J - 1) Symbol for 1 gram equivalent weight, 2) the mechanical equivalent of heat.
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/in2.
Jack Arch - A spring arch, flat or horizontal on the underside.
Jack, leveling - Small jacks (usually screw jacks) for leveling and holding work on planner beds and similar places.
Jacobs Chuck - Common term for the drill chuck used in either the headstock spindle or in the tailstock for holding straight shank drills,taps,reamers or small diameter workpieces.
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.
Jarno - A standard taper having 0.600-inch taper per foot used in some machine tools.
Jersey Fireclay Brick - Highly siliceous clay brick, semisilica brick.
Jet Cooler - Device that controls the cooling of the strip before it enters the hot-dip galvanize pot.
Jet Scrubber - IN air pollution control, a high velocity water jet directed into the throat of a venture section of a cupola to separate out particulates.
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 - Any device so arranged that it will expedite a hand or a machine operation.
Jig Saw Steel - Hardened, tempered and bright polished with round edges. Carbon content .85. Ranges of sizes .039 to 393 in width and .016 to .039 in thickness.
Jobbing Foundry - A foundry engaged in the manufacture of numerous types of castings.
Jog - Act of moving the strip forward or backward. This can be done with the pinch rolls or the reel.
Johannson Blocks (Jo Blocks) - Common term for the precision gage blocks used and accepted as dimensional standards by machinists,toolmaker and inspectors.
Join - IMIS action type indicating that parts of two or more coils have been combined to produce a single unit.
Join Count - Field incremented by one each time coil contains more than 1 Consumed IPM number - 2 coils welded together to make jumbo.
Joint - One length of pipe
Joint Welding - Production welding used to weld cast components together to obtain an integral unit.
Jolt Ramming - See Jar Ramming
Jolt-Squeezer Machine - A combination machine that employs a jolt action followed by a squeezing action to compact the sand around the pattern.
Jominy - A hardenability test for steel to determine the depth of hardening abtainable by a specified heat treatment.
Joule - A unit of energy. One joule is equal to the energy expended in one second by one ampere against the resistance of one ohm. I the mechanical testing of steel it is the unit used in the Charpy V notch impact test.
JP - 1) Fully alloyed galvanneal product. 2) On Galvanize the aluminum percentage is reduced from the pot on the Galvanize lines; primarily zinc left; produces a flat, dull coating on the steel (Jet-Process).
JP Bazooka - Device that introduces a flame to the strip as it exits the pot (used to produce JP product).
Jumbo Coil - A single coil produced by welding two or more coils.
Jumping Coil In - Moving a coil ahead of other coils in a line-up.
Junction Header - First steam distribution point after exiting the boiler drum.
Junk Batteries - This term usually refers to spent automotive lead-acid batteries, which are purchased by secondary lead smelters. The standard form of shipment is in the whole and undrained state to meet environmental regulations. Lead metal constitutes around half the weight of a junk battery. Other parts, including the plastic case, also are recycled.