Overview
ISO 28927-2:2009/Amd 1:2017 is a crucial amendment to the international standard for test methods evaluating vibration emission in hand-held portable power tools, specifically focusing on wrenches, nutrunners, and screwdrivers. Published by ISO, this amendment introduces significant changes in Annex C concerning brake devices. The update aims to improve testing accuracy and repeatability by specifying detailed assembly requirements and design examples for brake systems used in vibration emission testing rigs.
This amendment ensures that vibration tests are conducted under controlled and standardized conditions, directly impacting occupational safety, product development, and regulatory compliance within the power tool industry.
Key Topics
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Brake Device Specifications
The amendment outlines strict requirements for brake systems used in vibration testing, including:
- Socket sizes standardized per detailed figures (C.1 to C.5) to define consistent weights.
- Static friction coefficients limited to not exceeding the dynamic friction coefficient by more than 20%.
- Brake force variation must remain within 20% during test runs, generally achieved through conical disc springs.
- Test rig stabilization by bolting to a heavy concrete block (≥400 kg) to prevent resonance that could affect vibration measurements.
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Brake Device Design and Components
Annex C and new Annex D provide comprehensive drawings, assembly specifications, and examples of parts such as:
- Various socket sizes made from general engineering steel and carbonitrided steel.
- Brake blocks made from solid aluminum with friction linings or phenolic cotton laminate, ensuring friction material consistency.
- Support components including base frames, steel plates, cover plates, springs, screws, nuts, and washers.
- Design considerations for conical disc springs to maintain proper contact pressure during testing.
- Recommendations for air cooling to manage brake device performance during intense use.
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Testing Integrity and Repeatability
By standardizing brake device design and assembly, the amendment strengthens test reliability by eliminating variables that could distort hand–arm vibration results. This level of detail promotes consistent evaluation across different testing facilities and tool models.
Applications
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Power Tool Manufactures
Manufacturers of wrenches, nutrunners, and screwdrivers can apply this standard to verify vibration emission compliance, aiding in product certification and market readiness. It helps optimize tool ergonomics and reduce user exposure to harmful vibrations.
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Testing Laboratories
Laboratories can upgrade their vibration emission test rigs using the detailed brake device specifications and drawings to conduct standardized, repeatable testing aligned with ISO requirements.
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Safety and Compliance Specialists
Occupational health professionals and regulatory bodies can use the standard as a benchmark for assessing vibration risks related to power tool operation, facilitating informed regulations and protective measures.
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Research and Development
Engineers and researchers in tool design can use the amendment’s specifications to enhance the precision of vibration emission studies, leading to innovations in vibration reduction technologies.
Related Standards
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ISO 28927 Series
The series covers test methods for various hand-held power tools evaluating vibrations, with Part 2 specifically targeting wrenches, nutrunners, and screwdrivers.
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ISO/TS 21108:2011
Provides specifications for guided sockets applicable in some brake device assemblies referenced in the amendment.
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ISO 4014
Standard defining hex head dimensions referenced for socket designs in brake devices.
Summary
ISO 28927-2:2009/Amd 1:2017 advances the international standard for evaluating vibration emissions from portable hand-held power tools by refining brake device design requirements. It enhances testing consistency crucial for user safety, product quality, and regulatory adherence. Compliance with this amendment supports manufacturers, testers, and safety professionals in reducing vibration exposure risk and improving ergonomic tool performance.
Keywords: ISO 28927-2 amendment, vibration emission test, hand-held power tools, wrenches, nutrunners, screwdrivers, brake devices standard, power tool vibration testing, hand–arm vibration, brake device assembly, conical disc spring, socket specifications.
Open preview (PDF)Hand-held portable power tools — Test methods for evaluation of vibration emission — Part 2: Wrenches, nutrunners and screwdrivers — Amendment 1: Changes in Annex C — Brake devices