Metal-faced plywood -Specification

IS 13957: Scope - Key Specifications and Tables

1. Scope Overview (Clause 3.1)

• Defines plywood boards per IS 707:1976.
• Applies to metal-faced plywood boards.

2. Dimensions of Plywood Boards (Clause 6.1)

Note: Other sizes may be agreed upon between manufacturer and purchaser.

3. Thickness of Metal Faced Plywood (Clause 6.2, Table 1)

4. Permissible Tolerances (Clause 6.3)

• Edge straightness and squareness tested as per Annex B.

Summary Diagram of Dimensions and Tolerances

graph TD
    A[Plywood Board] --> B[Dimensions]
    B --> C[Length: +6/-0 mm]
    B --> D[Width: +3/-0 mm]
    B --> E[Thickness: ±10% (<6 mm), ±5% (≥6 mm)]
   

IS 13957 Key References, Dimensions & Tolerances

1. Definitions

• Refer to IS 707:1976 for definitions beyond those in IS 13957 Clause 3.1.

2. Thickness of Metal Faced Plywood Boards (Clause 6.2, Table 1)

3. Permissible Tolerances on Finished Boards (Clause 6.3)

• Note: Edge straightness and squareness testing per Annex B.

Annex B: Edge Straightness & Squareness Test (Summary)

• Procedure involves measuring deviations along edges over the length.
• Ensures compliance with tolerance limits for quality control.

flowchart TD
    A[Start] --> B[Measure edge length]
    B --> C[Check deviation from straight line]
    C --> D{Deviation ≤ 2 mm per 1000 mm?}
    D -- Yes --> E[Pass]
    D -- No --> F[Fail]

This summary aids in quick reference for design, quality checks, and compliance with IS 13957.

IS 13957: Definitions & Key Specifications Summary

1. Definitions (Clause 3.1)

• Definitions specific to metal faced plywood as per IS 13957.
• For other terms, refer to IS 707:1976.

2. Dimensions of Plywood Boards (Clause 6.1)

3. Thickness of Metal Faced Plywood (Clause 6.2, Table 1)

4. Permissible Tolerances on Nominal Sizes (Clause 6.3)

Edge straightness and squareness tested as per Annex B.

5. Testing (Annex B)

• Method for edge straightness and squareness detailed in Annex B.
• Ensures compliance with tolerances.

flowchart LR
    A[Definitions] --> B[Dimensions]
    B --> C[Thickness]
    C --> D[Tolerances

IS 13957: Metal Faced Plywood – Key Materials Specifications

1. Thickness of Metal Faced Plywood Boards (Clause 6.2, Table 1)

2. Metal Sheets

• Galvanized Iron or Aluminium Sheets only.
• Aluminium sheets must conform to IS 737:1986.
• Assembly by hot pressing at 145–150°C for 30 min.
• Pressure during pressing: 1.4 to 1.6 N/mm².
• Cooling to room temperature before removal.

3. Squareness Check (Clause 2.1)

• Use a set square with 500 mm arms.
• Apply one arm to plywood edge.
• Measure and record the maximum gap to verify squareness.

Summary Diagram: Metal Faced Plywood Assembly

flowchart LR
    A[Galvanized Iron / Aluminium Sheet] --> B[Bonding with Plywood]
    C[Plywood (3,5,7,9,11+ Ply)] --> B
    B --> D[Hot Pressing at 145-150°C, 1.4-1.6 N/mm², 30 min]
    D --> E[Cooling to Room Temperature]
    E --> F[Final Metal Faced Plywood Board]

This standard ensures adequate strength while economizing timber use by bonding metal sheets to plywood under controlled temperature and pressure conditions.

IS 13957: Preparation of Composite (Clause 5.3)

• Materials: Galvanized iron or aluminum sheets bonded to plywood (one/both sides).
• Hot Pressing Parameters:
  • Temperature: 145℃ to 150℃
  • Pressure: 1.4 N/mm² to 1.6 N/mm²
  • Duration: 30 minutes
• After pressing, cool the composite to room temperature before removal.

