The Manila Times 9 Inserts


9.1 The diameter of unsound knots, non-adhering knots, loose knots and holes or the length or width of splits and checks, exceeds the value permitted for classification by appearance of plywood with outer veneers specified in table 1.


9.2 Repairs must fit and be properly fixed. The matching in color and grain of patches and shims in grades B, C, D and E shall be in accordance with the requirements of the appropriate grade.


10 Dimensions


10.1 Length, width and tolerances - The length, width and tolerance of the plywood for general purpose shall be as specified in table 2.


Length 1820 2130 2440 3050 3050


Table 2 - Length and width of plywood, mm Width


x x x x x


910 910


1220 1220 1530


+5 mm, -2 mm


10.2 Thickness and number of plies 10.2.1The thickness and number of plies of plywood for general purpose shall be as specified in table 3.


Thickness, mm 2.5


3


3.6 4 5


5.5


85 ±0.45 9


10 11 12 15


18 19 22 25


7 9 ±0.60 ±0.60


NOTE For 15 mm and thicker plyboards, these shall be composed of the following: face/back veneer, crossband core veneer and well composed kiln dried lumber core in 5 plies.


10.3 Squareness - The difference between the two diagonal measurements shall not exceed 3.2 mm.


10.4 Edge straightness - The deviation in edge straightness shall not exceed ±1 millimetre per metre length of chord.


10.5 Flatness - The amount of distortion that can be tolerated will depend not only on the thickness of the panel, the construction and the specie but also on the requirements of the end use. Accordingly, the acceptable deviation in flatness shall be agreed upon between the supplier and the purchaser.


11 Moisture content


The moisture content of the plywood shall not exceed 13%. 12 Sampling


The plywood shall be sampled by the random method, and shall be taken on a reduced lot of 5% or 100 panels, whichever is smaller. A minimum of ten panels shall be selected at random from such a reduced lot.


12.1 Dimensional measurements - The samples shall be measured as described in annex A.


12.2 Laboratory tests - The size of test pieces shall be large enough to provide the number of shear strength specimens as indicated in table 4.


Table 4 - Number of shear strength test specimens per test piece Number of plies


Types I & II


34 58 712 916


11 n* = Number of samples


13 Method of tests 13.1 Moisture content - The moisture content of plywood shall be tested as described in annex B. 13.2 Bonding - The quality of bonding of plywood shall be tested as described in annex C. 14 Packing and marking 14.1


n* - 2


Average shear strength kg/cm2


Below 17.58 17.58 to 24.6 Above 24.6


Table 3 - Thickness, number of plies and tolerances Number of plies 3


Tolerance, mm ±0.15


±0.24 Tolerance


FRIDAY


July 23, 2010


B5


C.2.1.1 Type I, exterior plywood - The type I plywood test specimens shall be boiled in water for four hours and then dried for twenty hours at 63°C ±2°C. The specimens shall be boiled again for a period of four hours, cooled in water, and tested while wet by tension loading for failure in a shear testing machine operated at 270 to 450 kg/min. The specimen shall be gripped securely by the jaws of the machine to prevent slippage. Percentage of wood failure of the specimens in dry condition shall be evaluated as described in C.3.


C.2.1.2 Type II, interior plywood - The type II plywood specimens shall be submerged in water at 24°C ±2°C for four hours. The specimens are removed and dried at a temperature of 49°C ±2°C for 19 hours. This procedure shall be repeated until the specimen shows bond failure or until three cycles shall have been completed whichever occurs first. A specimen is not acceptable when any single delamination along a glue line is greater than 5.1 cm in continuous length and over 3.6 mm in depth at any point. Depth and width of separation may be ascertained by a “feeler gauge”.


NOTE In lieu of the delamination test described above, shear specimen shall be soaked in water at 60°C ±3°C for three hours. Cool the specimen to room temperature using tap water. Shear test while the specimen is wet using the procedure in C.2.2.


C.2.2 Shear test - The shear test shall be conducted on the specimens prepared in the manner shown in figure 1.


C.2.2.1. The ends of the specimens shall be gripped securely by the jaws of the machine to prevent slippage. The load shall be applied at the rate of 270 to 450 kg/min.


C.2.2.2. If the number of plies exceed three, the notches shall be made in such a manner as to test any two of the guidelines.


C.2.2.3. The specimens shall be notched in such a manner as to assure that during shear testing half of the number of the specimen per test piece shall have the lathe checks in the “to open” direction while the other half in the “to close” direction.


