CEN/TS 16526:2013

SLOVENSKI STANDARD
01-julij-2014
/HVQHSORãþH/DVWQRVWLLQ]DKWHYH]DVSHFLILNDFLMRVHQGYLþSORãþ]DSRKLãWYR
Wood-based panels - Determination of performance characteristics for specification of
sandwich boards for furniture
Holzwerkstoffe - Bestimmung der Leistungseigenschaften von Sandwich-Platten für
Möbel
Panneaux sandwiches pour meubles (SWB-F) - Produits manufacturés - Définition,
classification et méthodes d'essai pour la détermination des propriétés fonctionelles
Ta slovenski standard je istoveten z: CEN/TS 16526:2013
ICS:
79.060.01 /HVQHSORãþHQDVSORãQR Wood-based panels in
general
97.140 Pohištvo Furniture
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL SPECIFICATION
CEN/TS 16526
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
November 2013
ICS 79.060.01
English Version
Sandwich boards for furniture (SWB-F) - Factory made products
- Definition, classification and test methods for determination of
performance characteristics
Panneaux sandwiches pour meubles (SWB-F) - Produits Sandwichplatten für Möbel (SWB-F) - Werkmäßig
manufacturés - Définition, classification et méthodes d'essai hergestellte Produkte - Definition, Klassifizierung und
pour la détermination des propriétés fonctionelles Prüfverfahren zur Bestimmung der Leitstungseigenschaften
This Technical Specification (CEN/TS) was approved by CEN on 15 June 2013 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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, 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: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 16526:2013 E
worldwide for CEN national Members.

Contents Page
Foreword .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .6
4 Classification .9
4.1 General .9
4.2 Classification according to board lay-up .9
4.3 Classification according to surface appearance .9
4.4 Classification according to conditions of use .9
4.5 Classification according to application purposes .9
5 Symbols . 10
5.1 General . 10
5.2 Symbols related to conditions of use . 10
5.3 Symbols related to specific applications . 10
5.4 Combination of symbols for identification of sandwich boards . 10
6 Conditioning and test conditions . 10
7 Sampling, preparation and handling of test pieces and expression of test results . 11
7.1 General requirements . 11
7.2 Testing of SWB-F in combination with auxiliary material(s) or after execution of additional
processing steps . 12
7.3 Test piece size . 12
7.4 Determination of dimensions of test pieces . 12
7.5 Expression of test results . 13
8 Test methods . 13
8.1 General guideline on the description and use of test methods . 13
8.2 Physical properties . 13
8.2.1 Determination of board dimensions . 13
8.2.2 Moisture content . 13
8.2.3 Apparent density and mass per unit area . 14
8.2.4 Linear expansion due to changes in relative humidity . 14
8.2.5 Behaviour under humidity variations in successive uniform climates . 14
8.2.6 Moisture resistance . 14
8.3 Mechanical properties . 16
8.3.1 Flexural properties. 16
8.3.2 Surface soundness . 18
8.3.3 Compressive properties perpendicular to the plane of the board . 18
8.3.4 Impact resistance. 21
8.3.5 Shear strength . 22
8.4 Properties relevant to processing and to performance in use . 23
8.4.1 General . 23
8.4.2 Integrity of board edges . 24
8.4.3 Quality of edge banding . 24
8.4.4 Load bearing capacity of fasteners . 30
8.4.5 Shear resistance of a grooved board . 33
8.5 Formaldehyde emission . 34
9 Marking . 34
10 Test report . 34
Annex A (normative) Test methods . 36
Annex B (informative) Characterization of sandwich boards for different applications in furniture

manufacturing . 48
Bibliography . 51

Foreword
This document (CEN/TS 16526:2013) has been prepared by Technical Committee CEN/TC 112 “Wood-based
panels”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Specification: 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
SAFETY STATEMENT — Persons using this document should be familiar with the normal laboratory practice,
if applicable. This document does not purport to address all of the safety problems, if any, associated with its
use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure
compliance with any regulatory conditions.
ENVIRONMENTAL SAFETY— It is understood that some of the material permitted in this standard may have
negative environmental impact. As technological advantages lead to better alternatives for these materials,
they will be eliminated from this standard to the extent possible. At the end of the test, it is recommended that
the user of the standard takes care to carry out an appropriate disposal of the wastes, according to local
regulation.
