The Next Generation of Epoxy Adhesives Technology for Transportation Assembly:

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1 The Next Generation of Epoxy Adhesives Technology for Transportation Assembly: Low Bake One-Component Epoxies Daniel R. Daley Senior Consultant The ChemQuest Group, Inc.

2 Introduction With over 30 years of experience at Navistar International, a truck and engine OEM, Dan Daley has held various senior polymeric materials engineering and lab management positions. Daley s technical leadership included solving problems in material compatibility and chemical interactions, and improving material performance/cost ratios and strategic sourcing. The range of materials managed included soft trim such as textiles, foams, composites, seating, upholstery and acoustic materials and energy management solutions; fluid connectors; lubricants and fluid systems; elastomers; automotive paint and coatings; adhesives, sealants and joining systems. 2

3 What is the Unmet Need in Assembly? Automotive and truck body manufacturing plants have predominantly used 1K epoxy structural adhesives due to their superior bonding performance and manufacturingfriendly properties. Adhesives are co-cured in an electro-coat (e-coat) epoxy prime system at high temperatures (175ºC). Commercial vehicle body manufacturers that are unable to justify the capital equipment expense of a full immersion e- coat system cannot take advantage of the processing and performance benefits of a 1K Epoxy System. A school bus body assembled with mechanical fasteners and 2K epoxy or methyl methacrylate (MMA) adhesives is one such example. 3

4 A Significant Development is Currently Underway The emerging low bake 1K epoxy technology is a significant development. It promises to deliver all the advantages of 1K epoxy adhesives: Efficient assembly operations High strength with toughness Weld-thru property It provides assembly operations lacking the capital and infrastructure to invest in high bake systems with an ability to leverage the key advantages of technology commonly used in automotive and aircraft assembly. Finally, it will allow automotive manufacturers and others to use lighter weight materials that would not survive high bake conditions. 4

5 Vehicle Body Construction 5

6 Vehicle Body Construction The body is constructed predominantly of metal in spite of a wider range of available materials that offer key advantages Low Capitalized Body Systems mix arc welding (MIG, TIG) and fasteners 6

7 Vehicle Body Construction High Capitalized Body Systems utilize resistance spot welding Aluminum systems mix welding (resistance and arc) with fastening for reliability Prime systems are based on capital and final market requirements High-end Adhesives users use analytical tools to optimized performance 7

8 Construction Materials and Joining Methods Commercial Auto Body Light Truck Body Construction Stamped Steel Prime E-coat Body Construction Steel and Aluminum Prime E-coat Assembly Method Spot Weld Bonding Technologies 1K epoxy structural adhesive Assembly Method Spot Weld and SPR Bonding Technologies 1K epoxy structural adhesive Heavy Truck School Bus Body Construction Aluminum and Steel Prime E-coat, Precoat Body Construction Fabricated Steel Prime Precoat Assembly Method SPR, Rivets, Fasteners & Welding Bonding Technologies 1K & 2K Epoxies, PUR, methyl methacrylate (MMA) Assembly Method Rivets, SPR, Welding Bonding Technologies 2K Epoxy, 2K methyl methacrylate (MMA) SPR = self piercing rivets 8

9 Future Construction Materials and Unmet Needs Commercial Auto Body Future Construction Steel, Aluminum & Composite Unmet Needs Low bake 1K epoxy structural adhesive and primer Composite Fastening School Bus Light Truck / Heavy Truck Future Construction Aluminum & Composite Unmet Needs Low bake 1K epoxy structural adhesive and primer Future Construction Improved joining methods, paint systems Unmet Needs Low-bake cure 1K epoxy structural adhesive 9

10 School Bus Manufacturing School bus joints must be in compliance with federal regulation, 49 CFR Standard No. 221; School bus body joint strength Requirement shall hold the body panel to the member to which it is joined when subjected to a force of 60 percent of the tensile strength of the weakest joined body panel Test sections are cut into dog bones necked down to 8 through the joint. 10

