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UCD 621.951.7
IS0
I NT ERN AT1 ON AL ORGAN IZATl O N FOR STAND AR D IZ AT1 O N
IS0 RECOMMENDATION
R 522
SPECIAL TOLERANCES FOR REAMERS
1st EDITION
November 1966
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore oniy
by the national standards organization of that country, being
a member of ISO.
For each individual country the oniy valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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ISO/R 522 - 1966 (E)
IS0 Recommendation R 522 N ove m be r 1966
SPECIAL TOLERANCES FOR REAMERS
1. SCOPE
This IS0 Recommendation deals with special tolerances to be applied to the diameter of the
cutting portion of the hand and machine reamers covered by IS0 Recommendation R 236,
Hand Reamers and Long Fluted Machine Reamers, Morse Taper Shank, and IS0 Recommendation
R 521, Machine Chucking Reamers with Parallel Shanks or Morse Taper Shanks when a grade of
accuracy other than the standard stock grade (with m6 tolerance) provided for in these IS0
Recommendations is required.
2. DETERMINATION OF TOLERANCES
Unless otherwise specified in the order, reamers are made to the tolerance m6 (standard stock
grade) and it is impossible to infer in advance what tolerances can be guaranteed on the holes
produced with these tools.
The actual diameter of a hole produced by a given reamer depends in practice on very many
factors. These factors include:
(a) the type of material to be cut and the amount of material to be removed;
(b) the cutting angle of the reamer;
(c) the condition of the reamer at the time of use;
(d) the method of mounting and operation;
(e) the lubrication.
These different factors should be taken into account when determining the special tolerances to
be called for on a reamer for the production of a hole with a given tolerance. It is thus impossible
to establish, for this type of application, standard “special” tolerances likely to give guaranteed
results under all conditions.
In order to obtain uniformity, however, it is recommended that the method shown below for
determining the limits of tolerance on the reamer in relation to those of the hole to be produced
should be adopted for special grade reamers wherever possible.
2.1 Rule for determining the limits of tolerances on reamers
For a given hole with IT tolerance:
- the high limit of the diameter of the reamer is equal to the maximum diameter of
the hole, minus 0.15 IT.
The value 0.15 IT should be rounded upwards to a whole multiple of 0.001 mm
(or 0.0001 in).
- the low limit of the diameter of the reamer is equal to its maximum diameter,
minus 0.35 IT.
The
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