1 Scope
This European Technical Specification defines terms, establishes a classification and specifies test methods
for flat, factory made, non-structural, faced and unfaced sandwich boards for use in furniture manufacturing
(SWB-F) for dry (service class 1) and humid conditions (service class 2). This European Technical
Specification does not specify requirements.
Guidance is provided for the selection of board properties which are relevant for specific board applications.
This European Technical Specification is not applicable to products which are already covered by existing
standards.
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.
EN 311, Wood-based panels - Surface soundness - Test method
EN 318, Wood based panels - Determination of dimensional changes associated with changes in relative
humidity
EN 320, Particleboards and fibreboards - Determination of resistance to axial withdrawal of screws
EN 322, Wood-based panels - Determination of moisture content
EN 324-1, Wood-based panels - Determination of dimensions of boards - Part 1: Determination of thickness,
width and length
EN 324-2, Wood-based panels - Determination of dimensions of boards - Part 2: Determination of squareness
and edge straightness
EN 325, Wood-based panels - Determination of dimensions of test pieces
EN 326-1, Wood-based panels - Sampling, cutting and inspection - Part 1: Sampling and cutting of test pieces
and expression of test results
EN 326-2, Wood-based panels - Sampling, cutting and inspection - Part 2: Initial type testing and factory
production control
EN 326-3, Wood-based panels - Sampling, cutting and inspection - Part 3: Inspection of an isolated lot of
panels
EN 438-2, High-pressure decorative laminates (HPL) - Sheets based on thermosetting resins (usually called
Laminates) - Part 2: Determination of properties
EN 717-1, Wood-based panels - Determination of formaldehyde release - Part 1: Formaldehyde emission by
the chamber method
EN 717-2, Wood-based panels - Determination of formaldehyde release - Part 2: Formaldehyde release by
the gas analysis method
EN 789, Timber structures - Test methods - Determination of mechanical properties of wood based panels
EN 826, Thermal insulating products for building applications - Determination of compression behaviour
EN 950, Door leaves - Determination of the resistance to hard body impact
EN 1294, Door leaves - Determination of the behaviour under humidity variations in successive uniform
climates
EN 1383, Timber structures - Test methods - Pull through resistance of timber fasteners
EN 1464, Adhesives - Determination of peel resistance of adhesive bonds - Floating roller method
EN 1995-1-1, Eurocode 5: Design of timber structures - Part 1-1: General - Common rules and rules for
buildings
EN 14323:2004, Wood-based panels - Melamine faced boards for interior uses - Test methods
EN 14727:2005, Laboratory furniture - Storage units for laboratories - Requirements and test methods
DIN 53293, Testing of sandwiches - Bending test
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
sandwich board
SWB
laminar composite product consisting of at least two skins positioned on either side of a core, which is firmly
connected to the skins (e.g. by bonding, by core-generated adhesion) so that the three (or more) components
act compositely when under load
Note 1 to entry: Wood or other lignocellulosic materials constitute at least one of the components.
3.2
skin
flat sheet firmly connected to the core and designed to support in-plane tensile or compressive loads in a
sandwich board
Note 1 to entry: Sheets used as skins can consist of composite materials.
Note 2 to entry: Skins in sandwich boards for furniture commonly consist of particleboard (EN 309), fibreboard
(EN 316), plywood (EN 636) etc.
Note 3 to entry: If skins consist of or contain veneers (excluding decorative veneer applied to skins in faced SWB-F) or
plywood, this SWB can be considered as a core or composite plywood as defined in EN 313–2. The corresponding
standards can apply in particular, the requirements and test methods pertaining to the bonding quality.
3.3
core
centrally positioned layer of material, generally low in density, which is bonded between two skins and is
designed to support normal compressive and tensile loads and to transfer shear loads in a sandwich board
3.4
core material
homogeneous or inhomogeneous material used in manufacturing the core
Note 1 to entry: Homogeneous and inhomogeneous core materials provide continuous and discontinuous supports of
the skins, respectively. Homogeneous (e.g. balsa wood, foams) or inhomogeneous (e.g. honeycomb cores) core materials
can be isotropic or anisotropic.
