Easy Ergonomics: A Guide to Selecting Non-Powered Hand Tools

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Organization(s):

National Institute for Occupational Safety and Health (NIOSH) , California Occupational Safety and Health Administration

Summary Statement

A booklet designed to help select the best available ergonomically designed non-powered hand tools, based on peer-reviewed articles and expert input. Also explains the factors that make a tool ergonomic, symptoms of ergonomic issues and ways to work more ergonomically.
2004

This booklet is a joint effort between the California Occupational Safety and Health Administration (Cal/OSHA) and the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC).

Disclaimer

Mention of any company name or product does not constitute endorsement by Cal/OSHA or NIOSH/CDC.

This document is in the public domain and may be freely copied or reprinted.

For information about occupational safety and health topics contact NIOSH at:

1-800-35-NIOSH (1-800-356-4674)
Fax: 513-533-8573
E-mail: pubstaft@cdc.gov

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Download this publication from Cal/OSHA or NIOSH:
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Easy Ergonomics: A Guide to Selecting Non-Powered Hand Tools was developed and prepared for publication by the Research & Education Unit, Cal/OSHA Consultation Service, California Department of Industrial Relations and the National Institute for Occupational Safety and Health. It was distributed under the provisions of the Library Distribution Act and Government Code Section 11096.

Published by the California Department of Industrial Relations and the National Institute for Occupational Safety and Health, 2004.

DHHS (NIOSH) Publication No. 2004-164

About This Booklet

The purpose of this booklet is to help you select or purchase the best available ergonomically designed non-powered hand tool. The information and the hand tool checklist are based on peer-reviewed articles and expert input. The checklist has been evaluated for reliability in identifying the presence or absence of basic ergonomic design features (Dababneh et al.*). The right tool will help you reduce your risk of injury, such as carpal tunnel syndrome, tendonitis, or muscle strain.

*Dababneh A, Lowe B, Krieg E, Kong Y, and Waters T, A Checklist for the Ergonomic Evaluation of Non-Powered Hand Tools, accepted for publication in the December 2004 issue of the Journal of Occupational and Environmental Hygiene.

Note: This booklet covers most ergonomic features that should be considered when selecting or purchasing hand tools, but does not cover all features. Specifically, it does not address tool weight, tool balance, vibration or tool maintenance.

No one is required to use the information in this booklet. This booklet is not intended to provide employers with information on how to comply with Cal/OSHA regulations.

Foreword

Non-powered hand tools are widely used in a variety of industries including construction, manufacturing, and agriculture. National data suggests that a large number of injuries known as musculoskeletal disorders are attributable to hand tool use in occupational settings, resulting in unnecessary suffering, lost workdays, and economic costs. Prevention of work-related musculoskeletal disorders is a high priority for both the National Institute for Occupational Safety and Health (NIOSH) and the California Occupational Safety and Health Administration (Cal/OSHA). Both agencies recognize the importance of design and selection of hand tools in strategies to reduce injuries of this type.

To the untrained eye, however, it may be difficult to evaluate tools from an ergonomic point of view. The purpose of this document is to demystify the process and help employers and workers identify non-powered hand tools that are less likely to cause injury--those that can be used effectively with less force, less repeated movement, and less awkward positioning of the body. Presented here are the ergonomic basics of hand tool use. These principles are meant to complement the ordinary process of deciding on what tool to select by knowing how it is used and the task to which it will be applied.

The reasonable and common-sense approaches outlined in this document can be directly applied to challenges like these:

This document also contains an easy-to-use checklist for comparing tools against several design characteristics that have been shown to reduce physical stresses on the user. We hope this checklist and the accompanying background material will be of practical use to all who wish to select tools that get the job done more safely, comfortably, and productively.

John Howard, M.D.
Director, NIOSH

Len Welsh, M.S., J.D.
Acting Chief, Cal/OSHA

Is This An Ergonomic Hand Tool?
You be the judge...

