BS/EN 205-2016 pdf download.Adhesives Wood adhesives for non-structural applications Determination of tensile shear strength of lap joints.
It is permissible to prepare panels from different boards unless it is essential to minimize differences in the wood in order to conduct special comparative tests.
Ensure that the angle between the growth rings and the surface to be bonded is between 300 and 900.
Cut the panels across the direction of the grain to a length equal to a multiple of 300 mm with the necessary allowance for cross-cutting and along the grain to a width of approximately 130 mm making an allowance for the width of cut as shown in Figure 1.
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 the standard atmosphere (20/65) 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 before bonding, either lightly plane or lightly sand each surface to be bonded (using an abrasive paper of grain size P100 complying with Iso 6344-2:1998 is recommended). Remove any dust carefully. Do not touch or soil the prepared surfaces.
Comply with the adhesive manufacturer’s instructions regarding the processing conditions, including the preparation of the adhesive, the amount of adhesive to be applied, whether the adhesive is to be applied on one or both surfaces, the open and closed assembly time and the magnitude and duration of the 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 the bonded surface.
6.2 Preparation of test pieces
After pressing condition the assembly for 7 days in standard atmosphere.
A longer conditioning time may be used if recommended by the adhesive manufacturer.
The test pieces shall not be cut earlier than 5 days after bonding.
Cut five strips of width b = (20 ± 0.2) mm from each bonded assembly along the grain, avoiding areas within 7,5 mm of the outside long edges of the panel as shown in Figure 1. Cut these strips into test pieces of length 1, = (150 ± 5) mm as shown in Figure 2.
Make fiat bottomed cuts of (2,5 ± 0,5) mm wide in the bonded sections across the grain so that an overlap of length I = (10,0 ± 0,2) mm is defined in the middle section (see Figure 2). The cuts are to separate the wood layers. Take care that the cuts completely cut through the bond line but only penetrate as little as possible into the other part of the joint.
6.4 Treatment prior to tensile shear testing
Subject the test pieces from conditioned bonded assemblies as in 6.2 to the appropriate conditioning sequences.
Ensure that the test pieces are In a horizontal plane, not touching each other and are supported in such a way that no stress is applied to them.
NOTE For classifying an adhesive in accordance with EN 204:2016. or EN 12765:2016, the appropriate conditioning sequences are given In Table 2 of these standards.
6.5 Tensile shear test
Test the test pieces shown In Figures 2 and A.1 In a tensile testing machine.
Clamp the ends of the test pieces in the jaws of the tensile testing machine up to a length of 40 mm to 50 mm. Ensure that the force is applied centrally and in the plane of the bond. Load the test piece until rupture. Record the applied maximum force Fma in newtons (N).
For comparative tests of adhesives and for assigning an adhesive to the durability classes specified in EN 204 or EN 12765 conduct the test at a rate of traverse of approximately SO mm/mm for thermoplastic adhesives (EN 204) or 6 mm/mm tol2 mm/mm for thermosetting adhesives (EN 12765) respectively.
If a constant-rate-of-traverse machine is not available a constant-rate-of-loading machine shall be used causing a rupture after 5 s to 15 s for thermoplastic adhesives (EN 204) and 30 s to 60 s for thermosetting glues (EN 12765).
7 Expression of results.BS/EN 205-2016 pdf download.