C.2.2.4 Specimens with face plies more than 1.27 mm in thickness shall present a shear area of 25.4 mm as shown in figure 1, specimen A.


C.2.2.5 Specimens of plywood with face plies 1.27 mm or less in thickness shall be of the form shown in figure 1, specimen B. In specimen B, the shear area shall be reached without changing the width of the specimen, to one- half of 25.4 mm.


C.2.2.6 Breaking loads obtained from specimen B shall be multiplied by two and reduced by 10 percent for comparison with values for specimen A, shown in table 1.


C.2.2.7 In shear testing of lumber core plywood, the core shall be reduced to a thickness of about 2.54 mm. C.3


Interpretation of test data


C.3.1 Shear test - The shear-strength and wood failure relationships set forth in table 5 apply to shear test results for types I and II. Column 2 of table 5 applies to individual test specimens while column 3 to all specimens of such test piece. A panel shall be considered defective if:


a) The minimum wood-failure values of more than one specimen from any of three test pieces taken from a single panel shall fall below the minimum wood-failure values specified in table 5, or


b) The average wood-failure value of any of the three test pieces taken from a single panel shall fall below the average value specified in table 5. If none or only one panel is found defective among the ten sample panels, the lot shall be deemed to conform to the glue-bond requirements of this standard. If three or more defective panels are found defective among the ten sample panels (described in clause 10), the lot does not conform to this standard. If two panels are found defective, an additional set of ten sample panels shall be selected to the same tests. If the number of defective panels among the combined twenty panels is then found to be three or less, the lot shall be deemed to conform to the glue-bond requirements of this standard. If four or more panels are found to be defective, the lot shall be deemed not to conform to this standard.


Table 5 - Wood-failure Minimum wood


failure, % 25 10 10


Average wood failure, %


50 30 15


NOTE The shear strength values are based on the area of the adhesive joint. The wood failure values are based on the wood area of the fractured surface.


C.4 Delamination test for type II - Interior of the total number of test specimens from the ten sample panels of any given lot, 95 percent of such test specimens shall pass the first cycle and 85 percent of such test specimen shall pass the third cycle. If the specimens fail to meet these requirements, an additional ten panels should be selected from the same lot and tested in accordance with C.2.1.2. If the test specimens from the combined 20 panels fail to meet the test requirements, the entire lot shall be deemed not to conform to glue-bond requirements of this standard.


The plywood shall be packed or crated to provide suitable protection from the elements to the panels.


14.2 Each plywood shall be marked by edge branding. Stamp marking on the face or back shall be acceptable for panels thinner than 5 mm. The mark, whether on the edge, on the face or on the back shall contain the following information:


14.2.1 Name of manufacturer 14.2.2 Type, grade (face/back, in that order) and thickness 14.2.3 The words “Made in the Philippines”


Annex A Dimensional measurements A.1 Apparatus


A.1.1 Determination of thickness - A surface measuring instrument, having circular, flat and parallel measuring surfaces of 16 mm ±1 mm diameter, the contact area being 200 mm approximately. The graduation of the instrument shall allow a reading to an accuracy of 0.05 mm.


A.1.2 Determination of length and width - A suitable measuring instrument, allowing a reading to an accuracy of 1 mm.


A.2 Procedure for the determination of dimensions (Unscarfed panels)


A.2.1 Thickness - The thickness of panels shall be measured by applying, a pressure of approximately 20 kPa the flat and circular measuring surfaces of the measuring instrument detailed in A.1.1. The mean panel thickness shall be the average of measurements taken at the mid-point of each of the four sides and approximately 25 mm from the edge of the panel.


A.2.2 Edge straightness - The edge straightness of each panel shall be determined with an accuracy of 0.5 mm. A metal straight edge shall be arranged to touch the two corners of the panel (see figure 1). The maximum deviation from a line connecting the corners shall be noted and expressed to the nearest 1 mm per 1000 mm with a designation (+) if the edge is convex and designation(-) if the edge is concave. Each edge of the board shall be measured.


A.2.3 Length and width - Using the measuring instrument detailed in A.1.2, the length and width of boards shall be measured to the nearest millimetre at each edge of the panel, parallel to the edge and approximately 25 mm from the edge with a measuring instrument. Both measurements for length and width shall be recorded to the nearest millimetre, the length being measured in the direction of the grain of the face veneer and expressed as the first dimension.


