Advanced Ergonomics

MOS 6701, Advanced Ergonomics 1

Course Learning Outcomes for Unit VI Upon completion of this unit, students should be able to:

7. Evaluate common controls for mitigating ergonomic-related hazards. 7.1 Discuss the impact of hand tool design on injury and musculoskeletal disorder (MSD) risk. 7.2 Recommend control strategies for reducing ergonomic risk with proper tool design.

Course/Unit Learning Outcomes

Learning Activity

7.1

Unit Lesson Chapter 5, pp. 174–182 Chapter 13, pp. 477–504 Unit VI PowerPoint Presentation

7.2

Unit Lesson Chapter 5, pp. 174–182 Chapter 13, pp. 477–504 Unit VI PowerPoint Presentation

Reading Assignment Chapter 5: Repetitive Tasks: Risk Assessment and Task Design, pp. 174–182 Chapter 13: Displays and Controls, pp. 477–504

Unit Lesson Meet Ms. Margie Getta-Grip Margie Getta-Grip is a technician at Wrazer Pharmaceuticals, a small pharmaceutical manufacturer in Middleton, Tennessee. As a pharmaceutical technician, Ms. Getta-Grip is required to perform various tasks repetitively throughout her eight-hour work shift, including hand tightening vaccine jug lids, visually inspecting the jugs, loading the jugs into boxes, and manually transporting the boxes to a nearby pallet. Ms. Getta-Grip has been employed with the company for three years and often complains of pain and swelling in her hands at the end of the work day. Lately, the pain has become so intense that Ms. Getta-Grip is hardly able to tighten the lids as required. After noticing a decrease in productivity of several of the technicians performing the lid tightening task, Ms. Getta-Grip’s supervisor, Mr. Cardman, calls her to his office to discuss her job performance. Mr. Cardman explains if the lids are not properly tightened, the jugs could leak or the product could spoil that would potentially cost the company thousands of dollars. Ms. Getta-Grip assures Mr. Cardman that she is trying to do her best, but she is having problems tightening the lids properly due to the pain in her hands. Ms. Getta- Grip explains to Mr. Cardman that it is difficult to judge the cap torque. She also tells him she is placing extra stress on her hands trying to tighten the lids properly. Following his conversation with Ms. Getta-Grip and the other technicians, Mr. Cardman contacts the College of Safety and Emergency Services at Columbia Southern University (CSU) for assistance with his problem. The university informs Mr. Cardman there is a graduate of the Occupational Safety and Health (OSH) program who lives in his area and works as a safety consultant. Mr. Cardman thanks the university and immediately contacts the CSU alumnus who goes in and performs an evaluation of the lid tightening job.

UNIT VI STUDY GUIDE

Controlling Ergonomic Risks Factor Exposure: Tool and Equipment Design

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Upon completion of the evaluation, Mr. Cardman receives a report from the consultant with a recommendation for a simple, cost effective solution. Although he was a little skeptical at first, Mr. Cardman implemented the recommendation and was amazed at the results.

 The fix? The company redesigned the task and eliminated the manual hand tightening by purchasing a dial torque wrench, making a special cap torque attachment, and training the technicians how to use the new equipment.

 The cost? About $6 per worker

 The benefits? Increased production, increased quality, decreased injuries, improved employee morale—Priceless!

Ergonomic Tool Design Hand tools are commonly used in occupational settings, such as construction, manufacturing, and agriculture, to perform tasks that require more precision or more force than a person’s hands can safely sustain (Chengalur, Rodgers, & Bernard, 2004). Whether manual (e.g., screwdrivers, pliers, wrenches, clamps) or powered (e.g., air guns, chain saws, grinders), hand tools can be used to extend the capabilities of the human hand by increasing grip strength, torque strength, impact strength, fine control, and the ability to handle larger volumes of content (Lehto & Landry, 2012). Hand tools can also be used to give the hand new capabilities; for example, a disabled worker might use a hand tool to perform the function of a damaged limb or another body part thus allowing him or her to perform comparable to a nondisabled worker. In the past few years, ergonomic guidelines have received considerable attention in tool design, and many manufacturers are now marketing their tools as ergonomically designed. Drop by your local hardware or home improvement store, and you are sure to see aisles full of tools labeled ergonomic., but what exactly does that mean to consumers who may or may not be familiar with the term ergonomics? More importantly, what does that mean to you as a safety professional who may one day be required to help with tool selection as part of your job duties? How do you determine what makes a tool an ergonomic tool?

