Safety Evaluation of Handling (IPRs) Inside Profile Rolls At Forge and Roll Ring Mill Tooling 1. Introduction: Safety investigation of the inside profile rolls (IPRs) was assigned to the analyst (Ntokozo Makhubu) by Alricha Schoeman (Safety and Loss Control Officer) to analyse the validity of the risk of work-related musculoskeletal disorders which might be caused by the handling of the IPRs. 2. Assumptions: That the selected thin wall IPR is one of the lightest IPRs in weight. That the selected thick wall IPR is one of the heaviest IPRs in weight. Average mass of IPR, based on the thin and thick wall/base is an indication of the average mass carried by the Tooling operator during a change-over. An average of 2 change-overs occurs in a shift. 3. Gathering information: An experiment was done to measure to average weight of the material (IPR) which is to be handled during a Ring-mill change-over. Thin wall and thick base IPRs were selected and weighed on the Saw-bay scale. 10 kg and 27 kg were observed. A video and screenshots were taken of the handling exercise to observe the hand, arm and body movements/postures of the operator during the task. Weighed samples of IPRs to obtain the average weight, DCD Ringrollers: Saw-bay, 18-03-2015 IPRs and Tooling operator, DCD Ringrollers: Ring Mill, 18-03-2015 4. Analysis: Examination of the CTD risk index report shows that the posture and force factors are the major contributing factors to the risk involved in the task. Posture Factor Explained Hand and Body Actions: Reach, Grip, Pull, Move to/away from body, Carry and Release Reach: The reach is done standing balanced while bending the back/neck in an angle less than 45 degrees. Grip and/or Pull: The lateral pinch is used to lift the object, from an unbalanced platform i.e. placed on other IPRs, to plus/minus 20 degrees angle to carry the object. Source: Niebel, B.W. and Freivalds, A. 2003. Methods, Standards, and Work Design. 11th ed. Mc Graw Hill. Page 213-214. Move to/away from body and Release: Observations of the elbow angle being more than ninety degrees while there are signs of shoulder flexion at less than ninety degrees. Release or retrieve is a combination of elbow, shoulder and neck/back action resulting in up/down movements of reach with the IPR. Carry: Forearm rotation (in/out) while the wrists are in flexion during the carrying action. Radial and ulnar deviation when the operator handles/releases the IPR. Force Factor Explained F sin 20° = 181.49 sin 20° = 62.07 N m = F/a = (62.07/9.81) = 6.3 kg Ave. Mass = (10+27)/2 =18.5 kg F = ma = (18.5 x 9.81) = 181.49 N