Note 2 to entry: Core materials in sandwich boards for furniture are commonly lightweight materials such as paper,
metal or composite honeycomb, open and closed cell foam, corrugated material, bonded composite tubes, or naturally
occurring materials such as balsa wood or lightweight (wood) fibre-based boards.
3.5
homogenous material
material in which on a macroscopic scale relevant properties are not a function of the position within the
material itself but may be a function of such parameters as time, direction, temperature, etc.
3.6
inhomogeneous material
material, also often referred to as non-homogeneous or structured in which on a macroscopic scale relevant
properties are a function of the position within the material itself and relevant properties may be a function of
such parameters as time, direction, temperature, etc.
3.7
isotropic
exhibiting the same physical and mechanical properties along different axes
3.8
anisotropic
not isotropic
exhibiting different physical and mechanical properties along different axes
3.9
x-axis
in sandwich boards, an axis in the plane of the skins which is used as the 0 degree reference or major axis
Note 1 to entry: The board dimension in the direction of the x-axis is referred to as the length of the board.
3.10
x-y plane
in sandwich boards, the reference plane parallel to the plane of the skins
3.11
y-axis
in sandwich boards, the axis in the plane of the skins which is perpendicular to the x-axis and which is referred
to as the minor axis
Note 1 to entry: The board dimension in the direction of the y-axis is referred to as the width of the board.
3.12
z-axis
in sandwich boards, the reference axis normal to the plane of the skins
Note 1 to entry: The board dimension in the direction of the z-axis is referred to as the thickness of the board.
3.13
structural unit
SU
entity which is repeated periodically in an inhomogeneous core material whose properties vary along the x- or
y-axis of the sandwich board
Note 1 to entry: An example of a structural unit is a honeycomb cell in a honeycomb core or a single profile in a
corrugated core.
3.14
factory made
mass manufactured commodity product supplied on the open market for the purpose of fabrication of furniture
components or furniture
Note 1 to entry: Factory made SWB-F can be subjected by the board manufacturer to additional value-adding
processes (e.g. application of decorative surfaces to skins, cutting of boards to customer-specific dimensions, installation
of edge-banding).
Note 2 to entry: Purpose built or custom sandwich board manufactured by a furniture producer for a specific furniture
product is not considered SWB-F as covered by this European Technical Specification.
3.15
dry conditions
conditions corresponding to service class 1 of EN 1995-1-1 which is characterized by a moisture content in
the material corresponding to a temperature of 20 °C and a relative humidity of the surrounding air only
exceeding 65 % for a few weeks per year
3.16
humid conditions
conditions corresponding to service class 2 of EN 1995-1-1 which is characterized by a moisture content in
the material corresponding to a temperature of 20 °C and a relative humidity of the surrounding air only
exceeding 85 % for a few weeks per year
3.17
furniture
moveable or permanently installed articles for lying, sitting, working and storing of goods in areas intended for
living, working, dwelling etc.
3.18
non-structural use
all general applications, e.g. furniture and fitments under conditions other than load-bearing conditions as part
of a building or other construction or such conditions under which the board constitutes a construction product
as defined by the Council Directive 89/106/EEC
3.19
faced sandwich board
sandwich board with overlaid, coated, printed or veneered decorative surfaces applied to skins
3.20
unfaced sandwich board
sandwich board without overlaid, coated, printed or veneered decorative surfaces applied to skins
3.21
overlaid sandwich board
sandwich board surfaced with one or more overlay sheets or films, for example impregnated paper, plastics,
resin film, metal
3.22
coated sandwich board
sandwich board surfaced with a coating, normally applied in liquid form, for functional or decorative purposes
3.23
veneered sandwich board
sandwich board overlaid with a (decorative) veneer
3.24
mass per unit area
quotient of mass and area (i.e. length multiplied by width) of a piece of sandwich board expressed in
kilograms per square metres [kg/m ]
3.25
apparent density
mass per unit volume, expressed in kilograms per cubic metre [kg/m ], and based on the external dimensions
of the test piece to calculate the volume which is an average density of material and any hollow spaces
(pores, cells, channels etc.)
3.26
peel resistance
average force measured along the bond line, required to separate progressively the two members of a bonded
test piece under specified conditions of test
4 Classification
4.1 General
Sandwich boards can be classified according to different criteria. It is not possible to present an exhaustive
classification system.
In this European Technical Specification, a combined system of criteria is presented for the classification of
sandwich boards for furniture.
