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September 29 – October 1, 2008Doubletree Hotel Seattle Airport – Seattle, Washington
InvaLite Hybrid Tooling System for Advanced Composite Structure
Tom Sobcinski
Tooling Segment Manager
Remmele Engineering, Inc.
Overview
• Looking back at tooling for composites
• Finding an alternative to all-Invar, all-composite tooling
• InvaLite hybrid tool concept
• Design & testing
• Looking forward
Looking Back at Tooling forComposites
• In the 1980s, tools made from composites were the industry standard for aerospace manufacturing
– Light weight
– Close CTE match to the part
– Cost of masters could be amortized across rate tools
Looking Back at Tooling forComposites
• As rates increased composite tooling suffered substantial negatives
– Durability issues
– Replacement tools and repairs impacted cost of ownership
– Potential for tool failure during cure placed high value parts in jeopardy
– Limited supply chain for all-composite tooling
Looking Back at Tooling forComposites
• In the late 1980s, the aerospace industry started a shift to metals-based production tooling
– Invar becomes the baseline for tools used in production of advanced composite parts
– CTE closely matches CF/EP parts
– Durability reduces cost of ownership
– Tools last for life of program
Today
• As Aerospace OEMs and Tier 1’s start to produce larger integrated structure, they began to feel the limitations of Invar tooling
– Weight exceeds equipment capacities
– Reduced throughput due to longer cure cycles and decreased lay down rate on Automated Fiber Placement (AFP) equipment
Finding an Alternative
Goals
• Reduce tool weight
• Maintain durability & stability of Invar
• Cost competitive with other light weight solutions
• Ensure adequate supply chain for manufacture
Hybrid Tool Concept
• In 2007, Remmele developed a Hybrid Invar/composite tool concept
– Reduced thickness Invar face sheet
– Interlocking CF/BMI composite sub-structure
– Surface and support structure attached through bonded/fastened tongue & groove joints
Hybrid Tool Concept
• Weight reduction– Reduced thickness face sheet and CF/BMI sub-structure
translates into ~50% weight reduction over traditional Invar tooling
Hybrid Tool Concept
• Durability– The use of a metallic face sheet
provides the durability and vacuum integrity of Invar for the critical lay-up surface
– Minor alterations or continuous use will not induce leak paths
– Recurring cost benefit of Invar
Hybrid Tool Concept
• Stability– Analysis indicates Hybrid
Tooling provides reduced deflection over conventional Invar tooling
– Hybrid Tooling provides the CTE match needed for advanced composite curing
– Isotropic face sheet material provides predictable face sheet geometry at cure temperature with uniform CTE in all directions
Hybrid Tool Concept
• Cost and scheduling benefits– Hybrid tooling is cost-competitive with
CF/BMI composite tooling
– Additional cost for Invar masters eliminated
– Cost of ownership is lower
– Invar face sheet longevity means reduced repairs/replacement during life of tool
Hybrid Tool Concept
• Cost and scheduling benefits (cont’d.)– Reduced weight/mass over
conventional Invar = improved lay-down rates and reduced cure cycles
– Increases effective autoclave and AFP equipment capacity
– Reduces rate tool requirements
– Traditional metallic tooling supply chain
Cost Comparison
Invar Master Amortized Across (3) Tools
Totals
Invar Hybrid Carbon/BMI
Cost Comparison
4’ X 8’ Plate/Board
Hybrid Tool Concept
• Supply chain capability/capacity for tool manufacture
– Does not require expertise or capital equipment associated with composite manufacturing
– Composite sub-structure produced by water jet cutting of commercially available pre-molded CF/BMI boards
– Composite machining limited to interface joint
– Traditional tool manufacturers become part of the supply chain
– Use of both Invar and CF/BMI reduces pressure on material supply chain
Design and Testing
• July 2007: Remmele completes initial design specifications for a Hybrid Tool, conducts FEA analysis
• Fabricate and test sub-scale demonstrator tool for feasibility
• Refine design
Design and Testing
FEA analysis• Analysis indicates Hybrid Tooling provides ~50% weight
reduction with reduced deflection over conventional Invar tooling
Conventional Invar tool 31 lbs.- tool supported @ extremes with gravity load.
Invar/BMI Hybrid tool 13.4 lbs.- tool supported @ extremes with gravity load.
Building & Testing the Demonstrator
Fabricate and test small demonstrator• Sample parts were built from the demonstrator at Northwest
Airline’s composite repair facility in Eagan, Minnesota
Building & Testing the Demonstrator
Refine Design
• Continue development of Invar/Composite joint design
• Refine method of joining interlocked composite boards
• Develop reliable damage tolerant handling features
• Continue efforts towards refining design for manufacturability
Design and Testing
Researching composite materials
• CF/BMI materials found with CTE match to Invar 36, 5000 F. Tg and other required mechanical properties
• Source found to produce pre-molded quasi-isotropic CF/BMI boards and provide water jet cut sub-structure directly from CAD model
0
Joint Design: Invar / Composite
• Tongue and groove bonded/fastened construction
Design and Testing
Tensile testing
– Several bonded joint designs were tested
– Results shown for bonded only joints
– Average joint failure ~6,200 lbs. per linear inch
Looking Forward
• The concept is moving forward with a full-scale development tool with a major aerospace OEM partner
– Fourth quarter 2008 tool delivery
– Replaces existing production tool
– Jointly developing criteria for performance measurement/monitoring
– Results to be presented at future date
• Remmele Engineering continues to look at existing and new applications for the Hybrid design.
Looking Forward
Looking Forward
Finished Tool Weight- 162 Lbs.
Conclusion
InvaLite tooling offers advantages
• ~50% weight reduction over conventional Invar
• Cost competitive with CF/BMI
• Durability of Invar at critical tool layup surface
• Predictable face sheet geometry at elevated temperature
• Utilizes existing metallic tooling supply chain
• Use of both Invar and CF/BMI reduces pressure on material supply chain
Questions?
Thank you!
Tom Sobcinski, Tooling Segment Mgr. Remmele Engineering, Inc.
Phone: 651.635.4197
Email: [email protected]