![Table 2: Example Classification of Each Part for Original
Design (DFA worksheet)
Then, the theoretical minimum number of parts needs to be
estimate and tabulate. The theoretical minimum number of
parts represents a situation where separate parts are combined
into a single part unless, as each part is added to the assembly,
one of the following criteria is met.
Table 3: Example of theoretical minimum number of parts
7. Analysis
From the information gathered the assembly design
efficiency can be calculated by using the formula:
Design Efficiency = (3 ×NM) ÷TM
NM: Theoretical minimum number of parts
TM: Total manual assembly time
8. Propose for improvement
The improvement must be done for assembly design
efficiency by reducing part count by combining or eliminating
certain parts of the product. Possibilities of eliminate the
unnecessary parts by applying the theoretical minimum
number of parts. Major improvement and minor improvement
must be done by identify the highest assembly time.
(Boothroyd, G, 2002). After the reduction of part count, the
product will undergo redesign. After the redesign, the new
products will undergo same process as above to determine the
assembly design efficiency.
9. DFM methodology
Design for Manufacturing can reduce many costs, as the
products can be quickly assembled. Therefore, products are
easier to assemble, in fewer times and with better quality.
DFM process can be classified into three stages such as define,
analyze and justify. In the every stages of the DFM process,
there is a problem solving method on methodology. The three
stages briefly discussed below.
i. Define
In this stage, DFM analysis starts with the first step
which is part selection from the product after
improvement. There are seven improvement parts
which can select to perform DFM analysis.
The parts specification is prepared in order to define
the seven selected parts.
ii. Analyze
In this stage material and process selection method will
be carried out. In order to select the proper material and
process, the shape geometry of the part also known as
the 8 shape attributes must be identify. Shape attributes
is the consideration of size, shape, and cross-section of
the part. Afterward, the selection of process used to
manufacture the part can be done by using the pattern-
matching rules. The proper materials to produce the
part can be select by based on the theory of materials
selection
iii. Justification
As the final stage, the elimination process will be
carried out, as a result it will show the remaining
process which can be used to manufacture parts. The
process will be selected based on the material, cost and
amount of production of the part.
IV. RESULT
1. The Original Design
The descriptions of the original design of the product have
been already shown in previous Chapter 3. This chapter will
be discussing about the details descriptions of the original
product parts and the function of each product.
2. Efficiency of the original design
By using Design Efficiency formula as discussed in Chapter 2
the efficiency of original design is calculated:
Design Efficiency = (3 ×NM) ÷TM
= (3 ×63) ÷1345
=14 %
NM= theoretical minimum number of parts
TM= total time manual assembly parts
Estimated theoretical value of assembly time = 1800 seconds
3. Description of Part Improvements
Table below (Table 4) shows the parts which are
undergoing the improvement process.
Table 4: Example of Part Improvement Description
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10
Nameofpart
Partidnumber
Nooftimestheoperation
iscarriedout
i
Two-digitmanual
handling
Manualhandlingtime
perpart
Two-digitmanual
insertioncode
Manualinsertiontime
perpart
Operationtime(sec)
(2)x[(4)+(6)]
Operationcost(cents)
[0.0011(MAS)x7]
Estimationoftheoretical
minimumnumberofpart
Front Wheel 1 4 30 1.95 06 5.5 29.8 0.03576 1
Front wheel pin 2 2 10 1.5 35 7 17 0.0204 1
Swivel axle 3 2 30 1.95 06 5.5 14.9 0.01788 1
Rear Wheel 4 4 30 1.95 О6 5.5 29.8 0.03576 1
Name of part Description Theoretical minimum parts assessment
Relative
Motion
Different materials Separate for
assembly
●Front wheel
●Front wheel
pin
●Swivel axle
●Front wheel
holder with
body
●Pin 1
By using a bigger size
wheel and a basic
design of the swivel
axle, the two front
wheel and old swivel
axle can be eliminate.
