Session 5 DFMA Roadmap- Concurrent Engineering

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1 Session 5 DFMA Roadmap- Concurrent Engineering Lecture delivered by Prof. M. N. Sudhindra Kumar Professor MSRSAS-Bangalore 1

2 Session Objectives At the end of this session the delegate would have understood Road map of DFMA Why and when DFMA is used. Role and importance of DFMA in product design What is DFA, DFM, DFEA and DFNA Different types of Assembly Systems Goals of DFMA and drawbacks of DFA Concurrent Engineering Process 2

3 Session Topics 1. DFMA ROAD MAP 2. DFMA - Why and When 3. Role and Importance of DFMA in Product Design 4. Benefits of DFA 5. Components of the DFMA Process 6. Design Architecture 7. Number of Parts 8. DFMA and Process Capabilities 9. Process Classification 10. Material Handling and Fixtures 11. Theoretical Minimum Number of Parts 12. Assembly Efficiency 13. Assembly Systems 3

4 Session Topics 14. Process Characteristics 15. Choice of Assembly Method 16. Selecting a process 17. DFMA Goals 18. DFA Drawbacks 19. Concurrent Engineering Process 4

5 DFMA ROAD MAP PEMP 5

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9 DFX as lifecycle Oriented or Ability Oriented 9

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12 DFMA - Why and When 1. Increasing competition. 2. Being first in a market segment means setting the price levels and standards for how the product can be used (Technical improvements may create new business - and may be alone for a limited amount of time in that segment). Product development is one of the most important activities in order to create competitive products. Success of a product is dictated by its costs, performance and reliability which is to a very large extent are predetermined by the work of designers. 3. Manufacturing can be a competitive advantage - this requires awareness of manufacturing processes. As competition increases, lead times are shrinking and manufacturing processes are becoming more elaborate. Companies can not afford haphazard approach to design and manufacture. 12

13 DFMA - Why and When PEMP The answer is not "always!. The designers will normally concentrate first and foremost on getting the product to function within the economic limitations laid down. Time is at a premium; as a result the most important activity in the closing phase of design is to get the product detailed so it can be in production as soon as possible, in other words getting the drawing finished. Assembly deliberations can easily become a minor part of a large hectic process - the result being a non-optimal product from the assembly point of view. 13

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15 Role and Importance of DFMA in PRODUCT DESIGN Design dictates cost. Early decisions have far reaching impact on the product cost, quality and reliability. DFMA helps quantification of improvements very early in the design process and in many phases of the design process. As the basis for concurrent engineering studies DFMA provide guidance to the design team in simplifying the product structure - to reduce manufacturing costs - to reduce assembly costs - quantify the improvements 15

16 Role and Importance of DFMA in PRODUCT DESIGN As a benchmarking tool - to study competitor s products and quantify manufacturing and assembly difficulties. It can be used in simplifying new concepts. Simplifying fully embodied designs 16

17 Benefits of DFA Fewer parts major cost savings more reliability Simplified assembly reduced defects Shorter assembly time shorter throughput Enhances team work Shorter product cycle time- earlier to market Improved product quality Enhances value Increases customer satisfaction 17 PEMP

18 DFMA vs VA/VE VA/VE - Systematic review of the cost of producing a part/product and the evaluation of design alternatives that could produce desired results,the desired value at the lowest cost. Emphasis is in identifying needed functions and value appropriateness. Value analysis, unlike DFMA, does not give proper the structure of the product and its possible simplification. It focuses on identification of basic functions and unwanted functions(existing because of the present design). DFMA - emphasis on the structure of the product and its simplification. VA is a good adjunct to DFMA. attention to 18

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21 Design Architecture 21

22 Design Architecture 22

23 Design Architecture 23

24 Design Architecture 24

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33 Design for Assembly PEMP Design for assembly (DFA) focuses on simplifying the assembly process, which ultimately reduces manufacturing time and improves product quality. This means designing the product so that its assembly process is as mistake - proof as possible, because every bit of handling during the assembly process has the potential to introduce errors and variation. The entire fabrication, subassembly, and assembly process must be as clear as possible. Components should be designed so that they can only be assembled in one way. Cutouts, notches, asymmetrical holes, and stops are some of the ways to mistake - proof the assembly process by design. 33

34 Design for Manufacturability Design for manufacturability (DFM) seeks to maximize ease of manufacture by simplifying the design through part- count reduction. Reducing the number of parts is important. Each part in a product means an opportunity to introduce defects and assembly errors. As part counts are reduced, the probability of a high- quality product increases exponentially. Fewer parts also means higher reliability, lower life cycle costs, less design engineering labor (including less re-design ), and less purchasing, quality assurance labor, and fewer stores, as well as less floor space. 34

