EN 14081-2:2005

SLOVENSKI STANDARD
01-maj-2006
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SIST EN 518:1996
SIST EN 519:1996
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Timber structures - Strength graded structural timber with rectangular cross section -
Part 2: Machine grading; additional requirements for initial type testing
Holzbauwerke - Nach Festigkeit sortiertes Bauholz für tragende Zwecke mit
rechteckigem Querschnitt - Teil 2: Maschinelle Sortierung, zusätzliche Anforderungen an
die Erstprüfung
Structures en bois - Bois de structure de section rectangulaire classé selon la résistance
- Partie 2: Classement mécanique - Exigences supplémentaires concernant les essais
de type initiaux
Ta slovenski standard je istoveten z: EN 14081-2:2005
ICS:
79.040 Les, hlodovina in žagan les Wood, sawlogs and sawn
timber
91.080.20 Lesene konstrukcije Timber structures
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 14081-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2005
ICS 79.040 Supersedes EN 518:1995, EN 519:1995
English Version
Timber structures - Strength graded structural timber with
rectangular cross section - Part 2: Machine grading; additional
requirements for initial type testing
Structures en bois - Bois de structure à section Holzbauwerke - Nach Festigkeit sortiertes Bauholz für
rectangulaire classé pour sa résistance - Partie 2: tragende Zwecke mit rechteckigem Querschnitt - Teil 2:
Classement mécanique; exigences supplémentaires en Maschinelle Sortierung; zusätzliche Anforderungen an die
concernant les essais de type initiaux Erstprüfung
This European Standard was approved by CEN on 26 August 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14081-2:2005: E
worldwide for CEN national Members.

Contents Page
Foreword .3
Introduction.4
1 Scope .5
2 Normative references .5
3 Terms and definitions.5
4 Symbols.6
5 Requirements for strength grading machines.7
6 Additional initial type testing for machine controlled systems.8
6.1 General .8
6.2 Requirements for the derivation and verification of machine settings.8
6.3 Machine installation check.12
7 Additional initial type testing for output controlled systems .13
7.1 General .13
7.2 Requirements for the assessment of initial settings.13
Annex A (normative) Calculation of elementary cost matrix values for 6.2.5.7 .15
A.1 General .15
A.2 Factors for wrongly upgraded pieces .15
A.3 Factors for wrongly downgraded pieces .16
Annex B (informative) Guidance on the procedure of initial type testing for machine controlled
systems .17
B.1 Introduction.17
B.2 Guidance.17
Annex C (informative) Requirements for control planks .19
Annex D (informative) Control plank design concepts and materials.20
D.1 General design principles .20
D.2 Generic plank designs and materials.20
D.3 Generic machine types.22
Bibliography.31

Foreword
This European Standard (EN 14081-2:2005) has been prepared by Technical Committee CEN/TC 124
“Timber structures”, the secretariat of which is held by SFS.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by May 2006, and conflicting national standards shall be withdrawn at the
latest by August 2007.
This European Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association, and supports essential requirements of EU Directive(s).
This European Standard supersedes EN 518:1995 and EN 519:1995.
Other parts of this European Standard are:
EN 14081-1 Timber structures – Strength graded structural timber with rectangular cross section – Part 1:
General requirements,
EN 14081-3 Timber structures – Strength graded structural timber with rectangular cross section – Part 3:
Machine grading; additional requirements for factory production control,
EN 14081-4 Timber structures – Strength graded structural timber with rectangular cross section – Part 4:
Machine grading; grading machine settings for machine controlled systems.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and United Kingdom.
Introduction
Machine grading is in common use in a number of countries. The countries use two basic systems, referred to
as ‘output controlled’ and ‘machine controlled’. Both systems require a visual override inspection to cater for
strength-reducing characteristics that are not automatically sensed by the machine.
The output-controlled system is suitable for use where the grading machines are situated in sawmills grading
limited sizes, species and grades in repeated production runs of around one working shift or more. This
enables the system to be controlled by testing timber specimens from the daily output. These tests together
with statistical procedures are used to monitor and adjust the machine settings to maintain the required
strength properties for each strength class. With this system it is permissible for machine approval
requirements to be less demanding and for machines of the same type to have non-identical performance.
The machine controlled system was developed in Europe. Because of the large number of sizes, species and
grades used it was not possible to carry out quality-control tests on timber specimens drawn from production.
The system relies therefore on the machines being strictly assessed and controlled, and on considerable
research effort to derive the machines settings, which remain constant for all machines of the same type.
The acceptability of grading machines and the derivation of settings rely on statistical procedures and the
results will therefore depend on the method used. For this reason this document gives appropriate statistical
procedures.
The requirements in this European Standard are based on machines in current use and on future types of
machines as far as these can be foreseen. It is recognised that additional clauses or standards may be
required if unforeseen developments take place.
1 Scope
This European Standard specifies requirements, additional to those in EN 14081-1, for initial type testing of
machine graded structural timber with rectangular cross-sections shaped by sawing, planing or other
methods, and having deviations from the target sizes corresponding to EN 336. This includes requirements for
strength grading machines and test equipment for proof loading graded material, and optional requirements
for control planks to test the dynamic performance of grading machines.
2 Normative references
The following referenced documents are indispensable for the application of this European Standard. For
dated references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 338, Structural timber — Strength classes
EN 384, Structural timber — Determination of characteristic values of mechanical properties and density
EN 408:2003, Timber structures — Structural timber and glued laminated timber — Determination of some
physical and mechanical properties
EN 14081-1:2005, Timber structures — Strength graded structural timber with rectangular cross section — Part
1: General requirements
EN 14081-3, Timber structures — Strength graded structural timber with rectangular cross section — Part 3:
Machine grading; additional requirements for factory production control
3 Terms and definitions
For the purpose of this European Standard, the terms and definitions given in EN 14081-1:2005, and the
following apply.
3.1
characteristic strength
population 5-percentile value obtained from the results of tests with a duration of 300 s ± 120 s using test
pieces at an equilibrium moisture content resulting from a temperature of 20 °C and a relative humidity of 65
%
3.2
characteristic stiffness
population mean value obtained under the same test conditions as defined in 3.1
3.3
critical feed speed
speed within the intended usable range at which the grading machine is least accurate in measuring its
indicating property
3.4
depth
dimension perpendicular to the longitudinal axis of a timber beam, in the plane of the bending forces
3.5
grade determining property
mechanical or physical property for which a particular value of that property has to be achieved for the
material to be assigned to that grade, e.g. bending strength, mean modulus of elasticity and density for the
strength classes of EN 338
3.6
indicating property
measurement or combination of measurements made by the grading machine, which are closely related to
one or more of the grade determining properties. For grading machines which compute and predict values of
the grade determining properties directly from numerous measuring devices, the indicating property may be a
predicted value of a grade determining property
3.7
optimum grade
highest grade, of those for which settings are required, to which a piece of timber can be assigned, such that
the grade determining properties of the graded sample will meet the values required for the grade
3.8
settings
values of the parameters used to set the machine to grade timber, which are mathematically related to the
indicating property
3.9
sub-sample
number of specimens of timber of one species or species combination, from one growth area or source of
production
3.10
thickness
lesser dimension perpendicular to the longitudinal axis of a piece of timber
4 Symbols
b width of cross section (in mm)
E theoretical modulus of elasticity (in N/mm )
E actual modulus of elasticity measured in a proof load test (in N/mm )
p
E mean modulus of elasticity for assigned grade (in
...