Ergonomic Analysis of Lifting and Carrying Milling Screens

In many processing plants and specifically at Poet’s Lake Crystal MN ethanol plant there are hammermills used for grinding corn. These hammermills have screens that must be changed regularly, often two screens a week. The screens are roughly 48 by 74 inches and a quarter inch thick. They weigh 40 pounds, have poor grip, and are flimsy. They must be carried roughly 50 yards and up a flight of 27 steps. Revised NIOSH Lifting Equation and the SNOOK table assessments were conducted on the task and various ways of carrying it out. While the SNOOK tables were inadequate for an accurate analysis of the carrying task due to the long distance, some useful observations were obtained using the tables. For example, using the Snook Table for the highest distance, it is observed that only a small portion of the population can perform this task. Two improvement ideas (Jaw Claw and Magnet handle) were thought of as well, NIOSH assessment was conducted on them and it was found that they would greatly decrease the NIOSH lifting score, however neither improvement worked when tested out in the field. Neither the Jaw Claw, nor the Magnet Handle were proven to be better than using no assistance in carrying the screens. The original lifting method performed by a plant technician yielded a high NIOSH Index over three. However, another technique proposed by another technician was tested and observed to be a better lifting technique, which resulted in a lower NIOSH Lifting Index of 1.63. Therefore, proper training could help technicians lift with the safer technique. Nevertheless, none of these tools were observed to be fully capable of assessing the entire task. As no other appropriate tools were observed to be more effective for the ergonomic assessments for this type of task, the task was broken down for analysis, which could limit the use of these tools for a proper ergonomic assessment of this type of work-tasks, and therefore the findings from this study.  Nevertheless, the invaluable information obtained from using these tools has provided enough insight into the ergonomic issues resulting in better lifting and carrying techniques for these types of real-world industrial tasks.

Presenting Speaker