WHEN UNIT HOLE, WHEN UNIT MILE TOLEARNSI IS USED.
When to use unit hole and when to use unit shaft tolerance may be a preference of the designer, as well as sometimes determined by necessities. For example, if the fitting surfaces of a ready-made material purchased are provided with a certain tolerance, the tolerance suitable for that material is used. Example; A unit shaft tolerance is used for mounting a material with an inner diameter of "H" tolerance to the shaft, and a unit shaft tolerance is used for mounting a material whose outer diameter is provided with a tolerance of "h" to the hole diameter.
Example: Since a purchased bearing will be provided with an outer diameter of h, the tolerance that should be used is the shaft tolerance. This is a requirement for other ready-made components such as bearings provided with certain tolerances.

TOLERANCE PAIRS

Materials that will work with each other always take double tolerance values. These tolerance pairs have been reduced to some standards as a result of experience. These tolerance pairs to be used according to the places of use are usually matched as follows. (Note below are not guidelines, but advanced uses in practice.)

SPACED PASSING TOLERANCE PAIRS

H7-h6: Used for elements whose surfaces are lubricated. Example: Pulley hubs, retaining rings, clutches, moving bench parts that need frequent replacement.

H7-g6: Don't get stuck. Example: Gears that need to shift axially, couplings, connecting rod bearings, pistons

H8-h9: Don't be comfortable. Example: Transmission shafts fixing rings, belt pulleys, gears, clutches, etc.

H7-f7: Animated fit. Sample ; Machine tools main bearings, crank shafts,

H7-e8: Spaced inserts. Crossings that must maintain mobility in sample heat

H7-d9: Multi-cavity inserts.

TIGHT PASS TOLERANCE PAIRS

H7- j6: Click-to-click: They are easy tight joints made by hitting the wood with a hammer. Example: belt pulleys, gears, hand wheels, bearing bushes, etc.

H7-k6: Comfortable clamping with hammer: Example; pulleys, bearing inner rings, hand wheels etc.

H8-n6: Difficult hammering: Example; pulleys, clutches, couplings etc.

H7-n6: Pressing: Example; Pulleys that will not be removed again, rotors placed on the motor shaft, gears to be placed on the trunnion, bushings inside the hubs, etc.

PRESS PASSES

They are the joints made by pressing the press or by providing the expansion of the slot by heating and will not be removed again.

H7-r6: Inserts that will not play under the effect of moderate constant force. For example, steel ring fitting on cast iron core, bushings pressed into bearing in connecting rods, etc.

H8-u8: Will not play under large constant force.