Some tools are advertised as “ergonomic” or are designed with ergonomic features. A tool becomes “ergonomic” only when it fits the task you are performing, and it fits your hand without causing awkward postures, harmful contact pressures, or other safety and health risks. If you use a tool that does not fit your hand or use the tool in a way it was not intended, you might develop an injury, such as carpal tunnel syndrome, tendonitis, or muscle strain. These injuries do not happen because of a single event, such as a fall. Instead, they result from repetitive movements that are performed over time or for a long period of time, which may result in damage to muscles, tendons, nerves, ligaments, joints, cartilage, spinal discs, or blood vessels.

Definitions

Awkward Postures Postures that strain the neck, shoulders, elbows, wrists, hands, or back. Bending, stooping, twisting, and reaching, are examples of awkward postures.		Power Grip The hand grip that provides maximum hand power for high force tasks. All the fingers wrap around the handle.
Contact Pressure Pressure from a hard surface, point, or edge on any part of the body.		Pinch Grip The hand grip that provides control for precision and accuracy. The tool is gripped between the thumb and the fingertips.
Single-Handle Tools Tube-like tools measured by handle length and diameter. Diameter The length of a straight line through the center of the handle.		Double-Handle Tools Plier-like tools measured by handle length and grip span. Grip Span The distance between the thumb and fingers when the tool jaws are open or closed.

The cost of an injury can be high, especially if the injury prevents you from doing your job.

The best tool is one that:

How do you know if you have a problem?

You may have a problem if you have any of these symptoms:

These symptoms may not appear immediately because they develop over weeks, months, or years. By then, the damage may be serious. Take action before you notice any symptoms.

Reduce your risk of injury by using these guidelines to select hand tools:

Use the Checklist to select the best tool. The features listed on the Checklist correspond to the tips found in the, “Tips for Selecting Hand Tools” section.

A. Know Your Job

Before you select a tool, think about the job you will be doing. Tools are designed for specific purposes. Using a tool for something other than its intended purpose often damages the tool and could cause you pain, discomfort, or injury. You reduce your chances of being injured when you select a tool that fits the job you will be doing.

The list of tools in each category shows a few examples of tools that are most frequently used.

Cutting, pinching, gripping tools		Striking tools
Examples: Pliers Snips Cutters		Example: Hammers
Driving tools		Struck or hammered tools
Examples: Screwdrivers Hand wrenches Nut drivers T-handle wrenches		Examples: Punches Chisels Nail sets

Next, consider whether you need the tool to provide power or precision. Then select the tool with the correct handle diameter or grip span.

For Power Tasks
Single-Handle Tools		Double-Handle Tools
	HANDLE DIAMETER for power tasks is 1 1/4 inches to 2 inches	OPEN GRIP SPAN for power tasks is not more than 3 1/2 inches	CLOSED GRIP SPAN for power tasks is not less than 2 inches
For Precision Tasks
Single-Handle Tools		Double-Handle Tools
HANDLE DIAMETER for precision tasks is 1/4 inch to 1/2 inch		OPEN GRIP SPAN for precision tasks is not more than 3 inches	CLOSED GRIP SPAN for precision tasks is not less than 1 inch

B.Look at your work space

Now look at your work space. Awkward postures may cause you to use more force. Select a tool that can be used within the space available. For example, if you work in a cramped area and high force is required, select a tool that is held with a power grip. A pinch grip will produce much less power than a power grip. Exerting force with a pinch grip means you will work harder to get the job done.

pinch grip

power grip

If you work in a cramped space, you may not be able to use a long-handle tool. Use of a long-handle tool may cause awkward postures or harmful contact pressure on your hand as you use more force. Instead, use a tool that fits within the work space. A short-handle tool can help you reach your target directly as you keep your wrist straight.

long-handle tool

short-handle tool

C. Improve your work posture

Awkward postures make more demands on your body. In some cases, the placement of the work piece will affect your shoulder, elbow, wrist, hand, or back posture. Whenever possible, choose a tool that requires the least continuous force and can be used without awkward postures. The right tool will help you to minimize pain and fatigue by keeping your neck, shoulders, and back relaxed and your arms at your sides.

