SPRUING
metallurgical considerations
-welding technique
-need for strength
-gates, sprues, runners, vents, drains
-hot spots, filleting
-cracks and gaps
CERAMIC SHELL
Preparation
of waxes for dipping
-check for strength
-prewash
-dry thoroughly
Brief description of shell build-up
-slurry coat, stucco, dry, repeat
Materials for shell
and reasons for
their use
colloidal silica -
molochites
Theory of shell
binding system
coating of particles
-removal of water
-refractory gluing -functions of stuccos
Settling and remixing
-two bucket method
storage, evaporation prevention
-constant mixers
CORING for hollow castings
pins, stainless steel
-ceramic shell cores
-plaster/grog mixes
-ethyl silicate
-filling, light vibration
-core vents
During this day, pieces for casting are sprued and the first two ceramic coats applied