Specification For Rim Latches
1974 Edition

Overview of Scope for Rim Latches

• Defines dimensions, manufacturing, and sampling methods.
• Applies to latches made from mild steel, brass, aluminum alloy, and zinc alloys.
• Ensures compatibility with field practices and international standards.

Important Dimension Tables:

Dimensions for Type 2 Rim Latches (Mild Steel) - Clause 7.2 (All units in millimeters)

Permissible deviations: ±1 mm for dimension A, ±0.5 mm for D, G, H, and others.

Key Specifications on Handing of Rim Latches

Hand Orientation (Clause 2)

• Handing is assigned based on the door's swinging direction (right or left).
• This affects the positioning of the latch and strike plate.
• The latch bolt must correctly project according to the door's swing.

Dimensional Details & Tolerances (Clauses 7.1 & 7.2)

• Consult Tables 2 & 3 for full dimensional data (in mm).
• Includes measurements like latch body size, bolt length, backset, and hole placements.

Materials & Manufacturing (Clause 1.1 & 6.1)

• Approved materials include mild steel, brass, aluminium alloy, and zinc base alloy.
• Manufacturers may alter latch design but must maintain functional dimensions.

Illustration: Mild Steel Type 1 Rim Latch (100 mm Size)

Diagrammatic Summary of Rim Latch Dimensions

graph LR
A[Length of Latch (A)] --> B[Backset (D)]
B --> C[Bolt Length]

Overview of Rim Latch Types as per IS 1019

Type 1 Rim Latches (Clause 8.2 & Table 2)

• Constructed mainly from mild steel, also available in brass, aluminum, or zinc alloys.
• Typical dimensions (mm) for mild steel variants:

Refer to Clause 7.1 for applicable tolerances.

Type 2 Rim Latches (Clause 8.3 & Table 3)

• Available in mild steel, brass, aluminium, and zinc alloys.
• Dimensions and details provided in Clause 7.2.

Standard Size Specifications for Rim Latches

Dimension Tables (mm)

Type 1 Rim Latches (Mild Steel) - Clause 7.1 (Table 2)

Permissible deviations: ±1 mm on dimensions A and B; +1 mm on C; ±0.5 mm on D; etc.

Type 2 Rim Latches (Mild Steel) - Clause 7.2 (Table 3)

Material Specifications and Requirements for Rim Latches

Materials (Clause 5.1, Table 1)

Dimensions (Clauses 7.1 & 7.2)

• Detailed dimensions for mild steel latches are specified with tolerances as per earlier tables.

Dimension Standards for Rim Latches

Clause 7.1: Type 1 Rim Latches (Mild Steel)

Tolerances: ±1 mm for A and B; +1 / -0.5 mm for C and D; additional as defined.

Clause 7.2: Type 2 Rim Latches (Mild Steel)

• Dimensions and tolerances similarly defined (see Table 3).

Manufacturing Standards for Rim Latches

1. Material Criteria (Clause 5.1, Table 1)

2. Dimensional Requirements (Clauses 7.1 & 7.2)

• Detailed dimensions for mild steel rim latches with tolerances are specified in Tables 2 and 3.

Requirements for Workmanship and Finishing Quality

1. Workmanship (Clause 9)

• All parts including back plate, follower, locking pin, spindle, knobs, disc, and striking box must conform to quality standards.
• Surfaces should be smooth, free from cracks, burrs, and sharp edges.
• Assembly must allow proper movement without undue friction or looseness.

2. Dimensional Compliance (Clauses 7.1 & 7.2)

• Table 2 specifies dimensions for Type 1 mild steel rim latches.
• Example:

• Tolerances vary; ±1 mm for A and B, +1/-0.5 mm for C, etc.

3. Quality Assurance (Clause A-2.1)

• Inspections include dimensional accuracy, defect checks, workmanship, finish, and performance.
• Non-conforming latches are rejected.

