Specification for numerical
1982 Edition

Overview of Scope

The standard specifies quality control requirements for numerals concerning their materials or products, emphasizing sampling methods and acceptance criteria.

Sampling and Acceptance Table (Clause 9.2)

Explanation:

• Batch Quantity: Total numerals in a lot.
• Sample Count: Number of samples inspected.
• Maximum Allowed Defects: Defective pieces allowed for the batch to be accepted.

This table guides inspection sampling to verify product compliance with minimal defects.

flowchart LR
    A[Batch Quantity] --> B[Determine Sample Size]
    B --> C[Inspect Samples]
    C --> D{Defects ≤ Allowed?}
    D -->|Yes| E[Accept Batch]
    D -->|No| F[Reject Batch]

Material Specifications for Numerals

Approved Material Grades (Table 1, Clause 2.1)

Notes on Standards

• • IS 292-1961: Brass ingots and castings (revised)
• • IS 305-1961: Aluminium bronze ingots and castings (revised)
• $ IS 306-1968: Tin bronze ingots and castings (second revision)

7 IS 28-1975: Phosphor bronze ingots and castings (third revision)

• || IS 617-1975: Aluminium and aluminium alloy ingots and castings for engineering (revised)

Summary

• Brass numerals should use Grade 3 brass.
• Bronze numerals can be made from specified grades of aluminium bronze, tin bronze, or phosphor bronze.
• Aluminium numerals should be from designated alloys 5230 or 4600.

This ensures the numerals meet durability and manufacturing quality standards.

Design and Shape Guidelines for Numerals

Highlights from IS 10090:

• Clause 3.1:

  • The code does not prescribe fixed shapes or designs for numerals.
  • These should be mutually decided between the maker and the buyer.

• Material Grades (Clause 2.1 & Table 1):

  • Material selection impacts design considerations:

Practical Recommendations:

• Provide sufficient thickness for strength.
• Ensure numerals are clearly legible.
• Design should be compatible with the mounting environment.

Summary:

• Numeral shape is flexible and collaboratively defined.
• Use specified materials to ensure performance.

flowchart LR
    A[Manufacturer] --> C[Propose Design]
    B[Buyer] --> C
    C --> D[Agreed Design]
    D --> E[Manufacture per Material Specs]

Refer to additional engineering design standards for detailed mechanical properties.

Standard Sizes for Numerals

• Clause 4.1 specifies standard numeral heights as: 25 mm, 50 mm, 75 mm, 100 mm, 150 mm, and 300 mm.

• Clause 3.1 allows flexibility in shape and design beyond these sizes.

Typical Usage Table

Notes:

• Dimension refers to numeral height.
• Thickness and stroke width depend on application and visibility needs.

flowchart LR
    A[Manufacturer] -->|Agrees| B[Design & Shape]
    B --> C[Select from Standard Sizes]
    C --> D[Application-based Choice]

Use these sizes as a baseline and finalize design details through buyer-supplier agreement.

Manufacturing Standards for Numerals

Material Compliance (Clause 2.1 & Table 1)

Notes on IS Standards:

• IS 292-1961: Brass ingots and castings
• IS 305-1961: Aluminium bronze ingots and castings
• IS 306-1968: Tin bronze ingots and castings
• IS 28-1975: Phosphor bronze ingots and castings
• IS 617-1975: Aluminium and aluminium alloy ingots and castings

Manufacturing Guidelines

• Materials must adhere strictly to the specified IS grades for durability.
• Proper alloy composition and casting quality are essential for longevity and accuracy.

For detailed shape or formula requirements, refer to related standards such as IS 3177 for casting tolerances.

flowchart TD
    A[Select Material] --> B{Material Type}
    B -->|Brass| C[IS 292-1961 Grade 3]
    B -->|Cast Bronze| D[IS 305-1961 Grade 3]
    B -->|Cast Bronze| E[IS 306-1968 Grade 4]
    B -->|Cast Bronze| F[IS 28-1975 Grade 3]
    B -->|Cast Aluminium| G[IS 617-1975 Alloy 5230/4600]

Summary: Use specified IS grades to manufacture numerals per IS 10090.

Finish Requirements for Numerals

• Brass and Bronze Numerals:

  • Must have a smooth surface finish.
  • Allowed finishes include:
    • Bright polish
    • Satin/matte finish
    • Plated finishes such as nickel or chrome
  • Surface should be protected to prevent tarnishing (e.g., by lacquering).

• Aluminium Numerals:

  • Shall be anodized.
  • Anodizing quality must meet at least Grade AC 10 as per IS 1868:1968.
  • This treatment provides corrosion resistance and durability.

Finish Summary Table

Notes:

• Bright finish: Highly polished, reflective surface.
• Satin finish: Matte, less reflective.
• AC 10 anodizing: Minimum anodic coating thickness ensuring durability.

flowchart TD
    A[Numerals] --> B[Brass/Bronze]
    A --> C[Aluminium]
    B --> D[Finish: Bright/Satin/Plated]
    D --> E[Protection: Anti-tarnish]
    C --> F[Finish: Anodized]
    F --> G[Quality: Grade AC 10 (IS 1868)]

These finishes ensure longevity and visual appeal compliant with IS 10090.

Marking Instructions for Numerals

• Clause 7.1: Each numeral must bear a clear, permanent mark.
• Markings to include:
  • Manufacturer's name or
  • Registered trademark, if applicable.

Important Notes:

• Marking ensures traceability and authenticity.
• Methods include stamping, engraving, or durable printing.
• Marks should remain legible throughout the numeral's service life.

No specific formulas or tabulations are provided for marking in this standard.

flowchart LR
    A[Manufacturer] --> B[Apply Marking]
    B --> C[Permanent Identification]
    C --> D[Manufacturer Name or Trademark]
    D --> E[Legibility Maintained]

This facilitates easy identification and compliance.

Packaging Requirements for Numerals

• Clause 8.1: Each numeral must be individually wrapped using polythene or tissue paper to avoid damage.

• Wrapped numerals are then packed in multiples within cardboard cartons for transportation and storage.

• Clause 8.2: Each package must be clearly marked with:

  • The quantity of numerals contained
  • Manufacturer's name or trademark

• Clause 9.2.1: For quality verification, random samples should be drawn from at least 10% of the packages, with a minimum of 3 packages selected. Equal numbers of numerals are taken from each package for testing.

Packaging Summary Table

flowchart LR
    A[Numerals] --> B[Individually Wrapped]
    B --> C[Grouped in Sets]
    C --> D[Packed in Cardboard Boxes]
    D --> E[Package Marked with Quantity & Maker]
    E --> F[Sampling: 10% Packages, min 3, Equal Samples]

This ensures protection, identification, and quality control.

Sampling Scale and Acceptance Limits

Extracts from Clauses 9.2 & 9.4:

• Sample size is determined based on lot size as shown in the table below.
• The maximum number of allowable defective units determines if the lot is accepted.
• A lot passes if the number of defectives is less than or equal to the permissible limit.

Sampling Table

Summary:

• Determine sample size based on total lot quantity.
• Inspect samples for defects.
• Accept the lot if defectives are within allowed limits.
• Otherwise, reject the lot.

flowchart TD
    A[Identify Lot Size] --> B[Select Sample Size]
    B --> C[Inspect Samples]
    C --> D{Defects ≤ Allowed?}
    D -- Yes --> E[Accept Lot]
    D -- No --> F[Reject Lot]

This procedure enforces quality control per the standard.