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The committee responsible for this document is ISO/TC 213, Dimensional and geometrical product specifications and verification.

This second edition cancels and replaces the first edition (ISO 14253-1:1998), which has been technically revised.

ISO 14253 consists of the following parts, under the general title Geometrical product specifications (GPS) — Inspection by measurement of workpieces and measuring equipment:

This part of ISO 14253 is a geometrical product specifications (GPS) standard and is to be regarded as a global GPS standard (see ISO/TR 14638). It influences the chain links 4, 5 and 6 of all chains of general GPS standards.

The ISO/GPS Masterplan given in ISO/TR 14638 gives an overview of the ISO/GPS system of which this document is a part. The fundamental rules of ISO/GPS given in ISO 8015 apply to this document and the default decision rules given in this document apply in ISO/GPS, unless otherwise indicated.

For more detailed information on the relation of this part of ISO 14253 to other standards and the GPS matrix model, see Annex A.

The estimated measurement uncertainty is to be taken into account when providing evidence for conformity or nonconformity with specification.

The problem arises when a measurement result falls close to the upper or lower specification limit. In this case it is not possible to prove conformity or nonconformity with specifications, since the measurement result plus or minus the expanded measurement uncertainty includes one of the specification limits.

Therefore, a supplier/customer agreement should be foreseen in order to solve the problems which could arise. This part of ISO 14253 explains how to handle specification and measurement uncertainty and establishes decision rules for proving conformity or nonconformity with specification.

INTERNATIONAL STANDARD ISO 14253-1:2013 (E)

Geometrical product specifications (GPS) — Inspection by measurement of workpieces and measuring equipment —

Part 1:

Decision rules for proving conformity or nonconformity with specifications

1 Scope

This part of ISO 14253 establishes the rules for determining the conformity or nonconformity with a given tolerance for a characteristic of a workpiece (or a population of workpieces) or limits of maximum permissible errors for a metrological characteristic of a measuring equipment, taking into account the measurement uncertainty.

These rules are different for tolerances to individual workpieces and tolerances to workpiece populations.

It also gives rules on how to deal with cases where a clear decision (conformity or nonconformity with specification) cannot be taken, i.e. when the measurement result falls within the uncertainty range (see 3.23) that exists around the specification limits.

This part of ISO 14253 applies to specifications defined in general GPS standards (see ISO/TR 14638), i.e. standards prepared by ISO/TC 213, including:

—

workpiece/population of workpieces specifications (usually given as an upper tolerance limit or a lower tolerance limit or both), and;

—

measuring equipment specifications (usually given as maximum permissible errors).

This part of ISO 14253 only applies for characteristics expressed as numerical quantity values.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 3534-2:2006, Statistics — Vocabulary and symbols — Part 2: Applied statistics

ISO 9000:2005, Quality management systems — Fundamentals and vocabulary

ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)

ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated terms (VIM)

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 3534-2, ISO 9000, ISO/IEC Guide 98-3 and ISO/IEC Guide 99 and the following apply.

3.1

tolerance

T

difference between the upper and lower tolerance limits (3.3)

Note 1 to entry: The tolerance is a quantity without sign.

Note 2 to entry: A tolerance may be two-sided or one-sided. The tolerance zone does not necessarily include the nominal value.

[SOURCE: ISO 3534‑2:1993, 1.4.4, modified — The two notes to entry have been added.]

3.2

tolerance zone

tolerance interval

variate values of the characteristic between and including the tolerance limits (3.3)

[SOURCE: ISO 3534‑2:1993, 1.4.5]

3.3

tolerance limits

limiting values

specified values of the characteristic giving upper and/or lower bounds of the permissible value

[SOURCE: ISO 3534‑2:1993, 1.4.3]

3.4

maximum permissible measurement error

MPE

maximum permissible error

limit of error

extreme value of measurement error, with respect to a known reference quantity value, permitted by specifications or regulations for a given measurement, measuring instrument, or measuring system

Note 1 to entry: Usually, the term “maximum permissible errors” or “limits of error” is used where there are two extreme values.

Note 2 to entry: The term “tolerance” should not be used to designate “maximum permissible error”.

[SOURCE: ISO/IEC Guide 99:2007, definition 4.26, modified — The abbreviated term, MPE, has been added.]

3.5

specification

tolerance (3.1) on a workpiece characteristic or population characteristic or the maximum permissible error (3.4) of a measuring equipment characteristic

Note 1 to entry: A specification should refer to or include drawings, patterns or other relevant documents and indicate the means and the criteria whereby conformity can be checked.