Performance Requirements for Rim Latches

1. Performance Clause (Clause 10.1)

• Rim latches must meet all functional performance standards after assembly.

2. Dimensional Standards (Clauses 7.1 & 7.2)

• Dimensions are standardized for Type 1 and Type 2 latches made of mild steel, brass, aluminium, and zinc alloys.
• Sizes include 75, 100, 125, and 150 mm with detailed parameters.
• Tolerances ensure interchangeability and proper fit.

(Refer to Tables 2 and 3 for comprehensive details)

3. Finishing Requirements (Clause 9.2)

• Brass latches: bright or satin finish.
• Aluminium latches: anodized finish, minimum Grade AC 15 as per IS 1868.
• Steel latches: black japanned, stove enamelled black, or copper oxidized as specified.

Diagram: Rim Latch Type 1 Dimensions

flowchart LR
    A(Size) --> B(Dimensions A to D)
    B --> C(Tolerance Range)
    C --> D(Material & Finish)
    D --> E(Performance Testing)

Note: Verify dimensions and finishes as per purchaser requirements and ensure compliance with performance tests.

Sampling and Inspection Guidelines

Sampling Plan (Clause 1.2, Appendix A)

• Sample size selection depends on lot quantity according to Table 4.

• Sampling follows Clause 13.1 and Appendix A methods.

Acceptance Criteria (Clause A-3.1)

• Lot is accepted if defective count is less than or equal to permissible defects.
• Otherwise, the lot is rejected.

Summary:

• Determine sample quantity based on lot size.
• Inspect randomly selected samples for defects.
• Accept or reject the lot accordingly.

flowchart TD
    A[Lot Received] --> B{Lot Size Determined}
    B -->|Up to 200| C[Sample 15]
    B -->|201 to 300| D[Sample 20]
    B -->|301 to 500| E[Sample 30]
    B -->|501 to 800| F[Sample 40]
    B -->|Above 800| G[Sample 55]
    C & D & E & F & G --> H[Inspect Samples]
    H --> I{Defects ≤ Allowed?}
    I -->|Yes| J[Accept Lot]
    I -->|No| K[Reject Lot]

Refer to Table 3 and Figure 2 (Clause 7.2) for precise tolerances and dimensions.

Lot Acceptance and Rejection Criteria

Sampling and Defect Limits (Table 4)

• A lot consists of rim latches produced in one batch.
• Sample size is the number tested from the lot.
• The permissible number of defective items defines acceptance.

Conformity Clause (3.1)

• Lot passes if defective count ≤ permissible defects.
• Lot fails if defective count exceeds limit.

Inspection Focus (Clauses A-2.1, 7, 8, 9, 10)

• Dimensions
• Manufacturing defects
• Finish and workmanship
• Performance testing

Process Summary:

• Use Table 4 to determine sample size and defect limits.
• Inspect sample latches accordingly.
• Accept or reject lot based on defect count.

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

This procedure guarantees quality adherence as per IS 1019.

Appendix A: Sampling Procedures and Conformity Standards

Highlights:

• Sampling is proportionate to lot size as indicated in Table 4.
• Each selected rim latch is assessed for:
  • Dimensional accuracy (Clause 7)
  • Defects in manufacturing (Clause 8)
  • Quality of workmanship and finish (Clause 9)
  • Functional performance (Clause 10)
• Any failure in these checks deems the latch defective.

Table 4: Sampling and Defect Allowance

Acceptance Conditions:

• Lot accepted if defective items ≤ allowed defects.
• Lot rejected if defective items exceed allowed number.

Summary Flowchart:

flowchart TD
    A[Receive Lot] --> B[Determine Lot Size]
    B --> C[Select Sample as per Table 4]
    C --> D[Inspect Sample for Dimensions, Defects, Finish, Performance]
    D --> E{Defective Count ≤ Allowed?}
    E -->|Yes| F[Accept Lot]
    E -->|No| G[Reject Lot]

This appendix ensures consistent quality control through statistical sampling and defect thresholds.