casting by sk mondal
8/28/2011
Sand casting
Metal Casting
M t l C ti
By S K Mondal
Compiled by: S K Mondal Made Easy
Sand casting uses ordinary sand as the primary mould material.
The sand grains are mixed with small amounts of other materials, such as clay and water, to improve strength, mouldability and cohesive strength and are then packed around a pattern that has the shape of the desired casting.
The pattern must be removed before pouring, the mold is usually made in two or more pieces.
An opening called a sprue hole is cut from the top of the mold through the sand and connected to a
Compiled by: S K Mondal Made Easy system of channels called runners.
Contd….
The molten metal is poured into the sprue hole, flows through the runners, and enters the mold cavity through an opening called a gate.
Gravity flow is the most common means of introducing the metal into the mold.
After solidification, the mold is broken and the finished casting is removed.
The casting is then “fettled” by cutting off the ingate and the feeder head.
Because the mold is destroyed, a new mold must be made for each casting.
Compiled by: S K Mondal Made Easy
Contd…
Sequential steps in making a sand casting
A pattern board is placed between the bottom (drag) and top (cope) halves of a flask, with the bottom side up.
Sand is then packed into the drag half of the mold.
A bottom board is positioned on top of the packed sand, and the mold is turned over, showing the top (cope) half of pattern with sprue and riser pins in place.
The cope half of the mold is then packed with sand.
Compiled by: S K Mondal Made Easy
Contd…
Compiled by: S K Mondal Made Easy
The mold is opened, the pattern board is drawn
(removed), and the runner and gate are cut into the surface of the sand.
The mold is reassembled with the pattern board removed, and molten metal is poured through
Sand casting
Metal Casting
M t l C ti
By S K Mondal
Compiled by: S K Mondal Made Easy
Sand casting uses ordinary sand as the primary mould material.
The sand grains are mixed with small amounts of other materials, such as clay and water, to improve strength, mouldability and cohesive strength and are then packed around a pattern that has the shape of the desired casting.
The pattern must be removed before pouring, the mold is usually made in two or more pieces.
An opening called a sprue hole is cut from the top of the mold through the sand and connected to a
Compiled by: S K Mondal Made Easy system of channels called runners.
Contd….
The molten metal is poured into the sprue hole, flows through the runners, and enters the mold cavity through an opening called a gate.
Gravity flow is the most common means of introducing the metal into the mold.
After solidification, the mold is broken and the finished casting is removed.
The casting is then “fettled” by cutting off the ingate and the feeder head.
Because the mold is destroyed, a new mold must be made for each casting.
Compiled by: S K Mondal Made Easy
Contd…
Sequential steps in making a sand casting
A pattern board is placed between the bottom (drag) and top (cope) halves of a flask, with the bottom side up.
Sand is then packed into the drag half of the mold.
A bottom board is positioned on top of the packed sand, and the mold is turned over, showing the top (cope) half of pattern with sprue and riser pins in place.
The cope half of the mold is then packed with sand.
Compiled by: S K Mondal Made Easy
Contd…
Compiled by: S K Mondal Made Easy
The mold is opened, the pattern board is drawn
(removed), and the runner and gate are cut into the surface of the sand.
The mold is reassembled with the pattern board removed, and molten metal is poured through