Advancements in Composite Cover Technology for Calender Applications Bob Carney Stowe Weavexx PaperCon 2011 Page 2555
Composite Cover History Composite covers introduced in the late 1980 s I iti ll h d hi h f il t Initially had a high failure rate Replaced cotton filled rolls Improved calender capabilities - Higher load - Higher temperature PaperCon 2011 Page 2556
Original Composite Cover Details No reinforcement fiber Resin did not contain any fillers Fillers were eventually added to the resin Simple manufacturing processes PaperCon 2011 Page 2557
Original Composite Cover Issues Poor wear resistance Poor impact resistance Lack of experience Poor operator training Elementary cover design 25-50% of all covers replaced annually PaperCon 2011 Page 2558
Resin Improvements in Composite Calender Covers Filler improvements - Improved materials Silicon Carbide Titanium Dioxide - Filler shape and size Consistent filler shape Decreased filler size - Improved cover ductility PaperCon 2011 Page 2559
Material Improvements Silicon Carbide and Titanium Dioxide replace clay based fillers These fillers have a Mohs Hardness value of 7-9 and clay has a value of 2-3 These fillers are also available in smaller sizes PaperCon 2011 Page 2560
Filler Size Reduction PaperCon 2011 Page 2561
Nano Particle Fillers DIAMETER OF A HUMAN HAIR: 50µm Nano -Particle (300nm) on Hair Three major goals: Wear resistance F t Fracture toughness t h Surface smoothness PaperCon 2011 Page 2562
Wear Resistance Conventional Cover Matrix Nanotechnology Matrix Large flake, spherical, and block particles allow more pockets of pure matrix with poor resistance to wear as the matrix wears the filler falls out leaving large voids. Sub-micron treated particles distributed ib t d evenly in matrix yield improved wear resistance. PaperCon 2011 Page 2563
Fracture Toughness Free crack propagation Lower surface area Poor energy absorption Impedes crack propagation Higher surface area Improved energy absorption Crack Impact Impact Impact Impact Conventional Matrix Nanoparticle Matrix PaperCon 2011 Page 2564
Composite Cover Abrasion Resistance 120 Abrasion Resistance 100 80 60 40 20 0 1980's vintage cover 1995 vintage cover 2005 vintage cover current cover PaperCon 2011 Page 2565
Ductility Improvements Ductility allows the cover to come back after an impact I t i d i t Improvements increase damage resistance PaperCon 2011 Page 2566
Ductility Index Customer Focused. Technology Driven. 13 PaperCon 2011 Page 2567
Resin Mixture Improvements Converted from Torsional/paddle mixer to shear mixers I d i i i d di t ib ti f fill Improved mixing insured even distribution of fillers Shear mixers helped to overcome the thixotropic properties of the heavily filled resin PaperCon 2011 Page 2568
Manufacturing Changes Wrapping Methods Flat pass (original method) - Opportunity for resin rich areas to form - Chance for dry edges/defects Multiple passes are needed to build proper top stock thickness Only method to process TFP PaperCon 2011 Page 2569
Manufacturing Changes Wrapping Methods Angle Wrap Application Method Higher fiber fraction Virtual elimination of defects Eliminates resin rich areas Single pass application once topstock thickness is reached ed PaperCon 2011 Page 2570
Wrapping Method Comparison PaperCon 2011 Page 2571
Manufacturing The Wrapping Process PaperCon 2011 Page 2572
Manufacturing Improvements Kevlar tension control - Computerized control - Improved Kevlar consistency Improved resin flow control - Computerized flow monitoring - Improved pumps Improved resin mixture systems PaperCon 2011 Page 2573
Additional Technological Advances Addition of real time nip monitoring Thermal conductive base materials PaperCon 2011 Page 2574
Continuous Monitoring of Nip Performance Machine efficiency Product quality On-the-run diagnostics PaperCon 2011 Page 2575
Benefits of Continuous Nip Monitoring Real Time Knowledge True operating conditions Temperature, vacuu m, etc. Dynamic vs. static measurement On-the-run feedback Eliminates uncertainty Enables immediate adjustments PaperCon 2011 Page 2576
Thermal Conductive Base Material - Minimizes or eliminates localized hot spots Impacts Varying web width C ti t k Coating streaks - Potential for increased gloss by running warm water in the roll PaperCon 2011 Page 2577
ThermaGuard Base Test calender roll - Thermally conductive matrix (left side) - Standard matrix (right side) Thermo scan showing the temperature distribution - Left side homogeneous distribution - Right side no thermal distribution Damage caused by thermal overloading PaperCon 2011 Page 2578
Conclusion New Technology has improved composite cover performance - Improved impact resistance - Improved wear resistance - Improved ductility Manufacturing improvements have improved cover characteristics Calender performance has improved because of the new cover technologies PaperCon 2011 Page 2579