For example, avoid raising your shoulders and elbows. Relaxed shoulders and elbows are more comfortable and will make it easier to drive downward force.

If you are sitting...

stand

If you are standing...		Reposition your work piece
		Work on a lower work surface

D. Select the tool

Over time, exposure to awkward postures or harmful contact pressures can contribute to an injury. You can reduce your risk of injury if you select hand tools that fit your hand and the job you are doing.

Tips for Selecting Hand Tools

Tools used for power require high force. Tools used for precision or accuracy require low force.

1 For single-handle tools used for power tasks: Select a tool that feels comfortable with a handle diameter in the range of 1 1/4 inches to 2 inches. You can increase the diameter by adding a sleeve to the handle.

Tool with sleeve

2 For single-handle tools used for precision tasks: Select a tool with a handle diameter of 1/4 inch to 1/2 inch.

3 For double-handle tools (plier-like) used for power tasks: Select a tool with a grip span that is at least 2 inches when fully closed and no more than 3 1/2 inches when fully open. When continuous force is required, consider using a clamp, a grip, or locking pliers.

Closed grip span

Open grip span

4 For double-handle tools (plier-like) used for precision tasks: Select a tool with a grip span that is not less than 1 inch when fully closed and no more than 3 inches when fully open.

Closed grip span

Open grip span

5 For double-handled pinching, gripping, or cutting tools: Select a tool with handles that are spring-loaded to return the handles to the open position.

6 Select a tool without sharp edges or finger grooves on the handle.

7Select a tool that is coated with soft material. Adding a sleeve to the tool handle pads the surface but also increases the diameter or the grip span of the handle (see 1, 2, 3, or 4 above).

8 Select a tool with an angle that allows you to work with a straight wrist.

Tools with bent handles are better than those with straight handles when the force is applied horizontally (in the same direction as your straight forearm and wrist).

Tools with straight handles are better than those with bent handles when the force is applied vertically.

9 Select a tool that can be used with your dominant hand or with either hand.

10 For tasks requiring high force: Select a tool with a handle length longer than the widest part of your hand – usually 4 inches to 6 inches.

Prevent contact pressure by making sure the end of the handle does not press on the nerves and blood vessels in the palm of your hand.

If the handle is too short, the end will press against the palm of your hand and may cause an injury.

11Select a tool that has a non-slip surface for a better grip. Adding a sleeve to the tool improves the surface texture of the handle. To prevent tool slippage within the sleeve, make sure that the sleeve fits snugly during use.

Remember: A sleeve always increases the diameter or the grip span of the handle (see 1, 2, 3, or 4 above).

These guidelines are from the following resources:

American Industrial Hygiene Association, “An Ergonomics Guide to Hand Tools”, p. 18
Dababneh A, Lowe B, Krieg E, Kong Y, and Waters T, A Checklist for the Ergonomic Evaluation of Non-Powered Hand Tools, accepted for publication in the December 2004 issue of the Journal of Occupational and Environmental Hygiene.
Eastman Kodak Company, “Ergonomic Design for People at Work”, Vol. 2, p. 350
Eastman Kodak Company, “Ergonomic Design for People at Work”, Vol. 1, p. 146
Kodak’s Ergonomics Design for People at Work, 2nd Edition, p. 349

Acknowledgments

Writers, Editors and Photographers

Richard Hight, Associate Safety Engineer, Cal/OSHA Consultation, Research & Education Unit
Kristy Schultz, CIE, Certified Industrial Ergonomist, Cal/OSHA Consultation, Research & Education Unit
Fran Hurley-Wagner, MS, CRC, CIE, Certified Industrial Ergonomist, First Response Ergonomics
Mario Feletto, MS, MPH, Area Manager Cal/OSHA Consultation, Research & Education Unit
Brian D. Lowe, PhD, CPE, Research Industrial Engineer, National Institute for Occupational Safety and Health
Yong-Ku Kong, PhD, Associate Research Fellow, National Institute for Occupational Safety and Health
Tom Waters, PhD, CPE, Chief, Human Factors & Ergonomics Research Section, National Institute for Occupational Safety and Health