4.2 Classification according to board lay-up
— honeycomb sandwich board;
— solid core sandwich board;
— foam core sandwich board.
4.3 Classification according to surface appearance
— unfaced sandwich board;
— faced sandwich board.
4.4 Classification according to conditions of use
— dry conditions;
— humid conditions.
4.5 Classification according to application purposes
— sandwich boards for vertical elements in furniture;
— sandwich boards for horizontal elements in furniture;
— sandwich boards for front elements in furniture;
NOTE Front elements in furniture most commonly act as doors; thus the ability to install hardware in front elements is
often of vital importance.
5 Symbols
5.1 General
Different symbols are used for addressing different types of sandwich boards for furniture.
5.2 Symbols related to conditions of use
Table 1 specifies the symbols which shall be used to indicate the conditions of use.
Table 1 — Symbols related to conditions of use
Conditions of use Symbol
Dry conditions no symbol
Humid conditions H
5.3 Symbols related to specific applications
Table 2 specifies the symbols which shall be used to indicate the board application in furniture manufacturing.
Table 2 — Symbols related to board application in furniture manufacturing
Board application in furniture Symbol
manufacturing
general purpose no symbol
vertical elements VE
horizontal elements HE
front elements FE
5.4 Combination of symbols for identification of sandwich boards
The symbols indicating conditions of use and application purposes are added to the symbol “SWB-F” for
sandwich board for furniture after a full stop, in this sequence:
“SWB-F” condition of use application purpose
EXAMPLE 1 SWB-F.H.FE
sandwich board for furniture to be used in humid conditions as front elements (e.g. for doors in bathroom furniture)
EXAMPLE 2 SWB-F
sandwich board for furniture to be used in dry conditions for general purposes
6 Conditioning and test conditions
Unless otherwise stated in this European Technical Specification the test pieces shall be conditioned to
constant mass in an atmosphere with a relative humidity of (65 ± 5) % and a temperature of (20 ± 2) °C.
Constant mass is considered to be reached when the results of two successive weighing operations, carried
out at an interval of 24 h, do not differ by more than 0,1 % of the mass of the test piece.
Unless otherwise stated in this European Technical Specification tests should be carried out at ambient room
temperature and no requirements pertaining to the relative humidity during testing apply. However, if the
ambient conditions of testing are not the same as those in the conditioning chamber, tests shall be undertaken
immediately after the test pieces have been removed from the conditioning chamber.
7 Sampling, preparation and handling of test pieces and expression of test results
7.1 General requirements
Sampling, cutting of test pieces (also referred to as test pieces) and expression of test results shall be carried
out according to EN 326-1.
Unless otherwise stated in this European Technical Specification the minimum number of test pieces m to be
tested for determination of the respective property shall be taken from Table 3.
Table 3 — Minimum number of test pieces m which have to be tested to determine properties of
sandwich boards
Property Reference to test method Minimum number of test pieces m
Moisture content 8.2.2 4
Apparent density and mass per 8.2.3 6
unit area
Linear expansion due to changes 8.2.4 4
in relative humidity
Behaviour under humidity 8.2.5 2
variations in successive uniform
climates
Moisture resistance 8.2.6 see respective test method
Bending test 8.3.1.2 6
Bending properties of sandwich 8.3.1.3 5
board for shelving and similar
applications
Surface soundness 8.3.2 8
Flatwise compressive behaviour 8.3.3.1 10
Resistance to a concentrated 8.3.3.2 10
static point load
Resistance to a concentrated 8.3.3.3 10
static load applied in close
proximity to the board edge
Impact resistance 8.3.4 see respective test method
Shear strength 8.3.5 6
Resistance of the board edge with 8.4.3.2 6
edgebanding against a static
concentrated load
Peel resistance of edge-banding 8.4.3.3 6
Determination of axial withdrawal 8.4.4.2 10
resistance of fastener
Pull through resistance of 8.4.4.3 10
fasteners
Load bearing capacity of shelf 8.4.4.4 10
supports
Shear resistance of a grooved 8.4.5 10
board
In order to determine properties, which differ with respect to the x-axis and the y-axis of the board, two groups
of m test pieces shall be tested. For the purpose of ensuring and demonstrating compliance with specific
requirements in factory production control, testing can be limited to test pieces with the known weakest
orientation in the plane of the board.
