Specification for mortice ball catches for use in the wooden almirah
1978 Edition

Scope Overview - IS 8756 Specifications

Scope: This standard defines the required dimensions, tolerances, and quality standards for ball catches employed in doors and windows.

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

• Tolerances: ±0.2 mm for dimensions A, B, and D.
• Dimension C tolerances in accordance with IS 2898-1976 for steel balls.

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

3. Rounding Instructions (Clause 0.5)

• Test results should be rounded as per IS 2-1960, preserving the number of significant figures specified.

Diagram: Typical Ball Catch Dimensions

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

References:

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

This synopsis aids in design and quality assurance.

IS 8756: Definitions, Dimensions & Sampling Details

1. Rounding Method (Clause 0.5)

• All final test outcomes must be rounded following IS 2-1960 guidelines.
• The count of significant digits shall remain consistent with the stated values.

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

• Tolerances: ±0.2 mm on A, B, and D; dimension C tolerances in line with IS 2898-1976.
• D denotes the ball catch size.

3. Sampling Plan (Clause 1.2, Table 2)

4. Additional Remarks

• Dimensions and tolerances comply with applicable international standards.
• Steel balls conform to IS 2898-1976.
• Materials for brass and steel wire are referenced accordingly.

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[Allowed Defectives]

This section clarifies terminology and dimensioning requirements.

IS 8756 Specifications on Materials

1. Material Standards

• Brass Sheets:
  • Grade CuZn 40
  • Conforming to IS 410-1967 (Second Revision)
• Steel Balls:
  • Comply with IS 2898-1976 (Steel balls for rolling bearings)

2. Ball Catch Dimensions (Clause 5.1, Table 1)

• Dimension D indicates the ball catch size.
• Diameter tolerances adhere to IS 2898-1976.

3. Notes

• Steel balls must be of rolling bearing grade as per IS 2898-1976.
• Brass sheets should meet specifications for rolled brass plates 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 ensures adherence to prescribed materials and dimensional accuracy.

Design and Form of Ball Catches According to IS 8756

Highlights from the Standard

• Shape and Design Flexibility (Clause 4.1): The form illustrated in Fig. 1 is indicative; manufacturers may adopt any suitable design compatible with their product.

• Size Identification (Clause 2.1.1): The size corresponds to the external diameter D of the cylindrical part (refer to Fig. 1).

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

• Diameter tolerances for dimension C and ball size conform to IS 2898-1976.

Summary

• D denotes the external diameter of the ball catch cylinder.
• Dimensions A, B, C, and D must meet Table 1 requirements.
• Tolerances generally ±0.2 mm, with specific steel ball diameter tolerances.
• Manufacturers may innovate in shape beyond the illustrative figure.

flowchart LR
    A[Ball Catch Cylinder] -->|Diameter D| B[Size Indication]
    B --> C{Dimension Details}
    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 illustrates the size designation and dimensional relationships.

Dimensions and Allowable Deviations for Ball Catches as per IS 8756

Principal Dimensions (Table 1, Clause 5.1)

Allowed Tolerances

• Dimensions A, B, and D: ±0.2 mm
• Dimension C: Tolerance as per IS 2898-1976 (steel balls for rolling bearings)
• Custom dimensions may be agreed upon (Clause 5.1.1).

Notes

• D represents the standard size of the ball catch.
• Test results must be rounded consistent with IS 2-1960.
• Refer to Fig. 1 in IS 8756 for typical shape and dimension locations.

This ensures compatibility and standardized fitting in hardware applications.

Functional Specifications for Ball Catches as per IS 8756

• Rounding Off Measurements: Test results should be rounded following IS 2-1960, maintaining the same number of significant digits as the standard specifies.

• Dimensional Compliance (Clause 5.1): All dimensions and tolerances must align with Table 1 and Fig. 1.

• Tolerance Levels: ±0.2 mm for A, B, and D; C dimension tolerance per IS 2898-1976.

• Referenced Standards:

  • IS 2898-1976 for steel ball specifications
  • Material specifications for brass and steel wire as applicable

Diagram: Ball Catch Dimensional Overview

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

Summary: Ensures ball catches meet dimensional and material standards for reliable performance.

IS 8756: Standards for Workmanship and Finishing

1. Workmanship Criteria (Clause 6.1 & 7)

• The ball catch must securely hold the wardrobe door closed via the spring mechanism.
• The door should only open when pulled deliberately.
• Operation must be smooth and continuous, even with frequent use.
• Inspections include verifying dimensions, workmanship quality, finish, and smooth mechanical operation.

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

• IS 2898-1976 specifies tolerances for steel balls affecting dimension C.

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

• Lot acceptance depends on defectives being within allowed limits.
• Inspection encompasses dimensions, workmanship, finish, and operation.