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes](https://image.slidesharecdn.com/e3a0166b-d412-49f4-9581-e615177133bc-160206095819/85/Daniel-journal-4-320.jpg)
Daniel journal
- 1. Abstract— This project describes about the implementation of redesign the MY DEAR baby stroller (18007) by using the application of Boothroyd Dewhurst, Design for Manufacturing and Assembly (DFMA) methodology. The scope based on the existing baby stroller and the appropriate of DFMA methodology. The main focus is to reduce the part count, the assembly time and cost and ease of manufacturing. The tools of DFMA: Design for Assembly (DFA) and Design for Manufacturing (DFM) are going to be applying in this project. DFA method is applied on baby stroller to reduce assembly time and cost and generate the design efficiency of the baby stroller. The methodologies are followed in order to analyze the each parts of the product to determine design efficiency. Then the product will undergo redesigning process. The new design will undergo same process as above to determine the new design efficiency. Afterward, redesigned parts will undergo DFM method in order to select proper material and process. From the study, it was found that the design efficiency increases from 14% to 18% when Boothroyd Dewhurst theory was applied. The time of assemble also decreased from 1345s to 883.3s per product. From the result, it was proven that this DFMA method was able to improve the design in terms of design efficiency, product assemble time and operation cost. Index Terms— DFMA, Boothroyd Dewhurst, Baby Stroller I. INTRODUCTION HIS DFM and DFA are developed in the early 1970‟s by Dr Geoffrey Boothroyd and Dr Peter Dewhurst. Then, they created and developed the DFMA, Design for Manufacturing and Assembly (Xie X, 2006). Design for Manufacturing, DFM is the method of design for ease of manufacturing of the collection of parts that will form the product after assembly. Design for Assembly, DFA is the method of design of the product for ease of assembly. (Stienstra D et al, 2001) A baby stroller has been selected as a case study for this project. This project is going to be developing under Design Daniel S/O Pragasom undertook Diploma in Mechanical Engineering at University Selangor in 2009 and graduated in year 2012. He then went on to obtain his bachelor in mechnanical engineering in year 2012 at the same university and graduated honorably in year 2015. Daniel is with Institution of Engineers Malaysia, as on October 2015 onwards. for Manufacturing and Assembly (DFMA) technique. The main focus is to reduce the part count in baby stroller and the assembly time. The tools of DFMA: Design for Assembly (DFA) and Design for Manufacturing (DFM) are going to be applying in this project. The first stage of this project is to apply the DFA technique on baby stroller to reduce part count and assembly time and at same time finding the manual assembly efficiency of the baby stroller. The second stage is the implement of DFM technique on baby stroller. The software going to be used for drawing is CATIA V5R16. The objectives of this project are: i. To meets the manufacturers need to reduce cost and time. ii. To simplify current design of Baby Stroller in order to improve the manufacturing and assembly process. iii. To minimize parts counts. There are several significances in this project, they are firstly come up with a new simplified design where the time and cost reduced and at the same time efficiency is higher. Secondly, the assembly costs will be lower by using fewer parts, eliminating certain parts wherever possible and reduce the manpower required for assembly. Thirdly, reliability increases by lowering the number of parts, thus decreasing the chance of failure. Lastly, total time to market is shorter since products developed using DFMA. There are few indirect significances of this project; firstly, manufacturing company will gain financial benefit. Furthermore, the working environment becomes more pleasant and safe to the workers. In addition, the ergonomics in the working environment improved by reduce stress, eliminate injuries and disorders associated with the overuse of muscles, bad posture and repeated tasks. II. LITERITURE REVIEW 1. Introduction Boothroyd et al mentioned that in order to overcome complication during manufacturing process, the engineers have to consult with the designers. The action of consulting and discussing is known as simultaneous engineering. Simultaneous engineering or also known as concurrent engineering is vital in preventing many problems. Winner et al has stated that concurrent engineering or simultaneous engineering is a systematic approach to the integrated, concurrent design of products and their related processes, including manufacture and support. This approach is to cause the developers to consider all elements of the DESIGN FOR MANUFACTURING AND ASSEMBLY FOR BABY STROLLER (18007) Daniel S/0 Pragasom, Bachelor Mechanical (Hons) Engineering, University Selangor T
