A common application in design is the analogous approach, which is simple, fast and reasonable. The application requires adequate references and a wide range of materials and references are given in various current mechanical design guides. Commonly, surface roughness is compatible with dimensional tolerance levels. Generally speaking, the smaller the standard tolerances specified for machining and production of mechanical parts, the smaller the surface roughness value of mechanical parts, but there is no fixed functional relationship between them.
Mechanical parts machining strength is the ability of the part not to break or undergo more than the allowed plastic deformation during work, and is the most basic provision for all normal operation and production safety of the equipment. Standard countermeasures to improve the strength of the parts are: in order to expand the specifications of the part risk cross-section, expand the moment of inertia of the cross-section, effectively design the cross-section of the case; the use of high-strength raw materials, the raw materials to expand the heat treatment process to improve the strength and reduce thermal stress, operation manufacturing process to reduce or eliminate microscopic shortcomings, etc.; in order to reduce the load of the parts to reduce the stress level, etc., should be properly involved in the structure of the parts.
1, positioning error: positioning error mainly includes the benchmark does not overlap error and positioning vice manufacturing inaccuracy error.
2, measurement error: parts in the processing or measurement after processing, due to the measurement method, gauge accuracy, as well as the workpiece and subjective and objective factors are directly affected by the measurement accuracy.
3, tool error: any tool in the cutting process is inevitable to produce wear and tear, and thus cause the size and shape of the workpiece to change.
4, fixture error: the role of the fixture is to make the workpiece equivalent to the tool and machine tool has the correct position, so the geometric error of the fixture on the machining error (especially the position error) has a great impact
5, the machine tool error: including spindle rotation error, guide error and drive chain error. Spindle rotation error refers to the actual axis of rotation of the spindle moment relative to its average axis of rotation of the amount of change, it will directly affect the accuracy of the workpiece being machined.