Grinding of work pieces

Rectification improves the piece of surface condition.
It is by means of a machine tool called grinding and grinding of the tool with different grains depending on the result.

The purpose of the adjustment is to obtain a perfect surface. such valves of an engine, the rubbing surfaces .
There are several grinding techniques: the best known are the surface grinding , the double-sided and cylindrical grinding

Surface grinding
consists of a horizontal grinding the workpiece so as to eliminate repeatedly 
layers of material from 20 to 40 micrometers (0.0005 to 0.001 inch).
 Here, the piece makes a movement reciprocating longitudinal 
(which may be combined with a transverse scanning to correct a width
 greater than the width of the grinding wheel ) .
the double side grinding
It is to rectify the two faces of the workpiece simultaneously pa the same 

cylindrical grinding
the play revolves on itself by making its run parallel to the axis of the wheel.
 rectification allows high dimensional precision machining thanks to the principle of abrasive machining . In most cases correct, grinders need to use a coolant to water wheel and the parts to not make burns on the documents produced and to avoid a poor surface finish