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 Mechanical engineering designs generally
include off-the-shelf components and
fabricated parts.
 Knowing the strengths ...
1. Simplicity
2. Standard Materials and Components
3. Standardized Design of the Product
4. Liberal Tolerances
5. Use Mate...
6. Teamwork with Manufacturing Personnel
7. Avoidance of Secondary Operations
8. Design to Expected Level of Production
9....
 Description: minimize the number of parts,
intricate shapes, and manufacturing
operations
 Motivation: generally provid...
 Description: Use standard off-the-shelf parts
and widely available materials
 Motivation: eases purchasing, simplifies
...
 Description: For similar products, specify the
same materials, parts, and subassemblies as
much as possible.
 Motivatio...
 Description: make tolerances as forgiving as
possible
 Motivation: tight tolerances are expensive (in
a non-linear fash...
 Description: take advantage of materials
that have been developed for easy
processibility
 Motivation: while material m...
 Description: collaborate with the people who
will be producing your product (the earlier the
better)
 Motivation: they ...
 Description: minimize the need for secondary
operations
 Motivation: secondary operations (e.g.
deburring, inspection, ...
 Description: understand and take advantage
of the special capabilities of various
manufacturing processes
 Motivation: ...
 Description: on part drawings, specify only
the final characteristics needed; do not
specify the process to be used
 Mo...
Estimate the Manufacutring
Costs
Consider the Impact of DFM
Decisions on Other Factors
Recompute the
Manufacturing Costs
R...
 Estimate the manufacturing costs.
 Reduce the costs of components.
 Reduce the costs of assembly.
 Reduce the costs o...
Finished GoodsManufacturing System
Equipment Information Tooling
WasteServicesSuppliesEnergy
Raw Materials
Labor
Purchased...
 Sum of all the expenditures for the inputs of
the system (i.e. purchased components,
energy, raw materials, etc.) and fo...
Manufacturing Cost
OverheadAssemblyComponents
Standard Custom Labor
Equipment
and Tooling
Support
Indirect
Allocation
Raw
...
 Component Costs (parts of the product)
 Parts purchased from supplier
 Custom parts made in the manufacturer’s own pla...
 Fixed Costs – incurred in a predetermined
amount, regardless of number of units
produced (i.e. setting up the factory wo...
 Understand the Process Constraints and Cost
Drivers
 Redesign Components to Eliminate
Processing Steps
 Choose the App...
Redesign costly parts with the same
performance while avoiding high
manufacturing costs.
Work closely with design engineer...
 Reduce the number of steps of the
production process
 Will usually result in reduce costs
 Eliminate unnecessary steps...
Economies of Scale – As production volume
increases, manufacturing costs usually
decrease.
 Fixed costs divided among mor...
 Black box—only give a description of what the
component has to do, not how to achieve it
 Successful black box design r...
 Economies of Scale – The unit cost of a
component decreases as the production
volume increases.
 Standard Components—co...
DFM Design Principles
DFM Design Principles
DFM Design Principles
DFM Design Principles
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DFM Design Principles

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DFM Design Principles

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DFM Design Principles

  1. 1.  Mechanical engineering designs generally include off-the-shelf components and fabricated parts.  Knowing the strengths and limitations of the fabrication techniques makes for higher quality and more cost competitive designs.
  2. 2. 1. Simplicity 2. Standard Materials and Components 3. Standardized Design of the Product 4. Liberal Tolerances 5. Use Materials that are Easy to Process
  3. 3. 6. Teamwork with Manufacturing Personnel 7. Avoidance of Secondary Operations 8. Design to Expected Level of Production 9. Utilize Special Process Characteristics 10. Avoid Process Restrictiveness
  4. 4.  Description: minimize the number of parts, intricate shapes, and manufacturing operations  Motivation: generally provides reduced cost, improved reliability, easier servicing, and improved robustness  Example: Braun Lift
  5. 5.  Description: Use standard off-the-shelf parts and widely available materials  Motivation: eases purchasing, simplifies inventory management, and avoids tooling investments  Example: Screws
  6. 6.  Description: For similar products, specify the same materials, parts, and subassemblies as much as possible.  Motivation: provides economies of scale, simplifies operations, and simplifies inventory management  Example: Braun Lift
  7. 7.  Description: make tolerances as forgiving as possible  Motivation: tight tolerances are expensive (in a non-linear fashion) (Fig in the next slide)
  8. 8.  Description: take advantage of materials that have been developed for easy processibility  Motivation: while material may cost more, it will often provide lower overall cost  Example: “Free-Machining” Grades, Many polymer grades are tuned to a process
  9. 9.  Description: collaborate with the people who will be producing your product (the earlier the better)  Motivation: they provide a unique body of knowledge and useful insights  Example:
  10. 10.  Description: minimize the need for secondary operations  Motivation: secondary operations (e.g. deburring, inspection, painting, and heat treating) can be as expensive as the primary manufacturing operation  Example: Pre-painted steel, investment casting, MIM in firearms
  11. 11.  Description: understand and take advantage of the special capabilities of various manufacturing processes  Motivation: can often eliminate manufacturing operations and reduce the number of parts  Example: injection molding snap fits and living hinges
  12. 12.  Description: on part drawings, specify only the final characteristics needed; do not specify the process to be used  Motivation: potential cost savings
  13. 13. 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
  14. 14.  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.
  15. 15. Finished GoodsManufacturing System Equipment Information Tooling WasteServicesSuppliesEnergy Raw Materials Labor Purchased Components
  16. 16.  Sum of all the expenditures for the inputs of the system (i.e. purchased components, energy, raw materials, etc.) and for disposal of the wastes produced by the system
  17. 17. Manufacturing Cost OverheadAssemblyComponents Standard Custom Labor Equipment and Tooling Support Indirect Allocation Raw Material Processing Tooling
  18. 18.  Component Costs (parts of the product)  Parts purchased from supplier  Custom parts made in the manufacturer’s own plant or by suppliers according to the manufacturer’s design specifications  Assembly Costs (labor, equipment, & tooling)  Overhead Costs (all other costs)  Support Costs (material handling, quality assurance, purchasing, shipping, receiving, facilities, etc.)  Indirect Allocations (not directly linked to a particular product but must be paid for to be in business)
  19. 19.  Fixed Costs – incurred in a predetermined amount, regardless of number of units produced (i.e. setting up the factory work area or cost of an injection mold)  Variable Costs – incurred in direct proportion to the number of units produced (i.e. cost of raw materials)
  20. 20.  Understand the Process Constraints and Cost Drivers  Redesign Components to Eliminate Processing Steps  Choose the Appropriate Economic Scale for the Part Process  Standardize Components and Processes  Adhere to “Black Box” Component Procurement
  21. 21. Redesign costly parts with the same performance while avoiding high manufacturing costs. Work closely with design engineers—raise awareness of difficult operations and high costs.
  22. 22.  Reduce the number of steps of the production process  Will usually result in reduce costs  Eliminate unnecessary steps.  Use substitution steps, where applicable.  Analysis Tool – Process Flow Chart and Value Stream Mapping
  23. 23. Economies of Scale – As production volume increases, manufacturing costs usually decrease.  Fixed costs divided among more units.  Variable costs are lower since the firm can use more efficient processes and equipment.
  24. 24.  Black box—only give a description of what the component has to do, not how to achieve it  Successful black box design requires clear definitions of the functions, interfaces, and interactions of each component.
  25. 25.  Economies of Scale – The unit cost of a component decreases as the production volume increases.  Standard Components—common to more than one product  Analysis tools – group technology and mass customization

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