- 2. Time-to-market improvements 39% Improvements in quality and reliability 22% Reduction in manufacturing cycle time 17% Reduction in assembly time 13% Reduction in part counts/costs 9% product life cycle which includes quality, cost, schedule, and customer requirements and disposal. Furthermore, the main objective of this concurrent engineering is to achieve improved product development performance. O’Grady et al said that Design For X (DFX) is actually design decision support tool, such as Design for Assembly, Design for Manufacture, Design for Environment, Design for Disassembly, Design for Service, or Design for Six. These design decision support tools are consider as importance manufacturing and assembly processes of a product lifecycle. This tools leads to benefits in increased reliability, quality, shorter manufacturing time and overall efficiency in the assembly process, which is responsible for more than 50% of total manufacturing cost and 40% to 60% of total production time. Hermnann et al mentioned that DFX tools recognize design considerations occurring throughout a product development cycle, for instance manufacturing, assembly, quality, production, and environmental impact. Michel, K discussed that DFX tool is used for the design of manufacturing and assembly it descript as Design for Manufacturing (DFM) and Design for Assembly (DFA) respectively. DFM and DFA is the most common DFX tools as they allow better assessment to the manufacturing industries. Xie X thought that DFM is actually begins before the Second World War, where the FORD and CHRYSLER was used the DFM philosophy to design and manufacture their weapons, tanks and other military equipment. DFM and DFA are commencing in the early 1970’s. Dr Geoffrey Boothroyd and Dr Peter Dewhurst are researcher of this technologies Curtis, M.S proved that it was possible to measure the efficiency and cost of various assembly and manufacturing processes through their research. Boothroyd and Dewhurst were able to develop a wide-ranging database that is now available as a software toolkit or in traditional handbook form. 2. Advantages of DFMA Figure 1: Survey on importance of reductions produced by DFMA. (Reader poll, Computer-Aided Engineering, 1993) DFMA cut down assembly time by using of standard assemblies such as vertical assembly and self-aligning parts. DFMA also enhance the reliability by minimize the number of parts, as a result decreasing the chance of failure. As products developed using DFMA, the products make the fastest and smooth move into the production phase; the time for a product to reach the consumer is reduced. (Boothroyd, G, et al 2002) 3. Designs for assembly (DFA) Design for Assembly (DFA) is introduced by Boothroyd- Dewhurst (USA), Lucas-Hull (UK) and Hitachi (Japan). All of these three have been used in industry. Among these three methods, Boothroyd-Dewhurst is the most widely used. Design for Assembly (DFA) is describe as an approach to reduce the cost and time of assembly by simplifying the product. In the original design, assembly is done by using the common fasteners and then it undergoes DFA method, the product become as one-piece base with elimination of fasteners. At the final stage of design using the DFA, the product become more efficient in assembly by applies just a push and snap assembly which is really easy to assemble. 3. Design for manufacturing (DFM) The term of Design for Manufacturing (DFM) according to (Boothroyd G et al, 2002), is a method used for ease the manufacturing process of a product. The goal of DFM is to design a product which can simply and economically manufacture. DFM adapt the products design to manufacturing conditions in order to make the manufacturing process more efficient. At the same time DFM also minimizing the production cost and time of the product to market and also maintain the quality of the product III. METHODLOGY 1. DFA objectives The primary objective of DFA is to minimize part counts. This leads to fewer parts that must be manufactured and assembled, fewer parts that can fail, and fewer interfaces between parts. DFA's second objective is to have remaining parts of a nature that they are easily assembled together. These objectives lead to the primary expected DFA results for the assembly: (Tatikonda M. V, 1994) i. Reduced material cost ii. Reduced labor and/or automatic assembly cost iii. Reduced assembly cycle times iv. Higher product quality and reliability.
- 3. 2. Flow Chart 3. Product to be studied Figure 2: MY DEAR Baby stroller 18007 4. Disassemble product parts Figure 2 shows the baby stroller 18007. The parts are having been disassembled and labeled. 