Logs for Plywood

IS 656: Foreword - Key Points and Specifications

• Scope: IS 656 specifies requirements for logs used in plywood manufacture.
• Standard Mark (Clause 7.1.1):
  • Logs may be marked with the BIS Standard Mark, ensuring compliance with IS 656 under BIS supervision.
  • Use of the Standard Mark is governed by the Bureau of Indian Standards Act, 1986.
• BIS Role:
  • BIS ensures standardization, marking, and quality certification.
  • BIS conducts continuous inspection, testing, and quality control.
• Revision & Amendments:
  • Indian Standards are periodically reviewed and updated.
  • Users should verify they have the latest edition or amendments.
• Rounding Off (Clause 0.4):
  • Test results must be rounded per IS 2:1960.
  • The number of significant digits retained should match the specified value.

Contact & Offices

This foreword sets the framework for quality assurance and compliance for logs used in plywood production per IS 656.

Scope of IS 656 (Specification for Logs for Plywood)

• Purpose: Specifies requirements for logs used in plywood manufacture.

• Volume Calculation:
  [ V = \frac{1}{4\pi} \times G^2 \times L ] where:

  • (V) = Volume of log (m³)
  • (G) = Girth of log (m)
  • (L) = Length of log (m)

• Marking: Logs may carry the BIS Standard Mark ensuring compliance with quality and inspection requirements governed by BIS.

• Rounding Off: Final test or calculation values must be rounded per IS 2:1960 keeping the same number of significant digits as specified.

• Quality Assurance: Logs must meet quality requirements outlined in the standard (Clause 5).

Summary Table: Volume Formula

flowchart LR
    G[Girth (G) in meters] -->|Square| G2[G²]
    G2 -->|Multiply| Mul1[Multiply by Length (L)]
    L[Length (L) in meters] --> Mul1
    Mul1 -->|Multiply by 1/(4π)| V[Volume (V) in m³]

For detailed quality and marking requirements, refer to IS 656 Clause 5 and 7.1.1.

IS 656: Definitions & Key Specifications Summary

1. Definitions:

• As per Clause 2.1, definitions and terms follow IS 707-1976 (Seasoned Timber).
• Curvature (Clause 5.2.1): Permissible deviation in straightness is up to 30 mm per 1 m length from a straight line joining the ends.

2. Rounding Off (Clause 0.4):

• Final test or calculated values must be rounded per IS 2-1960.
• Number of significant digits retained should match the specified value in IS 656.

3. Marking (Clause 7.1.1):

• Logs may carry the Standard Mark indicating compliance with BIS quality control.
• Use of the Standard Mark is governed by the Bureau of Indian Standards Act, 1986.

Quick Reference Table: Curvature Tolerance

Notes:

• Refer to IS 707-1976 for timber species and detailed definitions.
• Always verify you have the latest amendments from BIS.

flowchart TD
    A[Timber Sample] --> B[Measure Straightness]
    B --> C{Deviation ≤ 30 mm/m?}
    C -- Yes --> D[Accept Timber]
    C -- No --> E[Reject or Reprocess]

This ensures timber quality per IS 656 standards.

IS 656: Key Points on Species of Timber

• Reference Standard: Definitions and species classification refer to IS 707-1976 (Code of Practice for Seasoning of Timber).

• Species Selection:

  • Logs for veneers and plywood must be from species mutually agreed upon by supplier and purchaser, typically from those listed in IS 707.

• Prophylactic Treatment:

  • Timber species require treatment per Table 2, Group 9 of IS 401-1982 to prevent decay and pests.
  • Treatment must be applied immediately after felling.

Important Tables and References

Typical Species Groups (from IS 707)

Treatment Summary (per IS 401-1982 Table 2, Group 9)

• Preservative: Copper Chrome Arsenate (CCA) or equivalent
• Method: Pressure impregnation or brushing
• Purpose: Protection against fungi, termites, and insects

flowchart LR
    A[Timber Species Selection]
    B[IS 707-1976 Classification]
    C[Agreement between Supplier & Purchaser]
    D[Prophylactic Treatment]
    E[IS 401-1982 Table 2, Group 9]
    F[Immediate Treatment after Felling]

    A --> B --> C --> D --> E --> F

For detailed species lists and treatment parameters, refer directly to IS 707 and IS 401.

