Specification for mortice ball catches for use in the wooden almirah

IS 8756: Scope - Key Specifications and Tables

Scope: IS 8756 covers dimensions, tolerances, and quality requirements for ball catches used in doors and windows.

1. Dimensions and Tolerances (Clause 5.1, Table 1)

• Tolerances: ±0.2 mm for A, B, and D.
• C dimension tolerance as per IS 2898-1976 (steel balls for rolling bearings).

2. Sampling and Quality Control (Clause A-1.2, Table 2)

3. Rounding Off (Clause 0.5)

• Final test values must be rounded as per IS 2-1960, retaining the same significant figures as specified.

Illustration: Typical Ball Catch Dimensions

graph LR
A[Dimension A] --> BallCatch[Ball Catch]
B[Dimension B] --> BallCatch
C[Dimension C] --> BallCatch
D[Ball Size D] --> BallCatch

References:

• IS 2898-1976 for steel ball tolerances.
• IS 2-1960 for rounding rules.

This concise summary aids in design,

IS 8756: Key Definitions, Dimensions & Sampling

1. Rounding Off (Clause 0.5)

• Final test values must be rounded per IS 2-1960.
• Retain the same number of significant digits as the specified value.

2. Dimensions of Ball Catches (Clause 5.1, Table 1 & Fig. 1)

• Tolerances: ±0.2 mm (except C, per IS 2898-1976 for steel balls)
• D = Ball catch size

3. Sampling Plan (Clause 1.2, Table 2)

4. Additional Notes

• Dimensions and tolerances align with international standards.
• Steel balls per IS 2898-1976.
• Brass and steel wire specifications referenced for materials.

flowchart LR
    A[Ball Catch Size] -->|Dimensions| B{Table 1}
    B --> A1[A, B, C, D]
    C[Lot Size] -->|Sampling| D{Table 2}
    D --> D1[Sample Size]
    D --> D2[Permissible Defectives]

This

IS 8756 Key Specifications for Materials:

1. Materials Specifications

• Brass Sheets:
  • Grade: CuZn 40
  • Standard: IS 410-1967 (Second Revision)
• Steel Balls:
  • Standard: IS 2898-1976 (Specification for steel balls for rolling bearings)

2. Dimensions of Ball Catches (Clause 5.1, Table 1)

• D = Size of Ball Catch
• Tolerances for diameters as per IS 2898-1976.

3. Notes

• Steel balls must meet rolling bearing quality per IS 2898-1976.
• Brass sheets must comply with rolled brass plate specifications in IS 410-1967.

flowchart LR
    A[Brass Sheets] -->|Grade CuZn 40| IS410_1967
    B[Steel Balls] -->|Rolling Bearing Grade| IS2898_1976
    C[Ball Catch Dimensions] --> Table1
    Table1 -->|Tolerance ±0.2 mm| IS2898_1976

This summary ensures compliance with material and dimensional standards for ball catches per IS 8756.

IS 8756: Design and Shape of Ball Catches

Key Points from IS 8756

• Shape & Design (Clause 4.1):
  The shape shown in Fig. 1 is illustrative only. Manufacturers may design ball catches in any shape suitable to their product.

• Size Definition (Clause 2.1.1):
  Size is denoted by the external diameter D of the cylinder (see Fig. 1).

• Dimensions & Tolerances (Clause 5.1, Table 1):

• Tolerances for diameters C and ball size follow IS 2898-1976 (steel balls for rolling bearings).

Summary

• D = external diameter of the ball catch cylinder.
• Dimensions A, B, C, D must conform to Table 1.
• Tolerances are ±0.2 mm generally, with specific ball diameter tolerances per IS 2898.
• Shape flexibility allows manufacturers to innovate beyond Fig.1 illustration.

flowchart LR
    A[Ball Catch Cylinder] -->|Diameter D| B[Size designation]
    B --> C{Dimensions}
    C --> A1[A]
    C --> B1[B]
    C --> C1[C]
    C --> D1[D]
    D1 -->|Tolerance ±0.2 mm| E[IS 2898 for ball diameter]

This diagram shows the relationship between size designation and dimensions with tolerances.

IS 8756 - Dimensions and Tolerances for Ball Catches

Key Dimensions (Table 1, Clause 5.1)

Tolerances

• A, B, D: ±0.2 mm
• C: As per tolerances for respective diameters in IS 2898-1976 (Steel balls for rolling bearings)
• Dimensions may be customized by agreement (Clause 5.1.1).

Notes

• Dimension D = Size of ball catch.
• Final test values should be rounded per IS 2-1960.
• Refer to Fig. 1 in IS 8756 for typical ball catch illustration.

This ensures compatibility and interchangeability of ball catches in builder's hardware applications.

IS 8756: Functional Requirements - Key Specifications

• Rounding Off Values:
  Final test values must be rounded as per IS 2-1960, maintaining the same number of significant figures as the specified values.

• Dimensions of Ball Catches (Clause 5.1):
  Dimensions and tolerances must conform to Table 1 and Fig. 1.

• Tolerances:
  ±0.2 mm for A, B, and D dimensions; C dimension tolerance as per IS 2898-1976 (steel balls for rolling bearings).

• Reference Standards:

  • IS 2898-1976 for steel ball tolerances
  • Specifications for brass and steel wire materials as applicable

Illustration of Ball Catch Dimensions (Fig. 1)

graph LR
A[Dimension A]
B[Dimension B]
C[Dimension C]
D[Ball Size D]
BallCatch[Ball Catch]
BallCatch --> A
BallCatch --> B
BallCatch --> C
BallCatch --> D

Summary: Ensure ball catches meet dimensional tolerances and material specs per IS 8756 and referenced IS codes for reliable functional performance.