5. Identification of part functions To improve the product, the information about the product and its assembly is important. To collect the information correctly, the each and every part of the product need to be disassemble. The disassembling process is done in Workshop Mechanical 1 in UNISEL. The grinder is used to disassemble all the parts because the parts are fixed with the rivets. The rivets used for this assembly are solid rivets. After the parts are disassembled, it will undergo a process to obtaining the dimensions of each part. The dimensions are obtained by using the rulers and measuring tape. Then the function of each part is needed to be defined. To know the complexity of the part, the part should be viewed in 3D. Afterward, each parts is need to define the axis of symmetry in degree (α + β) to identify the relative motion of assemble. The collected details are tabulated and referred as the part critique. Then, form Product Tree Structure to identify the sub-assemblies of the product. Table 1: Example of Part Critique Figure 3: Product tree structure (PTS) 6. DFA worksheet In this stage, a table is generated and referred as the Classification of Each Part for Original Design (DFA worksheet) .This table is actually to find the assembly time, assembly cost and assembly efficiency. Part No. Part Name Function Material Size(mm) Rotational SymmetryThickness Length 1 Front Wheel Easy to move, provide mobility Plastic 25 150 α – 360 + β – 360 2 Front Wheel pin To hold the wheel with the body. Steel 8 101 α – 360 + β – 0 3 Swive l axle Provides 360- degree of freedom for front wheels Plastic 15 122 α – 360+ β – 360 Start Title Selection and Proposal Study and research journals, books and articles Literature Review Analyze the design of the product Redesign the product and DFA analysis Result Report Writing End Calculate and measure the improvise parts are efficient for production benefit DFM analysis If efficiency low Sub Assembly 2 (Main body upper beam) Sub Assembly 1 (Main body rear bottom beam) Sub Sub Assembl y Front and rear bottom beam connector Sub Sub Assembly Main body front bottom beam Sub Sub Assembly Sub Sub Assembly Sub Sub Assembly Holder rod of tray Back wheel holder with body Seat Basement Product Tree Structure of ‘Baby Stroller’
- 4. Table 2: Example Classification of Each Part for Original Design (DFA worksheet) Then, the theoretical minimum number of parts needs to be estimate and tabulate. The theoretical minimum number of parts represents a situation where separate parts are combined into a single part unless, as each part is added to the assembly, one of the following criteria is met. Table 3: Example of theoretical minimum number of parts 7. Analysis From the information gathered the assembly design efficiency can be calculated by using the formula: Design Efficiency = (3 ×NM) ÷TM NM: Theoretical minimum number of parts TM: Total manual assembly time 8. Propose for improvement The improvement must be done for assembly design efficiency by reducing part count by combining or eliminating certain parts of the product. Possibilities of eliminate the unnecessary parts by applying the theoretical minimum number of parts. Major improvement and minor improvement must be done by identify the highest assembly time. (Boothroyd, G, 2002). After the reduction of part count, the product will undergo redesign. After the redesign, the new products will undergo same process as above to determine the assembly design efficiency. 9. DFM methodology Design for Manufacturing can reduce many costs, as the products can be quickly assembled. Therefore, products are easier to assemble, in fewer times and with better quality. DFM process can be classified into three stages such as define, analyze and justify. In the every stages of the DFM process, there is a problem solving method on methodology. The three stages briefly discussed below. i. Define In this stage, DFM analysis starts with the first step which is part selection from the product after improvement. There are seven improvement parts which can select to perform DFM analysis. The parts specification is prepared in order to define the seven selected parts. ii. Analyze In this stage material and process selection method will be carried out. In order to select the proper material and process, the shape geometry of the part also known as the 8 shape attributes must be identify. Shape attributes is the consideration of size, shape, and cross-section of the part. Afterward, the selection of process used to manufacture the part can be done by using the pattern- matching rules. The proper materials to produce the part can be select by based on the theory of materials selection iii. Justification As the final stage, the elimination process will be carried out, as a result it will show the remaining process which can be used to manufacture parts. The process will be selected based on the material, cost and amount of production of the part. IV. RESULT 1. The Original Design The descriptions of the original design of the product have been already shown in previous Chapter 3. This chapter will be discussing about the details descriptions of the original product parts and the function of each product. 