- Industry: Aviation
- Number of terms: 16387
- Number of blossaries: 0
- Company Profile:
Aviation Supplies & Academics, Inc. (ASA) develops and markets aviation supplies, software, and books for pilots, flight instructors, flight engineers, airline professionals, air traffic controllers, flight attendants, aviation technicians and enthusiasts. Established in 1947, ASA also provides ...
A method of case hardening steel. The steel to be case hardened is placed in a retort (a sealed, high-temperature furnace) and heated to a specified high temperature while it is surrounded by ammonia gas (NH3). The ammonia breaks down into nitrogen and hydrogen, and the nitrogen unites with some of the alloying agents in the steel to form an extremely hard surface.
Nitriding, which is used to harden crankshaft bearing surfaces and cylinder walls, is done at a lower temperature than other forms of case hardening, and it does not warp the parts being hardened.
Industry:Aviation
A method of case hardening the surface of a steel part without hardening the inside and making it brittle. The part to be case hardened is packed in a fire-clay container and entirely surrounded with a special ground-up charcoal. The container is sealed and put into a furnace and heated to a temperature greater than 910°C. At this temperature, the iron takes on a crystalline form called gamma iron.
The heated charcoal releases carbon monoxide, and since it cannot escape, it combines with the gamma iron and forms an extremely hard surface. The depth to which the carbon penetrates the steel is determined by the length of time it is held at this high temperature.
Industry:Aviation
A method of casting metal in which the ingot is continuously cooled and pulled as it is being poured. Continuous casting produces ingots whose length is not determined by the length of a mold.
Industry:Aviation
A method of casting metal parts in a mold made of sand. A pattern that duplicates the part to be molded is made of wood and is covered with a special casting sand that contains a resin to bind it together.
The mold is separated along a special parting line, and the pattern is removed. The mold is put back together, and the cavity is poured full of molten metal. When the metal cools, the sand is broken away from the molded part. Sand casting is less expensive than permanent-mold casting.
Industry:Aviation
A method of casting metal parts in which molten or plastic metal is forced into permanent molds under pressure.
Industry:Aviation
A method of casting such components as turbine blades. A highly polished internal cavity is made in the die, having the exact inverse shape of the finished part, and a special molten wax is injected into it to completely fill the cavity. When the wax solidifies, it is removed from the die.
Several of the wax patterns are assembled on a wax gating tree, which is then dipped into a liquid ceramic slurry a number of times until a ceramic coat about a quarter of an inch thick builds up. The resulting ceramic mold is fired at a temperature of about 1,000°C, which melts the wax out and prepares the mold for the next steps. The extremely hot mold is filled with the blade alloy which has been melted in an induction furnace. After the metal has cooled, the mold is removed and the blades are cleaned and inspected.
Industry:Aviation
A method of charging aircraft batteries in which a constant voltage is placed across the battery while it is being charged.
When a battery is discharged, its voltage is low and the charging current is high. But as the battery becomes charged, its voltage rises and the charging current decreases. When the battery voltage is the same as the voltage of the charging source, no more charging current flows. Aircraft generators charge the batteries with a constant-voltage charge.
Industry:Aviation
A method of classifying the fit of threads used in bolts and nuts. A class-1 fit is a loose fit, a class-2 fit is a free fit, a class-3 fit is a medium fit, a class-4 fit is a close fit, and a class-5 fit is a wrench fit. Most fasteners used in aircraft structure have a class-3 fit.
Industry:Aviation
A method of cleaning delicate mechanical parts. The parts are placed in a sonic cleaning machine and covered with a cleaning fluid. High-intensity sound waves are produced in the cleaning fluid, and the vibrations caused by these waves shake loose any contaminants on the parts being cleaned.
Industry:Aviation
A method of cleaning mechanical components by vibrating them at an ultrasonic frequency while soaking them in a cleaning solution.
Industry:Aviation
