Selection and Use of Various Types of Medium-Density Fibre Boards - Code of Practice

IS 15512: Scope & Key Specifications

• Scope: Covers grades and types of materials (Clause 4.2, Table 1) used in construction or manufacturing, referencing definitions from IS 707, IS 12406, IS 14587.
• Reference Standards: Annex A lists related standards; users should apply the latest editions.

Key Formula for Machine Saw Speed (Clause 9.1.2)

To calculate rpm of a machine saw:

[ \text{rpm} = \frac{\text{Rim Speed} \times 60}{\pi \times \text{Saw Diameter}} ]

• Rim Speed (m/s): Linear speed at saw rim
• Saw Diameter (m): Diameter of the saw blade
• (\pi \approx 3.14)

Table 1: Grades and Types (Summary)

(Refer IS 15512 Table 1 for full details)

Saw Geometry (Fig. 9 & 10)

• Clearance Angle: Angle between tooth face and workpiece
• Sharpness Angle: Tooth tip angle for cutting efficiency

flowchart LR
    A[Rim Speed (m/s)] --> B[Calculate rpm]
    C[Saw Diameter (m)] --> B
    B --> D[rpm = (Rim Speed × 60) / (π × Diameter)]

For detailed grades/types and cutting parameters, consult IS 15512 Table 1 and Clause 9.1.2 diagrams.

IS 15512 Key References, Tables & Specifications

• References:
  Definitions and related provisions refer to:

  • IS 707 (Wood-based panels)
  • IS 12406 (Plywood)
  • IS 14587 (Particleboards)

• Grades & Types:
  See Table 1 (Clause 4.2) for available grades/types of wood-based panels.

• Screws (Clause 7.2):

  • Use fully threaded parallel shank screws as per IS 7170 (see Fig. 1).
  • Cross recessed head screws per IS 7478 are also allowed.
  • Screw selection guided by Table 2 below.

Table 2: Thickness of Boards and Screw Size (Clause 7.2)

Fig. 1: Fully Threaded Parallel Shank Screw

(Refer IS 7170 for detailed dimensions and geometry)

flowchart LR
    A[Board Thickness] --> B{Select Screw Size}
    B -->|6 mm| C[No Suitable Screw]
    B -->|8-10 mm| D[ST 2.9]
    B -->|12-15 mm| E[ST 2.9, ST 3.5]
    B -->|18-40 mm| F[ST 2.9, ST 3.5, ST 4.2, ST 4.8]

Note: Always verify the latest editions of referenced IS codes for updated provisions.

IS 15512: Definitions & Specifications for MDF Boards

• Reference Standards for Definitions:
  • IS 707 (Wood-based panels)
  • IS 12406 (MDF Board for general purpose)
  • IS 14587 (Prelaminated MDF boards)

Grades and Types (Clause 4.2, Table 1)

Key Specifications:

• Hazard Classes:

  • Class 1: RH ≤ 70%, moisture content ≤ 15%
  • Class 2: RH > 70%, moisture content ≤ 20%

• Thickness Selection (Clause 5.2):

  • Creep can increase deflection by up to 50% in MDF surfaced with paint/thin laminates.
  • Lower creep and deflection expected if surfaced on both faces with decorative plastic laminates.

• Adhesives:

  • Use adhesives suitable for wood substrates.
  • Choice depends on surface characteristics, application method, flammability, and pressing conditions.

Summary Diagram of MDF Board Types and Classes

graph TD
  A[MDF Boards] --> B[General Purpose]
  A --> C[Prelaminated]
  B --> B1[Grade I (SBG I) - IS 12406]
  B --> B2[Grade II (SBG II) - IS 12406]
  C --> C1[Grade I - IS 14587]
  C --> C2[Grade II - IS 14587]
  
  classDef hazardClass fill:#f9f,stroke:#333,stroke-width:2px;
  D[Hazard Class 1: RH ≤ 70%, Moisture ≤ 15%]:::hazardClass
  E[Hazard Class 2: RH > 70%, Moisture ≤ 20%]:::hazardClass

This

IS 15512: Grade and Grade Selection for MDF Boards

1. Grades Available (Clause 4.2, Table 1)

2. Grade Selection (Clause 4.3)

• Hazard Class 1: Environment RH ≤ 70%, equilibrium moisture ≤ 15%
• Hazard Class 2: Environment RH > 70%, equilibrium moisture ≤ 20%

Select Grade I for higher moisture resistance or demanding environments.

3. Thickness Selection (Clause 5.2)

• MDF surfaced with thin laminates or paint may show up to 50% more creep deflection under long-term load.
• Using decorative plastic laminates on both faces reduces creep and initial deflection.

4. Adhesives

• Use adhesives suitable for wood substrates.
• Selection depends on surface characteristics, application method, flammability, and pressing conditions.

