Design for Manufacture

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Design for Manufacture
Source Ulrich and Eppinger, Chapter 11
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Role Of Design Engineer

• No longer totally responsible for product design
• Responsible for more than what was traditionally
  considered design
• Merging of design engineer and manufacturing
  engineer

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Where DFM fits in
System-Level Design
Concept Development
Detail Design
Testing Refinement
ProductionRamp-Up
?
DFM
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Example GM Intake Manifold
Aluminum 38.51
Thermoplastic 21.93 66 lighter
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Design for Manufacture (DFM)

• Estimate manufacturing costs
• Reduce the cost of components
• Reduce the cost of assembly
• Reduce the cost of supporting production
• Consider impact of DFM on other factors

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Outline

• Estimate manufacturing costs

• Input/output
• Unit costs
• Allocating costs
• Bill of materials (BOM)
• Estimating standard/custom components
• Estimating overhead costs

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Estimate Manufacturing Costs

• Input (Costs)
• Raw materials
• Labor
• Purchased Components
• Equipment
• Information
• Tooling
• Energy
• Supplies
• Services

• Output
• Waste (cost)
• Finished Goods (income)

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Unit Manufacturing Cost
Total manuf. Cost number of units
Unit Manuf. Cost
Usually calculated on a Quarterly or Annual basis
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Problems Allocating Costs

• Boundaries of manufacturing
• Support staff
• General purpose machinery
• Multiple product line

1. Component, assembly, overhead costs 2. Fixed
vs. Variable costs
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Bill of Materials (BOM)
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Estimating Costs of Standard Components

• Similar components
• Solicit price quotes
• Thomas Registry
• Web
• Production quantity

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Estimating Costs of Custom Components

• Based on materials, processing, and tooling
• Include waste, labor, and overhead

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Examples
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Estimating Overhead Costs

• Overhead (burden) rates
• Charged to labor, equipment, materials
• Cost ratebase
• typical values
• 110-150 material costs
• 200-350 labor costs

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Outline

• Estimate manufacturing costs
• Reduce the cost of components

• Understand processes and cost drivers
• Redesign to reduce processing steps
• Economies of scale
• Standardize components and processes
• Use Black Box procurement

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Processes Cost Drivers

• Understand the manuf. process (limits)
• Understand the cost drivers for process

• Tolerances
• Dimensions
• Drafts
• Undercuts
• Material type
• Thickness
• Throughput

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Eliminate Processing Steps

• Fewer steps lower cost
• Paint
• Machining
• Net-shape processes
• Assembly

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Economies of Scale

• Fixed vs Variable costs
• Size of production run

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Standardize Components Processes

• Same components/processes for more than one
  product
• Economies of scale
• Internal standardization
• External standardization
• Higher quality lower costs

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Black Box procurement

• Specify function, not process, to vendors
• Wide latitude for vendor
• Shifts design process to vendor
• Lower costs, higher performance
• Requires VERY CLEAR specifications
• Requires RELIABLE vendors

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Outline

• Estimate manufacturing costs
• Reduce the cost of components
• Reduce the cost of assembly

• keep score
• Integrate parts
• Ease of assembly

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Keeping Score

• Design for Assembly (DFA)

Calculating the Theoretical Minimum Does the part
have to move? Does the part have to be made of
different material? Is the part required for
access or repair?
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Integrating Parts

• Parts that are not theoretically required are
  candidates for integration
• No assembly
• Less expensive to fabricate
• Better dimensional control

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Ease of Assembly

• Assembly Grasp, orient, insert, secure
• Reduce axes of assembly
• dont require parts to be turned over
• Self-aligning
• Orientation not critical
• One-handed manipulation
• No tools required
• Single motion required to assemble
• Immediately secured upon insertion

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Design Simplification
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Estimating Cost of Assembly

• lt100,000 unit/year assembled manually
• Cost time (labor rate)
• Books tables (e.g. Boothroyd Dewhurst)

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Examples
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Outline

• Estimate manufacturing costs
• Reduce the cost of components
• Reduce the cost of assembly
• Reduce the cost of supporting production

• Systemic complexity
• Error proofing

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Minimize Systemic Complexity

• of unique parts
• Inventory
• human resource management
• of Processes
• of Suppliers

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Error Proofing

• Reduce assembly error by design

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Error Proofing

• Color coding
• Eliminate subtle difference
• Exaggerate differences

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Outline

• Estimate manufacturing costs
• Reduce the cost of components
• Reduce the cost of assembly
• Reduce the cost of supporting production
• Consider impact of DFM on other factors

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Impact of DFM

• Development time
• Development cost
• Product quality
• Component re-use
• Life-cycle costs

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Summary

• Design for Manufacture
• Estimate manufacturing costs
• Reduce the cost of components
• Reduce the cost of assembly
• Reduce the cost of supporting production
• Consider impact of DFM on other factors

Excellent reference Boothroyd Dewhurst
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DFM Guidelines

• Minimize the number of parts
• Develop a modular design
• Design parts for multi-use
• Avoid separate fasteners
• Eliminate adjustments
• Design for top-down assembly
• Design for minimum handling

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DFM Guidelines

• Avoid tools
• Minimize subassemblies
• Use standard parts when possible
• Simplify operations
• Design for efficient and adequate testing
• Use repeatable understood processes
• Analyze failures
• Rigorously assess value

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More Design Improvements

• Standardization
• uses commonly available parts
• reduces costs inventory
• Modular design
• combines standardized building blocks/modules
  into unique products

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Value Analysis (Engineering)

• Ratio of value / cost
• Assessment of value
• Can we do without it?
• Does it do more than is required?
• Does it cost more than it is worth?
• Can something else do a better job?
• Can it be made by less costly method, tools,
  material?
• Can it be made cheaper, better or faster by
  someone else?

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Design For Environment

• Design from recycled material
• Use materials which can be recycled
• Design for ease of repair
• Minimize packaging
• Minimize material energy used during
  manufacture, consumption disposal

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Measures Of Design Quality

• Number of component parts and product options
• Percentage of standard parts
• Use of existing manufacturing resources
• Cost of first production run
• First six months cost of engineering changes

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Measures Of Design Quality

• First year cost of field service repair
• Total product cost
• Total product sales
• Sustainable development

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Design For Robustness

• Product can fail due to poor design quality
• Products subjected to many conditions
• Robust design studies
• controllable factors - under designers control
• uncontrollable factors - from user or environment
• Designs products for consistent performance

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Consistency Is Important

• Consistent errors are easier to correct than
  random errors
• Parts within tolerances may yield assemblies
  which arent
• Consumers prefer product characteristics near
  their ideal values

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END