SOUTH AFRICAN NATIONAL STANDARD

Transcription

1 ISBN SOUTH AFRICAN NATIONAL STANDARD Plywood and composite board Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001 Tel: Fax: SABS

2 Table of changes Change No. Date Scope Amdt Amended to change the requirements for 3 grades of surface veneers for rotary-cut SA pine boards, and to change a definition. Amdt Amended to change the requirement for minimum bond strength for decorative laminates bonded to a substrate and to change requirements and references for decorative boards. Amdt Amended to change the test method for transverse tensile (internal bond) strength of particle boards. Amdt Amended to add two definitions and to add three surface veneer grades, including their requirements, for rotary-cut SA pine boards. Amdt Amended to change the designation of SABS standards to SANS standards, to update the definition of acceptable, to include onepart polyurethane as an adhesive, to delete a reference to the standardization mark scheme and to update referenced standards. Amdt Amended to update referenced standards and to include a classification system based on bending properties. Amdt Amended to add a definition, to delete two tables and to replace them with a new table to include requirements for rotary pine and eucalyptus surface veneer grades, to renumber the tables and to delete a footnote. Foreword This South African standard was approved by National Committee SABS SC 89C, Wood-based panel products Plywood and composite board, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in November This document supersedes SANS 929:2007 (edition 2.6). A vertical line in the margin shows where the text has been technically modified by amendment No. 7.

3 Contents Page Foreword 1 Scope Definitions Exposure class and type Materials Constructional requirements and board properties Physical and mechanical requirements Packing and marking Inspection and methods of test Inspection Visual determination of bleed-through area Moisture content of timber (oven-dry method) Diagonal difference (squareness of timber-based board products) Flatness (flatness of timber-based board products) Edge straightness (edge straightness of timber board products) Surface bond strength of particle boards Transverse tensile (internal bond) strength of particle boards Accelerated degradation of adhesive bonds in wood Wood failure percentage in an adhesive joint Knife test to determine bond quality of adhesive or glue lines Surface finish and appearance Amdt Surface laminae thickness Resistance to scratching Resistance to wear Resistance to high temperature Resistance to cigarette burns Resistance to light, wool scale Resistance to steam (water vapour) Resistance to cracking Resistance to staining Figures Appendix A Applicable standards Appendix B Notes to purchasers Appendix C Quality evaluation of board produced to the requirements laid down in the specification Appendix D Notes on the storage and handling of board

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5 Plywood and composite board 1 Scope 1.1 This specification covers requirements for materials, construction, preservative treatment, dimensions and performance of plywood and composite board. 1.2 Specific requirements for decorative aminoplast-faced board are included. 1.3 Board of thickness not exceeding 3 mm is not included in this specification. NOTES a) The standards referred to in the specification are listed in appendix A. b) Requirements that must be specified by the purchaser and one that must be agreed upon between the supplier and the purchaser are listed in appendix B. c) Information regarding the verification of the quality of plywood and composite board produced to this specification, and a sampling plan that could be used to assess compliance with this specification of a lot of plywood and composite board are given in appendix C. d) Notes on the storage and handling of plywood and composite board are given in appendix D. 2 Definitions 1) 2.1 For the purposes of this specification the following definitions shall apply: acceptable acceptable to the authority administering this standard, or to the parties concluding the purchase contract, as relevant Amdt 1; amdt 5 back the surface opposite to the face balanced construction a specific method of construction with specific materials, that gives a board the ability to withstand warpage during service NOTE Balancing is usually achieved by arranging similar laminae symmetrically around a core, as in figure 1(a). With present technology, balancing may still be achieved by using differing thicknesses of face and back veneers of different timber species cut by different methods, or by using specific backing materials for overlaid boards. 1) The definitions relevant to plywood are taken mainly from ISO 2074, in some cases with modifications. 3