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UDC 669.14
IS0
INTERN AT I ON AL ORGAN IZ AT1 O N FOR STAND AR D IZATION
IS0 RECOMMENDATION
R 156
VERIFICATION OF BRINELL HARDNESS TESTING MACHINES
2nd EDITION
November 1967
This second edition supersedes the first edition.
e
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 only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only 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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BRIEF HISTORY
The IS0 Recommendation R 156, Calibration of Brinell Hardness Testing Machines, was drawn up by
Technical Committee ISO/TC 17, Steel, the Secretariat of which is held by the British Standards Institution (BSI).
Work on this question by the Technical Committee began in 1953 and led, in 1958, to the adoption of a
Draft IS0 Recommendation.
In January 1959, this Draft IS0 Recommendation (No. 275) was circulated to all the IS0 Member Bodies
for enquiry. It was approved by 26 Member Bodies. Two Member Bodies opposed the approval of the Draft:
Australia and New Zealand.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council which decided,
in April 1960, to accept it as an IS0 RECOMMENDATION.
BRIEF HISTORY CONCERNING THE 2nd EDITION
Working Group ISO/TC 17/WG 1 was entrusted, in 1961, by the Technical Committee
ISO/TC 17, Steel, with the preparation of the Draft Revision of IS0 Recommendation R 156-1960.
This work led, in 1965, to the adoption of a Draft Revision.
Verification of Brinell Hardness Testing Machines, supersedes the title of the
The new title,
first edition, Calibration of Brinell Hardness Testing Machines; some amendments were made
to the text.
In February 1966, this Draft Revision (No. 925) was circulated to all the IS0 Member
Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature, by
the following Member Bodies :
Argentina Hungary Romania
Australia India Spain
Austria Israel Sweden
Belgium Italy Switzerland
Japan Turkey
Brazil
Canada Korea, Rep. of U.A.R.
Chile Netherlands United Kingdom
Czechoslovakia New Zealand U.S.A.
Norway U.S.S.R.
Denmark
France Poland Yugoslavia
Germany Rep. of South Africa
No Member Body opposed the approval of the Draft.
The Draft Revision of IS0 Recommendation R 156-1960 was then submitted to the IS0
Council which decided, in November 1967, to accept it.
The present edition (2nd edition) embodies this revision.
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ISO/R 158 - 1967 (E) I
IS0 Recommendation R 156 November 1967
VERIFICATION OF BRINELL HARDNESS TESTING MACHINES
1. SCOPE
This IS0 Recommendation applies to the verification of testing machines for determining Brinell
hardness in accordance with IS0 Recommendation R 79, * Brinell Hardness Test for Steel.
If a testing machine is also to be used for other methods of hardness testing, it should be verified
for each method.
It describes the indirect method, which is suitable for machines in service, and the direct method,
which is suitable for the initial verification of new machines by the manufacturer and for the
verification of rebuilt machines.
2. DIRECT VERIFICATION
Direct verification involves
(1) verification of the load-applying mechanism (see clause 2. l),
(2) verification of the steel balls (see clause 2.2) and
(3) verification of the measuring device (see clause 2.3).
Before verification is carried out, certain details of the testing machine should be checked (see
Annex).
2.1 Verification of the load-applying mechanism
2.1.1 The verification of the load-applying m chanism at th required 1 ids should be carried
out either by means of standardized weights or by means of an elastic proving device
or proving levers.
2.1.2 Each test load should be measured and, wherever possible, this should be done at not
less than three positions of the plunger throughout its range of movement.
2.1.3 The test load should be measured by one of the following three methods:
(a) balancing against standardized weights accurate to &O.l%, or
* 2nd edition, at present Draft IS0 Recommendation No. 924.
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ISO/R 156 - 1987 (E)
(b) balancing against a load, accurate to +0.2%, applied by means of standardized
weights with mechanical advantage, or
(c) measuring by means of the deformation of an elastic proving device previously
calibrated to an accuracy of &0.2%.
2.1.4
Three readings should be taken for each load at each position of the plunger (see clause
2.1.2). Immediately before each reading is taken, the plunger should have been moved
in the same direction as during testing.
2.1.5 Each reading of the measured load should be within & 1 .O % of the nominal load.
2.2
Verification of the steel balls
2.2.1
For the purpose of verifying the size and hardness of the steel balls used in indenters it is
considered sufficient to test a sample selected at random from a batch. The ball(s)
verified for hardness should be discarded.
2.2.2 The user should either measure the balls accurately to ensure that they meet the following
requirements or he should obtain balls from a supplier who
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