The authors thank the following persons and organizations for their review and comments in the development of this document:

Editorial and Technical Reviewers

Tom Anderson, Milwaukee Tools
Dave Bare, Cal/OSHA Consultation Service
Paul Bischofberger, Barbosa Cabinets, Inc.
Scott Boggess, CSP, CIE, State Compensation Insurance Fund
Richard DaRosa, MS, Cal/OSHA Consultation Service
Felipe Duran, Justin Framing, Inc.
Victor Duraj, University of California, Davis
Fadi Fathallah, PhD, University of California, Davis
Marti Stroup Fisher, Associated General Contractors of California
Jim Lopes, MSPH, CIH, Cal/OSHA Consultation Service
John Howard, MD, MPH, JD, LL.M, Director, National Institute for Occupational Safety and Health
Ira Janowitz, PT, CPE, University of California, Berkeley
Klein Tools
Mary Krost, RPT, OTR, Mary Krost and Associates
Faye Ong, Associate Editor, CDE Press California Department of Education
David Patzer, MS, MHMM, CUSA, California Sanitation Risk Management Authority
Suzanne H. Rodgers, PhD, Consultant in Ergonomics
Augie Sotelo, Sacramento Valley Sheet Metal Workers’ JATC
Dave Thomas, Sacramento Area Electrical Apprenticeship
Len Welsh, MS, JD, Acting Chief, Division of Occupational Safety and Health, California Department of Industrial Relations
Jason Whipple, Sacramento Area Electrical Apprenticeship

Layout and Design

Ken Jackson, Graphic Designer, Link One
Jitan Patel, Graphic Designer, Cal/OSHA Consultation Service

Use BOTH sides of the checklist to compare similar tools. For example, if you have two pliers and want to select the best of the two, compare each tool against the features on the checklist.

The more “Yes” answers the tool has, the better the tool.

Refer to Section D, Tips for Selecting Hand Tools, for more details.			Check if “YES”

Checklist for Hand Tool Selection Select the tool that has the most “YES” answers.		Examples		Single-handle tools		Double-handle tools
				Tool 1	Tool 2	Tool 1	Tool 2
1.	For single-handle tools used for power tasks: Does the tool feel comfortable and have a handle diameter between 1 1/4 inches and 2 inches?
2.	For single-handle tools used for precision tasks: Is the handle diameter between 1/4 inch and 1/ 2 inch?
3.	For double-handle tools used for power tasks: Is the grip span at least 2 inches when closed and no more than 3 1/2 inches when open?
4.	For double-handle tools used for precision tasks: Is the grip span no less than 1 inch when closed and no more than 3 inches when open?
5.	For double-handle tools: Is the handle spring-loaded?
6.	Is the tool handle without sharp edges or finger grooves?
7.	Is the tool handle coated with soft material?
8.	Can the tool be used while keeping your wrist straight?
9.	Can the tool be used with your dominant hand or with either hand?
10.	For high-force tasks: Is the handle longer than the widest part of your hand (usually 4 inches to 6 inches)?
11.	Does the tool handle have a non-slip surface?

Dababneh A, Lowe B, Krieg E, Kong Y, and Waters T, A Checklist for the Ergonomic Evaluation of Non-Powered Hand Tools, accepted for publication in the December 2004 issue of the Journal of Occupational and Environmental Hygiene.

NOTES:

Cal/OSHA and NIOSH value and welcome your comments about our booklet. Send your comments to us at: dosheducation@dir.ca.gov. We want to provide the best possible service to employers and employees.



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	DHHS (NIOSH) PUBLICATION No. 2004-164