high strength aircraft plywood

IS 4859: Scope - Key Formulas, Tables & Specifications

Scope:
IS 4859 covers test methods for plywood, including shear and bending tests.

1. Shear Strength Test (Clause 1.3)

• Shear Strength Formula:

[ F_s = \frac{2 \times t \times w \times P}{\text{Area}} ]

Where:

• (F_s) = Shear strength (kg/cm²)

• (P) = Ultimate load (kg)

• (t) = Thickness of plywood (cm)

• (w) = Width of specimen (cm)

• Loading Block Sizes (mm):

2. Bending Test Mandrel Diameter (Clause 2.1, Table 4)

3. Units (SI Units as per IS 4859)

flowchart LR
    A[Plywood Specimen] --> B[Placed on Compression Table]
    B --> C[Load Applied Axially]
    C --> D[Measure Ultimate Load (P)]
    D --> E[Calculate Shear Strength: Fs = 2twP]
``

IS 4859 - Definitions: Key Points & Formulas

1. Reference Standards:

• Definitions primarily follow IS 707:1968 (Timber and Timber Products glossary).
• Additional terms specific to plywood testing are included.

2. Shear Strength Formula (Clause 1.3):
[ F_s = \frac{2 \times t \times w \times P}{\text{Area}} ]

Where:

• ( F_s ) = Shear strength (kg/cm²)
• ( P ) = Ultimate load (kg)
• ( t ) = Thickness of plywood (cm)
• ( w ) = Width of specimen (cm)

3. Loading Block Sizes (mm):

4. SI Units Used:

Summary Diagram: Shear Test Setup

flowchart LR
    A[Compression Table]
    B[Supporting Blocks]
    C[Plywood Specimen]
    D[Loading Blocks]
    A --> B --> C --> D
    D --> Load[Load Applied Axially @ 455 kg/min]

Note: For detailed definitions, refer to IS 707:1968 and IS 4859 clauses. This ensures consistency in terminology and testing procedures.

Key Formulas and Tables from IS 4859 (Materials for Aircraft Plywood)

1. Shear Strength Formula (Clause 1.3)

[ F_s = \frac{2 \times t \times w \times P}{\text{Area}} ]

Where:

• ( F_s ) = Shear strength (kg/cm²)
• ( P ) = Ultimate load (kg)
• ( t ) = Thickness of plywood (cm)
• ( w ) = Width of specimen (cm)

2. Loading Block Sizes for Shear Test (All dimensions in mm)

3. Timber Species for Aircraft Plywood (Clause 3.1, Table 1)

4. Mandrel Diameter for Bending Test (Clause 2.1, Table 4)

5. SI Units Relevant to Materials Testing

IS 4859: Veneer Quality and Defects - Key Specifications

Face Veneers (Clause 4.9)

• No open defects: insect holes, splits, pitch pockets, pin worm holes.
• Knots:
  • No large, loose, or dead knots.
  • Small live knots ≤ 6 mm diameter allowed.
  • Sum of dead knots ≤ 10 mm diameter per 1000 cm².

Core Veneers (Clause 4.1b)

• Closed splits allowed up to 0.25 mm width.

Prohibited Defects (Clause 4.8)

• No brash wood.
• No sap stain discoloration.
• No ingrown bark.
• No filling or inlaying.

Additional Notes

• Veneers must be rotary cut or sliced from specified timber species (Clause 4.1).
• Sapwood is not permitted.
• Adhesive type can be purchaser-specified (Clause 3.2.2).
• Rounding off test results per IS:2-1960.

Summary Table: Veneer Defect Limits

flowchart TD
    A[Veneer Quality] --> B[Face Veneers]
    B --> C{Defects}
    C -->|No open defects| D[Insect holes, splits, pitch pockets, pin worm holes]
    C -->|Knots| E[Small live knots ≤ 6 mm]
    C -->|Dead knots sum| F[≤ 10 mm per 1000 cm²]
    A --> G[Core Veneers]
    G --> H[Closed splits ≤ 0.25 mm]
    A --> I[Prohibited Defects]
    I --> J[Brash wood, Sap stain, Ingrown bark, Filling/inlaying]

This ensures veneer quality complies with IS 4859 for durability and appearance.