7.2 Testing of SWB-F in combination with auxiliary material(s) or after execution of
additional processing steps
For certain purposes (e.g. evaluation of properties of SWB-F for a very specific application or furniture design)
it may be desirable to evaluate properties of SWB-F in combination with auxiliary materials or after the
execution of further processing steps which are to be applied to the respective SWB-F in the manufacturing of
furniture or furniture components.
Examples of such auxiliary materials and/or processing steps are the installation of edge reinforcements
and/or edge banding, the application of decorative surface finishes etc. The respective auxiliary materials
and/or processing steps etc. have to be specified and described in the test report. Test results are only
applicable to the tested SWB-F in combination with the specified auxiliary material and/or processing steps.
7.3 Test piece size
Unless other specifications are provided in this European Technical Specification for the respective test
method the test piece size shall be as follows:
The test piece shall be square. The side length of the test piece shall measure 100 mm. The thickness of the
test pieces shall be equal to the thickness of the sandwich board. For a sandwich board with an
inhomogeneous core the side length may have to be increased in order to meet the following criteria:
For inhomogeneous core materials with a longitudinal orientation of the structural units (e.g. channels in a
corrugated core) a minimum of three structural units shall be contained in the test piece cross section. For
inhomogeneous core materials with cellular structural units at least nine structural units shall be contained in
the test piece cross section.
Generally the person or entity applying this European Technical Specification is responsible for ensuring that
representative and reproducible test results can be obtained by considering characteristics of and local
variations within the respective sandwich board and its core material when choosing a sampling strategy, a
test piece cutting plan and a test piece size.
Test piece dimensions shall be stated in the test report.
If larger test pieces have to be employed to determine certain properties suitable modifications of the test
equipment may have to be implemented and described in the test report (e.g. larger loading plates for
determination of the flatwise compressive behaviour as described in 8.3.3.1).
7.4 Determination of dimensions of test pieces
Unless otherwise stated in this European Technical Specification dimension of test pieces shall be determined
following conditioning of test pieces according to the provisions stated in Clause 6. Dimensions of test pieces
with a maximum nominal length and/or width of 300 mm shall be determined according to EN 325.
Dimensions of test pieces which are larger in size shall be determined according to the provision of the
respective test method or in case that no provisions are given in the respective test method by applying the
procedures specified in 8.2.1.
The thickness of a test piece shall be measured at four points located 25 mm from the nearest edges. The
average thickness is recorded.
The length and width of a square test piece with a nominal size of 10 000 mm shall be measured at two
points located 2 mm from the nearest edge, respectively. The average length and width shall be recorded.
The length and width of a rectangular test piece or of a square test piece with a nominal size of ≥ 40 000 mm
shall be measured at two points located 25 mm from the nearest edge and at the point midway along the
edge(s) measuring ≥ 200 mm in length. The average length and width shall be recorded.
7.5 Expression of test results
Unless otherwise stated in this European Technical Specification test results shall be expressed as
5 percentile values (95 percentile values in case of properties for which an upper limit is imposed) based on
the mean values for individual boards and calculated in accordance with EN 326-1. Mean values and standard
deviations shall also be reported.
Evaluation and statistical analysis procedures of results shall be carried out in accordance with EN 326-2 if
test procedures provided in this European Technical Specification are employed by a manufacturer as part of
initial type testing or of factory production control.
Evaluation and statistical analysis procedures of results shall be carried out in accordance with EN 326-3 for
the inspection of an isolated lot of boards.
8 Test methods
8.1 General guideline on the description and use of test methods
Methods provided for determination of various properties are either described in full in this European
Technical Specification or they are based partially or fully on existing standards. Whenever test methods are
based on existing standards it shall be observed that unless otherwise stated in this European Technical
Specification the provisions of Clause 6 (“Conditioning and test conditions”) and Clause 7 (“Sampling,
preparation and handling of test pieces and expression of test results”) of this European Technical
Specification replace the respective provision of the referenced standards. Other modifications which apply to
specific, referenced test methods are provided in the description of the test method within this European
Technical Specification.
8.2 Physical properties
8.2.1 Determination of board dimensions
Thickness, width and length of a sandwich board shall be determined in accordance with EN 324-1.