Additional Specifications:

Process Summary:

1. Assemble metal sheets and plywood.
2. Hot press under specified temperature and pressure.
3. Cool composite to room temperature.
4. Remove from press.

flowchart LR
    A[Assemble Sheets & Plywood] --> B[Hot Pressing]
    B -->|145-150℃, 1.4-1.6 N/mm², 30 min| C[Cooling to Room Temp]
    C --> D[Remove Composite]

This ensures a strong, durable bond per IS 13957 standards.

IS 13957: Dimensions and Tolerances for Metal Faced Plywood Boards

1. Standard Dimensions (Clause 6.1)

Note: Other dimensions can be agreed upon by manufacturer and purchaser.

2. Thickness of Boards (Clause 6.2, Table 1)

3. Tolerances on Nominal Sizes (Clause 6.3)

4. Testing Method for Edge Straightness and Squareness (Annex B)

• Edge straightness and squareness are tested as per Annex B.
• Composite boards are hot pressed at 145–150°C for 30 minutes under a pressure of 1.4 to 1.6 N/mm².
• After cooling to room temperature, edges are checked for straightness and squareness within the specified

IS 13957: Workmanship and Finish - Key Specifications

1. Tolerances on Finished Boards (Clause 6.3, per IS 12049:1987)

2. Workmanship Requirements (Clause 7)

• Uniform thickness within above tolerance.
• Representative sampling & conformity per IS 7638:1975 (BWR grade plywood).
• Surface preparation as per Clause 5.1.

3. Testing Edge Straightness and Squareness (Annex B)

• Edge Straightness: Tested as per Annex B.
• Squareness: Checked using a 500 mm set square; max gap recorded.

Summary Diagram: Tolerance Checks

flowchart TD
    A[Finished Board] --> B[Measure Length & Width]
    B --> C{Within Tolerance?}
    C -->|Yes| D[Check Thickness]
    C -->|No| E[Reject or Rework]
    D --> F{Thickness Within ±%?}
    F -->|Yes| G[Check Squareness & Straightness]
    F -->|No| E
    G --> H{Within 0.2% or 2 mm/1000 mm?}
    H -->|Yes| I[Accept Board]
    H -->|No| E

Use IS 13957 along with IS 12049, IS 7638, and IS 303 for full conformity and quality control of metal faced plywood.

IS 13957: Sampling Key Points

1. Test Specimen (Clause 9.1)

• Specimens: 150 mm × 150 mm squares, full thickness.
• Cut from different board positions for representativeness.

2. Tolerances on Finished Boards (Clause 6.3)

• Edge straightness and squareness tested as per Annex B.

3. Edge Straightness & Squareness (Annex B)

• Edge Straightness: Measured by placing a straight edge along the board’s edge; deviation should not exceed tolerance.
• Squareness: Measured by comparing diagonals or using a square tool; deviation within specified limit.

Summary Diagram (Sampling & Testing Flow)

flowchart TD
    A[Select Boards] --> B[Cut 150x150 mm Specimens]
    B --> C[Measure Dimensions]
    C --> D{Check Tolerances}
    D -->|Within Limits| E[Accept]
    D -->|Outside Limits| F[Reject]
    C --> G[Check Edge Straightness & Squareness]
    G --> D

Note: Refer IS 707:1976 for additional definitions and sampling procedures.

IS 13957: Key Test Specifications and Formulas

1. Test Specimen (Clause 9.1)

• Size: 150 mm × 150 mm square, full thickness.
• Cut from various board positions for representative testing.

2. Bond Quality Test (Clause 9.3)

• Ensures proper adhesion between layers.
• Typically involves applying a force to test bond strength; no explicit formula provided in IS 13957.

