Mechanical tools

. state the process of case hardening by gas nitriding . state the process of case hardening by nitriding in a salt bath In the nitriding process, the surface is enriched not with carbon, but with nitrogen. There are two systems in common use, gas nitriding and salt bath nitriding. Gas nitriding The gas nitriding process consists of heating the parts at 500°c in a constant circulation of ammonia gas for up to 100 hours. During the gas nitriding process, the parts are in an externally heated gas tight box, fitted with inlet and outlet bores for the ammonia gas which supplies the nitrogen. At the completion of the soaking the ammonia is still circulated untill the temparature of the steel has fallen to about 150°c, when the box is opened, and the cooling completed in air. Nitriding causes a film to be produced on the surface but this can be removed by a light buffing. Nitriding in salt bath Special nitriding baths are used for salt bath nitriding. This process is suitable for all alloyed...

NEEDLE FILES AND SPECIAL FILES . the different shapes of need files . designate needle files as per BIS . the different types of special files . uses of esch type of special files Needle files are usually available in sets with assorted shapes. These types of files arw used for delicate, light kinds of work. These files are available in bastardization and smooth grade. Shapes The common shapes of needle files. The shape are round edge, flat edge, flat taper, half round, triangular, squre, round, kinfe, feather edge, crossing, barret and marking. Nomenclature of needle files These files are available in a nominal length of 120mm to 180mm. Grades The grades of cut may be identified by the cut number as follows- Bastard-cut 0 Smooth-cut 2 Designation of needle files The needle files are designated by their names grade of cut Nominal length BIS number Example A flat edge needle file with grade  of cut bastard, having a nominal length L=160mm shall be designated as flat edge needle file...