Introduction to Basic Manufacturing Processes and ... - always yours

Pattern and Core Making 189
density and mould composition. This effect becomes more pronounced with increase in moisture
content and temperature.
10.6 CORE AND CORE BOX
Cores are compact mass of core sand that when placed in mould cavity at required location
with proper alignment does not allow the molten metal to occupy space for solidification in
that portion and hence help to produce hollowness in the casting. The environment in which
the core is placed is much different from that of the mold. In fact the core (Fig. 10.12) has
to withstand the severe action of hot metal which completely surrounds it. Cores are classified
according to shape and position in the mold. There are various types of cores such as
horizontal core (Fig. 10.13), vertical core (Fig. 10.14), balanced core (Fig. 10.15), drop core
(Fig. 10.16) and hanging core (Fig. 10.17).
Mold
Cavity
Sand
Baked
Core
Parting
Line
Fig. 10.12 Horizontal core
Sand
Mould Cavity
Parting
Line
Cope
Drag
Dry sand core
Core
Mould
Fig. 10.13 Vertical core
Fig. 10.14 Balanced core
Fig. 10.15 Drop core
Mould
Fig. 10.16 Hanging core
There are various functions of cores which are given below
1. Core is used to produce hollowness in castings in form of internal cavities.
2. It may form a part of green sand mold