Civil Engineering Reference
In-Depth Information
FIGURE 49.5 The three tasks of the frozen food packaging job: (a) place two packages in box; (b) record date
time
/
of the packaging and (c) load full box onto pallet.
interpreted as a function of the defined job tasks, as well as in terms of workplace factors such as a box's
location on the pallet.
49.8 Collecting and Recording Workplace Data for Risk
Assessment
The trunk motion information that is used in the LBD risk model is automatically stored in the data
collection software. Trunk motions include the position, the velocity of movement, and the related accel-
eration of the trunk in all three directions of motion during a task — the sagittal (forward bending)
plane, the lateral (side bending) plane, and the rotational (twisting) plane. Two other components, lift
rate and maximum moment, must be determined and input manually.
49.8.1 Lift Rate
Lift rate is defined as the total number of MMH actions that a job requires per hour. This number is
related to the lifts for all tasks combined; it does not change from one task to another within a job.
As the task analysis in Table 49.2 found, on average, one box is fully prepared and loaded onto the
pallet per minute. Assuming this rate represents an average job cycle across the work shift, the packaging
task alone would require 360 lifts per hour, since the product is placed in each of the 60 boxes six times
(two packages per lift). For the palletizing task, 60 lifts are required per hour, for each fully packed box.
Both tasks combine for a total of 420 lifts required per hour for this job. The non-MMH date
time
/
recording task would not influence the lift frequency of the job.
Because the lift rate value is directly input into the LBD risk model, it is very important to get an accu-
rate estimate of the lifting frequency. It may be necessary to confirm the task analysis results by question-
ing the employees familiar with the job or the job supervisor.
TABLE 49.3 Task Analysis of One Cycle of the Frozen Food Packaging Job
Task
Length of Task
Notes
Place two food
packages in box
42 sec
Task time is 7 sec per two boxes
packaged; 12 packages fit
into each box
Record date
time of
10 sec
No manual materials handling
required
/
packaging
Load full box onto
pallet
8 sec
Full pallet contains seven layers
of boxes
Total time of job tasks
60 sec
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