2. Efficiency of the original design By using Design Efficiency formula as discussed in Chapter 2 the efficiency of original design is calculated: Design Efficiency = (3 ×NM) ÷TM = (3 ×63) ÷1345 =14 % NM= theoretical minimum number of parts TM= total time manual assembly parts Estimated theoretical value of assembly time = 1800 seconds 3. Description of Part Improvements Table below (Table 4) shows the parts which are undergoing the improvement process. Table 4: Example of Part Improvement Description C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 Nameofpart Partidnumber Nooftimestheoperation iscarriedout i Two-digitmanual handling Manualhandlingtime perpart Two-digitmanual insertioncode Manualinsertiontime perpart Operationtime(sec) (2)x[(4)+(6)] Operationcost(cents) [0.0011(MAS)x7] Estimationoftheoretical minimumnumberofpart Front Wheel 1 4 30 1.95 06 5.5 29.8 0.03576 1 Front wheel pin 2 2 10 1.5 35 7 17 0.0204 1 Swivel axle 3 2 30 1.95 06 5.5 14.9 0.01788 1 Rear Wheel 4 4 30 1.95 О6 5.5 29.8 0.03576 1 Name of part Description Theoretical minimum parts assessment Relative Motion Different materials Separate for assembly ●Front wheel ●Front wheel pin ●Swivel axle ●Front wheel holder with body ●Pin 1 By using a bigger size wheel and a basic design of the swivel axle, the two front wheel and old swivel axle can be eliminate. Yes Yes Yes No No Yes Yes Yes Yes No Yes Yes Yes Yes Yes
- 5. Example of Part Improvement: Front Wheel Category: Major improvement Reduce time: 31.2 sec Justification: A bigger size wheel and a basic design of the swivel axle replaced with the two front wheel and old swivel axle where it can improve the assembly time and manufacturing cost. 4. Efficiency of the new design By following the same step as mentioned in Chapter 3, new part critique, new product tree structure, new DFA worksheet, new theoretical minimum number of parts are prepared for new design. Finally, by using Design Efficiency formula as discussed in Chapter 2 the efficiency of new design is calculated: Design Efficiency = (3 ×NM) ÷TM = (3 ×51) ÷843 =18 % NM= theoretical minimum number of parts TM= total time manual assembly parts Estimated theoretical value of assembly time = 1200 seconds 5. New Design Description and Drawing New design of the product is designed by using the CATIA software as shown in Figure below. Figure 3: Assemble drawing for new design 6. Design for manufacturing (DFM) The improved parts are going to be analyzed for DFM process except the main seat because the main seat manufactured by the Fabric manufacturers. Table 5: Example of selected DFM parts specification 7. DFM Process As mentioned in Chapter 3, DFM process can be classify into three stages such as define, analyze and justify. Each part is defined by its name, analyzed based on shape attributes and process elimination based on eight geometric attributes. Finally it will be justified according to the data to choose the proper process. Parts Id No Name of Part Operation Time (sec) α+β 1 Front wheel 29.8 720 2 Front wheel holding pin 17 360 3 Swivel axle 14.9 720 7 Front wheel holder with body 17.9 720 62 Pin 1 35.8 720 Total time 115.4 Parts Id No Name of Part Operation Time (sec) α+β 07 Front wheel 6.9 720 09 Front wheel pin 17 360 3 Swivel axle 6.9 720 7 Front wheel holder with body 17.9 720 62 Pin 1 35.8 720 Total time 84.2 No Part ID No. Part Specification 1. 07 & 08 Part name: Wheel spoke. Dimension: Øin = 140mm; Øout =159mm Thickness: 40mm Material: Thermoplastic or Thermosets Function: To provide mobility and easy to move. Before After
- 6. 8. Comparison of New Design and Old Design Table 6 shows the data comparison between the original and new design. The comparison is done in order to obtain the percentage change from the original and new design. Table 6: Comparison Quantitative value for new design and old design Figure below (Figure 4) shows the bar chart of percentage change. Figure 4: Percentage change Bar Chart 9. Discussion The DFMA analyses have confirmed that improved designs are much effective than the original design by referring the Table 6 and Figure 4. The total product assembly time is 1345 sec (22.4 min) and total operation cost is RM 1.479. The efficiency of the original design is 14%. The product tree structure consist four levels of assemblies. From this analysis data, the product is able to improve and redesign in order to improve its efficiency and performance. By redesigning the product, the original efficiency, product assembly time and operation cost will improve. Once the product is redesigned by using similar methods as original design, the total assembly time of new design is 883.3 sec and operation cost is RM 0.929. The efficiency of new design improved up to 18%. Still the product tree structure consist four levels of assemblies but total number of parts has reduced without changing the product’s function and new design parts are introduced which are simplify the process of assembly. Once the DFA process is completely done, the new design will undergo DFM process in order to reduce the cost of manufacturing. By implementing DFM process, MY DEAR Company able to improve fabrication process and minimize the cost. The DFM process can be done by referring the guidelines as discussed in Chapter 2. By the way, the selection of the manufacturing process will be determined by the elimination of processes based on the characteristics of the parts and the materials properties of the part. From the analysis, it is necessary to select the process according to the characteristic of product parts. Most of the baby stroller’s parts are