Construction Solutions - Rebar-Tying Tools



Solution: Rebar-Tying Tools
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	Description:	Ironworkers tie rebar by hand with pliers and tie wire. This work requires repeated, fast hand and arm movements while applying a lot of force. If you tie rebar at ground level, you also have to work in a stooped position, with your body bent deeply forward. The image on the left shows the problem, while the image on the right illustrates the solution. More Detail Both manual and battery-powered rebar-tying tools are currently available. Battery-powered rebar tiers automatically fasten the bars together with tie wire. They can be used whenever a simple "wrap and twist" tie is needed. However, they do not provide the strength of "saddle" or "figure-8" ties. Several companies offer power rebar tiers. On the MAX USA models, when you press the trigger, the tool feeds wire around the bars and then twists and cuts the wire. The MAX USA models are not stand-up tools, but an adjustable extension handle is available. The TyTecker® is a stand-up power tier that uses coiled wire to hold the bars together. The tool automatically "screws" (or spins) fat coiled wire around the intersecting bars. The TyTecker® was designed using ergonomic principles. One manual tool, the Jiffy Clip, holds the rebar together using molded polymer-based clips. You position the tool over the intersecting bars and push down to fix the clip. The Jiffy Clip holds 30 clips in a magazine and lets you work standing up. Less Detail
	Risks Addressed:	Tying rebar by hand increases your chance of developing hand-wrist disorders due to the high hand forces used to grip pliers, the rapid hand movements used to wrap and twist wire, and the high pressure on the hand and fngers when twisting and cutting wire. If you work at ground level, you also are at risk of low back injuries from frequent and prolonged stooping and bending.
	How Risks are Reduced:	Use a rebar-tying tool. This lowers your risk of hand and wrist injury because it eliminates the frequent rapid hand motions required when using pliers. Some rebar tiers allow you to work standing up, so there is less stress on your low back due to stooping and bending. Quality of Evidence Safety and health experts believe there is a risk reduction. Biomechanical research shows that high compression forces occur in the spine while stooping, and that sustained or repeated flexion of the spine may decrease the stability of the lower back and increase the risk of fatigue, leaving the back more vulnerable to injury. While there is considerable research that shows that working in stooped, kneeling and squatting postures causes low back disorders, the research mostly focuses on those postures in combination with other risk factors such as bending or twisting or heavy loads. The literature combining stooped, squatting or kneeling postures with load handling shows rapid and severe spinal damage. There is much less in the literature regarding the health effects of these postures in an unloaded situation - that is, stooping without lifting. However, safety and health experts believe that it is important to avoid prolonged and repeat forward bending of the back (stooping) even in the absence of the other risk factors for low back disorders.
	Effects on Productivity:	There have been documented increases in productivity. The NIOSH-Ontario studies found that power tying tools can tie rebar twice as fast as hand tying. Actual productivity increases will depend on the type of work and the frequency of tying. Also, contractors and rod busters who used the model of power tool involved in the studies reported they preferred it to manual tying for that work. Before using one of these tying tools, make sure the ties are approved for the job you will be doing. Quality of Evidence Manufacturers or vendors have reported an increase in productivity. Safety and health experts believe there is an increase in productivity. Workers should experience fewer injuries. Studies conducted by NIOSH and the Construction Safety Association of Ontario (Canada) compared manual methods and one model of power tying tool, and showed that using the power tool may reduce the risk of injury to workers' hands, wrists, and low back.
	Return on Investment:	No specific calculation ROI information exists for this particular solution, however, there are some general approaches that might be useful for a “Return On Investment” analysis. For a general discussion of these approaches, visit our “Return on Investment Calculation” page.
	Availability:	Where to Get It MAX USA Corp., Mineola, NY, www.maxusacorp.com TyTecker®, Rotterdam, Netherlands, www.tytecker.com Jiffy Clip Inc., Salem, OR, www.jiffyclip.com Approximate Cost MAX USA models are under $2,700 and wire costs around 2 cents per tie. TyTecker® models are under $1,300 and wire costs around 3 cents per tie. Powered models generally require extra batteries and chargers, which may be included in the price. Jiffy Clip models are under $400, but the polymer clips are more expensive than the wire used by other manufacturers' tools. Clips cost around 12 cents per tie. Jiffy Clips may be used with or without an extended applicator, which could be useful for small jobs where more expensive rebar tiers may not be cost effective.
	Additional Considerations:	Design or engineering specifications should use rebar diameters that allow tying all rebar with the same tool, and use performance-based specifications that allow non-traditional clips or other connectors. Most specifications already use performance-based language for describing rebar ties. Use of these devices requires performance based specification that allow this as an option. While rebar tying tools can reduce the risk of injury to iron workers, the workers themselves are resistant to using them. One reason given is that the tools are 'deskilling'. To increase the potential for successful adoption it will be important to gain worker support to using these tools prior to purchase.
	Sources:	Albers, James T., and Estill, Cheryl F. Simple Solutions: Ergonomics for Construction Workers. DHHS (NIOSH) Publications. March 2007. http://www.cdc.gov/niosh. To view the Table of Contents for the Simple Solutions Document, please visit: http://www.cpwr.com/simple.html. Please send requests for copies of this publication to cdcinfo@cdc.gov, referencing document number 2007-122.