Machine tool hole machining accuracy including what aspects?

1. Hole size accuracy When using more holes or robbing holes. Hole accuracy up to H6 level, surface roughness of Ral. 6jim, hole roundness in the hole size tolerance half the range. When machining non-ferrous metals, the accuracy can be stable up to H6 grade after 3-4 times of machining by using precision fixtures. Surface roughness up to RaO. 8^-RaO. 4.m. 2. hole coaxiality When multi-axis machining from both sides. Hole coaxiality is generally 0. 05mm. when from one side of the fine robbing holes, and the use of fixed fixtures, robbing tool bar ends have precision guides. Fixture in good precision conditions. In 1000mm length, the coaxiality of several holes of machined parts can be guaranteed within 0. 0150. 03mm. When respectively from two sides of the same axis of the hole for single-axis machining. In the middle of the precision guide device conditions. Its coaxiality can also be guaranteed at 0. 015-0. 03mm. 3. parallelism of holes in the combined machine tool processing. Hole and hole parallelism between each other and the parallelism of the hole on the machining surface, in the 1000mm length of up to 0. 02-0. 05mm. 4. Hole positional degree of hole positional accuracy and fixtures, machine tool type and accuracy has a great relationship. In the fixed fixture machine tool on the hole, the distance between the hole and the hole axis and positioning of the base surface of the positional accuracy can be stabilized to reach Shi 0. 025-0. 05mm. in the multi-station machine tool, due to the rotary table or rotary drum wheel there are positioning errors. Therefore, the machining accuracy is not high. If in the same station, with a hanging movable template, the positional accuracy of the hole finishing can reach 0.05mm. when the hole is machined in different stations. Accuracy is lower. Vertical multi-station rotary table machine tool processing, its accuracy can reach 0. lmm. drum wheel machine tool processing, its accuracy can only reach 0. 2mm. or even lower. When drilling holes in the same station, the positional accuracy is generally within the range of 0.2mm. When drilling holes on machines with fixed drilling templates, the accuracy can be as high as 0.15mm. 5. The verticality of the holes is processed on the combined machine tool. Its centerline to the base and relative to another hole centerline perpendicularity can be achieved in the 100mm length deviation of 0.02mm. 6. Threaded hole accuracy The combination of machine tools for processing threaded holes on the use of tapping against the mold device, if the lubrication conditions are good, the cast iron parts can be processed on the threaded holes in the precision of the 7 - its surface roughness for Ral. 61.tm, the positional accuracy of the threaded holes as a result of the tapping of its bottom hole as a positioning reference. When tapping the bottom hole for the positioning reference. Together with other errors, the positional accuracy of the threaded hole is slightly lower than that of the drilled hole. Generally, it can reach 0.25mm, and when the machine tool precision is higher, it can reach 0.15mm.