BS 205:2016 pdf download – Adhesives — Wood adhesives for non-structural applications — Determination of tensile shear strength of lap joints
This European Standard specifies tests for adhesives for wood and derived timber products for theassessment of their resistance to hot and cold water. It can be used for the assessment of the strength ofbonds with a thin bond-line. It does not apply to adhesives for structural use or to the manufacture ofparticleboards, fibreboards and plywood.It does not replace tests on finished products.
2Normative references
The following documents, in whole or in part, are normatively referenced in this document and areindispensable for its application. For dated references,only the edition cited applies.For undatedreferences, the latest edition of the referenced document (including any amendments) applies.
EN 204,Classification of thermoplastic wood adhesives for non-structural applications
EN 923,Adhesives – Terms and definitions
EN 12765,Classification of thermosetting wood adhesives for non-structural applications
ISO 5893,Rubber and plastics test equipment —Tensile, flexural and compression types (constant rate oftraverse) -Specification
ISO 6344-2:1998,Coated abrasives — Grain size analysis — Part 2: Determination of grain sizedistribution of macrogrits P12 to P220
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 923 and the following apply.3.1
thin bond line
close contact adhesive joint where the adhesive layer is nominally 0,1 mm thick4Principle
A symmetrical bonded single lap joint between two symmetrical wooden adherends is subjected tospecified conditioning treatments and strained to rupture by a tensile force parallel to the grain.
The testing machine shall be a constant-rate-of-traverse machine as described in ISO 5893. If aconstant-rate-of-traverse machine is not available, a constant-rate-of-loading machine shall be usedcausing a rupture within the time limits specified in 6.5.
The jaws shall grip the test pieces with a wedge action and permit self-alignment while the test piecesare being pulled.
6 Procedure
6.1 Preparation of bonded assemblies
Prepare two panels (see Figure 1) from a thick unsteamed, conditioned, straight-grained board of beech(Fagus sylvatica L.) with a nominal density of (700 ± 50) kg/m3 with a moisture content of (12± 1)%.
lt is permissible to prepare panels from different boards unless it is essential to minimize differences inthe wood in order to conduct special comparative tests.
Ensure that the angle between the growth rings and the surface to be bonded is between 30° and 90°.Cut the panels across the direction of the grain to a length equal to a multiple of 300 mm with thenecessary allowance for cross-cutting and along the grain to a width of approximately 130 mm makingan allowance for the width of cut as shown in Figure i.
For tests use two panels of (5,0±0,1) mm thickness.
For conventional tests, condition the panels at a temperature of either (20 ±2) C and (65±5) %relative humidity or (23±2) C and (50±5) % relative humidity subsequently referred to as thestandard atmosphere (20/65j or (23/50) for a minimum of 7 days.
Prepare bonded assemblies using thin (approximately 0,1 mm) bond-lines. Not more than 24 h beforebonding,either lightly plane or lightly sand each surface to be bonded (using an abrasive paper of grainsize P100 complying with lSO 6344-2:1998 is recommended). Remove any dust carefully. Do not touchor soil the prepared surfaces.
Comply with the adhesive manufacturer’s instructions regarding the processing conditions, includingthe preparation of the adhesive, the amount of adhesive to be applied, whether the adhesive is to beapplied on one or both surfaces, the open and closed assembly time and the magnitude and duration ofthe assembly pressure and report them in the test report.
Where no manufacturer’s instructions are available the following processing conditions shall be used:
– adhesive applied on both sides;
adhesive spread: (150± 10) g/m2;
– open assembly time: (120± 10) s;
– closed assembly time (180±10) s;
-pressing pressure (0,7±0,1) N/mm2;
-pressing time: 2 h;
Bond the two 5 mm thick panels as shown in Figure 1 with the pressure uniformly distributed over thebonded surface.BS 205 pdf download.