Jogging sheets
This case study shows a worker handling several stacks of large sheets from a weigh table to a jogging table. Before reading this, it may be useful to read the "try it out" overview if you have not already.
Task description
- The worker handles large sheets from a weigh table onto to a jogging table, fanning the sheets to separate them. This is repeated until the correct number of sheets are placed on the jogging table. The sheets are then slid across to an automatic lift table.
- Each sheet weighs 0.164kg with the worker lifting around 42 sheets in each stack (7kg). The worker reports that a strong pinch force is required to lift the stack of sheets.
- The cycle time is 90 seconds on average. During this time, the worker picks up a stack of sheets 6 times – it takes about 9 seconds to handle each stack of sheets.
- The shift is 12 hours in duration (7:00 am until 7:00pm) with a 15 minute break at 11:00 and a 15 minute break at 15:00.
- For the purposes of this assessment, assume there is no task rotation.
Scores
Hover over individual rows for an explanation of each risk score.
A1. Arm movements
Arm movements are frequent, but there are regular pauses between handling and when operating the machines.
A2. Repetition
About 6 stacks of sheets are handled within a 90 second cycle time.
B. Force
Each stack lifted weighs about 7kg (3.5 kg in each hand) and is held in a pinch grip. The worker also reports that a strong pinch force is required to lift the bundles. The force is applied for a part of the time (ie 15- 30%), and so this factor is given a Red 9 score.
C1. Head / neck posture
While the worker occasionally looks down at the sheets, the head/neck is held mainly upright and not bent for any significant period of time.
C2. Back posture
While there are occasions when the worker bends forward slightly, this is not more than 20°. This is scored Green 0.
C3. Arm posture
The elbows are raised out to about chest height for a part of the time when handling the sheets. This is due to the width of the sheets.
C4. Wrist posture
The wrists are deviated and bent when fanning the sheets at the beginning of the lift. However, this is only for a very small part of the cycle time (less than 15%) and so an intermediate score of Amber 0.5 is given.
C5. Hand / finger grip
A pinch grip is used for a part of the time to handle the sheets.
D1. Breaks
In addition to the formal breaks, the worker can take frequent short breaks about every minute when the machines are in use. For this reason, the score is Green 0.
D2. Work pace
The worker sets their own pace and reports that it is not difficult to keep up with the work.
D3. Other factors
The work is carried out in a well lit environment, and there are no other reported issues.
Task score
The task score, calculated for each arm separately, is the sum of the scores of all the risk factors.
For example:
3 + 0 + 9 + 0 + 0 + 2 + 0.5 + 1 + 0 + 0 + 0 = 15.5
D4. Duration multiplier
If there is no task rotation, the task is performed for more than 8 hours per day. The duration multiplier is 1.5.
Exposure score
The exposure score, calculated for each arm separately, is found by multiplying the task score by the duration multiplier.
For example:
15.5 x 1.5 = 23.25
The exposure score can be interpreted using the table of exposure levels.
Possible solutions to consider
Reduce force
Height adjustable tables (possibly self levelling) set between the weigh table and the jogging machine might allow the worker to drag the sheets across rather than lift them with a forceful pinch grip.
Reduce exposure
The introduction of air blowers is sometimes helpful to reduce the amount of jogging (and knocking up) of the paper stacks. Regular task rotation could reduce exposure to forceful gripping of the paper stacks.