Squareness and edge straightness of a sandwich board shall be determined in accordance with EN 324-2.
Warping of a sandwich board shall be determined and expressed according to EN 14323:2004, 5.2.
The edges of a sandwich board have to be trimmed in a precise manner such that any deviations in size of the
two skins are negligible. Width, length, squareness and edge straightness of a sandwich board are equal to
the width, length, squareness and edge straightness of its skins.
8.2.2 Moisture content
The moisture content of a sandwich board shall be determined according to EN 322 using 4 test pieces with a
minimum weight of at least 100 g each.
The method for determination of moisture content according to EN 322 is based on differential weighing of
board material prior to and after drying of material at a temperature of (103 ± 2) °C. If the sandwich board to
be tested contains particularly temperature sensitive (i.e. volatile) substances the method according to EN 322
may lead to an incorrect and non-reproducible result. In order to obtain accurate results SWB-F containing
volatile, heat-sensitive or readily flammable materials shall be dried over a desiccant under vacuum conditions
(pressure: < 100 Pa) at low temperatures (temperature: max. 50 °C) in a desiccator.
8.2.3 Apparent density and mass per unit area
Apparent density of a sandwich board shall be determined according to the principle of EN 322 using external
test piece dimensions in calculating the volume.
2 3
The mass per unit area [kg/m ] shall be calculated as the product of the apparent density [kg/m ] multiplied by
the board thickness [m].
8.2.4 Linear expansion due to changes in relative humidity
The linear expansion due to changes in relative humidity shall be determined in accordance with EN 318. Test
pieces shall measure (300 ± 2) mm in length and (100 ± 2) mm in width. The thickness of the test pieces shall
be equal to the board thickness. Larger test pieces may also be used.
For SWB-F with inhomogeneous core material the test piece size may have to be increased to meet the
following criteria:
— for inhomogeneous core materials with a longitudinal orientation of the structural units (e.g. channels in a
corrugated core) a minimum of three structural units shall be contained in the test piece cross section;
— for inhomogeneous core materials with cellular structural units at least nine structural units shall be
contained in the test piece cross section.
8.2.5 Behaviour under humidity variations in successive uniform climates
The resistance of SWB-F against moisture induced warping shall be determined and expressed following the
principles of EN 1294. Two SWB-F test pieces measuring (2 000 ± 5) mm in length and (850 ± 5) mm in width
shall be tested. Unfaced SWB-F and faced SWB-F test pieces shall be stored in the different climates for at
least 7 days and 21 days, respectively or until constant mass is reached. Constant mass is considered to be
reached when the results of two successive weighing operations, carried out at an interval of 24 h, do not
differ by more than 0,1 % of the mass of the test piece.
Local deflections shall be determined and stated only upon special request. Any alterations in visual
appearance and in particular any damage shall be documented and reported.
8.2.6 Moisture resistance
8.2.6.1 Principle
Moisture resistance of SWB-F shall be assessed by evaluating the effect of elevated temperature and
moisture conditions on a specified property (or specified properties) of SWB-F. For this purpose prior to
testing two groups of test pieces are conditioned at reference conditions and at elevated temperature and
moisture conditions, respectively. The property to be assessed shall be specified by the user of this European
Technical Specification. The relative effect of the elevated moisture and temperature conditions is expressed
as the property retention index on the basis of the reference level determined subsequent to conditioning at
reference conditions.
For certain applications or products the moisture resistance may be evaluated on the basis of two or more
property retention indices.
The property/properties to be evaluated shall be selected on the basis of the application of the respective
SWB-F. For example the bending test according to 8.3.1.3 shall be selected for SWB-F.H.HE intended for
shelving. For other applications testing of the axial withdrawal resistance of fasteners (see 8.4.4.2) may be
regarded as crucial.
The property/properties to be evaluated may also be selected on the basis of the estimated impact of high
moisture conditions on the different components of SWB-F (e.g. by testing of the compressive strength
according to 8.3.3.1 for moisture sensitive core materials) or on the interface between the respective
components of SWB-F (e.g. by evaluating the shear strength according to 8.3.5).
