The front and back centers, and also different flood devices treat number of the main devices used when processing shaft and pipes. In case of processing of the nonrigid shaft characterized by big length-to-diameter ratio it is necessary to apply the lunettes warning deflection of the piece of works under the influence of forces of cutting and curb weight or supporting the end of shaft at its console fixing in the boss of the machine.
Development of high-speed methods of processing reasonable has caused improvement of the designs of all called above adaptation. Instead of the normal motionless centers the centers equipped with firm alloy, and the improved designs of the rotating centers were widely used; during the work on the adjusted machines "the floating centers" are used, allow to establish parts to axial emphasis. Normal screw collets are replaced with new designs of high-speed flood devices. Also designs of lunettes are improved.
The motionless back centers work as sliding bearings with big specific pressure, are exposed to strong heating and wear. For this reason the centers made from tool carbonaceous by staly are not suitable for processing on are high speeds.
The center is persistent. Morse cone No. 2,3,4,5,6