plastic material which can easy produce by one single process which can lead to reduction of manufacturing cost. V. CONCLUSIONS AND RECOMMENDATIONS 1. Recommendations Through this research, MY DEAR Company is recommended to implement the DFMA techniques in their products in order to increase their productivity, reduce manufacturing and assembly cost and time and enhance the demand from customer. MY DEAR is one of the leading companies for baby care product. Application of DFMA on MY DEAR Company will lead to produce their product with unique design by simplifying the parts. Consequently, the assembly time and labor cost will reduce. In addition, product development process will improve. As result MY DEAR can sustain its place and become fore-runners in the market. Among the other method, Boothroyd and Dewhurst DFMA method mostly recommended. Boothroyd and Dewhurst created and developed the DFMA concept which is used in developing the products of their company (DFMA software system). The Boothroyd-Dewhurst methods provide a quantitative measure known as the design efficiency based on analysis of a product. (Boothroyd. G, 1987). Moreover, Boothroyd and Dewhurst DFMA method doesn’t demand for higher design efficiency for improved product Further improvement can carried out on the product if more time is provided. Further improvement includes reducing the number fasteners (rivet) or replacing new type of fastener and some design improvement. By reducing the number of fastener, the efficiency of product will improve. Possibly in future the fasteners (rivet) are able to replace with other fastener to improve the assembly time and design efficiency as well. 2. Conclusion DFMA is successfully applied on MY DEAR baby stroller 18007. The three objectives of the study were achieved. DFMA analysis has reduced the operation cost and assembly time of product. The total operation cost of new design has reduced from RM 1.479 to RM 0.929 and the percentage change is 37.19%. Meanwhile, the total assembly time also reduced from 1345 seconds to 883.3 seconds and the percentage change is 34.32%. The design efficiency has improved from 14% to 18% after the successful DFMA analysis. The increment of efficiency is only 4% and it’s acceptable in Boothroyd and Dewhurst DFMA method as mentioned in recommendation. The efficiency can be improved if the product is undergoing further improvement by using same DFMA method. -40.00% -20.00% 0.00% 20.00% % change Total Part Unique Part Total Operation Cost (RM) Total Assembly Time (second) Design Efficiency (%) Original Design Improved Design % change Total Part 167 127 23.95% (decrease) Unique Part 69 52 24.63% (decrease) Total Operation Cost (RM) 1.479 0.929 37.19% (decrease) Total Assembly Time (second) 1345 883.3 34.32% (decrease) Design Efficiency (%) 14% 18% 4% (increase)
- 7. REFERENCES Boothroyd, G. (1980). Design Project: Design for Assembly Handbook. Amherst, United States: University of Massachusetts Boothroyd, G., (2010). DFMA Design For Manufactuirng and assembly. Executive White Paper: Design for Manufacture & Assembly Reduce Costs Increase Profit. Page 5 of 28 Boothroyd, G (1987). International Journal: Advanced Manufacturing Technology, Bedford. U.K: IFS Publications Ltd. Boothroyd G, Peter Dewhurst and Winston Knight (2002). Product design for manufacturing and assembly. (2nd ed). Switzerland: Marcel Dekker AG. Curtis, M.S, (1992) Product Development. Boothroyd Dewhurst's DFMA(R) and JCB excavators’ New York City: The Institute of Electrical and Electronics Engineers. Herrmann, J. W., Cooper, J., Gupta, S. K., Hayes, C. C., Ishii, K., Kazmer, D., Sandborn, P. A. & Wood, W. H. (2004) Proceedings of the ASME Design Engineering Technical Conferences and Computers and Information in Engineering Conference. New directions in design for manufacturing. United States: University of Utah. Michel, K., Tezera Wodajo (2012). Application of a Design Method for Manufacture and Assembly. Flexible Assembly Methods and their Evaluation for the Construction of Bridges. Sweden: Chalmers University Of Technology. Retrieved from http://publications.lib.chalmers.se/records/fulltext/164233 O'Grady and Wu, (1999) A Concurrent Design Method Based on DFMA-FEA Integrated Approach. Catania, Italy: University of Catania. Retrieved from http://cer.sagepub.com/content/17/3/183.abstract Reader poll (1993). Computer Aided Engineering. Survey on importance of reductions produced by DFMA. Stienstra, D. (n.d.). Introduction to Design for (Cost Effective) Assembly and Manufacturing. Tatikonda, M. V. (1994). Production and Inventory Management Journal: Design- For-Assembly: A Critical Methodology for Product Reengineering and New Product Development. Chapel Hill, Carolina: University of North Carolina. Winner, Robert, I., Pennell, James, P., Bertrand, Harold E., and Slusarczuk, Marko M. G. (1991). The Role of Concurrent Engineering in Weapons System Acquisition. Alexandria, Virginia: Institute for Defense Analysis. Xie, X. (2006). Design for Manufacture and Assembly. United States: University of Utah. Retrieved fromhttp://www.cc.utah.edu/~u0324774/pdf/DFMA.pdf