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Full text of "Modern Mechanical Engineering Vol-I"

126

FOUNDRY WORK

CHAPTER   III
Moulding in Loam

Moulding in loam is essentially an application of the form or profiling
principle on a large scale to the making of moulds.   The loam mixture

used is a strong sand, mixed
with horse manure. The mix-
ture, having been rendered plas-
tic with water, and thoroughly
mixed in a mill resembling a
mortar mill, is swept in this con-
dition with the bevelled edge of
a board, which is attached to a
vertical bar and rotated. The
profile of the mould in vertical
section therefore corresponds
with the profiled edge of the
board, and its diameter is set by
the radius of the board, measured
from the centre of the bar. The
mould has to be dried after
sweeping. Large central cores
are swept like the moulds, but
small cores are rammed in boxes
and dried.

Methods of Affording Support
to Loam.  Since the treatment
of a plastic material, when swept,
differs entirely from that of sand
rammed within flasks, suitable
methods of supporting it have
to be provided. All the load of
a mould (fig. 18) is carried on
massive plates, or rings of cast
iron. These are from 2| in. to
3 in. thick, studded with prods
all over the face that receives the
loam, and provided with three or
four lugs to receive slings for the
purpose of lifting the moulds,

.                       r           ,     t

or, in the case or central cores,
with long rods cast in, with eyes.

The vertical walls of moulds are swept against tiers of common bricks,
built up in a somewhat rough fashion of whole bricks and broken frag-

. 18.  A Loam Mould with Central Core in situ, Pouring
Basin, ingates, and Flow-off Gate