Design for Manufacturability

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Design for Manufacturability Prototyping

• Sam Chiappone, Manager
• Fabrication Prototyping SoE
• GMP Class Fall 2010

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Learning Objectives

• Gain an awareness of DFM
• Understand that various methodologies and
  approaches exist to address the objectives of DFM
  
• Learn that design complexity is a key parameter
  associated with cost

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Design for X

• Performance
• Overall features
• Reliability
• Serviceability
• Environmental impact
• Conformance to a standard
• Manufacturability
• Durability
• Serviceability
• Aesthetics
• Perceived quality

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DFM Defined

• Realizes reducing manufacturing cost begins at
  the design phase of a product.
• Design revisions are made in an effort to reduce
  part count to eliminate non-value added elements
  of a component, subassembly, and/or final
  assembly.
• Overall quality is not compromised as a result of
  the reduced costs.
• Reduced costs higher profit margins

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DFM Process Inputs

• Conceptual ideas
• Sketches/drawings
• Prototypes
• Product specifications
• Estimated manufacturing and assembly costs
• Production numbers
• Delivery dates
• Manufacturing engineering
• Customer
• Manufacturing and assembly process analysis and
  justification
• Bill of materials

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DFM Process Inputs
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Process Steps

• Estimate manufacturing costs
• Reduce cost of components
• Reduce the cost of assembly
• Reduce the cost of support operations
• Consider the impact of DFM

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Manufacturing Costs
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Costs

• Cost Factors
• Fixed cost does not change based on production
  numbers
• 125,000 CNC Milling Machine
• Variable cost changes as a result of production
  numbers
• Raw material aluminum stock .. plastic
• Assembly labor costs (sometimes temp help is used
  and can be adjusted based on demand)

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Costs
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Step 1 Manufacturing Costs

• Component costs
• Make or buy
• Make Design and build from raw material
• Costs Labor, equipment, tooling
• In-house vs. supplier
• Buy vendor standard items (nuts, bolts,
  motors, gears)

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Step 1 Manufacturing Costs

• Assembly Costs
• Assembly costs
• Discrete components packaged into subassemblies
  and final assemblies
• Similar to manufacturing (processing tooling)
• Typically products produced in quantities less
  then 100,000 are hand assembled which equals high
  labor costs in US industry.

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Step 1 Manufacturing Costs

• Overhead Costs
• Indirect cost of supporting manufacturing
• Housekeeping, security, utilities, administration

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Step2 Reduce Component Costs

• Understand the available and potential process
  capabilities
• Example 90 degree corner in an internal pocket
• Two step process milling and EDM
• Is the feature needed?
• Increased processing equals increased cost and
  delivery time
• Understand the acceptable tolerance range
• Make it as good as you can

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Step2 Reduce Component Costs

• Understand the advantages and disadvantages of
  basic manufacturing processes
• Why use forging?
• Use net shape processes when possible (plastic
  injection molding)
• Maximize tooling design for high production
  numbers
• Family die/mold
• Pool stair example Latham Plastics

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Step2 Reduce Component Costs

• Use standard components for jigs, fixtures,
  molds, and dies
• Allow suppliers to develop manufacturing plans
  around your specifications. Do not tell them how
  to make it.

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Step 3 Reduce Assembly Costs

• Eliminate nonessential parts
• Optimized Part Count Benefits Include
• Reduced Weight
• Reduced Complexity
• Reduced Opportunity for error
• Reduced Assembly Time

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Step 3 Reduce Assembly Costs

• Eliminate nonessential parts
• Integrated part - Can the part be combined with
  another part?
• Inset molding a metal bracket in the plastic
  injection molding process could eliminate a
  fastener, assembly process, and potential point
  of failure.
• No assembly
• Reduced tooling/processing
• Assist in quality specifications (orientations
  are set)

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Step 3 Reduce Assembly Costs

• Guidelines for design for assembly
• Part inserted from top axis (Z) top down
  assembly
• Self alignment features
• Tapers and chamfers
• No orientation required
• Phillips head screw aligned with driver bit
• One hand assembly
• Less time, availability of the other hand to do
  another task
• No tools required for assembly
• Reduce the number of snap rings, cotter pins,
  springs, bolts/nuts
• Use Single motion assembly items
• Pins and snap-fits
• Secure part with single motion
• Press fit

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Step 4 Reduce Support Costs

• Reduced parts reduced inventory
• Reduced storage, reduced inventory control, raw
  material costs
• Reduced supply chain management costs

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Step 5 Consider Impact

• Overall cost reduction
• Labor
• Raw materials
• Purchased components
• Tooling
• Reduced product development cycle
• Constant review of quality specifications will
  result in continuous product improvements
• Increased manufacturing and assembly knowledge
• Share with future design teams on similar product
  concepts
• Product review will evaluate material selection
• Environmental impact (materials, part count,
  reduced manufacturing byproducts coolants,
  reduced parts equals reduced energy into a
  system)

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Tools

• Past Experience

Material and Processes in Manufacturing Tenth
Edition - DeGarmo
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Tools

• Supplier network
• Consultants and software
• Boothroyd Dewhurst DFMA software tools developed
  by Dr. Boothroyd and Dr. Dewhurst in 1983.
  Current customers include Harley-Davidson, John
  Deere, and Abbott Laboratories.
• Website http//www.dfma.com/
• Prototyping

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Prototyping

• What Is It?
• A model of a product or process with one or more
  dimension of interest. The model may include
  conceptual sketches, mathematical models,
  critical design elements, and or fully functional
  physical models.

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Why Do It?

• Learning
• Communication
• Proof of Concept
• Testing
• Experimentation
• Experience
• Marketing
• Evaluation
• DFM/DFA Analysis

www.machinedesign.com
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Expected Outcome

• Verify
• Form
• Function
• Fit
• Analyze
• Cost
• Learn
• Process Knowledge
• Continuous Improvement

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Basic Types

• Simulation
• CAD, CAM, FEA, Solid Models, etc.
• AutoForm
• Assemblies in SolidWorks / NX
• Physical
• Machined
• Components or full working models
• Rapid Prototypes
• Prototype mfg and assembly systems