3. Optional Additional Tests (Clause 9.4)

Performed if purchaser requires:

Typical formulas:

• Modulus of Elasticity (E):
  [ E = \frac{\sigma}{\varepsilon} = \frac{\text{Stress}}{\text{Strain}} ]

• Modulus of Rupture (MOR):
  [ MOR = \frac{3PL}{2bd^2} ] Where:

  • (P) = load at failure (N)
  • (L) = span length (mm)
  • (b) = width of specimen (mm)
  • (d) = thickness of specimen (mm)

• Core Shear Stress ((\tau)):
  [ \tau = \frac{P}{2bd} ]

• Facing Stress ((\sigma_f)):
  [ \sigma_f = \frac{P L}{2 t_f b d} ] Where (t_f) = thickness of facing layer.

4. Dimensional Tolerances (Clause 6.3)

Marking Requirements as per IS 13957

• Location: Markings must be on the face of the board near one corner (Clause 10.1.1).

• Content of Marking (Clause 10.1):

  • Source of manufacture
  • Year of manufacture
  • Batch number
  • Type of metal sheet used

• BIS Certification Mark (Clause 10.2):

  • Metal-faced plywood may carry the BIS Standard Mark.
  • Use of the Standard Mark is governed by the BIS Act, 1986 and related rules (Clause 10.2.1).

Summary Table for Marking Details

Additional Notes

• Markings must be legible and indelible.
• BIS Standard Mark usage requires a license from BIS.
• Refer to IS 13957 Annex A for related standards on materials and testing.

flowchart LR
    A[Metal Faced Plywood Board] --> B[Marking on Face Near Corner]
    B --> C{Marking Content}
    C --> D[Source of Manufacture]
    C --> E[Year of Manufacture]
    C --> F[Batch Number]
    C --> G[Type of Metal Sheet]
    B --> H[BIS Standard Mark (Optional)]

This ensures traceability and quality assurance for metal-faced plywood boards.

IS 13957:1994 — List of Referred Indian Standards

IS 13957 references key Indian Standards essential for metal faced plywood specification:

Important Notes:

• Metal faced plywood uses galvanized iron or aluminium sheets bonded to plywood.
• Testing and definitions refer to IS 707 and IS 460.
• Certification and marking governed by BIS Act, 1986 (Clause 10.2.1).
• Squareness check: Use a 500 mm set square; record max gap (Clause 2.1).

Summary Diagram of Reference Flow:

graph LR
A[IS 13957 Metal Faced Plywood] --> B[IS 277 Galvanized Steel Sheet]
A --> C[IS 737 Aluminium Sheet]
A --> D[IS 303 Plywood]
A --> E[IS 707 Timber Glossary]
A --> F[IS 460 Test Sieves]
A --> G[IS 7638 Sampling Methods]
A --> H[IS 12049 Wood Panel Dimensions]

This ensures all materials, sampling, and terminology conform to recognized Indian standards for quality and uniformity.

IS 13957: Method of Test for Edge Straightness and Squareness

Edge Straightness (Annex B, Clause B-1.1)

• Use a straight edge at least as long as the plywood length.
• Hold the plywood edge against the straight edge.
• If convex, position to give equal gaps at ends.
• Measure the largest gap (mm) between plywood edge and straight edge.
• Record gap to nearest millimeter.

Squareness (Annex B, Clause B-2.1)

• Use a set square with 500 mm arms.
• Place one arm along plywood edge.
• Measure the maximum gap between the other arm and plywood edge.
• Record the gap.

Tolerances (Clause 6.3)

Summary:

• Straightness & Squareness are verified by measuring gaps against a straight edge and set square.
• Permissible deviation: max 2 mm per meter length.
• Use calibrated tools and record measurements precisely.

flowchart LR
    A[Plywood Edge] -->|Place against| B[Straight Edge (full length)]
    B --> C[Measure largest gap]
    D[Plywood Corner] -->|Check with| E[Set Square (500 mm arms)]
    E --> F[Measure max gap]
    C & F --> G[Record & compare with tolerance limits]

This ensures compliance with IS 13957 for metal faced plywood quality control.