Summary Table for Grade Selection

flowchart LR
  A[Environment RH] -->|≤ 70%| B[Hazard Class 1]
  A -->|> 70%| C[Hazard Class 2]
  B --> D[Use Grade I or II MDF]
  C --> E[Use Grade I MDF]

Use Grade I for humid or demanding environments to ensure durability and minimal creep.

IS 15512: Thickness Selection for MDF Shelves

Key Formula (Clause 5.1)

For a simply supported shelf, required thickness ( t ) is:

[ t = \sqrt[5]{\frac{32 \times E \times b \times d^5}{W \times L^3 \times 9.81}} ]

Where:

• ( t ) = shelf thickness (mm)
• ( W ) = total uniformly distributed load (kg)
• ( L ) = span between supports (mm)
• ( E ) = modulus of elasticity (N/mm²)
• ( b ) = shelf width (mm)
• ( d ) = allowable center deflection (mm)

Thickness Selection Notes (Clause 5.2)

• Creep can increase deflection by up to 50% for painted/thin laminate surfaces.
• Double-sided decorative laminates reduce creep and initial deflection.
• Choose grade and thickness based on Hazard Class (4.2) and environment humidity.

Table 2: Board Thickness vs Screw Size (Clause 7.2)

Grades & Types (Clause 4.2)

Summary:

• Calculate thickness using the

Adhesives and Bonding per IS 15512

Adhesive Selection:

• MDF uses adhesives suitable for wood substrates.
• Choice depends on the surface characteristics of materials bonded to MDF.
• Application methods: hand, glue roller, spray.
• Consider flammability and pressing conditions (room/elevated temp).

Hazard Classes:

• Class 1: RH ≤ 70%, MDF moisture ≤ 15%
• Class 2: RH > 70%, MDF moisture ≤ 20%

Key Specifications for Bonding MDF

Screws for Bonded MDF (Clause 7.2)

• Screw length = Board thickness + 1.5 × surface thickness
• Drill pilot hole (see Table 3):

• Maintain screw distance from corners: 75 mm (edge), 25 mm (face)
• Avoid screwing edges of MDF < 12 mm thick.

flowchart TD
    A[Surface Cleaning] --> B[Apply Polyurethane Primer (2 coats)]
    B --> C[

IS 15512 - Hardware and Fixtures for MDF

Key Specifications & Tables

1. Screw Selection (Clause 7.2, Table 2)

• Use fully threaded parallel shank screws (IS 7170).
• Cross recessed heads per IS 7478 preferred.

2. Screw Length (Clause 1.5b)

[ \text{Screw length} = \text{Thickness of board} + 1.5 \times \text{thickness of surface} ]

3. Pilot Hole (Clause 7.2c, Table 3)

• Drill pilot holes before fixing screws.
• Avoid screwing edges of MDF <12 mm thick.

4. Screw Placement (Clause 7.2d)

• Distance from edge: 75 mm
• Distance from face: 25 mm

5. Repeated Fixing (Clause 7.2e)

• Use plastic or metal sleeves for repeated screw removal.

6. Avoid

• Hammering screws.
• Over-tightening screws.

Summary Diagram: Screw Fixing on MDF

graph TD
A[MDF Board] --> B[Screw Length =

IS 15512: Handling and Storage of MDF Panels

Key Specifications & Formulas

• Nailing (Clause 1.40):

  • Max shank diameter: 1.40 mm
  • Distance from corners/edges (surface): ≥ 25 mm
  • Distance from corners (edges): ≥ 75 mm
  • Nail spacing: ≥ 150 mm

• Storage (Clause 8):

  • Store MDF sheets horizontally on dry bearers.
  • Use polyethylene sheets on damp floors.
  • Bearer spacing:
    • For boards ≥ 15 mm thick: ≤ 800 mm c/c, minimum 3 bearers.
    • For thinner boards: spacing ≤ 50 × board thickness.
  • Bearers in successive layers must be vertically aligned.
  • Maximum overhang during stacking: ≤ 100 mm.
  • Storage RH: ~50% to maintain moisture content 7-9%.
  • Wrap pallets in plastic if exposed to extreme moisture/dryness.
  • Use ≥18 mm thick scrap boards as top/bottom cover.

Table: Bearer Spacing

Visual: Stacking Guidelines

flowchart TB
    A[Horizontal MDF Sheets] --> B[Dry Bearers at ≤ 800 mm c/c]
    B --> C[Bearers vertically aligned in layers]
    C --> D[Max Overhang ≤ 100 mm]
    D --> E[Top & Bottom Covers ≥ 18 mm thick]
    E --> F[Storage RH ~50% for 7-9% moisture content]

This ensures MDF panels maintain structural integrity and dimensional stability during storage and handling.