3.6

specification zone

specification interval

variate values of the workpiece characteristic or population characteristic or the measuring equipment characteristic between and including the specification limits (3.7)

3.7

specification limit

tolerance limit (3.3) of a workpiece characteristic or population characteristic or maximum permissible error (3.4) of a measuring equipment characteristic

3.8

upper specification limit

USL

specified value giving either:

—

the upper boundary of the permissible values of the tolerance limits (3.3) of a workpiece characteristic or population characteristic; or

—

the upper boundary of the permissible values of the permissible errors of a measuring equipment characteristic

3.9

lower specification limit

LSL

specified value giving either:

—

the lower boundary of the permissible values of the tolerance limits (3.3)of a workpiece characteristic or population characteristic; or

—

the lower boundary of the permissible values of the permissible errors of a measuring equipment characteristic

3.10

measurand

Y

quantity intended to be measured

[SOURCE: ISO/IEC Guide 99:2007, definition 2.3, modified ─ The notes are not reproduced. The symbol has been added.]

3.11

measurement result

result of measurement

y

set of quantity values being attributed to a measurand (3.10) together with any other available relevant information

[SOURCE: ISO/IEC Guide 99:2007, definition 2.9, modified ─ The notes are not reproduced. The symbol has been added.]

3.12

nominal value

designated value of a characteristic in a given design specification or drawing

3.13

measurement uncertainty

uncertainty of measurement

uncertainty

non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand (3.10), based on the information used

[SOURCE: ISO/IEC Guide 99:2007, definition 2.26, modified ─ The notes are not reproduced.]

3.14

standard measurement uncertainty

standard uncertainty of measurement

standard uncertainty

measurement uncertainty (3.13) expressed as a standard deviation

[SOURCE: ISO/IEC Guide 99:2007, definition 2.30, modified ─ The notes are not reproduced.]

3.15

combined standard measurement uncertainty

combined standard uncertainty

standard measurement uncertainty (3.14) that is obtained using the individual standard measurement uncertainties associated with the input quantities in a measurement model

[SOURCE: ISO/IEC Guide 99:2007, definition 2.31, modified ─ The note is not reproduced.]

3.16

expanded measurement uncertainty

expanded uncertainty

U

product of a combined standard measurement uncertainty (3.15) and a factor larger than the number one

[SOURCE: ISO/IEC Guide 99:2007, definition 2.35, modified ─ The notes are not reproduced. The symbol has been added.]

3.17

coverage factor

k

number larger than one by which a combined standard measurement uncertainty (3.15) is multiplied to obtain an expanded measurement uncertainty (3.16)

[SOURCE: ISO/IEC Guide 99:2007, definition 2.38, modified ─ The notes are not reproduced. The symbol is added.]

3.18

complete measurement result

y'

measurement result (3.11) including the expanded measurement uncertainty (3.16)

Note 1 to entry: The complete measurement result is expressed by the equation given in Clause 4.

3.19

conformity

fulfilment of a requirement

Note 1 to entry: The term “conformance” is synonymous but deprecated.

[SOURCE: ISO 9000:2005, definition 3.6.1]

3.20

conformity zone

specification zone (3.6) reduced by the expanded measurement uncertainty (3.16)

Note 1 to entry: The specification is reduced by the expanded measurement uncertainty at the upper specification limit (3.8) and/or the lower specification limit (3.9).

Note 2 to entry: See Figure 1.

Figure 1 — Conformity zone
Key A one-sided specification B two-sided specification 1 specification zone 3 conformity zone

3.21

nonconformity

non-fulfilment of a requirement

[SOURCE: ISO 9000:2005, definition 3.6.2]

3.22

nonconformity zone

zone(s) outside the specification zone (3.6) extended by the expanded measurement uncertainty (3.16)

Note 1 to entry: The specification is extended by the expanded measurement uncertainty, U, at the upper specification limit (3.8) and/or the lower specification limit (3.9).

Note 2 to entry: See Figure 2.

Figure 2 — Nonconformity zone
Key A one-sided specification B two-sided specification 1 specification zone 4 nonconformity zone

3.23

uncertainty range

range(s) close to the specification limit(s) (3.7) where neither conformity (3.19) nor nonconformity (3.21) can be proved taking into account the measurement uncertainty (3.13)

Note 1 to entry: The uncertainty range(s) is(are) located around the specification limit (one-sided specification) or specification limits (two-sided specification) and has the width of 2 × U.

Note 2 to entry: The measurement uncertainty on the upper and lower side of the measurement result may be of different magnitudes.

Note 3 to entry: See Figure 3.

Figure 3 — Uncertainty range
Key A one-sided specification B two-sided specification 1 specification zone 5 uncertainty range

3.24

population

totality of items under consideration

Note 1 to entry: An item in the field of GPS can be seen as a value of a GPS global characteristic defined on one workpiece (see ISO 25378).

[SOURCE: ISO 3534‑1:2006, definition 1.1, modified ─ The notes are not reproduced. Note 1 to entry is added.]