EN 14081-2:2018

SLOVENSKI STANDARD
01-december-2018
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Timber structures - Strength graded structural timber with rectangular cross section -
Part 2: Machine grading; additional requirements for 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 à section rectangulaire classé pour sa résistance -
Partie 2 : Classement mécanique par machine; exigences supplémentaires concernant
les essais de type
Ta slovenski standard je istoveten z: EN 14081-2:2018
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.

EN 14081-2
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2018
EUROPÄISCHE NORM
ICS 79.040 Supersedes EN 14081-2:2010+A1:2012
English Version
Timber structures - Strength graded structural timber
with rectangular cross section - Part 2: Machine grading;
additional requirements for 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
Classement mécanique par machine; exigences 2: Maschinelle Sortierung; zusätzliche Anforderungen
supplémentaires concernant les essais de type an die Erstprüfung
This European Standard was approved by CEN on 13 August 2018.

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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14081-2:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Symbols and abbreviations . 8
5 Requirements for strength grading machines . 9
6 Derivation of settings for machine control systems . 10
6.1 Requirements on sampling . 10
6.2 Requirements for grading process, destructive testing and calculation of grade
determining properties . 11
6.2.1 Grading process . 11
6.2.2 Destructive testing . 11
6.2.3 Calculations of grade determining properties . 11
6.3 Requirements for a setting area . 12
6.3.1 General . 12
6.3.2 Standardized areas . 12
6.4 Requirements for the derivation and verification of machine settings . 12
6.4.1 Derivation of machine settings . 12
6.4.2 Verification of machine settings . 13
6.5 Fixed settings . 15
6.6 Reporting . 15
7 Additional verification requirements for a new grading machine or a change in
scope of existing grading machines for machine control systems . 17
7.1 Repeatability . 17
7.2 Machine installation check . 17
8 Derivation of settings for output control systems . 18
8.1 General . 18
8.2 Initial machine settings. 18
8.3 Verification of machine settings . 18
8.3.1 Sampling . 18
8.3.2 Destructive testing and calculation of characteristic values. 18
8.3.3 Requirements for verification of machine settings . 18
8.4 Report . 18
9 Requirements for adaptive settings . 19
9.1 Method . 19
9.2 Conditions . 20
Annex A (informative) Guidelines for sampling a growth area for deriving machine settings . 21
Annex B (informative) Prediction limit method . 23
B.1 General . 23
B.2 Model determination . 23
B.3 Settings calculation . 24
Annex C (normative) Determination of the global cost matrix . 25
C.1 Introduction. 25
C.2 Optimum grading . 25
C.3 IP grading . 25
C.4 Calculation of size matrix . 26
C.5 Calculation of elementary cost matrix . 26
C.5.1 Introduction. 26
C.5.2 Factors for wrongly upgraded pieces . 26
C.5.3 Factors for wrongly downgraded pieces . 27
C.5.4 Examples of elementary cost matrices for C, T and D classes . 27
C.6 Calculation of a global cost matrix. 30
Annex D (informative) Settings for C and T-classes . 31
Bibliography . 38

European foreword
This document (EN 14081-2:2018) has been prepared by Technical Committee CEN/TC 124 “Timber
structures”, the secretariat of which is held by AFNOR.
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 April 2019, and conflicting national standards shall be
withdrawn at the latest by April 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document will supersede EN 14081-2:2010+A1:2012.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
Compared to EN 14081-2:2010+A1:2012, the following main modifications have been made:
— new definitions added in Clause 3;
— new requirements for sampling, settings areas and minimum cross-section area;
— introduction of standardized areas;
— method for deriving settings is no longer normative, since several methods may be used; an example
of a method is given in Annex B;
— new method for verification of settings;
— cost matrix requirements are changed, to better allow settings that aim for reduced reject rather than
yield in the highest grade;
— new method for output control systems;
— introduction of adaptive settings;
— introduction of fixed settings.
This standard is part of a series of standards on Timber structures — Strength graded structural timber
with rectangular cross section ("EN 14081") that includes:
— Part 1: General requirements;
— Part 2: Machine grading; additional requirements for type testing;
— Part 3: Machine grading; additional requirements for factory production control.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands,
Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
the United Kingdom.
Introduction
Machine grading is in common use in a number of countries. There are two basic systems, referred to as
“output control” and “machine control”. Both systems require a visual override inspection to cater for
performance reducing characteristics that are not automatically sensed by the machine.
The output control system is suitable for use where the grading machines are situated in sawmills grading
...