Core removal Howard Pickard LBBC Technologies Welcome Thank you to EICF

Suppliers of autoclave systems Core removal LBBC Technologies Suppliers of autoclave systems Why are we here?, 40 years of experience in industry Contacts, knowledge, here to help Dewaxing BoilerclaveTM Core Leaching autoclave

Suppliers of autoclave systems with QuicklockTM doors 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 Why are we here?, 40 years of experience in industry Contacts, knowledge, here to help

Shell removal vs Core removal Often considered together, but some fundamental differences

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 Often considered together, but some fundamental differences

Cores 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

Removal of core Key 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

Removal of core methods Hydraulic cleaning Sand blasting Caustic bath / mechanical agitation Caustic autoclave Molten caustic Ultrasonics

Removal of core methods 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

Removal of core methods 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

Removal of core methods 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

Removal of core methods Hydraulic cleaning Sand blasting Caustic bath / mechanical agitation Caustic autoclave Molten caustic Ultrasonics

Core leaching autoclave

Core examples Courtesy of Certech

The process The Equipment

The process Load Baskets

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

The process Dump

The process Wash

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

Removal of core methods 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

Removal of core methods 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.

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

Shell and Core removal Dr Brian Robson Casting Solutions Limited 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

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