11 Current Process Assembly Steps Coil coated (primed) steel is fabricated into sheets and forms Assemblies adhesive applied, fixture, drilled (unless SPR) then riveted Major structures are Arc welded Final structures fixture, bonded, drilled and fastened Prime and seal with cure bake Top-coat paint usually yellow with black rails and white roofs Pitfalls Mostly arc welding, little spot welding Metal debris from drilling may contaminate the joint Riveting may cause excessive equipment wear (and worker fatigue/repetitive use injuries) 11

12 Current School Bus Joining Methods Self Piercing Rivet Semi Tubular Rivet Mono Bolt Rivet Source: American Society of Mechanical Engineers (ASME) 12

13 Comparison of Adhesive Technologies that Meet Required Joint Strength 2K Epoxies Long open time systems Often pre mixed and used at application Ultimate strength may require bake Full cure shear strength at MPa (2,000 2,500 psi) Issues Open assembly time, waste, clean up, post bake bonding 2K Methyl Methacrylate (MMA) Short open times Mix at application Ultimate strength independent of bake Ultimate shear strength Mpa ( psi) Issues sociability - odor, open assembly time, cannot weld thru, flammable, repair 13

14 Contrasted to a Low Bake (120ºC) 1K Epoxy Adhesive Compatible with any current fastener type Can be resistance spot welded Can co-cure with sealant and prime bakes Does not cure until bake (pre-bake clean up is easy) Bulk dispense, bulk purchase No mix High strength shear Mpa (3,500 4,000 psi) Higher strength is greater tolerance on regulation or opportunity to reduce fastening No open time limits - No line stripping for partially assembled joints. Low bake is practical with large bodies 14

15 Required Testing Methods Substrate 1"x4" Plate Steel (1.6mm) Cure Schedule 250 F Closed Joint Open Joint Lap Shear (psi) Lap Shear (psi) Initial 3,877 3,877 CF CF 1 week 4,021 3,978 CF CF CF = Cohesive Failure FMVSS 221 Joint Test Joint A B C D E F G H I 2k Epoxy 220F Heat Cure k Heat Cure Estimate Min. req FMVSS Factor

16 Benefits for School Bus Manufacturers Lower Manufacturing Costs Replace fasteners for spot welds Reduce fastener usage Reduce drilling Less waste Better Assembly Line Management Better energy management opportunity Co cure in existing process Improved Joint Performance (e.g., side intrusion, roll over, roof strength) Improved Quality Better corrosion control Reduced repetitive injuries to workers Less paint damage 16

17 Additional Savings and Opportunities Paves the way for a greater freedom in body design and improved efficiency in vehicle body assembly operations Opportunity to incorporate lower temperature resistant materials into assemblies. Compatible primer technologies Low bake E-coat is under development Lower energy usage (bake ovens estimated to be 60% of an assembly plant s energy consumption) Opportunity for non-automotive assembly operations to take advantage of the process improvements 17

18 Conclusions While 1K Epoxies offer superior processing and performance advantages, the direct (and indirect) costs of conventional high temperature curing created barriers to use. Those barriers are removed with a low bake 1K Epoxy System a significant advantage to non-automotive industries. When an OEM switches from a 2K to 1K system: Waste is greatly reduced Quality is improved Superior joining methods become available Greater freedom in body design is realized. 18

19 Conclusions Moreover, a low bake system coupled with low bake immersion primer systems (120ºC or lower cure) will reduce energy costs and broaden the range of materials that can be used to meeting lightweighting requirements and further reduce costs. The 1K Epoxy technology will facilitate new methods and materials in the process, assembly and paint operations for other vehicle assembly operations (including School Bus assembly) for improved efficiency, performance and safety. 19

20 A Special Thanks to Frank Billotto at Dow Automotive (248) Headquarters The ChemQuest Group, Inc Corporate Park Drive Suite 250 Cincinnati, Ohio Phone: (513) Fax: (513) Contacts Dan Murad President and CEO Dan Daley Senior Consultant 20

21 Thank You ChemQuest Group.... The Obvious Choice TM 21