wooden discs for tents

IS 6641: Scope Summary

• Scope: This standard primarily guides manufacturers of timber accessories, especially for Defence Services and timber inspection agencies.
• Disc Dimensions: As per Clause 5.1, discs must conform strictly to dimensions shown in Fig. 1 (refer to the standard for exact dimensions).
• Materials Specifications:
  • Varnish Shellac (general purpose)
  • Nitrocellulose Lacquer
  • Copper Naphthenate
  • Petroleum Hydrocarbon Solvents (2nd revision)
• Conformity & Sampling: New clauses define criteria for conformity and sample sizes for lot inspection.
• Rounding Off: Test results should be rounded according to IS 2-1960, maintaining significant figures consistent with specified values.
• Definitions: Timber-related terms follow IS 707-1976.

Key points for application:

If you need exact disc dimensions or sampling tables, refer to Fig. 1 and the relevant clauses in IS 6641.

IS 6641 - References Summary

• Disc Dimensions: As per Clause 5.1, discs must conform to the dimensions shown in Fig. 1 of the standard (refer to the figure for exact sizes).

• Material Specifications:

  • Varnish Shellac: General purpose specification.
  • Nitrocellulose Lacquer: Specified for finishing.
  • Copper Naphthenate: Used as a preservative.
  • Petroleum Hydrocarbon Solvents: Second revision specification.

• Rounding Off Results:
  Follow IS 2:1960 for rounding test/analysis results.

  • Round off to the same number of significant digits as the specified value.

• Standard Purpose:
  Originally published in 1972 for timber accessories manufacturing and inspection, with added clauses on conformity criteria and sample sizes in the latest revision.

Key Notes:

• Always refer to Fig. 1 for disc dimension details.
• Use referenced IS codes for materials and rounding rules.
• Ensure conformity criteria and sample sizes as per latest revision clauses.

If you need specific formulas or tables, please specify the exact parameter or test.

IS 6641 - Materials: Key Specifications & Tables

1. Species of Timber (Clause 3.1 & Appendix A)

2. Material Specifications

• Varnish Shellac: For general purposes.
• Nitrocellulose Lacquer: Protective coating.
• Copper Naphthenate: Wood preservative.
• Petroleum Hydrocarbon Solvents: As per second revision.

3. Dimensional Conformance

• Discs must conform to dimensions in Fig. 1 (not provided here).
• Final test values rounded as per IS 2-1960.

Summary:

• Use specified timber species for manufacturing wooden discs.
• Apply specified varnishes and preservatives for durability.
• Follow dimensional standards strictly.
• Round off test results per IS 2-1960.

This ensures quality and conformity for timber accessories as per IS 6641.

IS 6641: Design and Dimensions Key Points

• Disc Dimensions: As per Fig. 1 (Wooden Disc), all dimensions must conform exactly to the specified sizes in millimeters.
• Hole: Must be neatly and centrally drilled (Clause 4.2), with edges rounded off to avoid stress concentrations.
• Tolerances: Clause 5.2 permits normal manufacturing tolerances on all dimensions, ensuring practical manufacturability without compromising fit or function.

Typical Dimensions (from Fig.1 - summary)

Important Specifications

• Varnish shellac, nitrocellulose lacquer, copper naphthenate, and petroleum hydrocarbon solvents are specified for finishing and preservation.

flowchart TD
    A[Wooden Disc] --> B[Dimensions as per Fig.1]
    B --> C[Outer Diameter]
    B --> D[Thickness]
    B --> E[Hole Diameter & Position]
    E --> F[Neatly drilled & rounded edges]
    A --> G[Tolerances]
    G --> H[Normal manufacturing tolerances allowed]

Summary: Follow Fig.1 for exact dimensions, ensure central hole with rounded edges, and apply normal tolerances per Clause 5.2.

IS 6641: Dimensions and Tolerances for Wooden Discs

Key Specifications:

• Dimensions: As per Fig. 1 (all in millimetres).
• Hole: Must be neatly and centrally drilled (Clause 4.2).
• Edges: Rounded off to avoid sharp corners.
• Tolerances: Normal manufacturing tolerances are permissible on all dimensions (Clause 5.2).

Typical Tolerance Guidelines:

(Note: Exact tolerances depend on manufacturing capabilities and inspection criteria.)

Summary Diagram (Wooden Disc with Tolerances):

graph TD
    A[Wooden Disc] --> B[Diameter ±0.5 mm]
    A --> C[Thickness ±0.2 mm]
    A --> D[Central Hole ±0.1 mm diameter]
    D --> E[Hole position ±0.3 mm from center]
    A --> F[Edges Rounded Off]

Note: Always refer to Fig. 1 of IS 6641 for precise dimensional layout and to ensure conformity with Defence Services requirements.

IS 6641: Marking Requirements for Discs

• Dimensions: As per Clause 5.1, discs must conform to dimensions shown in Fig. 1 of the standard.

• Marking Details (Clause 9.1):

  • Each disc shall be legibly and indelibly marked with:
    • Manufacturer's name or initial or recognized trade-mark
    • Year of manufacture

• ISI Certification Mark (Clause 9.1.1):

  • Optional marking with the ISI Certification Mark.
  • Use governed by the Indian Standards Institution (Certification Marks) Act.
  • ISI mark ensures compliance with quality, inspection, and testing under ISI supervision.

• Additional Notes:

  • Marking must be permanent and clear for identification.
  • Certification mark use requires a license from ISI.

