Core removal

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Core removal

• Howard Pickard
• LBBC Technologies

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Core removal

• LBBC Technologies
• Suppliers of autoclave systems

Dewaxing BoilerclaveTM
Core Leaching autoclave
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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
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Shell removal vs Core removal
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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
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Cores
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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

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Removal of coremethods

• Hydraulic cleaning
• Sand blasting
• Caustic bath / mechanical agitation
• Caustic autoclave
• Molten caustic
• Ultrasonics

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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

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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

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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

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Removal of coremethods

• Hydraulic cleaning
• Sand blasting
• Caustic bath / mechanical agitation
• Caustic autoclave
• Molten caustic
• Ultrasonics

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Core leaching autoclave
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Core examples
Courtesy of Certech
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The process
The Equipment
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The process
Load
Baskets
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The process
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The process
Dump
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The process
Wash
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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

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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

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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.
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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
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Shell and Core removal

• Special thanks to
• Dr Brian Robson
• Casting Solutions Limited
• Email brianrobson_at_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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• Thank you