPTION-II

  20. PARAMETER OPTION - I OPTION - II NATURAL FREQUENCY 250 Hz 548 Hz ESTIMATED ACCURACY ± 3.5 MINUTES ± 1.5 MINUTES MEASURED ACCURACY ± 2.7 MINUTES ± 1.5 MINUTES EMI GASKET PROVISION NO YES SIZE 254 x 117 x 86 mm 254 x 117 x 78 mm ESTIMATED WEIGHT (W/O ELECTRONICS) 1.90 Kg 1.80 Kg MEASURED WEIGHT (W/O ELECTRONICS) 1.92 Kg 1.72 Kg NUMBER OF FABRICATED PARTS 25 15 MACHINING TIME 18.1 Hours 8.3 Hours MACHINING COST Rs 559.17 Rs 256.75 COMARISON TABLE ASA OPTIONS

  21. DFMA IN WW II • WORLD WAR II EXPERIENCE: • US AVIATION INDUSTRY GREWW TEN FOLD • P-51 MUSTANG FIGHTER • - TO FACILITATE EASE OF MANUFACTURE • STABILISERS FINS WINGTIPS SQUARED OFF • - FUSELAGE – THREE SECTIONS- COMPLETE • PLUMBINGS, CABLE DISCONNECTS TO • FACILITATE ASSEMBLY AND DISASSEMBLY • FOR PACKING AND SHIPPING

  22. DFMA IN WW II (CONTD.) • DFMA INFLUENCE ON DESIGN OF GRUMMAN F-6F HELLCAT • - USED FEWER COMPOUND CURVES IN • EXTERNAL DESIGN-UGLY- SEVERELY • CLIPPED WINGS • - PRODUCED IN LARGE QUANTITIES • - 32 KPH SLOWER THAN F4U HERITAGE 1980 • DFMA INFLUENCE PERMITTED SHIPMENT BY BOAT OR LAND. OUT WING PANELS AND EVEN TAIL ASSEMBLIES REMOVED AND REPLACED AT THE DESTINATION POINT.

  23. SPITFIRE VS. MESSERCHMIDST • IN 1940 Me’s OUTNUMBERED SPITFIRES THREE TO ONE. DESIGN ATTRIBUTABLE TO DFMA PHILOSOPHY. Me’s 4000 LABOUR HOURS TO SPITFIRE 13000 HOURS • AIR WAR HISTORIANS DESIGNATE SPITFIRES AS THE BETTER AIRCRAFT, THE LONG AND SUCCESSFUL CAREER OF ME 109’s DURING ARAB ISRAELI WAR 1948 DEMONSTRATED THAT MAJOR ATTENTION TO DFMA PRODUCES EFFECTIVE AIRCRAFT DESIGN EVEN AS EARLY AS 40’s

  24. SPITFIRE VS. MESSERCHMIDST. • SPITFIRE: • DESIGNED FOR AERODYANAMIC PERFORMANCE AND STRUCTURAL EFFICIENCY • BEAUTIFUL ELLIPTICAL WINGS CHOSEN FOR AERODYNAMIC PERFORMANCE WAS A NIGHTMARE TO MASS PRODUCE • DIFFICULT TO LEARN TO FLY, HIGHLY MANOEUVERABLE • WAS PRODUCED IN LARGE NUMBERS BECAME A MAJOR FORCE IN BATTLE OF BRITAIN AIR CAMPAIGN 1940-41

  25. SPITFIRE VS. MESSERCHMIDST • MESSERCHMIDST • DESIGN WAS A DFMA CLASSIC • A MINIMUM OF COMPOUND CURVES USED IN THE EXTERIOR • RUDDER AND HORIZONTAL STABILISERS WERE SQUARED OFF FOR PRODUCTION EFFICIENCY • COCKPIT CANOPY WAS MADE ALMOST ENTIRELY OF FLAT GLASS • 20 MM CANNON FIRED THROUGH A HOLLOW PROPELLER SHAFT TO OVERCOME COMPLEXITIESOF WING INSTALLATION AND TO ELIMINATE SIGHTING PARALLAX

  26. INTEGRATED DESIGN AND MANUFACTURE • SIMULTANEOUSLY ADDRESS DESIGN FOR PERFORMANCE AND DESIGN FOR PRODUCTION • SYSTEMS ENGINEERING HAS ALIGNED DESIGN ENGINEERS IN REQUIREMENTS ANALYSIS, THE DEVELOPMENT OF FUNCTIONAL FLOWS etc. • INCLUDING THE ASPECTS OF MANUFACTURING PROCESS DEVELOPMENT IN THE SYSTEM ENGINEERING PROCESS HAS BEEN MORE DIFFICULT TO ACHIEVE

