Converters and suppliers work together to find ergonomic solutions.
Bend, lift, twist and push, and repeat. These may sound like instructions for an aerobics class, but these can be motions for converting operations, too. The difference between the two is that the class is probably only an hour, and the weights lifted are less than 4.53 kilograms. Converters, however, deal with these movements all day and lift items like steel shafts that can weight up to 54 kilograms.
Movements such as repetitive exertions of the hand, heavy lifting or pushing, and prolonged awkward postures, are all risk factors for work-related musculoskeletal disorders (WMSD). WMSDs range from mild symptoms to severe debilitating conditions. Examples include carpal tunnel syndrome, tension neck syndrome and low back pain.
Along with distress, WMSDs also cause temporary or permanent disability, which can lead to lost time from work and an increase in workers compensation costs. One way converters can prevent WMSDs and the related costs is through ergonomics.
"Ergonomics is about designing jobs or workplaces to match the capabilities and limitations of the human body," says Sean Craig, product manager for winding products at Tidland Corp. (Camas, WA). "In any converting application, machine operators are performing a variety of functions repeatedly every day. With every roll change there is the potential that someone is going to handle the shaft or roll, and these components need to be designed so that there is no risk of WMSDs over time."
Ergonomic solutions
The following is a list of potential caution jobs in the the converting workplace, the physical risk factor and ergonomic solutions.
Caution job: handling, aligning and loading rolls. Risk factors: awkward posture, repeated impact and heavy lifting. Solution: use automated roll handling equipment, provide adjustable work surfaces and place materials close to the operator in order to reduce twisting motions.
Caution job: handling and loading shafts. Risk factors: awkward posture and heavy lifting. Solution: reduce shaft weight, have adjustable work surfaces to position the roll center 28 to 37 in. from the floor and use automated shaft handling equipment.
Caution job: shaft/chuck actuation. One risk factor is awkward posture. Solution: provide quick-disconnect air valves, pnuematic wrenches and position shaft/chuck at elbow height for ease of actuation.
Caution job: changing core sizes. Risk factors: awkward posture and heavy lifting. Solution: position shafts/chucks above elbow height and use lightweight adapters for changing core sizes.
Caution job: maintaining shafts/chucks. Risk factors: awkward posture, repeated impact and heavy lifting. Solution: position shaft/chucks above elbow height, provide mechanical pullers and use the on-machine maintenance feature.
This list is not all-inclusive. In order to determine and implement solutions, converters should work with their suppliers to come up with proper ergonomic tools. They can also turn to the Occupational Safety & Health Administration (OSHA), which has a comprehensive approach for addressing WMSDs and providing strategies for reducing injury rates. OSHA also has 10 ergonomic coordinators who can help set up ergonomic programs.
"As converters learn from their employees which tasks are the most difficult and/or dangerous, they ask their vendors to design and supply equipment with features which eliminate the need for operators to perform actions such as lifting and turning rolls by hand, that may cause injury and fatigue," says Jeff Damour, engineering mgr. for Converter Accessory Corp. (Wind Gap, PA).
Keep ergonomics in mind
According to suppliers of rolls, shafts and materials-handling equipment, converters look for lighter weight components. Standard steel shafts with 7.62 cm. diameters weigh about 23 to 34 kilograms and shafts with 15 cm. diameters weigh 41 to 54 kilograms. Converters want shafts that weight about half as much but still maintain the strength needed to handle heavy roll weights and fast line speeds. But, lightweight components often have less roll-carrying capacity or speed capabilities.
Tidland Corp. has dealt with this dilemma by engineering a more rigid aluminum cross-section for the shaft bodies that can be extruded. "By doing this, we were able to compensate for the strength and deflection limitation inherent in standard aluminum tubing," Craig says. "For core shafts, the result is a lightweight, yet very strong, rigid tube which can support the desired roll weights and run at higher speeds."
Despite some of the drawbacks of lightweight equipment, it is still one of the most requested types of products. "A lighter shaft is frequently a simpler and more cost-effective solution than cumbersome handling devices," says Bret Hardy, marketing mgr. at Double E Co. (Bridge-water, MA).
However, there are converters looking for handling equipment for materials that only weigh 20 to 40 lbs. "This may seem like an overreaction, but consider the employee handling hundreds of these objects throughout the day," says Chris van Haasteren, president of Schlumf, Inc. (Windham, ME). "Operators under these circumstances are subject to extreme fatigue and repetitive motion injuries, so in the long run it's very worthwhile for a company to invest in an ounce of prevention."
When looking for materials-handling equipment it is important to get everyone involved in the decision-making process, especially the people who must use the equipment.
"The simpler a handling device is, the more likely the operator is to use it," van Haasteren says. "We often find that the least complex solution is often the best solution."
Benefits of ergonomics
The availability of ergonomic tools and increased awareness about WMSDs, has helped the industry realize the benefits of ergonomics. The Puget Sound Human Factors and Ergonomics Society in Olympia, WA, evaluated 250 case studies on the benefits of ergonomics and found that places with ergonomics programs showed an average reduction in WMSDs by 55 percent. The average reduction in WMSD-related costs was 70 percent and productivity increased by 20 percent. These results are typical nationwide, the society says.
"The high cost of workers' compensation insurance, medical costs and the pain and suffering borne by employees has significantly increased employer awareness and therefore increased the demand for ergonomic handling equipment," van Haasteren says. "Where a chronic repetitive motion injury, carpal tunnel syndrome for example, may have been overlooked or ignored in the past, employers are now very focused on injury avoidance and early treatment to keep the effected employees healthy and at work, which can result in significant cost savings.