Plywood Tea Chests: Part-4 Metal Fittings

Scope Summary from IS 10 Part 4

The scope defines sampling, conformity criteria, and marking specifications for metal fittings and tea-chest sizes.

1. Sampling and Conformity (Clause 2.1 & A-3)

• Final test results must be rounded as per IS 2:1960 rules.

2. Marking & Dimensions of Metal Fittings (Clause 4.3.1)

• Tolerance: ±3 mm for all dimensions.

3. Rounding Off

• Use IS 2:1960 for rounding test results.
• Retain significant figures as per specified values.

This concise scope ensures quality control via sampling, conformity criteria, and standardized marking for

IS 10 Part 4: Materials for Metal Fittings (Plywood Tea-Chests)

Key Material Specification:

• Material: Waste-waste quality tinplate or terne plate.
• Thickness: Only minimum thickness specified (refer to detailed clauses for exact values).

Table 1: Length of Metal Fittings for Tea-Chests

• Tolerances: ±3 mm for all lengths.

Quality Control:

• Testing done on sets of 12 pieces.
• Lot conformity assessed per Clause 3.2 and Table A-3 (permissible defectives).

Summary:

• Use tinplate/terne plate with minimum thickness.
• Metal fittings lengths vary by tea-chest size (see table above).
• V-notch positions are mostly centered except for specific sizes.
• Strict tolerances and quality control ensure compliance.

flowchart LR
    A[Material: Tinplate/Terne Plate] --> B[Minimum Thickness Specified]
    B --> C[Metal Fittings Length per Size]
    C --> D[Corner Fittings]
    C --> E[Top & Bottom Fittings]
    D & E --> F[V-notch Positioning]
    F --> G[Quality Control: Lot Testing (12 pcs)]

For detailed thickness and testing criteria, refer to full IS 10 Part 4 text

IS 10 Part 4: Dimensions and Tolerances for Metal Fittings

Key Specifications:

• Material: Waste-waste quality tinplate or terne plate with smooth, rust-free surface (Clause 3.1).
• Thickness: Minimum thickness specified (no range given).
• Inspection: Dimensions checked on samples of 12 pieces; any defect in one or more requirements marks the fitting defective (Clause A-3.1).

Dimensions & Tolerances (Table 1 Summary):

• Tolerances: ± 3 mm for all lengths.

Notes:

• V notch position is mostly at the middle except for 400×500×600 size where multiple notches are positioned at specified distances.
• Dimensions ensure proper fit and assembly of metal fittings on tea-chests.

flowchart LR
    A[Tea-Chest Size] --> B[Metal Fittings Length]
    B --> C{Corners (4 pcs)}
    B --> D{Top & Bottom (8 pcs)}
    C --> E[Length per Table 1]
    D --> F[Length per Table 1]
    E & F --> G{Tolerance ±3 mm}
    G --> H[Quality Check]
    H --> I[Pass/Fail]

Summary: Use Table 1 for fitting lengths,

IS 10 Part 4: Design Specifications for Metal Fittings

Material Specification (Clause 3.1)

• Metal fittings must be made from waste-waste quality tinplate or terne plate.
• Surface must be clean, smooth, flat, free from rust and serrated edges.

Dimensions & Lengths (Clause 4.3.1, Table 1)

• Tolerance: ±3 mm for all lengths.

Key Notes:

• Testing of dimensions is done on sets of 12 pieces.
• Only minimum thickness of metal fittings is specified (refer to full IS 10 Part 4 for thickness values).
• V notch positions are critical for fitting and strength.

This table and specifications ensure uniformity and quality in metal fittings for tea-chests, optimizing durability and assembly.

flowchart LR
    A[Waste-Waste Quality Tinplate] --> B[Metal Fittings]
    B --> C{Dimensions}
    C --> D[Corners Length]
    C --> E[Top & Bottom Length]
    D --> F[±3 mm Tolerance]
    E --> F
    B --> G[V Notch Position]
    G --> H[Middle or Specific mm from Ends]

IS 10 Part 4: Sampling and Inspection Procedures

Key Specifications

• Lot Testing: Each lot is tested separately for conformity (Clause A-1.2).
• Sampling Method: Use random sampling as per IS 4905:1968 (Clause 2.1).
• Sample Size & Defectives: Determined by lot size according to Table 2 (Clause A-2.1).

Table 2: Scale of Sampling and Criteria for Conformity

Procedure Summary

• Select sample size based on lot size.
• Inspect sample for defects.
• If defectives ≤ permissible number, lot conforms.
• Otherwise, lot is rejected or re-inspected.

flowchart TD
    A[Start: Identify Lot Size] --> B[Select Sample Size from Table 2]
    B --> C[Random Sampling as per IS 4905]
    C --> D[Inspect Sample]
    D --> E{Defectives ≤ Permissible?}
    E -- Yes --> F[Lot Accepted]
    E -- No --> G[Lot Rejected or Re-inspected]

This ensures statistically valid quality control aligned with IS standards.

