Precision Machining is a machining methods of 1 micron precision. Precision Machining mainly have fine cars, fine boring, precision milling, grinding and grinding processes.
It is controlled under conditions strictly, the use of precision machine tools, precision measuring tools and measuring instruments to achieve it. Processing accuracy and more than 0.1 micron is precision machining. In the aerospace industry, mainly for machining precision equipment in the aircraft control precision mechanical parts, such as hydraulic and pneumatic servo frame of precision fitting, gyroscope, housing, air, liquid and floating bearing assemblies float like. Aircraft precision parts complicated structure of small rigidity, requiring high precision, and difficult to process a large proportion of the material.
The effect of machining process are:
① micron accuracy or arcsecond level;
② part or feature limits the dimensional tolerance in microns;
③ parts of the surface micro-roughness (surface roughness average height difference) of less than 0.1 microns;
④ with each other accessories to meet the requirements of the force;
⑤ some parts but also to meet the exact requirements of mechanical or other physical characteristics, such as the float gyroscope torsional stiffness of the torsion bar, flexible element stiffness coefficient.
It mainly fine cars, fine boring, precision milling, grinding and grinding processes.
① fine cars and fine boring: most sophisticated aircraft light alloys (aluminum or magnesium alloys, etc.) and more parts processed using this method. General use of natural single crystal diamond tool edge radius of less than 0.1 microns. Irregularities in the high-precision lathe get 1 micron accuracy and average height is less than 0.2 micron surface coordinate accuracy up to ± 2 microns
② milling: for machining complex shapes or beryllium aluminum alloy structure. And relying on the accuracy of the machine spindle rail mutual position to achieve higher accuracy. After careful use of diamond grinding heads available for high-speed precision milling mirror.
③ grinding: for machining shaft or hole parts. Most of these parts using hardened steel with high hardness. Most high-precision grinding spindle with static or dynamic pressure fluid bearing to ensure high stability. In addition to the limits of precision grinding machine spindle and the affected bed stiffness, but also with the choice and balance of the workpiece center hole machining accuracy and other factors related to the grindstone. Grinding obtain dimensional accuracy of 1 micron and 0.5 micron roundness.
④ Grinding: fitting using the principle of mutual inquiry on the machined surface is irregular protrusions site selection process. Abrasive diameter, cutting force and cutting heat can be precisely controlled, precision processing technology thus obtained is the most high-precision machining methods. Aircraft precision servo hydraulic or pneumatic component fittings, the dynamic pressure bearing gyro motor parts are processed using this method, to achieve the precision of 0.005 or 0.01 micron 0.1 micron micro roughness.