Assembly of concrete formwork can be one of the most physically demanding tasks done on a regular basis. It often requires repetitive motions of swinging a hammer to fix forms in place.
The American Conference of Governmental Industrial Hygienists (ACGIH) published Threshold Limit Value (TLV) for upper limb localized fatigue for recommendations for workplace tasks that require the use of upper limbs. This limit is based on what it is believed that most healthy workers can be exposed to daily and still maintain a normal performance and work capacity without experiencing localized musculoskeletal fatigue. This fatigue can be caused by sustained or repeated exertions of the hands and arms that can cause discomfort or reduced upper limb function. This fatigue may be a precursor to chronic soft tissue injuries.
Work performance and duty cycles are measured by the ability to repeat and sustain biomechanical loads. In an effort to study potential options for reducing localized fatigue and the potential for soft tissue injuries, a study was conducted comparing manually hammering duplex nails to using the Milwaukee M18 FUEL Duplex Nailer. In the case of this study, the biomechanical load is the force (% MVC determined based on surface electromyography) it requires to drive a duplex nail in the concrete form. The limiting muscle group for both the M18 Duplex Nailer and using a hammer to drive duplex nails was a forearm extensor muscle. This muscle plays a key role in ulnar deviation of the wrist. For the duplex nailer, the wrist experiences ulnar deviation to grip the main handle of the nailer. In driving the duplex nail with a hammer, the wrist is actively moving to be deviated in the ulnar direction with the swing of the hammer.
The testing revealed a significant increase in the duty cycle when using the Milwaukee M18 FUEL Duplex Nailer versus driving the duplex nails manually. This means, a worker can use the Milwaukee M18 FUEL Duplex Nailer for over 30 minutes longer without experiencing risk of localized fatigue. This difference is amplified by the average time difference between using the M18 Duplex Nailer to drive a duplex nail (approx. 3 seconds) versus manually driving a duplex nail (approx. 15 second average). With this, approximately 2,170 more duplex nails can be driven in concrete formwork when using the Milwaukee M18 FUEL Duplex Nailer versus using a hammer without reaching the duty cycle limit recommendation.
The M18 FUEL Duplex Nailer is just one example of a Milwaukee Tools dedication to improving safety and productivity for the Concrete trades.
