European Standards: BS EN 324, APA Europe

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BS EN 324

Euro Standards

5. BS EN 324 - Wood-based panels - Determination of dimension of boards

(Along with BS EN 315 and BS EN 325, this standard has superseded in part BS 6566 Part 4 - Specification for tolerances on the dimensions of plywood panels.)

Part 1 : 1993 (re-confirmed 2001) - Determination of thickness, width and length

Thickness:- using a particular micrometer measure at approximately 50mm from the panel edges at points in each corner and in the middle of each side - 8 points in all. Readings must be within 1% of the thickness but to be not less than 0.1mm. Average the 8 readings and express this figure to the nearest 0.1mm.

Points of measurement of thickness

Fig.1
Points of measurement of thickness

Length and Width:- Measure both length and width of each panel along two lines parallel to and at a distance of 100mm from the edges to an accuracy of 0.1% but not less than 1mm. Average the two readings each for length and width and express the result to the nearest 1mm

Points of measurement for length and width of panel

Fig.2
Points of measurement for length and width of panel

APA calculations for thickness, length and width as per PS1-95 Construction and Industrial plywood

Thickness:- Measured using a specific micrometer

Plywood	Nominal Thickness	Tolerance

Sanded	<= 19mm (3/4")	± 0.4mm (1/64² )
Sanded	> 19mm (3/4")	± 3%

Unsanded )	<= 20.6mm (13/16² )	± 0.8mm (1/32² )
Touch sanded )	> 20.6mm (13/16² )	± 5%
Overlaid )

Table 4

Measure mid-width on one end of a panel. If the reading is below minimum or above maximum tolerance then three additional measurements shall be taken: one at approximately mid-width on the opposite end and one at approximately mid-length on each side of the panel. Calculate the average of these four readings. If the result is within the allowable tolerance then the panel is acceptable; if outside the allowable tolerances then the panel is below/above thickness.

Length and Width:- A tolerance of plus 0mm, minus 1.6mm (1/16² ) shall be allowed on the specified length and width.

Part 2 : 1993 (re-confirmed 2001) - Determination of squareness and edge straightness

Squareness:- Use a mechanical square having two arms each of 1000mm (± 1mm) length fixed at right angles to one another. Place one side of the square against one side of the panel. At the end of one arm measure the distance between the side of the arm and the edge of the panel. Follow the same procedure for each of the other corners. The result is the largest measured value of the deviation expressed in mm over 1m panel edge-length to the nearest 0.5mm/m.

Use of mechinical square to measure board squareness
Fig. 3
Use of mechanical square to measure board squareness

Straightness of panel edge:-Use a straight -edge, equal in length to the length of the panel or a wire of constant cross section and flexible enough to be stretched taut. Place the straight-edge against the panel edge or locate the wire at the corners of the panel and stretch it. Measure the largest deviation between the straight-edge (wire) and the panel edge. Read the result to the nearest 0.5mm. The result, which is expressed separately for width and length in mm/m, is the largest value of the measured deviation divided by the appropriate length or width.

APA calculation of squareness and straightness according to PS1-95 Construction and Industrial Plywood

Squareness:- The maximum allowable difference between the length of the diagonals is 3mm (1/8² ) for an 8’ x 4’ panel.

Straightness:- The maximum distance from the panel edge to a straight-edge drawn tight between two adjacent corners shall be 1.6mm (1/6")