  27. DESIGN HAS DIFFERENT MEANINGS • TO SOME IT IS AESTHETIC DESIGN • TO SOME IT MEANS ESTABLISHING THE BASIC PARAMETERS OF A SYSTEM • TO SOME IT IS DETIALING OF THE MATERIALS, SHAPES,AND TOLERANCE OF THE INDIVIDUAL PARTS OF THE PRODUCT • DFMA ADDRESSES THE LAST ASPECT OF PRODUCT DESIGNS

  28. DFMA • THREE MAIN APPROACHES TO DESIGN FOR ASSEMBLY HAVE BEEN DEVELOPED AND USED Viz.: • DESIGN HEURISTICS • DESIGN RATINGS • DESIGN REVISION

  29. DESIGN HEURISTICS • GENERAL SET OF RULES eg.: • MINIMIZE THE NUMBER OF PARTS & ASSEMBLY DIRECTIONS • AVOID PARTS THAT SHINGLE TANGLE etc. • HEURISTICS CAN BE APPLIED TO A DESIGNER’S THINKING PRIOR TO ACTUAL PRODUCT DEVELOPMENT OR ONCE AN ASSEMBLY IS COMPLETE • USED TO SIMPLIFY PRODUCT

  30. DESIGN RATING • PROVIDE RATINGS FOR COMPONENTS AS WELL AS OVERALL DESIGN • ASSEMBLY RATINGS CAN BE CALCULATED • BDI HAS THEORETICAL HANDLING AND MATING RATINGS • OTHER DFA RATING METHODS PROVIDE DIFFERENT SCHEMES

  31. DESIGN REVISION METHOD • COMBINATION OF HEURISTICS AND RATING METHOD eg. BDI • BDI COMBINES A COMPONENT RATING SCHEME WITH AN ASSEMBLY TIME AND COST ESTIMATION METRIC AS WELL AS SPECIFIC RULES IN AN ORDERED SEQUENCE FOR DECIDING HOW TO REVISE A DESIGN. THIS HAS ENABLED PRODUCT DESINERS IN MINIMISING ASSEMBLY SIMPLICITY

  32. DFMA METHODOLOGY • WALKING THROUGH A CONCEPTUAL OR EXISTING DESIGN IN A VERY SPECIFIC PROCEDURE THROUGH OUT • THE PROCEDURE FOLLOWED AND THE DATA BASE SYSTEM ALLOWS A DESIGN ENGINEER OR CROSSFUNCTIONAL TEAM TO ANALYSE AND RATE PRODUCT DESIGNS FOR EASE OF ASSEMBLY, DESIGN EFFICIENCY AS WELL AS PREDICT PRODUCT ASSEMBLY AND MANUFACTURING COST

  33. DFMA METHODOLOGY(CONTD.) • CAD RESULTED IN POWERFUL QUANTITATIVE OR ANALYTICAL TOOLS, PROVIDED BASIS FOR JUDGING A DESIGNER’S PERFORMANCE. DFMA HAS GIVEN MANUFACTURING ENGINEERS SUCH A TOOL. • DFMA IS ATTEMPTING TO FORESEE AT THE PRODUCT CONCEPTUAL DESIGN STAGE , WHAT MANUFACTURING ASSEMBLY AND QUALITY PROBLEMS WILL BE TO ARRIVE AT A BETTER PRODUCT

  34. DFMA tools • Are tools for DFM & DFA

  35. DFM ACTIVITY DFM TOOLS SIMPLIFY OPTIMIZE CONCEPT ENSURE PROCESS CONFORMANCE OPTIMIZE PRODUCT FUNCTION DFM TOOLS DESIGN AXIOMS DFM GUIDELINES DESIGN FOR ASSY. METHOD TAGUCHI METHOD MFG. PROCESS DESIGN RULES DESIGNERS TOOLKIT COMPUTER AIDED DFM GROUP TECHNOLOGY FMEA VALUE ANALYSIS