IS 4859: Dimensions and Tolerances for Plywood

1. Tolerances on Nominal Sizes (Clause 5.3)

2. Edge Straightness and Squareness

• Applies for both lengths < 6 m and ≥ 6 m.
• Testing as per Annex A.

3. Thickness (Clause 1.0)

Available thicknesses (mm):
1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0

4. Shear Strength Formula (Clause 1.3)

[ F_s = \frac{2 \times t \times w \times P}{\text{Area}} ]

Where:

• (F_s) = Shear strength (kg/cm²)
• (t) = Thickness of plywood (cm)
• (w) = Width of specimen (cm)
• (P) = Ultimate load (kg)

5. Sizes of Loading Blocks for Shear Test

Summary Diagram: Tolerances Check

flowchart TD
    A[Start: Plywood Board] --> B{Check Dimensions}
    B -->|Length| C[+6 / -0 mm]
    B -->|Width| D[+3 / -0 mm]
    B -->|Thickness

IS 4859 - Manufacture and Assembly Key Points

Shear Strength Test (Clause 1.3)

• Shear Strength Formula:

[ F_s = \frac{2 \times t \times w \times P}{\text{(cm}^2\text{)}} ]

Where:

• (F_s) = Shear strength (kg/cm²)

• (t) = Thickness of plywood (cm)

• (w) = Width of specimen (cm)

• (P) = Ultimate load (kg)

• Loading Blocks Dimensions (mm):

Assembly Procedure

• Place the assembly on the compression table with supporting blocks square on the base.
• Apply axial load uniformly at ~455 kg/min on loading blocks.

Additional Specifications

• Mandrel Diameter to Thickness Ratio: Refer Table 4 (Clause 2.1) for bending tests.
• Squareness Check: Use a 1200 mm × 1200 mm square; record max gap (Clause 2.1).

Units (SI)

• Force: Newton (N) = kg·m/s²
• Pressure/Stress: Pascal (Pa) = N/m²
• Length: meter (m), Mass: kilogram (kg)

flowchart TD
    A[Place Assembly on Compression Table] --> B[Ensure Supporting Blocks Rest Square]
    B --> C[Apply Load Axially at 455 kg/min]
    C --> D[Record Ultimate Load P]
    D --> E[Calculate Shear Strength Fs = 2 × t × w × P]

This summarizes the key formulas and assembly specifications from IS 4859 for plywood testing and manufacture.

IS 4859: Mechanical Properties of Plywood - Key Formulas & Tables

1. Shear Strength (Clause 1.3)

• Formula:

[ F_s = \frac{2 \times t \times w \times P}{\text{Area}} ]

Where:

• (F_s) = Shear strength (kg/cm²)

• (P) = Ultimate load (kg)

• (t) = Thickness of plywood (cm)

• (w) = Width of specimen (cm)

• Loading Block Sizes (mm):

2. Bending Test Mandrel Diameter (Clause 2.1)

3. Modulus of Elasticity (MOE) & Modulus of Rupture (MOR) (Clause 10.3)

4. SI Units for Reference

IS 4859 - Key Formulas, Tables & Specifications for Durability and Resistance Tests

1. Shear Strength Test (Clause 1.3)

• Formula:

[ F_s = \frac{2 \times t \times w \times P}{\text{cm}^2} ]

Where:

• (F_s) = Shear strength (kg/cm²)

• (t) = Thickness of plywood (cm)

• (w) = Width of specimen (cm)

• (P) = Ultimate load (kg)

• Loading Block Sizes (mm):

2. Bending Test (Clause 2.1)

• Mandrel Diameter based on Plywood Thickness:

3. Static Bending Strength (Clause 10.3)

4. Important Notes

• Maintain moisture content consistency during sample preparation (Clause 3.1).
• Use IS 1734 (Part 11) for bending test

IS 4859: Moisture Content - Key Formulas and Specifications

Moisture Content Calculation (Clause 2.1 & Appendix B)

[ \text{Moisture Content (%)} = \frac{W_1 - W_d}{W_d} \times 100 ]

• (W_1) = Weight of original (wet) sample
• (W_d) = Oven-dry weight of the sample

Moisture Content Requirements

• Test pieces moisture content: 8% to 12% (Clause 9.1)
• Specimen conditioning moisture content: 10% to 14% (Clause 2.3)

Additional Notes

• Report percentage of wood failure along with moisture content (Clause 4.3).
• Oven drying is typically done at 103 ± 2°C until constant weight is achieved.

