About some hardware machining
By shumijia | 03 November 2021 | 0 Comments

Which parts are suitable for precision machining?


     We know that precision machining requirements for precision is very high, precision machining of good rigidity, high manufacturing accuracy, accurate tool setting, so can process parts with high precision requirements, so which parts are suitable for precision machining? The following is the chief engineer of our Fuqiu machinery to introduce to you.

First of all, compared with ordinary lathe, CNC lathe has constant linear speed cutting function. No matter for turning end face or different diameter outer circle, it can be processed with the same linear speed, that is to say, the surface roughness value is guaranteed to be consistent and relatively small. The surface roughness depends on the cutting speed and feed rate under the condition that the material of workpiece and tool, finishing allowance and tool angle are certain.

      In processing the surface roughness of different surfaces, the roughness of the small surface to choose a small feed rate, the roughness of the large surface to choose a larger feed rate, good variability, this is difficult to do in ordinary lathes; contour shape of complex parts, any plane curve can be approximated by a straight line or arc, CNC precision machining with circular interpolation function, can process a variety of complex contours of the parts, CNC precision machining of the use of good or bad need to be carefully used by the operator.
      CNC precision machining mainly includes fine turning, fine boring, fine milling, fine grinding and lapping processes.
(1) fine turning and fine boring: most of the precision light alloy (aluminum or magnesium alloy, etc.) parts in the aircraft are mostly processed by this method, generally with natural single crystal diamond tools, the radius of the cutting edge circle is less than 0.1 microns, processing in high precision lathe can obtain 1 micron accuracy and the average height difference is less than 0.2 microns of surface unevenness, coordinate accuracy can reach ± 2 microns.
(2) Fine milling: It is used for machining complex shaped aluminum or beryllium alloy structural parts, relying on the accuracy of the machine tool's guide and spindle to obtain high mutual position accuracy, and using carefully ground diamond tips for high-speed milling can obtain accurate mirror surfaces.

(3) Fine grinding: Used for machining shaft or hole type parts. Most of these parts are made of hardened steel with high hardness, and most high-precision grinding machine spindles use hydrostatic or dynamic pressure liquid bearings to ensure high stability. The ultimate accuracy of grinding is influenced by the machine tool spindle and bed stiffness in addition to the selection and balance of the grinding wheel and the machining accuracy of the center hole of the workpiece, etc. Fine grinding can obtain a dimensional accuracy of 1 micron and an out-of-roundness of 0.5 micron.

(4) Grinding: Using the principle of mutual research of mating parts to selectively process the irregular raised parts on the machined surface, the grinding grain diameter, cutting force and cutting heat can be precisely controlled, so it is the processing method to obtain the highest precision in precision machining technology. Hydraulic or pneumatic mating parts in precision servo components of aircraft, and bearing parts of kinematic gyro motors are machined by this method to achieve 0.1 or even 0.01 micron accuracy and 0.005 micron microscopic unevenness.

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