Grinding is the process of removing metal by the application of abrasives which are bonded to form a rotating wheel. When the moving abrasive particles contact the workpiece, they act as tiny cutting tools, each particle cutting a tiny chip from the workpiece. It is a common error to believe that grinding abrasive wheels remove material by a rubbing action; actually, the process is as much a cutting action as drilling, milling, and lathe turning. The grinding machine supports and rotates the grinding abrasive wheel and often supports and positions the workpiece in proper relation to the wheel. The grinding machine is used for roughing and finishing flat, cylindrical, and conical surfaces; finishing internal cylinders or bores; forming and sharpening cutting tools; snagging or removing rough projections from castings and stampings; and cleaning, polishing, and buffing surfaces. Once strictly finishing machines, modem production grinding machines are used for complete roughing and finishing of certain classes of work.
What is Cylindrical Grinding :
This operation is carried out on a cylindrical grinding machine which is made in two varieties ‘‘plain’’ and the ‘‘universal’’ type. The fundamental design is the same in both cases, but the universal machine can be adopted for internal grinding operation as well.
In cylindrical grinding operation, the work is mounted between two centres and is rotated. A grinding wheel is mounted on a spindle and revolves at much higher r.p.m. than the work. The work centres are mounted on a table which can traverse at various feeds so that the entire length of the work passes to and fro in front of the wheel. The depth of cut is very small, about 0.015 mm. When the entire length of work has passed infront of the wheel, the wheel advances forward by another 0.015 mm at the end of the traverse and so the cycle of machining goes on, until the desired daimeter of the work piece is reached. The result is a long cylinder of perfectly circular profile with very fine surface finish.