J
Symbol for a 1-gram equivalent weight.
Jack Arch
A spring arch, flat or horizontal on the underside.
Jacket, Mold
A wood or metal form slipped over a mold made in a snap or slip flask, to support the four sides of the mold during pouring. Jackets and mold weights are shifted from one row of molds to another during the pouring period. See Flask.
Jamb
Usually an upright structural member forming the side of an opening in a refractory or furnace wall.
Jamb Brick
A brick modified so one corner is rounded.
Jar Ramming
Packing sand in a mold by raising and dropping on a table the sand, pattern, and flask. Jolt squeezers, jarring machines, and jolt rammers are machines using this principle. See Jolt Ramming, Jolt Squeezer Machine, Jolt Machine.
Jarring Machine
A molding machine that packs the sand by jarring. See Jar Ramming.
Jersey Fireclay Brick
Highly siliceous clay brick, semisilica brick.
Jet Scrubber
A high velocity water jet directed into the throat of a venture section of a cupola to separate out particulates in air pollution control.
Jet Tapping
A method of tapping a melting furnace by firing a small explosive charge instead of using an oxygen lance. The tapper consists of an explosive charge enclosed in a plastic case surrounded by a hollow bullet-shaped body.
Jib
Projecting part of crane from which lifting chain or gear is suspended.
Jig
A device arranged to expedite a hand or machine operation.
J-Integral
A mathematical expression used to characterize the fracture toughness of a material having appreciable plasticity prior to fracture. The J-integral eliminates the need to describe the behavior of the material near the crack tip. Units are MN/m or in in-lb/in 2.
Jobbing Foundry
A foundry engaged in the manufacture of numerous types of castings and is not a part of a manufacturing plant, and produces castings for sale that usually makes a wide variety of castings in small lots or quantities. See Casting, Foundry.
Joint Welding
Production welding used to weld cast components together to obtain an integral unit.
Jolt
To raise the flask filled with sand and allow it to drop, thereby compacting the sand against the pattern. See Flask, Sand.
Jolt Machine
Molding machine which packs or rams the sand around the pattern by raising the table on which the flask, sand, and pattern are mounted a few inches and allowing the whole to drop suddenly. The table is raised pneumatically, and the operation is repeated until the desired sand density is reached.
Jolt Ramming
Packing sand in a mold by raising and dropping the sand, pattern, and flask on a table. Jolt squeezers, jarring machines, and jolt rammers are all machines that use this method.
Jolt Squeezer Machine
A combination machine that employs a jolt action followed by a squeezing action to compact the sand around the pattern. See Jar Ramming.
