PRODUCT DESIGN AND DEVELOPMENT NPTEL SWAYAM

PRODUCT DESIGN AND DEVELOPMENT

1. Lesson 14
Product Design and Development
Design for X (DFX)
Dr. Inderdeep Singh
Department of Mechanical and Industrial Engineering
1

2. •Design for Excellence or DFX is a systematic design approach that entails
wide range of guidelines and standards focused on optimizing the product
realization lifecycle.
•In reality, the term DFX is better thought of as Design for “X” where the
variable X is interchangeable with one of many values depending on the
particular objectives of the venture.
DesignforExcellence(DFX)

3. Theseguidelineensurestheissuesrelatedtomanufacturing,cost,quality,
assemblyandserviceabilityareaddressedatthedesignstage.
Iftheseguidelinesarenotadheredduringthedesignstage,itcanleadto
engineeringchangesoccurringatlaterstagesofproductlifecyclewhichare
highlyexpensiveandcancauseproductdelaysandcostover-runs.
DesignforExcellence(DFX)cont..

4. DFX
Design for
Assembly
Design for
Manufacturing
Design for
Production
Design for Cost
Design for
Service
Design for
Safety
Design for
Manufacturing
and Assembly
Design for
Reliability
Some of the most common
substitutes for X includes:
•Design for Manufacturing
(DFM)
•Design for Assembly (DFA)
•Design for Manufacturability
and Assembly (DFMA)
•Design for Production

5. 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”
“Optimization of the manufacturing process”
Definition

6. Design for Manufacturing cont..
•Designformanufacturing(DFM)isadevelopmentpractice,emphasizing
manufacturingissuesthroughouttheproductdevelopmentprocess.
•SuccessfulDFMresultsinlowerproductioncostwithoutsacrificing
productquality.

7. Estimate the Manufacturing CostsFinished Goods
Manufacturing
System
Equipment
InformationTooling
WasteServicesSuppliesEnergy
Raw Materials
Labor
Purchased
Components
Source: Ulrich, K. & Eppinger, S. (2000). Product Design and Development.Boston, MA: Irwin McGraw-Hill.

8. Elements of the Manufacturing Cost of a ProductManufacturing
Cost
OverheadAssemblyComponents
Standard Custom Labor
Equipment
and Tooling
Support
Indirect
Allocation
Raw
Material
Processing Tooling

9. Manufacturing Cost of a Product
•ComponentCosts(partsoftheproduct)
Partspurchasedfromsupplier
Custompartsmadeinthemanufacturer’sownplantorbysuppliersaccordingtothe
manufacturer’sdesignspecifications
•AssemblyCosts(labor,equipment,&tooling)
•OverheadCosts(allothercosts)
SupportCosts(materialhandling,qualityassurance,purchasing,shipping,receiving,
facilities,etc.)
IndirectAllocations(notdirectlylinkedtoaparticularproductbutmustbepaidfor
tobeinbusiness)

10. Fixed Costs vs. Variable Costs
•FixedCosts:incurredinapredeterminedamount,regardlessofnumberof
unitsproduced(i.e.settingupthefactoryworkareaorcostofaninjection
moldingmachine)
•VariableCosts:incurredindirectproportiontothenumberofunits
produced(i.e.costofrawmaterials)

11. Estimate the
Manufacutring Costs
Consider the Impact of
DFM Decisions on
Other Factors
Recompute the
Manufacturing Costs
Reduce the Costs of
Supporting Production
Reduce the Costs
of Assembly
Reduce the Costs of
Components
Good
enough
?
N
Y
Acceptable Design
Proposed Design Ulrich, K. & Eppinger, S. (2000). Product Design and Development.Boston,
MA: Irwin McGraw-Hill.
DFM Method

12. DFM Method
•Estimate the manufacturing costs.
•Reduce the costs of components.
•Reduce the costs of assembly.
•Reduce the costs of supporting production.
•Consider the impact of DFM decisions on other factors.

13. Source: http://machinedesign.com/metals/following-dfm-guidelines-working-sheet-metal
•In a sheet-metal design, specifying hole sizes, locations, and their alignment is critical.
•It is always better to specify hole diameters that are greater than the sheet’s thickness (T).
•Spacing between holes also matters. It should be at least two times the sheet thickness
(2T), if not more.
•Distance between holes ensures strength of the metal and prevents holes from deforming
during the bending or forming processes.
Example

14. Design for Assembly
(DFA)

15. Design for Assembly
DFA is the method of design of the product for ease of assembly.
“Optimization of the part/system assembly”
Definition

16. Design for Assembly cont..
.
•DFA is a tool used to assist the design teams in the design of products that
will transition to production at a minimum cost, focusing on the number of
parts, handling and ease of assembly.

17. Design for Assembly Principles
•Minimize partcount
•Design parts with self-locating features
•Design parts with self-fastening features
•Minimize reorientationof parts during assembly
•Design parts for retrieval, handling, & insertion
•Emphasize ‘Top-Down’assemblies
•Standardizeparts…minimum use of fasteners.
•Encourage modulardesign
•Design for a base partto locate other components
•Design for component symmetryfor insertion

18. •Original design for a thermal
gunsight reticle in a US tank,
made by Texas Instruments,
Inc.
•There are a large number of
fasteners.
Example 1
Source: Boothroyd, Dewhurst and Knight (1994)

19. •Redesigned thermal gunsight reticle:
simpler to assemble, and less to go
wrong!
Source: Boothroyd, Dewhurst and Knight (1994)

20. Original Redesign Improvement
Assembly time (h) 2.15 0.33 84.7%
Number ofdifferent parts 24 8 66.7%
Total number of parts 47 12 74.5%
Total number of operations 58 13 77.6%
Metal fabricationtime (h) 12.63 3.65 71.1%
Weight (lb) 0.48 0.26 45.8%
Measuring Improvement

21. Example 2
•Redesign of
motor drive
assembly
following
design for
assembly
(DFA)
analysis.

22. Part Count Reduction
Assembly Saving
(DFA)
Part Manufacture
Saving (DFM)
Saving
Optimum
Total Saving
Cost of Assembly Vs Cost of Part Manufacture