The IS 7692:1993 standard outlines the precise dimensions and fabrication criteria for headforms utilized in helmet testing, ensuring uniformity and accuracy in assessing helmet fit and impact resistance. It defines multiple standardized head sizes and shapes consistent with global norms, offering essential instructions for producing and employing headforms in helmet safety evaluations. This code is vital for manufacturers, testing agencies, and safety engineers involved in helmet certification and development.
Overview
The IS 7692:1993 standard outlines the precise dimensions and fabrication criteria for headforms utilized in helmet testing, ensuring uniformity and accuracy in assessing helmet fit and impact resistance. It defines multiple standardized head sizes and shapes consistent with global norms, offering essential instructions for producing and employing headforms in helmet safety evaluations. This code is vital for manufacturers, testing agencies, and safety engineers involved in helmet certification and development.
Audience
Contents
Structure
This section defines the detailed geometric specifications for headforms, emphasizing polar coordinate data referenced to a baseline plane. It includes dimensional values in millimeters for various heights and angular positions around the headform, essential for consistent helmet testing.
Details the key dimensional parameters (height, vertical length, and internal circumference) for different headform codes, including tolerance limits and reference planes used to ensure uniformity during helmet evaluations.
Describes the recommended manufacturing processes, materials, markings, and mounting provisions for headforms to guarantee durability and precise fitment in testing environments.
Specifies the preferred materials, including hardwood density and layering techniques, ensuring the headforms mimic real head dimensions accurately while maintaining structural integrity.
Explains the use of reference planes and polar coordinate measurement points around the headform, facilitating consistent sizing and fitting during helmet testing procedures.
Provides tables and diagrams illustrating standard headform sizes, shapes, and corresponding circumferences, including guidance for selecting appropriate sizes based on helmet internal dimensions.
Outlines permissible deviations in dimensions during headform production, emphasizing the use of polar coordinate tables to verify compliance and ensure precision.
Details the implementation of headforms during helmet impact tests, including size selection, mounting positions, and marking requirements to simulate realistic impact scenarios.
Highlights inspection and testing procedures mandated for headforms under BIS supervision, including dimensional checks and certification processes to maintain standard compliance.
Describes mandatory marking of headforms and the licensing framework governed by the Bureau of Indian Standards for authorized use of the standard mark.
Summarizes rules for rounding off measurements and applying dimensional tolerances to ensure uniformity and adherence to the standard.
Lists key tables and annexures providing polar coordinate data and dimensional details essential for designing and verifying headforms.
Compiles relevant clauses and tables referenced throughout the standard, supporting accurate 3D modeling and dimension verification.
Records updates to dimensional tables and specifications, ensuring users are informed of the latest modifications to the standard.
Frequently Asked
IS 7692 specifies headform sizes with detailed dimensions outlined in Table 1 (Clause 2.4). Each size is identified by a code letter with corresponding height (H), vertical length (V), and internal circumference values as follows:
| Code Letter | H (mm) | V (mm) | Inside Circumference (mm) |
|---|---|---|---|
| 0 | 89.5 | 216.4 | 500 |
| 1 | 96.0 | 223.4 | 540 |
| 2 | 102.5 | 232.4 | 570 |
| 3 | 107.0 | 249.0 | 600 |
The inside circumference corresponds to the helmet's internal headband level (Plane AA'). For intermediate circumferences, the next smaller headform size is used. Dimensional tolerances, except for circumference, are ±0.25 mm, ensuring precise fit during testing.
The standard recommends manufacturing headforms from layers of hardwood with a density ranging between 640 and 720 kg/m³ at 12% moisture content. These layers are assembled by gluing and screwing, with each successive layer's grain oriented at 90° to the previous one to enhance strength. After pressing until the adhesive cures, the headform is shaped to specified dimensions and sealed with multiple varnish coats. Alternative materials and construction techniques may be employed provided the final shape conforms to the polar coordinate dimensions specified in Tables 2 and 3. Markings and mounting features are also required for testing purposes.
IS 7692 ensures compatibility with global helmet testing protocols by adopting headform sizes consistent with international standards such as ISO/DIS 6220 and ECE Regulation No. 22. It specifies precise dimensional parameters and tight tolerances to promote consistent helmet fit and minimize measurement errors. The standard explicitly references international coordination efforts, harmonizing Indian helmet testing practices with worldwide safety and performance benchmarks.
According to IS 7692 Clause 2.4, all headform dimensions except the internal circumference must adhere to a tolerance of ±0.25 mm. For helmet internal circumferences that fall between defined sizes, the next smaller headform size should be selected instead of applying a tolerance. This strict control ensures accurate helmet fitting and reliable testing outcomes.
Headforms must be chosen based on the helmet's internal circumference at the headband level, selecting the next smaller size if the measurement is intermediate. Each headform is marked with a reference line and circumference on both sides and can be mounted in either vertical or inclined orientations during impact testing to replicate real-world conditions. Dimensions for headform codes 0 to 3 are clearly specified, with tolerances ensuring precise fit. Proper use of these headforms guarantees accurate measurement of impact forces during helmet shock absorption tests.
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