This standard delineates the specifications and fabrication procedures for metal-faced plywood, which involves bonding plywood with galvanized iron or aluminum sheets on one or both sides. It is crucial for producers and users seeking consistent quality, optimal dimensions, robust adhesion, and durability, especially in applications demanding enhanced mechanical strength and conservation of timber resources.
Overview
This standard delineates the specifications and fabrication procedures for metal-faced plywood, which involves bonding plywood with galvanized iron or aluminum sheets on one or both sides. It is crucial for producers and users seeking consistent quality, optimal dimensions, robust adhesion, and durability, especially in applications demanding enhanced mechanical strength and conservation of timber resources.
Audience
Contents
Structure
Frequently Asked
According to IS 13957, the metal sheets allowed for laminating with plywood include galvanized iron sheets complying with IS 277:1985 and aluminum sheets meeting IS 737:1986. For galvanized iron, the bonding surface must be treated by acid pickling to fully remove zinc or by using one-side galvanized sheets with the non-galvanized side free from rust. Post acid treatment, thorough washing with running water and detergent is required to eliminate residual acids. The plywood used must be of BWR grade as specified in IS 303:1989.
The standard recommends using BWR grade plywood as per IS 303:1989. The plywood surface should be sanded and cleaned of dust and splinters, maintaining a moisture content between 4 to 6 percent or using freshly manufactured panels. Aluminum sheets require acid pickling followed by thorough washing to remove oxides and residues. Although IS 13957 does not mandate a specific adhesive type, phenol-formaldehyde resin adhesives of BWR grade are commonly employed due to their strong adhesion and water resistance. The adhesive is evenly applied on the plywood surface, after which the metal sheet is bonded by hot pressing under controlled temperature and pressure.
The thickness of the metal-faced plywood boards depends on the number of plies, for example, 3-ply boards have thicknesses of 3, 4, 5, or 6 mm, while 5-ply boards range from 5 to 9 mm, as detailed in Table 1 (Clause 6.2). Other dimensions and tolerances follow the guidelines in IS 12049:1987, including length tolerances of +6 mm / -0 mm and width tolerances of +3 mm / -0 mm. Squareness is checked using a 500 mm set square, with the maximum allowable gap recorded. Boards must have uniform thickness within specified tolerances to ensure quality.
Bond quality testing involves preparing specimens from the plywood boards and subjecting them to visual inspection and adhesion tests. A specimen is considered acceptable if no delamination occurs between the glue lines or at the interface between plywood and metal sheet, and if, upon forced separation, wood fibers adhere uniformly across the metal surface. Optional mechanical tests such as modulus of elasticity, modulus of rupture, core shear stress, and facing stress may be performed based on purchaser agreement.
Metal-faced plywood boards must bear markings on the face near one corner, including details such as the manufacturer's identity, year of production, batch number, and type of metal sheet used. Additionally, these boards may carry the BIS Standard Mark if licensed under the BIS Act, 1986. The plywood core must be of BWR grade as specified in IS 303:1989, ensuring traceability and compliance with quality standards.
Ask AI about any clause, requirement, or provision in IS 13957. Get instant, clause-cited responses powered by our indexed library.
Free tier includes 150 queries (50 AI + 100 Reference) · No credit card required