Castings Practice: The Ten Rules of Castings
by John Campbell
Brief contents
Rule 1 – Achieve a good quality melt
- Background
- Melting
- Holding
- Pouring
- Melt treatments
- Degassing
- Additions
- Filtration
- Packed beds
- Alternative varieties of filters
- Practical aspects
Rule 2 – Avoid turbulent entrainment (the critical velocity requirement)
- Maximum velocity requirement
- The ‘no fall’ requirement
- Filling system design
- Gravity pouring of open-top moulds
- Gravity pouring of closed moulds
- Horizontal transfer casting
- Counter-gravity
- Surface tension controlled filling
- Inclusion control: filter sand traps
- Practical calculation of the filling system
Rule 3 – Avoid laminar entrainment of the surface film
(the non-stopping, non-reversing condition)
- Continuous expansion of the meniscus
- Arrest of vertical progress
- Waterfall flow
- Horizontal stream flow
- Hesitation and reversal
Rule 4 – Avoid bubble damage
- Gravity-filled running systems
- Pumped and low-pressure filling systems
Rule 5 – Avoid core blows
- Background
- Prevention
Rule 6 – Avoid shrinkage damage
- Feeding systems design background
- Gravity feeding
- Computer modelling of feeding
- Random perturbations to feeding patterns
- Dangers of solid feeding
- The non-feeding roles of feeders
- The seven feeding rules
- rule 1: Do not feed
- rule 2: Heat-transfer requirement
- rule 3: Mass-transfer requirement
- rule 4: Junction requirement
- rule 5: Feed path requirement
- rule 6: Pressure gradient requirement
- rule 7: Pressure requirement
- The new feeding logic
- Background
- The new approach
- Active feeding
- Freezing systems design
- External chills
- Internal chills
- Fins
Rule 7 – Avoid convection damage
- Convection: the academic background
- Convection: the engineering imperatives
- Convection damage and casting section thickness
- Countering convection
Rule 8. Reduce segregation damage
Rule 9 – Reduce residual stress (the ‘no water quench’ requirement)
- Residual stress from casting
- Residual stress from quenching
- Distortion
- Heat treatment developments
Rule 10 – Provide location points
- Datums
- Location points
- Rectilinear systems
- Cylindrical systems
- Trigonal systems
- Thin-walled boxes
- Location jigs
- Clamping points
- Mould design: the practical issues
- Casting accuracy
- Tooling accuracy
- Mould accuracy
- Summary of factors affecting accuracy
- Metrology
Appendix
- The 1.5 factor
- The Bernoulli equation
- Rate of pour of steel castings from a bottom-pour ladle
- Running system calculation record
- Design methodology for investment castings