Key Specifications & Formulas for Working on MDF Panels (IS 15512)

1. Nailing MDF (Clause 1.40)

• Nail shank diameter: ≤ 1.40 mm
• Distance from edges/corners:
  • Surface: ≥ 25 mm
  • Edges: ≥ 75 mm
• Nail spacing: ≥ 150 mm

2. Handling & Storage (Clause 8)

• Store horizontally on dry bearers, clear of floor.
• Bearer spacing:
  • For ≥15 mm thick boards: max 800 mm c/c, min 3 bearers
  • For thinner boards: spacing = 50 × board thickness
• Bearers aligned vertically for stacked layers.
• Max overhang during stacking: 100 mm
• Maintain 50% RH to keep moisture content 7-9%.
• Wrap pallets in plastic if exposed to damp/dry conditions.
• Use 18 mm thick scrap boards as top/bottom covers.

3. Adhesives & Bonding (Clause 9)

• Use adhesives suitable for wood substrates.
• Consider surface characteristics, application method, flammability, and pressing conditions.
• Hazard Classes:
  • Class 1: RH ≤ 70%, moisture ≤ 15%
  • Class 2: RH > 70%, moisture ≤ 20%

4. Profiling MDF (Clause 9.2)

• Use tungsten carbide tools.
• Cutter speed: ≥ 3600 rpm
• Cutter angles:
  • Cutting angle: 10° to 20°
  • Clearance angle: 20° to 22°
• Round off all sharp edges.

Table: Bearer Spacing for MDF Storage

Diagram: MDF Stacking & Bearer Alignment

graph LR
A[Bottom Bearer] --> B[MDF Panel Layer 1]
B --> C[Bearer Layer 2 (aligned

IS 15512: Surface Finishes Key Points & Specifications

Clause 10: Surface Finishes

• Purpose: Achieve functional, aesthetic, and color scheme requirements.
• Common finishes: Laminates, veneers, paints, polishes on exposed surfaces.
• Unexposed surfaces: Must be polyurethane primed, painted, or polished including edges.
• Number of coats: As recommended by panel manufacturers.
• Decorative veneers: Require polishing or waxing.

Finishing Coat Application (Clause 10.2.2)

• Refer IS 2338 (Part 1 & 2) for detailed finishing practices on wood and wood-based materials.

Additional References

Summary Diagram: Surface Finishing Process

flowchart TD
    A[Panel Fabrication] --> B[Surface Preparation]
    B --> C{Surface Type}
    C -->|Exposed| D[Apply 2 coats paint/polish]
    C -->|Unexposed| E[Apply primer + balance coat]
    D --> F[Polishing/Waxing (for veneers)]
    E --> F
    F --> G[Final Inspection & Quality Control]

Note: Always follow manufacturer recommendations for types of finishes and number of coats for durability and appearance.

IS 15512: List of Referred Indian Standards & Key Specifications

• Referenced IS Codes for Definitions:

  • IS 707: Plywood
  • IS 12406: Blockboard
  • IS 14587: Flush Doors

• Screws (Clause 7.2):

  • Use fully threaded parallel shank screws as per IS 7170.
  • Cross recessed head screws as per IS 7478 are also permitted.

• Screw Selection Table (Table 2): Thickness of Boards vs Screw Size

• Fig. 1 illustrates the fully threaded parallel shank screw per IS 7170.

This table guides proper screw size selection based on board thickness, ensuring structural adequacy and fastening performance.

Committee Composition (IS 15512)

• The Committee responsible for IS 15512 formulation is the Wood and Other Lignocellulosic Products Sectional Committee, CED 20.

• Key organizations represented include:

  • Indian Plywood Industries Research and Training Institute, Bangalore (Chairman: Dr. C. N. Pandey)
  • All India Agro-Board Association, Pune
  • Building Materials & Technology Promotion Council, New Delhi
  • Central Building Research Institute, Roorkee
  • Ministry of Defence (DGQA), Kanpur
  • Federation of Indian Plywood & Panel Industry, New Delhi
  • Various plywood manufacturers and research institutes across India

• The detailed list of members and alternate representatives is provided in Annex B of the standard.

Related Specifications & Tables

• Finishing coat application (Clause 10.2.2): Two coats on exposed surfaces, balance coat on unexposed.
• Screws for assembly (Clause 7.2):

• Screws must be fully threaded parallel shank as per IS 7170 and may have cross recessed heads per IS 7478.

Summary Diagram: Committee Structure

graph TD
A[Wood & Lignocellulosic Products Committee] --> B[Chairman: Dr. C.N. Pandey]
A --> C[Research Institutes]
A --> D[Government Departments]
A --> E[Industry Representatives]
C --> F[IPIRTI, Bangalore]
C --> G[Forest Research Institute]
D --> H[Ministry of Defence]
D --> I[Central Public Works Dept.]
E --> J[Plywood Manufacturers]
E --> K[Coir Board]

This committee ensures multi-disciplinary inputs for the standard's development.