Summary Table

flowchart LR
    A[Original Sample (W1)] --> B[Oven Drying at 103°C]
    B --> C[Oven-Dry Weight (Wd)]
    C --> D[Calculate Moisture Content]
    D --> E[Moisture Content % = ((W1 - Wd)/Wd)*100]
    E --> F{Is Moisture Content within 8-12%?}
    F -- Yes --> G[Proceed with Test]
    F -- No --> H[Condition Sample to 10-14% Moisture]

This ensures accurate and standardized moisture content measurement in wood samples per IS 4859.

IS 4859: Strength Tests - Shear Strength

Key Formula (Clause 1.3, Appendix D)

Shear strength ( F_s ) is calculated as:

[ F_s = \frac{2 \times t \times w \times P}{\text{Area}} ]

Where:

• ( F_s ) = Shear strength (kg/cm²)
• ( t ) = Thickness of plywood (cm)
• ( w ) = Width of specimen (cm)
• ( P ) = Ultimate load (kg)

Test Setup (Clause 1.3, Fig. 4)

• Specimen size: 150 mm x 100 mm
• Load applied axially at ~455 kg/min on loading blocks.
• Supporting blocks rest square on the compression table.

Loading Block Sizes (mm)

Bending Test Mandrel Diameter (Clause 2.1, Table 4)

Notes:

• Shearing strength values from tests should be averaged (Clause 4.1).
• Use SI units where applicable (N/m² for stress).

flowchart LR
    A[Specimen Preparation] --> B[Place on Compression Table]
    B --> C[Apply Load Axially at 455 kg/min]
    C --> D[Measure Ultimate Load P]
    D --> E[Calculate Shear Strength Fs]

This summarizes the key formulas, test setup, and specifications for shear strength testing per IS 485

IS 4859: Inspection and Sampling Key Points

1. Sampling (Clause 12.1 & Table 3)

• Samples are drawn randomly from each batch.
• Number of samples depends on batch size:

2. Shear Strength Test (Clause 1.3)

• Load applied axially at ~455 kg/min.
• Shear strength formula:

[ F_s = \frac{2 \times t \times w \times P}{\text{cm}^2} ]

Where:

• (F_s) = shear strength (kg/cm²)
• (t) = thickness of plywood (cm)
• (w) = width of specimen (cm)
• (P) = ultimate load (kg)

3. Loading Block Sizes for Shear Test

4. Inspection (Clause 13.2)

• Veneers inspected individually before gluing for conformity as per Clause 4.
• Specimens bent to specified radius in U shape without tension side support.

This ensures quality control by standardized sampling and testing methods per IS 4859.

IS 4859 - Marking and Identification of Plywood Boards

Key Marking Requirements (Clause 11.1)

Each plywood board must have the following indelibly stamped on one side:

• Manufacturer's name or trade-mark
• Specification number (e.g., IS 4859)
• Veneer species (symbol)
• Board thickness (in mm or cm)
• Type of adhesive used
• Date of manufacture
• Batch number and press load number

Optional Marking (Clause 11.1.1)

• ISI Certification Mark may be added to indicate compliance with IS standards and quality control.

