Document 2gQJLRz1Eb4ZdrBd94ZQGREb

Hot Working of Metals FlC 28-J4 -- "Pill" of radioactive cobalt-60 is placed inside newly cast pump housings Radiation exposes X-ray film strapped to outside of castings and shows up defects Aluminum rod is long enough to keep operators and radiation source safely separated Second man monitors exposure during inspection minute quantities of current generated when two metdllurgicallv or chemically unlike con ductors are moved into frictional contact If the conductors are alike, no current will be generated The equipment consists of a control unit and a portable sorting head connected by means of a cable The sorting head contains all the main controls for actuating the test and is designed for one-handed operation This method is designed to sort and identih metal parts ot not more than four alloy types Electromagnetic methods Two types of electromagnetic tests are currently being used m industry magnetoinductive and eddy current A third type, employing radar frequency, is also being used, but only to a limited extent The magneto-inductive method utilizes variations in the permeability of magnetic materials to create variations in a pickup coil or probe Eddy current The second tvpe ol elec tromagnetic testing utilizes AC in a coil or probe to induce eddv current into the part being tested Delects and variations in properties or geometis cause changes in the strength and distribution ol the eddv current Readout is presented on a cathode ray tube, on a meter, by audible or visible alarm, or bv a combination ot these methods Radar frequency methods use high-frequenev radar waves to measure the electro magnetic properties of thin coatings and surface layers of material To make such tests, a wave guide or cavity oscillator is 828