Hand tool (Kuzmenkova, 2017)

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You may recall from a previous unit, ergonomics is the science of designing and producing tools, equipment, and processes that improve a worker's efficiency while reducing discomfort, fatigue, and risk of injury. Therefore, a tool design is considered ergonomic if it does the following.

Ergonomic design enhancements include features such as angled handles, padded handgrips, and non-slip coatings. Regardless of how many ergonomic features it has or how impressive the design may be, a hand tool is rarely universally ergonomic. Peoples’ hand characteristics vary greatly as do the types of job tasks for which the hand tools are used. Therefore, one of the most fundamental challenges in hand tool design is optimizing the dimensions of the tool in relation to the user’s hand anthropometry. A tool becomes ergonomic only when it fits the user performing the task, without requiring or causing awkward postures, harmful contact pressures, or other safety and health risks (Stack, Ostrom, & Wilhelmsen, 2016).

Ergonomic criteria (Radwin, 2003, Slide 6)

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Another common issue associated with hand tools is ensuring the use of the right tool for a particular task. Unfortunately, many people select the wrong tools, use tools improperly, and/or improvise with what they have on hand, literally. Just think of how many times you have seen someone using his or her hand as a hammer rather than simply getting a hammer, or perhaps you have seen someone moving something with his or her hands that could be more efficiently transferred with another tool, such as a shovel. Even using an ergonomically designed tool may do more harm than good if it is used inappropriately. Tools are designed for specific uses hence the reason screwdrivers come in various lengths and tip styles and pliers come with different head shapes. The key things to consider when selecting hand tools for a job are whether or not the tool fits the user’s hand, whether the tool is appropriate for the job being done, and whether or not the tool eases the work and prevents the user from straining in ways that could lead to injury. Hand Tool Design and Musculoskeletal Disorders (MSDs) Hand tools may be used occasionally for tasks such as opening a valve in a maintenance and repair operation or repetitively for tasks such as grinding burrs from metal parts in an assembly operation. MSD risk factors are significantly influenced by the type and design of the hand tools selected as well as the duration of the use of the hand tool. Using a hand tool for several hours daily can stress muscles and ligaments. Risk factors associated with the use of hand tools include awkward wrist and hand postures, static muscle loading, mechanical stress, vibration, noise, forceful exertion, temperature, and pinch points. While disorders commonly associated with the use of non-powdered and powered hand tools include acute musculoskeletal problems; muscle, tendon, or ligament tears; bone fractures; chronic MSDs; vascular disorders; vibration white finger; hearing impairments; and respiratory disorders. Hand tools designed with consideration for the work tasks to be performed can greatly minimize the worker’s exposure to risk factors for MSD. However, using a poorly designed tool or using an inappropriate tool for the job task could have a negative impact on the entire body as the hand tool dictates the postures assumed by the worker to complete the task and determines the force requirements necessary to operate the tool. Such tools can also directly apply unwanted forces or vibrations to other body parts. Exposure to continuous vibration can also cause numbness or poor circulation in hands and arms. Controlling Ergonomic Risk Exposure with Proper Tool Design How can risk for work-related musculoskeletal disorders resulting from the use of hand tools be reduced? Proper attention to selection, design, and layout of tools are all key factors in making hand tool use safe and minimizing the risk of developing musculoskeletal injuries. An effective prevention strategy must address all aspects at the same time. The following are some guidelines to remember when making tool selection.

Using hands as a shovel (Valmedia Creatives, 2017)

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Ergonomic Selection Criteria for Selecting Hand Tools to Reduce Risk of Injury

Select tools designed for the specific application. Using a tool that fits the job reduces the risk of damaging the tool and injuring the user. Consideration should be given to the whether the task requires precision or power, as that will also determine the most appropriate hand tool to use. For example, trying to use a screwdriver, which is better suited for precision tasks, to do something that requires pliers, which are better suited for power tasks. Select tools that can be used within the work space available. Using the wrong tool in a cramped work space will increase the force requirements and make it harder to get the work completed. For example, trying to use a long-handled tool in a cramped work space may cause the user to exert more force and have to work in an awkward posture to operate the tool. Select tools that require the least continuous force and allow work to be performed in a neutral or natural posture. Trying to perform work on items that are not positioned appropriately can affect the work posture, for example, raising the shoulder and elbow to use a tool. Using the right tools can help with keeping the body in a relaxed and neutral position. Select tools that are most appropriate for the job. Using manual hand tools requires frequent and repetitive use of force to perform a task or job and increases the risk of contracting a MSD. One of the most effective ways to reduce injury risk associated with the use of manual hand tools is to replace them with power tools. Consideration should be given to all aspects of the powered tool (weight, size, etc.) to ensure that one type of hazard has not been exchanged for another.