35 Design for Ease of Assembly Designers do not only have a major influence on the costs and the quality of the production of components, but also on the costs and quality of assembly. By assembly we refer to the combination of components into a product and to the auxiliary work needed during and after production. The cost and quality of an assembly depend on the type and number of operations and on their execution. The type and number, in their turn, depend on the layout design of the product and on the type of production (one-off or batch production) 35

36 Design for ease of assembly requires expert knowledge of the following: Joining methods and processes; The connection between product design and assembly process; and The connection between product design and the type and quality of assembly systems. 36

37 IMPACT OF DESIGN Design Cost & Quality Components Cost & Quality Assembly Cost & quality of assembly Type and number of operations Layout design of product Type of production-one of batch 37

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40 Design for Manufacturability Knowledge based Technique PEMP Involves a series of guide lines,principles,recommendations or rules of thumb for designing a. product that is easy to make Manufacturability ease with which a product or component can be produced - its simplicity - straightforwardness of its configuration - the degree to which it minimises labour,materials and overhead costs - freedom that its design has from inherent quality and processing problems RESULT: LOWER MANUFACTURING COST 40

41 Assembly systems Design for assembly is an optimization task which pre-requires knowledge of both design and assembly principles. It is therefore useful to have an overview of some types of assembly systems 41

42 PROCESS CHARACTERISTICS: Early in the design of any product it is important to decide which type of assembly process is likely to yield the lowest cost. This decision has a major bearing on the design because manual assembly differs widely from automatic assembly. Each type of process has its own advantages and limitations. The cost of assembling a product is related both to the design of the product and to the assembly process used for its production. Assembly cost is lowest when the product is designed so that it can be economically assembled by the most appropriate process. 42

43 PROCESS CHARACTERISTICS: Basic Processes: Manual assembly Special purpose machine assembly Programmable machine assembly 43

44 Assembly Systems Manual assembly: Assembly is carried out by the assembler who has simple equipment at his disposal, such as tables, fixtures, component boxes, conveyor belt and hand tools. Semi-automatic assembly: A machine system, where some operations are manual and some are automatic Special purpose automatic machine assembly: A machine system, which is built for automatic assembly of a specific product Programmable automatic machine assembly: This is a system, which can be programmed for variation of certain product characteristics 44

45 PROCESS CHARACTERISTICS: Manual Assembly: Tools are generally simpler, less expensive Down time caused by defective parts negligible Cost of manual assembly is relatively constant Cost of manual assembly is independent of production volume Process is flexible and adaptable Mechanical assistance can reduce assembly time 45

46 PROCESS CHARACTERISTICS: Special Purpose Assembly Machine (Consist of transfer devices with single - purpose work heads and part feeders at the various workstations): Transfer devices can operate on an indexing (synchronous) principle or on a freetransfer ( non - synchronous ) principle Built to assemble a specific product Costly, require considerable engineering development Downtime caused by defective parts can be a serious problem unless the parts have relatively high quality Work on a fixed cycle time, with fixed rate of production If under utilised they can not be used for any other purpose, resulting in increase in assembly cost. 46 PEMP

47 PROCESS CHARACTERISTICS: PEMP Programmable Assembly Machine (similar to non-synchronous special-purpose machine except that the work heads are generalpurpose and programmable): Allows more than one assembly operation to be performed at each workstation Provides considerable flexibility in production volume Greater adaptability to design changes and different product styles 47

48 MA: Manual assembly on a multistation assembly line. The transfer device is a free-transfer machine with one buffer space between each operator. PEMP MM: Manual assembly with mechanical assistance. This system is the same as MA, but feeders or other devices are provided and the assembly time per part thereby reduced 48

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50 AP: Automatic assembly using manually loaded part magazines and a free-transfer machine with programmable work heads capable of performing several assembly tasks. One Supervisor and one assembly operator for the machine. PEMP AR: Automatic assembly using manually loaded part magazines and a sophisticated two-arm robot with a special-purpose gripper that can handle all the parts for one assembly. One supervisor needed for the robot. 50

51 AI: Automatic assembly using special-purpose indexing machines, work heads, and automatic feeders. One supervisor for the machine when Na < 6 (rotary indexing machine) and one supervisor together with one assembly operator when Na > 6 (in-line indexing machine). AF: Automatic assembly using special-purpose free-transfer machine, work heads, and automatic feeders. One supervisor and one assembly operator for the machine. 51

52 Programmable Automatic PEMP Assembly 52

53 Special Purpose Automatic PEMP Assembly 53

54 Programmable Automatic PEMP Assembly 54

55 Choice of Assembly Method 55 PEMP Make a choice between manual, special purpose automatic or programmable automatic assembly based on good estimate of the most economical assembly method. Information required: Production volume per shift Number of parts in assembly Single product or a variety of products Number of parts required for different styles of the product. Number of major design changes excepted during the product life. Investment policy regarding labor saving machinery.

