The
thermal instrument pack is placed in the center of the mold cavity - over what will be the
surface of the casting. The picture at the left shows preparation of the bottom of
one of the molds. Jon is carefully uncoiling the wires before sand is introduced to
form the actual mold.
Next a layer of sand is laid over the bottom of the mold through a mesh screen.
This provides a relatively smooth finish for the casting. The photo at the
right shows a mold top being prepared - the downsprue is visible near the right edge of
the mold (under the wooden mallet!). The dowel rods provide vent holes to prevent
air from becoming trapped in the mold when the molten metal is poured.
More
sand is then scooped into the mold and hand rammed with these wooden hammers. It is
important to pack the sand as firmly as possible, but to be careful not to damage the
instrument pack.
Once the sand is packed above the level of the top of
the instrument pack, more sand can be added. With resin-bonded sands, hand-packing
is adequate at this stage. Here green sand is used, and Chris uses a small pneumatic
hammer is to ram the sand into the mold. A finished mold ready for pouring can be
seen in the background.
The
thermal instrument pack is placed in the center of the mold cavity - over what will be the
surface of the casting. The picture at the left shows preparation of the bottom of
one of the molds. Jon is carefully uncoiling the wires before sand is introduced to
form the actual mold.
Next a layer of sand is laid over the bottom of the mold through a mesh screen.
This provides a relatively smooth finish for the casting. The photo at the
right shows a mold top being prepared - the downsprue is visible near the right edge of
the mold (under the wooden mallet!). The dowel rods provide vent holes to prevent
air from becoming trapped in the mold when the molten metal is poured.
