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5. Runner
Mold and Core Making 225
It is a channel which connects the sprue to the gate for avoiding turbulence and gas entrapment.
6. Riser
It is a passage in molding sand made in the cope portion of the mold. Molten metal rises in
it after filling the mould cavity completely. The molten metal in the riser compensates the
shrinkage during solidification of the casting thus avoiding the shrinkage defect in the casting.
It also permits the escape of air and mould gases. It promotes directional solidification too
and helps in bringing the soundness in the casting.
7. Chaplets
Chaplets are metal distance pieces inserted in a mould either to prevent shifting of mould or
locate core surfaces. The distances pieces in form of chaplets are made of parent metal of
which the casting is. These are placed in mould cavity suitably which positions core and to
give extra support to core and mould surfaces. Its main objective is to impart good alignment
of mould and core surfaces and to achieve directional solidification. When the molten metal
is poured in the mould cavity, the chaplet melts and fuses itself along with molten metal
during solidification and thus forms a part of the cast material. Various types of chaplets are
shown in Fig. 12.10. The use of the chaplets is depicted in Fig. 12.11.
Radiator chaplets
Break-off nicks
Shoulder
Knitting nicks
Riveted
chaplet
Welded
chaplet
Double-head chaplets
Cast chaplets
Stem chaplets
Sheet metal chaplets
Fig. 12.10 Types of chaplets
Chaplets
Cavity
Sand core
Use of chaplets to support a core
Fig. 12.11 Use of chaplets