8.2.6.2 Conditioning
Two equal sets of test pieces shall be prepared and randomly assigned to the following two conditioning
groups:
— reference group (index: ): storage at reference conditions as stated in Clause 6;
— elevated moisture group (index: ): storage at a temperature of (30 ± 2) °C and a humidity of (90 ± 5) %.
w
Unfaced SWB-F and faced SWB-F test pieces shall be stored in the different climates for at least 7 days and
21 days, respectively or until constant mass is reached. Constant mass is considered to be reached when the
results of two successive weighing operations, carried out at an interval of 24 h, do not differ by more than
0,1 % of the mass of the test piece.
Subsequent to the respective conditioning steps tests shall be conducted according to the method selected.
8.2.6.3 Calculation of the property retention index
From the test results based on m test pieces the property retention index is calculated using the formulas
given below.
The mean of the results obtained for the reference group constitutes the level of the reference property and is
calculated as follows:
m
p
o,i
∑
i=0
p = (1)
o
m
where
ρ is measured initial property of each test piece of the reference group.
,i
ο
The property retention index (%) for each test piece from the elevated moisture group (z ) is calculated
w,i
according to the formula:
p
w,i
z = (2)
w,i
p
o
where
p is measured initial property of each test piece of the elevated moisture group.
w,i
The mean property retention index (%) for the elevated moisture group is calculated according to the formula:
m
z
∑ w,i
i=0
Z = (3)
w
m
The standard deviation of the property retention index is calculated using the following formula:
m
(z −Z )
∑ w,i w
i=0
s = (4)
w,z
m− 1
The mean property retention index and the standard deviation are to be reported together with all
observations regarding changes in the boards or the failure modes observed during testing.
If applicable information on the moisture resistance of components and materials (e.g. adhesives) used in
manufacturing SWB-F for use in humid conditions shall be reported. If standardized wood-based panels are
used as components in the manufacturing of SWB-F for use in humid conditions (e.g. particleboard according
to EN 312, MDF according to EN 622-5, plywood according to EN 636) then these wood-based panels have to
meet the moisture resistance requirements specified in the respective product standards.
NOTE If standardized wood-based panels complying with applicable moisture resistance requirements (e.g.
application of P3 particleboard in the skins) are employed in the skins then the determination of the property retention
index of the surface soundness according to 8.3.2 can be omitted.
8.3 Mechanical properties
8.3.1 Flexural properties
8.3.1.1 General
Research results and experience have shown that bending stiffness of SWB-F varies with the span employed
during testing due to large deformation in the sandwich core. The test method given in 8.3.1.2 is regarded as
unsuitable to reliably measure the bending properties of sandwich boards with core materials of relatively low
shear strength. The test method according to 8.3.1.3 shall be employed to determine the bending properties in
such a case.
8.3.1.2 Bending test
DIN 53293 shall be employed for testing SWB-F in bending under 4-point loading. Test piece sizes shall be
based on the provisions of DIN 53293.
8.3.1.3 Bending properties of sandwich board for shelving and similar applications
Bending properties of SWB-F for shelving and similar applications shall be assessed following the principle of
EN 14727:2005, 7.1.2.
NOTE DIN 68874–1:1985, 5.3.1 describes a similar test set-up in more detail.
Testing is to be conducted in a purpose-built and rigid test frame not in an actual furniture carcass. Testing
shall be conducted under stable climatic conditions preferably in a room maintained at a constant temperature
of (22 ± 2) °C and relative humidity of (57 ± 10) %. Test pieces shall measure (850 ± 5) mm in length and
(200 ± 5) mm in width. Test pieces shall not show any signs of warping or other out-of-plane deflection.
Test pieces shall be placed on two cylindrical or rounded supports which are positioned at a distance of
(800 ± 2) mm measured on centre (i.e. span). The radius of supports shall be large enough to avoid local
deformations of the boards as a result of compressive forces (e.g. indentations).The test piece and loading
configuration is depicted in Figure 1 The measuring points “A” and “D” located at midspan are more clearly
shown on the underside of a test piece in Figure 2.
Dimensions in millimetres
Key
1 test piece
2 central measurement point A for deflection
3 weights for application of uniform load
4 support
Figure 1 — Test method for determination of bending properties of SWB-F for horizontal elements
such as shelving
Figure 2 — Locations of measuring points “A” and “D” for the test method for determination of
bending properties of SWB-F for horizontal elements such as shelving
A uniformly distributed load shall be applied to the test piece using individual weights with
...