The range of tolerance level H11 is 0.11. The basic deviation is the upper deviation 0; the lower deviation is -0.11; this 0.11 is obtained by looking up the table.
The tolerance is a range and the calculation is: upper deviation -Lower deviation.
Tolerance grade refers to the grade that determines the degree of dimensional accuracy. The national standard stipulates that it is divided into 20 grades, from IT01, IT0, IT1, IT2 to IT18. The larger the number, the lower the tolerance grade (processing accuracy). The larger the allowable variation range (tolerance value) of dimensions, the less difficult it is to process.
Extended information:
Tolerance level
Application scope and examples
IT8
It belongs to mechanical manufacturing Medium precision. In the manufacturing of instruments, meters and watches, due to the small basic size, it belongs to the higher precision range. It is widely used in agricultural machinery, textile machinery, printing and dyeing machinery, bicycles, sewing machines, and medical equipment.
For example, the gauge used for inspecting IT16 grade workpieces, the dimensional fit of the bearing seat bushing in the width direction, the fit of the span pinion in the watch, the pawl dial dial, etc. and the splint, the general fit in the radio instrument, etc. .
IT9
The application conditions are similar to IT8, but it is used when the accuracy is lower than IT8, and the tolerance value is slightly larger than the old national standard level 4 accuracy.
For example, the cooperation between the outer diameter and hole of the shaft sleeve in machine tools, the control part and the shaft, the idle pulley and the shaft, the shaft and bearings of the control system, etc., the general matching parts in textile machinery, printing and dyeing machinery, and the matching parts in engines. The hole in the oil pump body, the inner hole in the valve guide, the fit between the flywheel and the flywheel sleeve, the general fit dimensions in automated instruments, etc.
IT10
The application conditions are similar to IT9, but it is used when the accuracy is required to be lower than IT9, which is equivalent to the level 5 accuracy tolerance of the old national standard.
For example, the fit on the bracket in electronic instruments and meters, the fit size of the insulating bushing hole and the bus ring bushing shaft in the navigation instrument, the fit size of the riveting parts in the typewriter, the basic size in the watch is less than 18 mm It requires general un-tolerance dimensions, and requires higher un-tolerance dimensions greater than 18 mm, the matching size of the oil seal retaining ring hole in the engine and the crankshaft belt hub, etc.
IT11
It is widely used in situations where the gap is large and significant changes will not cause danger. It can also be used in situations where the fit accuracy is low and a large gap is allowed after assembly. , equivalent to the level 6 precision tolerance of the old national standard.
For example, flange joints and holes on machine tools, sliders and sliding gears, grooves, etc.; agricultural machinery, motorcycle carriage parts and matching parts for stamping processing, unimportant parts in watch manufacturing , dimensions without tolerances in tools and equipment used in watch manufacturing, rougher movable fits in textile machinery, lower-required fit dimensions in printing and dyeing machinery, etc.
Reference: Baidu Encyclopedia entry--Tolerance level