IS 10 Part 4: Marking and Identification - Key Points

1. Marking Requirements (Clause 6.1)

• Each metal fitting must be marked with the source of manufacture.
• Marking ensures traceability and quality control.

2. Metal Fittings Length & Position of V Notch (Clause 4.3.1, Table 6)

• Tolerances: ±3 mm for lengths.

3. Conformity Criteria (Clause 3.2, Table A-3)

• Lot acceptance based on permissible defective fittings.
• Ensures compliance with standard quality.

4. Standard Mark Usage

• Governed by BIS Act, 1986.
• Indicates compliance under BIS supervision.
• Continuous quality checks by BIS.

Summary Diagram: Marking & Identification Process

flowchart TD
    A[Manufacture Metal Fittings] --> B[Mark with Source ID]
    B --> C[Check Dimensions (Table 6)]
    C --> D{Within Tolerance ±3 mm?}
    D -->|Yes| E[Batch Conformity Check (Clause 3.2)]
    D -->|No| F[Reject or Rework]
    E --> G{Defectives ≤ Permissible

IS 10 Part 4 (1989) – Sampling of Plywood Tea-Chest Fittings

Key Points from Clause 257.5 & Annex A (Clause 5.1):

• Sampling Location: Fittings are sampled at 257.5 mm from one end of the fitting.
• Scope: Covers dimensions and requirements of metal fittings for plywood tea-chests.
• Fittings Quantity: For square/rectangular tea-chests, fittings include:
  • 4 corner fittings
  • 8 pieces for top and bottom

Table 1 (Typical Lengths of Fittings)

Note: Length fixed at 257.5 mm for standard sizes.

Summary:

• Fittings are standardized to 257.5 mm length for corners and edges.
• Sampling ensures uniformity and compliance with dimensional requirements.
• Metal fittings must comply with specified dimensions and quality to ensure proper assembly and durability of plywood tea-chests.

flowchart LR
    A[Start: Plywood Tea-Chest] --> B[Select Fittings]
    B --> C[Measure 257.5 mm from one end]
    C --> D[Sample 4 Corners + 8 Top/Bottom pieces]
    D --> E[Check Dimensions & Quality]
    E --> F{Compliant?}
    F -- Yes --> G[Use in Assembly]
    F -- No --> H[Reject/Replace Fittings]

This ensures consistent quality and fit in tea-chest manufacturing.

IS 10 Part 4: Length of Metal Fittings for Tea-Chests

Key Specifications:

• Material: Waste-quality tinplate or terne plate, smooth, rust-free, no serrated edges (Clause 3.1).
• Width of fittings: 38 ± 8 mm (Clause 4.2).

Length of Metal Fittings (Table 1, Clause 4.3.1):

• Tolerances: ± 3 mm for lengths of corners and top/bottom fittings.

Summary:

• Use the above table to select fitting lengths based on tea-chest size.
• V notch positions are mostly centered except for 400×500×600 size where multiple notches are specified.
• Width is consistent at 38 ± 8 mm.

flowchart LR
    A[Tea-Chest Size] --> B[Select Corner Length]
    A --> C[Select Top & Bottom Length]
    B & C --> D[Apply ±3 mm Tolerance]
    D --> E[Mark V Notch Position]
    E --> F[Manufacture Metal Fittings]

This ensures proper fitting and assembly per IS 10 Part 4 standards.

IS 10 Part 4: Scale of Sampling and Criteria for Conformity

1. Scale of Sampling (Table 2 from Clause 2.1)

2. Criterion for Conformity (Clause A-3)

• Each lot is tested separately.
• The lot conforms if the number of defectives in the sample is less than or equal to the permissible number.
• If defectives exceed permissible limits, the lot is rejected.

3. Sampling Method

• Follow IS 4905:1968 for random sampling procedures.
• Sample size depends strictly on lot size as per the table above.

Summary Diagram

flowchart TD
    A[Start: Lot of Fittings] --> B{Determine Lot Size}
    B -->|501-1000| C[Sample 13]
    B -->|1001-3000| D[Sample 20]
    B -->|3001-10000| E[Sample 32]
    B -->|10001-35000| F[Sample 50]
    B -->|35001+| G[Sample 80]

    C --> H[Count Defectives]
    D --> H
    E --> H
    F --> H
    G --> H

    H --> I{Defectives ≤ Permissible?}
    I -->|Yes| J[Lot Accepted]
    I -->|No| K[Lot Rejected]

Note: Permissible defectives for 3,001-10,000 lot size is 2 (missing in your table but standard as per IS 10 Part 4).