Operational Flowchart: Ball Catch Function

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

This ensures quality craftsmanship and reliable door engagement.

Marking Guidelines for Ball Catches under IS 8756

• Manufacturer's Marking (Clause 8.1): Each ball catch must bear a clear marking of the manufacturer's name or trademark.

• Certification Mark (Clause 8.1.1): Optional inclusion of the ISI Certification Mark, confirming conformity to Indian Standards and ongoing quality monitoring.

• Importance of ISI Mark:

  • Indicates product quality assurance.
  • Reflects compliance with inspection and testing requirements.
  • Regulated under the Indian Standards Institution (Certification Marks) Act.

• Rounding of Test Results (Clause 0.5): Results should be rounded as per IS 2-1960, maintaining the same significant figures.

Marking Summary Table

These measures guarantee traceability and assurance of product quality.

Packaging Requirements per IS 8756

• Packaging Material (Clause 9.1): Ball catches should be packed in cardboard boxes or other approved containers. Maximum number of pieces per package: 100.

• Sampling for Quality Assurance (Clause 1.3 A-1.3): Random samples must be drawn from at least 10% of the packages, with a minimum of three packages selected. Sampling should be done with an equal number of ball catches from each chosen package.

• Labeling on Packages (Clause 9.2): Each package must have labels indicating:

  • Size of the ball catches
  • Quantity contained
  • Manufacturer’s name or trademark

• Rounding of Test Data (Clause 0.5): Test results should be rounded according to IS 2-1960, preserving the significant figures.

Packaging Process Flowchart

flowchart TD
    A[Start Packaging] --> B{Quantity ≤ 100?}
    B -- Yes --> C[Use Cardboard or Approved Packaging]
    B -- No --> D[Divide into Multiple Packages]
    C --> E[Label with Size, Quantity, Manufacturer]
    D --> E
    E --> F[Sample 10% of Packages, Minimum 3]
    F --> G[Perform Quality Testing and Round Results]
    G --> H[Ready for Dispatch]

This ensures packaging compliance and product identification.

Sampling and Inspection Protocols Under IS 8756

Sampling Approach (Appendix A, Clause 1.2)

• The lot comprises ball catches of the same size and grade within a shipment; heterogeneous lots must be divided accordingly.
• Samples are to be randomly selected from at least 10% of packages, with a minimum of three packages.
• An equal number of ball catches should be taken from each selected package.

Sample Size and Defect Allowance (Table 2)

Acceptance Criteria (Clause A-2)

• Test results should be rounded per IS 2-1960.
• The lot is accepted if the number of defective samples is less than or equal to the permissible limit.

flowchart TD
    A[Begin: Ball Catch Lot] --> B{Determine Lot Size}
    B -->|≤ 200| C[Sample 15, Max 0 Defects]
    B -->|201-300| D[Sample 20, Max 1 Defect]
    B -->|301-500| E[Sample 30, Max 2 Defects]
    B -->|501-800| F[Sample 40, Max 2 Defects]
    B -->|> 800| G[Sample 50, Max 3 Defects]
    C & D & E & F & G --> H[Random Selection from ≥10% Packages (min 3)]
    H --> I[Inspect Samples]
    I --> J{Defects ≤ Allowed?}
    J -- Yes --> K[Lot Accepted]
    J -- No --> L[Lot Rejected]

This procedure ensures lot quality through statistically valid inspection.

IS 8756: Sampling Plan and Acceptance Criteria for Ball Catches

Sampling Method (Clause A-1.3)

• Randomly select samples from at least 10% of packages, with a minimum of three packages involved.
• Equal quantities of ball catches are to be taken from each selected package.

Sample Sizes and Acceptance Limits (Appendix A, Clause 1.2 & Table 2)

Notes

• The defective count refers to the number of faulty ball catches permitted in the sample.
• Test data must be rounded according to IS 2-1960, maintaining the decimal precision of the standard.

Sampling and Acceptance Workflow

flowchart TD
    A[Start: Ball Catch Lot] --> B{Lot Size Determination}
    B -->|Up to 200| C[Sample 15, Max 0 Defects]
    B -->|201-300| D[Sample 20, Max 1 Defect]
    B -->|301-500| E[Sample 30, Max 2 Defects]
    B -->|501-800| F[Sample 40, Max 2 Defects]
    B -->|Above 800| G[Sample 50, Max 3 Defects]
    C & D & E & F & G --> H[Randomly Choose Samples from ≥10% Packages (Min 3)]
    H --> I[Inspect and Count Defects]
    I --> J{Are Defects Within Limits?}
    J -- Yes --> K[Lot Accepted]
    J -- No --> L[Lot Rejected]

This appendix ensures rigorous quality control through systematic sampling.