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Core removal

Core removal. Howard Pickard LBBC Technologies. Core removal. LBBC Technologies Suppliers of autoclave systems. Dewaxing Boilerclave TM. Core Leaching autoclave. Core removal. LBBC Technologies Suppliers of autoclave systems with Quicklock TM doors. Independent family owned

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Core removal

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  1. Core removal Howard Pickard LBBC Technologies

  2. Core removal LBBC Technologies Suppliers of autoclave systems Dewaxing BoilerclaveTM Core Leaching autoclave

  3. Core removal LBBC Technologies Suppliers of autoclave systems with QuicklockTM doors Independent family owned Established over 130 years Variety of autoclave applications Equipment development Service and support

  4. Shell removal vs Core removal

  5. Shell vs Core removal • Removal of the shell involves… • Removal of a core involves… • metal shrinkage assists the process • large ceramic particles • mechanical methods • small ceramic particles • complex geometry • enclosed areas

  6. Used by a minority of foundries Increases applications for investment castings Implications throughout process Removal perceived to be the hardest stage Considering only Silica based cores Cores

  7. Removal of coreKey issues • Geometry • Is it possible to remove? • Metal Alloy • Susceptible to attack • Cost • Market potential, capital investment • Health & Safety • Exposure of operators, waste by-products • Environment • By-products of the process

  8. Removal of coremethods • Hydraulic cleaning • Sand blasting • Caustic bath / mechanical agitation • Caustic autoclave • Molten caustic • Ultrasonics

  9. Removal of coremethods • Hydraulic cleaning • Sand blasting • Caustic bath / mechanical agitation • Caustic autoclave • Molten caustic • Ultrasonics Description High pressure water jets erode core particles then recirculate within machine Advantages Good method for simple core geometry. Low health and safety issues. Disadvantages Can be difficult and time consuming to remove the core. • Best practice • Large non complex cores

  10. Removal of coremethods • Hydraulic cleaning • Sand blasting • Caustic bath / mechanical agitation • Caustic autoclave • Molten caustic • Ultrasonics Description Grit or shot is fired at the core passage within a cabinet either by compressed air or an impeller. Advantages Effective at removing large cores with low complexity. Low health and safety issues. Good casting finish Disadvantages High level of dust. High possibility of casting wear. • Best practice • Grade of shot/grit. • Mechanical separation

  11. Removal of coremethods • Hydraulic cleaning • Sand blasting • Caustic bath / mechanical agitation • Caustic autoclave • Molten caustic • Ultrasonics Description Sodium or potassium hydroxide solution (35 – 50%) in a tank at room or elevated temperature. Parts placed into solution and left for liquid to break down the core material. Mechanical or air agitation may be added. Advantages Low cost, simple method for removing cores. Minimises erosion of casting. Disadvantages Can take long time for large or complex cores. High level of health, safety and environmental risks • Best practice • Consider agitation • Automate systems • Drill holes first

  12. Removal of coremethods • Hydraulic cleaning • Sand blasting • Caustic bath / mechanical agitation • Caustic autoclave • Molten caustic • Ultrasonics

  13. Core leaching autoclave

  14. Core examples Courtesy of Certech

  15. The process The Equipment

  16. The process Load Baskets

  17. Typically 120 psi 160 oC NaOH 20% KOH 40% Fill & Cycle The process

  18. The process Dump

  19. The process Wash

  20. Core leaching autoclave • Best practice • NaOH or KOH • Speed, recycle • Concentration • High / low, temperature • Component orientation • Up or down, horizontal • Cycle parameters • Dwell, vent, mid way break • Recycle caustic • Cost, efficiency • Post leach operations • Water wash

  21. Removal of coremethods • Hydraulic cleaning • Sand blasting • Caustic bath / mechanical agitation • Caustic autoclave • Molten caustic • Ultrasonics Description Bath of molten concentrated caustic. Castings placed inside Advantages Quick and effective at removing cores Disadvantages Many health and safety issues. Likely to attack the casting alloy surface • Best practice • Take great care • Check suitability of alloy

  22. Removal of coremethods • Hydraulic cleaning • Sand blasting • Caustic bath / mechanical agitation • Caustic autoclave • Molten caustic • Ultrasonics Description Use of ultrasonic rays to break down macroscopic structures • Best practice • Research phase – no commercial system Advantages Speeds up the process Non contact Disadvantages Early development of the process. Untested.

  23. Removal of core Consider the key issues Be aware of the alternative methods Review the operation Increase application of investment castings Increase yield Improve quality

  24. Shell and Core removal Special thanks to : Dr Brian Robson Casting Solutions Limited Email : brianrobson@live.com • References • Fettling and finishing, Dr Alan Clegg, EICF workshop 2004 • Leaching of preformed ceramic cores, Miller & Eppink, Sherwood Refractories, ICI 1983

  25. Thank you

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