K2010
Turning Metal into Plastic - Challenges, Solutions, Benefits
Edwin Verhorst Jos van Laerhoven
Outline 1. Introduction • New application development challenges • Perceptions about metal replacement • Materials • Metal conversion processes 2. Overview of Die Cast Replacement • Advantages/disadvantages • Benefits of plastics vs. DC metals 3. Overview of Sheet Metal Replacement • Advantages/disadvantages • Single sheet metal part vs. SM assemblies • Understanding and attacking SM assemblies 4. Examples 5. Wrap-up/Summary
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Today’s Application Development Challenges •
World-wide product take back legislation
•
More emphasis on life cycle management
•
End of life pressures driving the need for easy disassembly & recycle
•
Demand increasing for sustainable content – Post consumer recycle, bio-based
•
Demand for higher material performance
•
Continued push for COST-OUT
New design requirements challenge existing materials
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Myth or Fact about Plastics? Metal
•
Plastics cannot compete in structural applications based on modulus/strength
•
Plastics do not perform well at elevated temperatures
•
Plastics are an insulator and can not dissipate heat
•
Plastics are not conductive and can not be used for EMI/RFI applications
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It is difficult to powder coat plastics
•
Metal is more environmentally friendly
Historically, the above statements are true ….. But material developments are changing game! 4
Plastic
Turning Metal into Plastic is Straightforward …
Providing that you: • Clearly define and understand the application requirements • Identify the basic weaknesses of the incumbent conversion technology and material • Build a strong value proposition as it pertains to the application • Select the right material
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Opportunities exist ….. Identification is the key !
Three Factors that Drive Metal Replacement
1.
Cost out
2.
Performance enhancement
3.
Product differentiation
… or a combination of the 3
Importance of each driver is highly dependent on the market segment
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Understand the Competition Four basic metal conversion processes 1.
Machined metal
2.
Die casting
3.
Sheet metal stamping – –
4.
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Single sheet metal parts Sheet metal assemblies – producing complex shapes from simple sheet metal shapes Extrusion – continuous profile
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Die Casting
Die Casting Tool Life Comparison
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• •
• •
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Common materials: – Zinc - small parts (<200 g) – Aluminum – Magnesium – Brass/Copper
1000
] s t o h s 0 0 0 1 * [ e f i L l o o T
DC mold is slightly less expensive than IM Should consider cost of trimming dies and machining fixtures as part of tooling investment for DC Tool life - significant advantage for plastics 2 strategies for tight tolerance parts – High accuracy mold – requires high tool maintenance – Low accuracy mold – significant secondary machining
750
500 250 0 Zinc
Magnesium
Aluminium
ETPs
Advantage Metal:
Advantage Plastic:
•
•
Net cast parts – no secondary operations required
•
Applications designed for stiffness
•
Geometries with very thick sections •
Castings requiring secondary ops. –
Trimming
–
Drilling/taping
–
Dimensional machining
–
Assembly w/fasteners
–
Paint
Tool life
Key Considerations •
1 for 1 material replacement is not uncommon
•
Stiffness can be enhanced by slight geometry modifications
•
Operating temperature needs to be considered
•
Primary areas to drive cost-out – Improve assembly efficiency by the elimination of separate fasteners – Elimination of secondary operations Washing Trimming Sanding/filling Painting
Ultem* resin 290 g
Throttle Body
Aluminum 600 g
Metal
Hospital Bed Pedal
•
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Consider die cast mold conversions for prototyping
Verton* resin
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Sheet Metal Stamping
Single Part Materials used: •
Low carbon steel
•
Stainless steel – specialty products
•
Special alloy grades of steel
•
Aluminum
Advantage Metal: • High priority on cost … nothing else • Simple geometry • Very high volume – progressive dies • Little emphasis on styling/design/aesthetics • High stiffness/strength & limited space • Large parts, low to medium volume
Advantage Plastic: • Medium volume • Performance deficiencies – Weight – Dent/impact resistance – Corrosion resistance – Electrical insulation – Paint elimination • Desire for more design freedom
Cost-out difficult to achieve with simple sheet metal parts 12
Assemblies Materials used: •
Low carbon steel
•
Stainless steel – specialty products
•
Special alloy grades of steel
•
Aluminum
Advantage Metal:
Advantage Plastic:
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High volume – simple configuration – minimal assembly
•
Multiple sub-components
•
•
High level of factory automation
Medium volume – complicated assembly
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Multiple fasteners
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Welding/finishing/painting – highly aesthetic parts
Sheet metal assemblies can offer many opportunities for cost-out and simplification 13
Considerations
Primary areas to drive cost-out:
Secondary:
•
System simplification - Combining multiple parts - Removal of fasteners - Assembly time reduction
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Product differentiation
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Weight reduction
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Corrosion resistance
Functional integration
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Dent resistance
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Scratch resistance
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Noise dampening
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• Aesthetics, Eliminate secondary operations Quality & System-Cost Reduction - Welding/grinding - Painting - Labels
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Sheet Metal Assemblies …. How to Get Started?
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Identify goals …. Aesthetics, cost-out, weight reduction, environmental impact
•
Understanding the application … Initiate a “teardown” exercise – – – – – –
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Disassemble the full product and sub-assemblies Understand functionality of all components Clearly document individual components and assembly methods Brainstorm design alternatives Prioritize ideas – safe, reach, stretch Initiate technical feasibility assessment for high priority ideas
Teardowns most effective with cross-functional teams – design, manufacturing, molder, material supplier
Successful teardowns require a team effort 15
Maximize Advantages – Use DFMA Principles 1.
2.
3.
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Reducing number of parts –
Parts consolidation
–
Fastener reduction
Improve assembly efficiencies –
Reduce the need for secondary operations
–
Simplify assembly methods – snap fits, press-fits, heat staking
–
Eliminate sanding, grinding, painting
Optimize part handling –
Consider designs that limit assembly orientation options
–
Minimize added handling difficulties
Example: Part Count Reduction Ask the following questions about each part . . .
Must parts move relative to each other?
Must parts be made of different materials?
Would combination of parts prevent further assembly or disassembly?
If all three answers are “No”, the part is a candidate for elimination
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Examples
Goal: Cost and Weight Reduction Surface box lid
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Original in cast iron:
Re-design:
•Corrosion
•Colors possible
•Heavy weight
•Weight saving > 8 kg
•High energy cost
•UV resistant
•Theft risk
•Less transport cost
Goal: Cost Reduction, Assembly Simplification Medical chassis Existing:
13 piece metal chassis assembly (Purchase price = €200)
Proposal: 2 piece molded plastic chassis (rough estimate = € 56) Decision: Potential cost saving warrants detailed feasibility study
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Goal: Cost Out, Equivalent Performance Heavy truck side fairing support structure
Original Assembly Included 9 Parts • 2 die-cast aluminum stabilizers • 2 fiberglass extruded frame bars • 1 painted stamped steel brace • 4 painted stamped steel brackets • labor intensive assembly
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One piece molded structure Fastening clips, releasing handles and locking pins assembled during molding cycle
Savings = €60 and 5 kg per truck
Summary •
New material technologies exist to tackle today’s challenges
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Die cast metal parts offer good opportunities. Assess the following performance requirements first: – Thermal Management (inside out) – Shielding – Heat Requirements – Stiffness, strength, creep resistance
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Simple sheet metal parts offer little opportunity, if cost is main driver
•
Sheet metal assemblies are worth looking at closely. More difficult to assess the real opportunity without going through a teardown.
Metal replacement continues to offer growth opportunities
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