资源描述
,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Rotational Molding,Rotational Molding,An Introduction to the Basics,Personal Introduction,R. Dru Laws,Employed with Mity-Lite Engineering throughout and after schooling,Bachelors in Mechanical Engineering,From BYU,Masters in Polymer Engineering,From QUB (in Ireland),Engineering Director for Mity Fence Systems,Owner/Founder of RotoScientific,Example Product,Example Product,Example Product,Example Product,Example Product,Example Product,Presentation Outline,Introduction,The Materials,The Machines,The Molds,The Method,Conclusion,Introduction,Also known as rotomolding or rotocasting,Process for manufacturing large, hollow, one-piece plastic products,Best know for the manufacture of tanks and toys (Little-Tykes),Suitable for small & complex shapes,Introduction,Historical Development,1850s:Patent granted for rotomolding principle,1910s:Method used for chocolate products,1940s:Method used for vinyl plastisols,1950s:Invention of PE for the process,1960s:Rapid expansion in toy industry,1970s:Gradual expansion for technical products,1990s:Significant improvement in process control (at QUB),Introduction,1500 Rotomolders around the world,Introduction,North American Market Segments,Introduction The Process,Introduction,Strengths,Small production runs,Large part capability,Low tooling costs,Stress-free” products,Short product development lead times,Introduction,Weaknesses,Slow cycle times,Limited material choices,Difficult to automate,Poor image,Low technology culture,Presentation Outline,Introduction,The Materials,The Machines,The Molds,The Method,Conclusion,The Materials,The Materials,Low,Zero Shear Viscosity,is required to aid in the flow of the polymer within mold,MFI,Lower MFI resins high strength products,Higher MFI good surface finish and surface detail,The Materials,Particle shape and size is crucial to the flow characteristics as the mold is rotating,Standard size is a 35 mesh powder (500 micron, 0.0197 inches),The Materials,Dry-flow/Bulk-density characteristics,Dry-flow,is the time it takes 100 grams of resin powder to pass through a funnel of given dimensions,Bulk-density,is the quantity of undisturbed powder than can fit inside a beaker of specified dimensions,Inversely proportional to each other,The Materials,The Materials,Other Material,Foams,Post-process,In-process,Liquid reactive polymers,Micro-pellets,Additives,Ceramics,Presentation Outline,Introduction,The Materials,The Machines,The Molds,The Method,Conclusion,The Machines,Rock-and-Roll,Clamshell,Vertical,Shuttle,Carousel,Fixed,Independent,Electric & Jacket,Rock-and-Roll Machines,Rock-and-Roll Machines,Clamshell Machines,Vertical Machines,Shuttle Machines,Fixed Carousel Machines,Independent Carousel Machines,Electric Machines,The Machines,The “ARM” and “PLATE”,Presentation Outline,Introduction,The Materials,The Machines,The Molds,The Method,Conclusion,The Molds,Materials,Steel,Mild,Stainless,Aluminum,Cast,Machined,Plate,The Molds,Anatomy,Frame and Spider,Two or more sections (with draft),Parting line with alignment features,Clamping hardware and pry-points,Vent (breather) tubes,Texture and other features,Release agents,The Molds Frame and Spider,The Molds - Mold Sections,The Molds - Parting Line,The Molds - Parting Lines,The Molds - Parting Lines,The Molds - Clamping Hardware,The Molds Pry Points,The Molds - Vents,The Molds - Vents,The Molds Kiss-Offs,The Molds - Threads,The Molds - Inserts,Presentation Outline,Introduction,The Materials,The Machines,The Molds,The Method,Conclusion,The Method,Loading,Heating,Cooling,Unloading,The Method - Loading,A predetermined amount of resin is loaded into the mold,The mold is closed after the flanges have been cleared of resin particles,The mold is secured shut,Rotate the mold to ensure no tools have been left on the machine,The Method - Heating,Rotate the mold in a high-temperature environment,The resin will always sit at the lowest point of the cavity (powder pool),It will slowly coat the mold interior until all the resin has melted,The resin will then continue to densify as the gap between the particles disappears,Remove the mold from the oven when the powder has completely melted and densified,The Method - Cooling,Rotate the mold in a room temperature environment,This allows the layer of resin to cool and solidify,Water can also be used, but care should be exercised,The Method - Unloading,Remove the clamping system,“Pry” open the mold,Lift the completed, hollow, one-piece part from the mold.,Repeat the cycle,The Method,The concern,How do you really know when it is time to do the next step?,When is the resin melted?,When is it cooled?,In the early 90s, QUB invented an instrument that revolutionized process comprehension and control,The Rotolog,The Method Rotolog,Temperature sensors (4 type-K Thermocouples),RF Transmitter,RF Receiver and Signal Conditioner,Computer Software,Real time monitoring of the temperatures,The Method Rotolog,The Method Rotolog,The Method Temperature Profiles,The Method IAT Profile,The Method IAT Profile,The Method IAT Profile,The Method IAT Profile,The Method IAT Profile,The Method IAT Profile,The Method IAT Profile,We can thus observe:,When powder first sticks to the mold,When the powder has been consumed,When optimal melt sintering has occurred,When solidification is occurring,When the plastic separates from the mold,A,B,C,D,E,The Method IAT Profile,The Peak Internal Air Temperature,(PIAT),is the key process control parameter and is independent of all other process variables (point C),C,The Method,Other important (QUB) developments,Pressurization (Dynamic Venting),Permanent temperature feedback (K-Kontrol),RotoSim computer simulation,Worldwide training seminars and consulting,PPRC Rotomolding division,Presentation Outline,Introduction,The Materials,The Machines,The Molds,The Method,Conclusion,Conclusion,Though in a state of infancy, Rotomolding offers unique advantages over other plastics processes,There are endless opportunities for research and development,Rotomolding has a very promising future, more so than many competing processes,Acknowledgements,Thank-you to Dr. Brent Strong for providing me with this opportunity,Thank-you for your attention,?,
展开阅读全文