IS 656 - Dimensions of Logs for Veneer Manufacture

Key Specifications:

• Length Measurement (Clause 4.3.1.1):

  • If a napha or chain-groove is present at one end, measure length from the other end to the middle of the outer edge of the napha/chain-groove and the first felling cut of the snouted end.
  • Length rounded down to the nearest 0.01 m.
  • Uneven ends can be trimmed off in measurements if ends are not square cut.

• Girth Measurement (Clause 4.3.2):

  • Girth is measured in meters around the log's circumference at the midpoint of the length.

Summary Table for Log Dimensions:

Notes:

• Logs must be from agreed timber species.
• Measurement methods ensure uniformity for veneer quality.
• Uneven ends permissible to be excluded for accuracy.

flowchart LR
    A[Log End with Napha/Groove] --> B[Measure to middle outer edge of Napha]
    C[Opposite Log End] --> B
    B --> D[Length Measurement]
    E[Midpoint of Log] --> F[Girth Measurement around circumference]

This ensures precise log sizing for veneer manufacturing as per IS 656.

IS 656: Quality Requirements Summary

Key Quality Requirements (Clause 5 & related)

• Rounding off test results:
  All final test or analysis values must be rounded as per IS 2:1960.

  • Retain the same number of significant digits as specified in the standard.

• Log Marking (Clause 7.1.1):
  Logs may bear the Standard Mark, indicating compliance with IS 656 under BIS supervision.

  • The Standard Mark assures quality via inspection, testing, and control by BIS.
  • Use of the mark is regulated under the Bureau of Indian Standards Act, 1986.

• Quality Control:
  Logs supplied for plywood manufacture must meet minimum quality criteria to ensure economic and technical suitability.

Volume Calculation (Clause 4.3.3)

[ V = \frac{G^2}{4\pi} \times L ]

• V = volume of log (m³)
• G = girth (circumference) in meters
• L = length of log in meters

Notes:

• Logs must be selected to meet minimum quality to ensure plywood grade conformity.
• BIS periodically revises standards; always check for latest amendments.

flowchart TD
    A[Log Supply] --> B[Quality Inspection]
    B --> C{Meets IS 656?}
    C -- Yes --> D[Mark with Standard Mark]
    C -- No --> E[Reject or Reprocess]
    D --> F[Supply to Plywood Factory]

For detailed specs, consult the full IS 656 document and IS 2:1960 for rounding rules.

Protection of Plywood Logs — IS 656 Key Points

• Defect Limits (Clause 5.2.9):
  Total defects (knots, wounds, bird pecks, bark pockets) must not exceed 4 per 3 m length of log.

• Log Quality:
  Logs must meet minimum quality standards to ensure plywood conforms to IS specifications.

• General Protection Guidelines:

  • Logs should be stored off the ground on platforms or sleepers to avoid moisture and fungal attack.
  • Cover logs with waterproof sheets to protect from rain.
  • Avoid exposure to direct sunlight to prevent drying and checking.
  • Use preservatives if storage exceeds 3 months.

Summary Table: Defect Limits per 3 m Log Length

Protection Measures Diagram

flowchart LR
    A[Log Harvesting] --> B[Transport & Storage]
    B --> C{Storage Conditions}
    C -->|Off-ground| D[Use sleepers/platforms]
    C -->|Cover| E[Waterproof sheets]
    C -->|Avoid Sun| F[Shade/log yard]
    C -->|Long Storage| G[Preservative treatment]

Note: For detailed preservative types and application methods, refer to IS 13601 (Preservative treatment of timber).

IS 656 - Marking of Logs: Key Points

Clause 7.1: Marking Requirements

Each log shall be legibly and indelibly marked on both ends with:

• Supplier's identification mark (abbreviated initials)
• Length and mid girth of the log

Clause 7.1.1: Standard Mark

• Logs may also carry the BIS Standard Mark, indicating compliance with Indian Standards.
• Use of the Standard Mark is regulated by the Bureau of Indian Standards Act, 1986.
• The mark assures production under strict inspection, testing, and quality control supervised by BIS.

Additional Notes:

• Length measurement is as per Fig. 1 (outer edge of naptha or chain groove).
• End coating to prevent splitting must comply with IS 1141-1973.
• Rounding off test values should follow IS 2-1960 guidelines.

Summary Table: Marking Details

flowchart LR
    A[Log Ends] --> B[Mark Supplier ID]
    A --> C[Mark Length]
    A --> D[Mark Mid Girth]
    A --> E[Optional: BIS Standard Mark]

References:

• IS 656: Clause 7.1, 7.1.1
• IS 1141-1973 (End Coating)
• IS 2-1960 (Rounding off values)