Shear Strength Formula (Clause 1.3)

[ F_s = \frac{2 \times t \times w \times P}{t \times w} = 2 \times t \times w \times P ]

Where:

• ( F_s ) = Shear strength (kg/cm²)
• ( P ) = Ultimate load (kg)
• ( t ) = Thickness of plywood (cm)
• ( w ) = Width of specimen (cm)

Loading Block Sizes for Shear Test

Summary Diagram of Marking on Board

graph LR
A[Board Surface] --> B[Manufacturer Name/Trade Mark]
A --> C[Specification Number]
A --> D[Veneer Species Symbol]
A --> E[Thickness]
A --> F[Adhesive Type]
A --> G[Date of Manufacture]
A --> H[Batch & Press Load Number]
A --> I[ISI Certification Mark (optional)]

This ensures traceability, quality assurance, and standard compliance for plywood products as per IS 4859.

IS 4859: Type Testing and Approval - Key Points

1. Type Testing (Clause 13.1.1)

• Plywood must pass type tests at an approved laboratory before approval for use.

2. Shear Strength Test (Appendix D, Clause 1.3)

• Use a compression testing machine with loading blocks placed squarely.
• Load applied axially at 455 kg/min.
• Shear strength formula:

[ F_s = \frac{2 \times t \times w \times P}{150 \times 100} ]

Where:

• (F_s) = shear strength (kg/cm²)

• (P) = ultimate load (kg)

• (t) = plywood thickness (cm)

• (w) = specimen width (cm)

• Loading block sizes (mm):

3. Bending Test Mandrel Diameter (Clause 2.1, Table 4)

Summary Diagram: Shear Test Setup

graph TB
    A[Compression Testing Machine]
    B[Supporting Blocks (base)]
    C[Specimen (150x100 mm)]
    D[Loading Blocks (Block A/B/C)]
    A --> B --> C --> D
    style C fill:#f9f,stroke:#333,stroke-width:2px

**Use these guidelines for type testing and approval of plywood as per IS 485

IS 4859: Packaging and Storage - Key Formulas & Tables

Shear Strength Formula (Clause 1.3)

[ F_s = \frac{2 \times t \times w \times P}{150 \times 100} ]

• (F_s) = Shear strength (kg/cm²)
• (t) = Thickness of plywood (cm)
• (w) = Width of specimen (cm)
• (P) = Ultimate load (kg)

Loading Blocks Dimensions (mm)

Moisture Content Calculation (Clause B-2.1)

[ \text{Moisture %} = \frac{W_1 - W_2}{W_1} \times 100 ]

• (W_1) = Weight before oven drying
• (W_2) = Oven-dry weight

Mandrel Diameter for Bending Test (Table 4)

Storage & Handling Tips:

• Prevent moisture change between sampling and weighing.
• Store plywood flat, dry, and protected from direct sunlight.

flowchart LR
    A[Sample Cutting] --> B[Weigh Sample (W1)]
    B --> C[Oven Dry Sample]
    C --> D[Weigh Oven-Dry Sample (W2)]
    D --> E[Calculate Moisture %]
    E --> F[Shear Strength Test]

This ensures accurate moisture and strength evaluation per IS 4859.

IS 4859: References and Amendments - Key Points

Shear Strength Formula (Clause 1.3)

[ F_s = \frac{2 \times t \times w \times P}{\text{Area}} ]

• (F_s) = Shear strength (kg/cm²)
• (P) = Ultimate load (kg)
• (t) = Thickness of plywood (cm)
• (w) = Width of specimen (cm)

Loading Block Sizes (mm)

Amendments Summary

• Amendment No. 3 (Dec 2005):

  • Appendix renamed to Annex (A → B, B → C, C → D, D → E)
  • Clause 4.16: Treatment of boards with trichlorophenol or sodium pentachlorophenate at specified retention levels (8 or 6 kg/m³).

• Amendment No. 2 (Mar 2005):

  • IS 848:1974 replaced IS 848:1957 reference.
  • Updated dimensions and tolerances (Clause 5 and Table 2).

SI Units Reference

• Force: Newton (N) = 1 kg·m/s²
• Pressure/Stress: Pascal (Pa) = 1 N/m²

flowchart LR
    A[Specimen Setup] --> B[Load Applied Axially]
    B --> C[Measure Ultimate Load P]
    C --> D[Calculate Shear Strength Fs]
    D --> E[Use Formula: Fs = 2*t*w*P]

This concise summary covers essential formulas, block sizes, amendments, and unit references for IS 4859.