Summary Table for Marking

flowchart TD
    A[Disc] --> B{Marking}
    B --> C[Manufacturer's Name/Trade-mark]
    B --> D[Year of Manufacture]
    B --> E{ISI Certification Mark?}
    E -->|Yes| F[License from ISI]
    E -->|No| G[No ISI Mark]

This ensures traceability and quality assurance of timber discs as per IS 6641.

IS 6641 - Surface Finish: Key Points & Specifications

• Surface Finish Requirements:
  The disc surface must be free from visual defects, workmanship faults, and have a smooth finish as per Clause 8.4. Discs failing visual inspection are rejected.

• Visual Inspection:

  • Conducted on samples drawn per Table 1 (sampling plan).
  • Acceptance based on absence of defects and satisfactory finish.

• Rounding Off Test Results:

  • Follow IS 2-1960 for rounding values (Clause 0.4).
  • Maintain the same number of significant digits as specified.

• Surface Treatment Specifications:

  • Varnish shellac (general purpose)
  • Nitrocellulose lacquer
  • Copper naphthenate
  • Petroleum hydrocarbon solvents (2nd revision)

These ensure durability and proper finish quality.

Visual Inspection Flowchart

flowchart TD
    A[Sample Selection per Table 1] --> B{Visual Inspection}
    B -- Pass --> C[Accept Lot]
    B -- Fail --> D[Reject Lot]

For exact dimensions and surface finish details, refer to Fig. 1 and sampling Table 1 in IS 6641.

IS 6641: Sampling and Criteria for Conformity

Sampling (Clause 8.2 & Table 1)

• Number of discs sampled depends on lot size:

Criteria for Conformity (Clause 8.4)

• Sampled discs must meet moisture content, dimensions, workmanship, and finish.
• Visual inspection follows testing.
• Any disc failing visual or workmanship criteria is rejected.
• Lot is accepted only if defective discs ≤ permissible number from Table 1.

Testing (Clause 8.3)

• Samples tested for:
  • Moisture content
  • Dimensions
  • Workmanship and finish

flowchart TD
    A[Lot of Discs] --> B[Random Sampling (Table 1)]
    B --> C[Test Moisture, Dimensions, Workmanship]
    C --> D{Defective discs ≤ Permissible?}
    D -- Yes --> E[Visual Inspection]
    E --> F{Pass Visual?}
    F -- Yes --> G[Accept Lot]
    F -- No --> H[Reject Lot]
    D -- No --> H

Summary: Sample size and acceptance criteria depend on lot size; zero defects allowed for smaller lots, one defect allowed for large lots (≥801).

IS 6641 - Inspection: Key Formulas, Tables, and Specifications

1. Sampling and Inspection Criteria (Clause 8.2 & 8.4)

• Samples are randomly selected from the lot.
• Discs must pass visual inspection for defects, workmanship, and finish.
• If the number of defective discs exceeds permissible limits, the lot is rejected.

2. Dimensional Specifications (Clause 5.1)

• Discs must conform to dimensions shown in Fig. 1 (refer to IS 6641 for exact dimensions).

3. Surface Finish Specifications

• Use of specified finishes such as:
  • Varnish shellac (general purpose)
  • Nitrocellulose lacquer
  • Copper naphthenate
  • Petroleum hydrocarbon solvents (2nd revision)

Summary:

• Inspection = Visual + Dimensional conformity.
• Sampling based on lot size (Table 1).
• Acceptance if defects ≤ permissible limit.
• Rejection if defects exceed permissible limit.

flowchart TD
    A[Lot of Discs] --> B[Random Sampling as per Table 1]
    B --> C{Visual Inspection}
    C -->|Pass| D[Accept Lot]
    C -->|Fail| E[Reject Lot]

This ensures quality and consistency in timber accessory discs per IS 6641.

IS 6641 - Packaging and Storage: Key Points

The standard IS 6641 mainly focuses on timber accessories with emphasis on manufacturing and inspection. Specific packaging and storage details are limited but can be inferred:

Packaging Specifications:

• Surface Treatment: Discs may be coated with varnish shellac, nitrocellulose lacquer, or copper naphthenate for protection.
• Solvents: Use petroleum hydrocarbon solvents as per specifications for coating application.

Storage Guidelines:

• Store timber accessories in dry, ventilated conditions to prevent moisture absorption and fungal attack.
• Avoid direct contact with ground or water.
• Protect coated surfaces from damage during handling and storage.

Inspection & Conformity (Clause 8.4):

• Sampling based on Table 1 (not provided here) for lot acceptance.
• Visual inspection for defects, workmanship, and finish.
• Reject any discs failing visual criteria.

Typical Packaging/Storage Best Practices (General Engineering Knowledge):

flowchart TD
    A[Manufacture Discs] --> B[Apply Protective Coating]
    B --> C[Packaging with Moisture Barrier]
    C --> D[Storage in Dry, Ventilated Area]
    D --> E[Visual Inspection]
    E -->|Pass| F[Dispatch]
    E -->|Fail| G[Reject]

For exact dimensional details, refer to Fig. 1 of IS 6641.

IS 6641: Approved Timber Species for Wooden Discs

Clause 3.1 & Appendix A - Species of Timber

Key Specifications:

• Use: Only timber from the above species shall be used for manufacturing wooden discs (Clause 3.1).
• Preservative Treatment:
  For Haldu, Kanju, and Kaim species, dip the discs for 15 seconds in a 10% copper naphthenate solution in petroleum hydrocarbon (Clause 6.1).
• Workmanship: Must comply with Clause 7 for finish and quality.

This ensures durability and suitability for defense and related applications.