1. Create internal cavities
Core‑Making
Create internal cavities

2. Most common core materials
1. green sand cores ‑ little strength
2. dry sand cores ‑ sand and binders ‑ baked

3. Cores must be strong yet collapsible

4. base sand:
silica

5. binders: Organic Inorganic
flour, starch, resins, oils ‑ liquid binders
Inorganic
clays, cement

6. Two problems with making cores:
1. gas ‑ caused by excessive organic binders
2. moisture

7. Cores usually made in a core box made of wood or matel
box is half, split, or booked type

8. Making a core: (p. 65)
1. sand and binder are mixed in muller so the grains of sand are coated with the binder
2. core sand rammed into core box
3. surface is struck off flat
4. flat plate clamped to flat surface of box
5. box and plate are rolled over together
6. box lifted off
7. sand core is left on the plate to be dried in oven

9. irregular ‑ shaped cores may be supported by a contoured metal plate called a "drier”

10. cores are rammed by: 1. Hand 2. Jolting 3. Squeezing
4. blowing (most common) ‑ core box requires vents for escaping air and flowability of sand is a factor

11. Some continuous cross section cores are extruded (CAT)

12. Positioning the core:
Core pints ‑ recesses in the sand to support the core
Chaplets ‑ (p. 66) metal props that become part of the casting ‑ made of same metal as casting

13. Mold must be vented to allow core oil binder gases to escape form the mold