A riser, also known as a feeder, is a reservoir built into a metal casting mold to prevent cavities due to shrinkage.
Most metals are less dense as a liquid than as a solid so castings shrink upon cooling, which can leave a void at the last point to solidify.
Which of the following welding method uses a pool of molten metal?
This is a well established and extremely versatile method of welding. Submerged-arc welding (SAW) involves the formation of an arc between a continuously fed electrode and the work piece.
A blanket of powdered flux, which generates a protective gas shield and a slag (and may also be used to add alloying elements to the weld pool), protects the weld zone. A shielding gas is not required.
A casting defect which occurs due to improper venting of sand is known as