56 Choice of Assembly Method PEMP These questions, combined with several tables, are used to generate recommendations for the general type of process to be used for assembly, from the following categories: Purely manual; Manual with Mechanical assistance; Dedicated automation on indexing machines; Dedicated automation on station linked by free transfer device; Flexible automation using programmable or selectable work heads (pick & place units); Flexible automation using programmable manipulators (Robots) The outcome of this stage also includes an indication of the relative cost of assembly, which can be used for comparisons between designs or benchmarking across competitors. 56

57 Selecting a process: PEMP DFA rests on the hypothesis that through improvements in assemblability of a product, improvements in other processes will follow (Erixon 1998) Increasing productivity through automation is one avenue of achieving competitiveness Human being is very flexible in movement, speed, force, vision and in the ability to feel if an operation is correct and perhaps change it The above is not simple for a mechanical assembly or a robot 57

58 Selecting a process: Trying to automate an assembly operation without defining, evaluating and possibly redesigning the product is like trying to improve a parachute release system without checking the condition of the parachute (Maczka 1985 ) Any product designed for automated assembly will be easier to assemble manually. However, products designed for manual assembly generally do not make products suitable for automatic assembly A Product designed for automatic assembly allows maximum flexibility in the actual assembly process, since the product can be assembled manually or automatically Designing a product for automatic assembly will also result in great increase in both productivity and product quality, even if automation is not used 58

59 Contrast approaches to design for Manual assembly & Automatic assembly to determine the cost of assembly Manual Assembly Assembly cost is based on prediction of time taken to accomplish various activities such as grasp, orient, insert and fasten. Attention is paid for ease of handling Automatic assembly Assembly cost is based on rate at which the assembly system cycles - at the end of each cycle a complete assembly is produced Attention is paid for ease of automatic feeding, orienting and insertion. PEMP Simplification of product structure results in substantial savings in assembly cost and parts cost. Part simplified for part handling (acquiring, orienting and moving the parts), insertion and fastening (mating to another part or group of parts) Elimination of part is even more important may eliminate complete station reduction in investment. Parts modified to reduce control of the placement device, or even eliminate the need for a placement device by introduction of guides, chamfers (compliance features) that directly facilitate assembly. 59

60 Contrast approaches to design for Manual assembly & Automatic assembly to determine the cost of assembly PEMP Manual Assembly Automatic assembly Difficulty in assembly from a direction other than directly above. To be built up in layers, each part assembled from above and positively located so that there is no tendency for it to move under action of horizontal forces during the machine index period. Avoid expensive and time considering fastening operations screw fastening, soldering etc In addition of geometric features, thin parts cause overlapping during feeding leading to problem with orienting devices. Sticky, delicate, flexible parts are considered for feeding difficulties. 60

61 DFM concepts help Designers change from doing the right thing to doing things right (Fabricius 1994) 61

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63 Demands on DESIGN PEMP Fig 6:Demands on the design from all parts of the product lifecycle(wdk,1993) Since Design for manufacturing,dfm,and design for assembly,dfa,were introduced, there is now an acronym for almost any activity of focus for designers.dfm is sometimes referred to as Design for manufactured and assembly,dfma(egan,1997),fig7.however, the term DFMA is also a trademark for one of the commercial DFA method available. Fig 7: DFMA consists of DFM and DFA (Egan,1997). 63

64 DFA & DFX PEMP While concurrent engineering become more and more applied in industry,the job of a designer Is not become easier.one way of making sure that more department of the company can give Direct input to the design work is to work in multifunctional teams. To these teams,the use of a DFX tool is a way to focus their attention and to provide a common language. DFAA as a part of DFA,based on life cycle properties. 64

65 DFMA GOALS: Short term. Initial goals for implementing DFA are often cost based,typically: Reduced number of components Reduced assembly time Reduced manufacturing and assembly costs Long term. When applying DFA on more then one product there are potential long term goal for the whole company, such as : Improved product quality An environment for concurrent engineering 65

66 DFA in PRODUCT DEVELOPMENT 66

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68 DFA - DRAWBACKS PEMP 68

69 DESIGN METHOD 69

70 MFD Modular Function Deployment 70

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72 CONCURRENT ENGINEERING PROCESS PEMP 72

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74 Summary The designer should understand The roadmap of DFMA Why and when DFMA is used Product Architecture Role of DFMA in product design Different types of assembly systems Concurrent engineering process 74