1. Core removal Howard Pickard LBBC Technologies Welcome
Thank you to EICF

2. 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

3. 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

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

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
Often considered together, but some fundamental differences

6. 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

7. 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

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

9. 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

10. 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

11. 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

12. Removal of core methods
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. The process
Typically
120 psi
160 oC
NaOH 20%
KOH 40%
Fill &
Cycle

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 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

22. 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.

23. 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

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

25. Thank you