IS 8756: Workmanship and Finish - Key Points & Tables

1. Workmanship Requirements (Clause 6.1 & 7)

• Ball catch must hold the almirah door securely when closed via the spring section.
• Door should open only when pulled.
• Smooth, continuous operation under frequent usage is mandatory.
• Inspection includes dimension, workmanship, finish, and smooth working.

2. Dimensions & Tolerances (Clause 5.1, Table 1 & Fig. 1)

• IS 2898-1976 covers steel balls for rolling bearings, affecting dimension C.

3. Sampling & Quality Control (Clause A-1.2, Table 2)

• Lot passes if defectives ≤ permissible number.
• Inspection covers dimensions, workmanship, finish, and smooth operation.

Summary Diagram: Ball Catch Operation

flowchart LR
    A[Door Closed] --> B{Ball Catch Spring Engaged?}
    B -- Yes --> C[Door Retained Securely]
    B -- No --> D[Door Not Secure]
   

IS 8756 - Marking Requirements for Ball Catches

• Clause 8.1:
  Each ball catch must be clearly marked with the manufacturer's name or trade-mark.

• Clause 8.1.1:
  Ball catches may also bear the ISI Certification Mark, indicating compliance with Indian Standards under ISI supervision.

• ISI Mark Significance:

  • Assures product quality and conformity to the standard.
  • Implies ongoing inspection, testing, and quality control.
  • Use of the ISI Mark is regulated by the Indian Standards Institution (Certification Marks) Act.

• Rounding Off (Clause 0.5):
  Test results should be rounded off per IS 2-1960, maintaining the same number of significant digits as the specified values.

Summary Table for Marking

This ensures traceability and quality assurance of ball catches under IS 8756.

IS 8756 - Packaging Specifications Summary

• Packing Material (Clause 9.1):
  Ball catches must be packed in cardboard boxes or other approved packing.
  Max pieces per pack: 100.

• Sampling for Quality Check (Clause 1.3 A-1.3):
  Random samples taken from at least 10% of packages, minimum 3 packages.
  Equal number of ball catches sampled from each package.

• Labeling Requirements (Clause 9.2):
  Each package must have a label showing:

  • Size of ball catches
  • Quantity of ball catches
  • Manufacturer's name or trademark

• Rounding Off Test Results (Clause 0.5):
  Use IS 2-1960 rounding rules; retain the same number of significant digits as specified values.

Packaging Compliance Flow (Mermaid.js)

flowchart TD
    A[Start Packaging] --> B{Pieces ≤ 100?}
    B -- Yes --> C[Pack in cardboard box or approved packing]
    B -- No --> D[Split into multiple packages]
    C --> E[Label package with size, quantity, manufacturer]
    D --> E
    E --> F[Sampling: select 10% packages, min 3]
    F --> G[Quality Testing & Rounding as per IS 2-1960]
    G --> H[Package Ready for Dispatch]

This ensures compliance with IS 8756 packaging and labeling requirements.

IS 8756: Sampling and Inspection of Ball Catch Locks

Sampling Procedure (Appendix A, Clause 1.2)

• Number of samples depends on lot size as per Table 2 below.
• Samples must be randomly selected from at least 10% of packages, minimum 3 packages.
• Equal number of ball catches taken from each selected package.

Table 2: Sampling & Permissible Defectives

Criteria for Conformity (Clause A-2)

• Use IS 2-1960 rounding rules for test results.
• Round off to the same decimal places as specified values.
• If defective count ≤ permissible number, lot is accepted.

flowchart TD
    A[Start: Lot of Ball Catches] --> B{Determine Lot Size}
    B -->|Up to 200| C[Sample 15, max 0 defectives]
    B -->|201-300| D[Sample 20, max 1 defective]
    B -->|301-500| E[Sample 30, max 2 defectives]
    B -->|501-800| F[Sample 40, max 2 defectives]
    B -->|801+| G[Sample 50, max 3 defectives]
    C --> H[Randomly select samples from ≥10% packages]
    D --> H
    E --> H
    F --> H
    G --> H
    H --> I{Count Defectives}
    I -->|≤ permissible| J[Accept Lot]
    I -->|> permissible| K[Reject Lot]

This ensures quality control by statistically validating batches before acceptance.

IS 8756: Sampling and Criteria for Conformity of Ball Catches

Sampling Procedure (Clause A-1.3)

• Select samples randomly from ≥10% of packages, minimum 3 packages.
• Equal number of ball catches from each selected package.

Sample Size & Acceptance Criteria (Appendix A, Clause 1.2 & Table 2)

Notes:

• Defectives are the number of faulty ball catches allowed in the sample.
• Use IS 2-1960 rounding rules for test results.
• The number of significant figures in rounded values must match the standard's specified values.

Summary Flowchart of Sampling & Acceptance

flowchart TD
    A[Start: Lot of Ball Catches] --> B{Determine Lot Size}
    B -->|Up to 200| C[Sample Size = 15, Max Defectives = 0]
    B -->|201-300| D[Sample Size = 20, Max Defectives = 1]
    B -->|301-500| E[Sample Size = 30, Max Defectives = 2]
    B -->|501-800| F[Sample Size = 40, Max Defectives = 2]
    B -->|801+| G[Sample Size = 50, Max Defectives = 3]
    C & D & E & F & G --> H[Randomly select samples from ≥10% packages, min 3]
    H --> I[Test samples and count defectives]
    I --> J{Defectives ≤ Max allowed?}
    J -->|Yes| K[Lot Accepted]
    J -->|No| L[Lot Rejected]

This ensures quality control by statistically verifying conformity of ball catches per IS 8756.