Cylindrical Fits and Tolerances Table for IP and Metric

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Cylindrical Fits and Tolerances Table for IP and Metric

Geometric Tolerances, Limits Fits Charts, Mechanical Tolerances Tables and Calculators

The ANSI B4.1 Standard arranged fits classes in three general groups according to the field and type of usage. Standard fits are designated by means of some symbols which facilitate reference to classes of fits to get better understanding. The symbols are not intended to be shown on the manufacturing detail drawings, only sizes should be specified on the detail drawings.

RC Running or Sliding Clearance Fit	RC 1	Close sliding fits are intended for the accurate location of parts that must assemble without perceptible play.
	RC 2	Sliding fits are intended for accurate location, but with greater maximum clearance than Class RC 1. Parts made to this fit move and turn easily but are not intended to run freely, and in the larger sizes may seize with small temperature changes.
	RC 3	Precision running fits are about the closest fits that can be expected to run freely, and are intended for precision work at slow speeds and light journal pressures, but are not suitable where appreciable temperature differences are likely to be encountered.
	RC 4	Close running fits are intended chiefly for running fits on accurate machinery with moderate surface speeds and journal pressures, where accurate location and minimum play are desired.
	RC 5 RC 6	Medium running fits are intended for higher running speeds, or heavy journal pressures, or both.
	RC 7	Free running fits are intended for use where accuracy is not essential, or where large temperature variations are likely to be encountered, or under both these conditions.
	RC 8 and RC 9	Loose running fits are intended for use where wide commercial tolerances may be necessary, together with an allowance, on the external member.
FN Force or Shrink Fit	FN 1	Light drive fits are those requiring light assembly pressures, and produce more or less permanent assemblies.
	FN 2	Medium drive fits are suitable for ordinary steel parts, or for shrink fits on light sections.
	FN 3	Heavy drive fits are suitable for heavier steel parts, or for shrink fits in medium sections.
	FN 4 FN 5	Force fits are suitable for parts that can be highly stressed, or for shrink fits where the heavy pressing forces required are impractical.
Locational Fits	LC	Locational clearance fits are intended for parts which are normally stationary, but that can be freely assembled or disassembled.
	LT	Locational transition fits are a compromise between clearance and interference fits, for applications where accuracy of location is important, but either a small amount of clearance or interference is permissible.
	LN	Locational interference fits are used where accuracy of location is of prime importance, and for parts requiring rigidity and alignment with no special requirements for bore pressure.

Source: Oberg, Erik, Franklin D. Jones, Holbrook L. Horton, and Henry H. Ryffel, Machinery's Handbook,
28th ed., New York: Industrial Press, Inc., 2008.

SI System of Limits and Fits

ISO Symbols and Descriptions

ISO Symbols		Description
Hole Basis	Shaft Basis	Description
H11/c11	C11/h11	Loose running fit for wide commercial tolerances or allowances on external members	Clearance Fits
H9/d9	D9/h9	Free running fit for use where accuracy is essential, but good for large temperature variations, high running speeds, or heavy journal pressures.
H8/f7	F8/h7	Close running fit for running on accurate machines and for accurate speeds and journal pressures.
H7/g6	G7/h6	Sliding fit not intended to run freely, but to and turn freely and locate accurately.
H7/h6	H7/h6	Locational clearance fit provides snug fit for locating stationary parts, but can be freely assembled and disassembled.
H7/k6	K7/h6	Locational transition fit for accurate location; a compromise between clearance and interference.	Transition Fits
H7/n6	N7/h6	Locational transition fit for more accurate location where greater interference is permissible	Transition Fits
H7/p6*	P7/h6	Locational interference fit for parts requiring rigidity and alignment with prime accuracy of location but without special bore pressure requirements.	Interference Fits
H7/s6	S7/h6	Medium drive fit for ordinary steel parts or shrink fits on light sections, the tightest fit usable with cast iron.
H7/u6	U7/h6	Force fit suitable for parts which can be highly stressed or for shrink fits where the heavy pressing forces required are impractical.

*Transition fit for basic sizes in range from 0 thru 3 mm