BS EN 311-2002 pdf download.Wood-based panels Surface soundness Test method.
This BS EN 311 specifies a method of assessing the surface soundness of overlaid wood-based panels and unfaced particleboards. wet and dry process fibreboards and cement bonded particleboards.
NOTE The grid patterned face of wet processed hardboards cannot be tested according to this European Standard.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments).
EN 326-1, Wood-based panels — Sampling, cutting and inspection — Part 1: Sampling and cutting of test pieces and expression of test results.
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions apply.
surface soundness
strength or quality of bonding between the particles or fibres at the surface of a board and the layer below (unfaced panels) or between the coating material and the underlying board (overlaid panels)
3.2
overlaid panel
panel surfaced with one or more overlay sheets or films, for example impregnated paper, plastics, resin film, metal, decorative veneer
4 Principle
Measurement of the tensile load required to pull oft a defined surface area of overlaid or untaced panel.
5 Apparatus
5.1 Devices to produce a groove as illustrated in Figure 1 within the tolerance specified in 6.2.
On half of the test pieces this groove shall be on one surface of the board and on the other half it shall be on the other surface.
The groove shall have an inside diameter of 35,7 ± 0,2 mm (enclosing an area of 1 000 mm2) and a depth of (0.3 ± 0,1) mm.
6.2.2 Overlaid panels
A circular groove shall be cut through the coating material so that it just breaks through into the underlying board.
The groove shall not penetrate more than 0,3 mm into the board. The groove shall have an inside diameter of
35.7 ± 0,2 mm. lithe panel has the same type of coating on both sides then on halt of the test pieces the groove
shall be on one surface of the board and on the other half it shall be on the other surface.
lithe panel has different types of coating on its two surfaces then 8 test pieces for each surface shall be used.
6.3 Conditioning
All test pieces shall be conditioned to constant mass in an atmosphere with a percentage relative humidity of (65 ± 5) % and a temperature of (20 ± 2) C prior to the bonding of the steel mushroom-shaped pad (5.2) to the surface. 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.
7 Procedure
7.1 Bonding the steel pad to the surface
NOTE 1 The type of adhesive used. the quantity used, and the manner of application can all affect the measured strengths.
In general use a hot-melt adhesive with a melting point under 150 °C, spread evenly across the face of the heated steel pad. The centring frame is used to position the pad exactly on the test piece. Whilst in the centring frame the hot pad shall be pressed onto the surface of the piece and held with a light pressure of 0,1 N/mm2 to 0,2 N/mm2 until the adhesive has cooled and hardened.
If there is a weakening effect to the surface soundness from the heating procedure with hot melts (e.g. in the case of dry process fibreboards (MDF) or some kinds of overlaid boards) a cold setting epoxy adhesive shall be used instead of the hot melt.
If the boards to be tested are thinner than 15 mm the test pieces shall be strengthened by bonding a 50 mm x 50 mm steel plate of at least 10 mm thickness to their underside.
NOTE 2 When testing overlaid boards, in order to obtain an efficient bond between the steel pad and the surfacing material it can be necessary to prepare the surface by sanding or solvent cleaning.BS EN 311-2002 pdf download.