A.2.4 Flatness - The panels to be measured shall be held upright without restraint, with the shorter dimension vertical, on an essentially level floor.


A.2.4.1 A straight edge shall be placed vertically, or a thin cord stretched vertically, at three positions, namely the two ends and the center of the panel and the maximum deviation from the straight edge or cord shall be recorded for each position, using a suitable rule, to the nearest millimetre.


A.2.4.2 Measurements relating to the longer dimension shall be made by placing a straight edge or stretching a thin cord from end to end, again three positions, namely, at the two edges and the center of the panel, and the maximum concavity at each position recorded as before.


A.2.4.3 For thin panels liable to bow under their own mass when held vertically, flatness shall be measured by placing the panel on a horizontal plane surface and measuring the distance from the plane surface of the underside at the margin of the board when the middle is held in close contact with the horizontal surface. Measurements both along and across the panel shall be turned so that the measurements are made with both surfaces in turn in contact with the plane surface and the maximum figure recorded.


Annex B


Determination of moisture content test (Oven-dry method)


B.1 Apparatus B.1.1 Balance allowing reading to an accuracy of 0.01 g. B.1.2 Air convention drying oven, the temperature of which can be maintained at all points at 103°C ±2°C. B.1.3 Desiccator containing a desiccant to maintain air as close as possible to the absolutely dry condition. B.2 Specimens B.2.1 The test specimen shall be cut from each sample panel.


B.2.2 The test specimen shall not be less than 58 cm in area with a minimum dry mass of 20 g, provided they are representative of the whole cross section of the piece. The test specimen shall be free from all loose splinters and sawdust.


B.3 Procedure


B.3.1 Weigh each test specimen in the same state at the time of sampling and the mass shall be recorded as original mass. B.3.2 The specimen shall then be dried in an oven at 103°C ±2°C until constant mass is attained.


B.3.3 After cooling in the desiccator, weigh each test specimen immediately to avoid an increase of moisture content greater than 0.1%.


NOTE Constant mass is considered to be reached when the results of two successive weighing operations carried out at an interval of 6 h do not differ by more than 0.1% of the mass of test specimen.


B.3.4 Calculate the moisture content of each test specimen as a percentage by mass to the nearest 0.1% using the following formula:


Mo MC = MD where


MC is the moisture content, % Mo


MD


is the original mass of sample is the mass of dried sample


Annex C Bond test


C.1 Preparation of specimens


C.1.1 Type I, exterior plywood - Three test pieces shall be cut from each panel selected. Each test piece shall be approximately 18 cm by 18 cm in size to provide at least six specimens for cyclic boil testing, as illustrated in figure 1.


C.1.2 Type II, interior plywood - Three test pieces of 12.7 cm by 56 cm in size shall be taken from two ends and middle of the sample panel. Five test specimens shall be cut from each test piece.


The test specimens shall be cut 5.10 cm wide and 12.7 cm long, and shall be cut in such a manner that the grain direction of the face ply runs parallel to the length of the specimen. No test specimens shall have common edges with any other test specimen.


C.2 Procedure C.2.1 Cyclic-boil, hot and cold soaking (delamination) test


6 Agatha Lim Vic Supan*


Philippine Constructors Associations 7 Edward Y. C. Tan


Association of Structural Engineers of the Philippines Project Officer


15 Ma. Teresita del Rosario Bureau of Product Standards


* Alternate - MD x 100


Research and testing institution: 4 Romulo C. Eala


Felisa Chan* Forest Products Research and Development Institute


12 Amie M. Lorica Findlay Millar


Associations: 5 Jacqueline C. Vega United Architects of the Philippines


14 Henry M. Young Rosewood, Inc.


13 Alfonso C. Keh, Jr. EMCO Plywood


Bureau of Product Standards Department of Trade and Industry


Technical Committee 35 - Plywood and Veneer


Co-Chairman Private:


1 Alfonso M. Verdadero, Jr. Philippine Wood Products Association


Members Government agencies:


2 Emilio A. Jaranilla Dennis R. Miralles* Board of Investments


3 Gregorio O. Carillo Bureau of Design


Department of Public Works and Highways Manufacturers;


8 Priscilla Florentino Ariel Sunico*


Arturo Co* C. Alcantara and Sons


9 Francisco Balagtas Paper Industries Corporation of the Phils. 10 Ernesto S. Chua Industries Development Corporation


11 Emily G. Malit Interwood


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