  36. KEY TO ADVANTAGES • NARROW RANGE OF POSSIBILITIES • RESULTS IN INHERENT ROBUSTNESS • READY REFERENCE TO BEST • PRACTICES • EMPHASISES EFFECTS OF • VARIATIONS • HELPS IDENTIFY AND PRIORITIZE • CORRECTIVE ACTION • PROVIDES BOTH GUIDANCE AND • EVALUATION • CAN SHORTEN DESIGN /TOOLING • CYCLE • CAN REDUCE TOOLING AND • FIXTURING COST KEY TO DISADVANTAGES A. INTERPRETATION NOT ALWAYS SIMPLE B.. REQUIRES “BUY IN” ON PART OF USER C. EXCEPTIONS ARE NOT INDICATED D. RATES ONLY EASE OF ASSY.DOES NOT ADDRESS PART HANDLING OR OTHER RELATED MFG. PARAMETERS E. DEVELOPMENT REQUIRES INPUT FROM EXPERIENCED EXPERTS FAMILIAR WITH SPECIFIC PROCESS CAPABILITIES AND NEEDS F. TO BE USED ON A REGULAR BASIS IMPLEMENTATION MUST BE USER FRIENDLY G. MUST BE DEVELOPED AND/OR CUSTOMISED FOR EACH SPECIFIC APPLICATION H. OFTEN REQUIRES DIFFICULT TO OBTAIN INFORMATION DFM METHODOLOGY COMPARISON (CONTD) • KEY TO APPLICATIONS • MECHANICAL AND ELECTROMECHANICAL DEVICES AND ASSEMBLIES • ELECTRONIC DEVICES AND SYSTEM • MANUFACTURING AND OTHER PROCESSES • SOFTWARE INSTRUMENTATION AND CONTROL SYSTEM INTEGRATION • MATERIAL TRANSFORMATION PROCESSES • SPECIFIED AND OR UNIQUE MANUFACTURING FACILITIES SUCH AS • FLEXIBLE ASSEMBLY SYSTEMS

  37. DFMA application areas • DFMA has been applied successfully to • Structural design • System design • Landing gear system • Flight controls • Electrical, electronic hydraulic systems • Environment controls

  38. COST AND EASE OF MODIFICATIONS

  39. BENIFITS OF IMPROVED ASSY. MANUAL DESIGN ASSEMBLY EFFICIENCY (%) ( DFA INDEX ) IMPROVED ASSEMBLY DESIGN EFFICIENCY RESULTS IN INCREASED RELIABILITY

  40. When to apply DFMA • WHEN CONCEPTUAL LAYOUTS ARE BEING MADE. THEN DESIGNER ENVISIONS AN ASSEMBLY EASY TO INSTALL THAT REQUIRES MINIMUM NUMBER OF PARTS TO PERFORM THE REQUIREMENTS PREVIOUSLY ESTABLISHED • WHEN ASSEMBLY LAYOUTS ARE BEING MADE. DESIGNER IMPLEMENTS OPTIMISATION TO EASE OF MANUFACTURING , RELIABILITY AND MAINTAINABILITY

  41. Who are using DFMA • Over 400 companies and institutions • Aerospace companies • Allied signal • Hughes Aircraft • McDonnell Douglas Corpn. Have implemented DFMA philosophy throughout their product line • Automotive industries • Medical electronic equipment • PC – industry and others

  42. DFMA Team Multidisciplinary teams • Design engineers • Manufacturing engineers • Shop floor mechanics • Suppliers reps • Specialist in product support • Maintainability • Reliability

  43. DFMA • BDI software • Is used by manufacturing team members to estimate and predict the savings that can be obtained. • Data are entered system does its analysis in different areas. • A complete listing of all the activities required to perform the assembly including • It provides complete overview of the tasks to be performed

  44. DFMA TECHNIQUE DESIGN CONCEPT SUGGESTIONS FOR SIMPLIFICATION FOR PRODUCT STRUCTURE DESIGN FOR ASSEMBLY ( DFA ) SELECCCTION OF MATERIALS AND PROCESSES AND EAZRLY COST ESTIMATES SUGGESTIONS FOR MORE ECONOMIC MATERIALS AND PROCESSES BEST DESIGN CONCEPT DETAIL DESIGN FOR MINIMUM MANUFACTURING COST DESIGN FOR MANUFACTURE ( DFM ) PROTOTYPE PRODUCTION

  45. BDI software • It does an assembly analysis profile on a standard format where it theorizes the number of tasks to be performed, fasteners required, connectors to be installed, candidates for elimination, acquisition of items not in reach or in stock, requisition of tools not in hand, standard operations, library of operations and recommendations. • All these activities are numbered and plotted. It automatically provides suggestions for improvement. • System provides suggestions for design and indicating every task with its time saving and its percentage reduction. It indicates specific instructions to perform the related tasks in order to obtain the suggested savings. • It also lists design for assembly analysis totals all parameters used for analysis such as total assembly time, totally assembly cost, total assembly weight, number of parts, sub assemblies theoretical minimum numbers of parts or unanalysed sub assemblies and the hourly labour rate. • All suggestions and comments included in the computer generated tables are automatically provided to aid the designers and manufacturing engineers to obtain a better view of the job

  46. Questions asked in DFMA about each part in a product design • Does the part move with respect to other parts already assembled • Must the part be made from a different material or isolated from all other parts already assembled • These questions lead the reviewers to re-evaluate each part and process that has been specified • If a part does not meet any of these criteria – it is a candidate for elimination or consolidation with another part

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