Ergonomic criteria (The National Institute for Occupational Safety and Health, 2004)

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Conclusion The design of hand tools can be a complicated ergonomic task when given all the factors that must be simultaneously considered. Hand tools should be designed to fit the contours of the hand and accommodate the strength and energy capabilities required for task performance without overloading the body. In addition, tools should be designed so that they can be held securely while maintaining a straight wrist and proper arm posture (McCauley-Bush, 2012). Selecting the appropriate hand tool for a task must be done with consideration for the ergonomic impact of the design of the tool. User and task characteristics need to be evaluated prior to hand tool selection to ensure that the hand tool can be used safely and efficiently. Emphasis should also be placed on characteristics such as orientation, handle specifications (size, span, material), activation methods, and required applied forces to ensure the tools selected reduce the risk of injury as well as minimize the potential for the development of MSDs.

References Chengalur, S. N., Rodgers, S. H., & Bernard, T. E. (Eds.). (2004). Kodak’s ergonomic design for people at

work (2nd ed.). Hoboken, NJ: Wiley. Kuzmenkova, V. (2017). ID 103061233 [Photograph]. Retrieved from https://www.dreamstime.com/hand-

holding-tool-tool-kit-car-isolated-white-background-hand-holding-tool-tool-kit-car-image103061233 Lehto, M. R., & Landry, S. J. (2012). Introduction to human factors and ergonomics for engineers (2nd ed.).

Boca Raton, FL: CRC Press. McCauley-Bush, P. (2012). Ergonomics: Foundational principles, applications, and technologies. Boca Raton,

FL: CRC Press. National Institute for Occupational Safety and Health. (2004). Easy ergonomics: A guide to selecting non-

powered hand tools (DHHS [NIOSH] Publication No. 2004–164). Retrieved from https://www.cdc.gov/niosh/docs/2004-164/pdfs/2004-164.pdf?id=10.26616/NIOSHPUB2004164

Radwin, R. G. (2003). Ergonomically-designed hand tools [PowerPoint slides]. Retrieved from

http://eadc.engr.wisc.edu/Web_Documents/AIHCE%202003.pdf Stack, T., Ostrom, L. T., & Wilhelmsen, C. A. (2016). Occupational ergonomics: A practical approach.

Hoboken, NJ: Wiley. Valmedia Creatives. (2017). ID 121747298 [Photograph]. Retrieved from https://www.dreamstime.com/man-

working-landscaping-project-man-using-his-hands-to-take-load-wood-chips-inside-wheelbarrow-as- part-image121747298

Suggested Reading Reading Chapter 14 of the course textbook will give you some ideas on the use of the Internet and visibility. Chapter 14: Interactive Devices and the Internet, pp. 517–539 In order to access the following resource, click on the link below. The U.S. Department of Transportation, Federal Aviation Administration has compiled a report entitled Human Factors Criteria for Displays: A Human Factors Design Standard. This report is recommended to supplement the required readings on displays and controls.

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Ahlstrom, V., & Kudrick, B. (2007). Human factors criteria for displays: A human factors design standard (Report No. DOT/FAA/TC-07/11). Retrieved from http://hf.tc.faa.gov/publications/2007-human- factors-criteria-for-displays/full_text.pdf

Learning Activities (Nongraded) Nongraded Learning Activities are provided to aid students in their course of study. You do not have to submit them. If you have questions, contact your instructor for further guidance and information. The following activity is designed to help you understand the importance of handle size in tool selection. Select two screwdrivers from your toolbox or tool drawer. Try to find one whose handle has a diameter size that complements your hand and another one whose handle has a smaller diameter size. Use the two screwdrivers to remove and replace a few screws around your house. Make a notation of the observed differences in gripping the two screwdrivers.