Overexertion injuries from lifting and other manual materials handling activities account for $25\%$ of

industrial accidents involving $12$ million lost days and $$14$ billion in costs. In this case study, you will

you conduct a biomechanical analysis of lifting in a typical palletizing operation at Upstate

Engineering Co$.$ and provide recommendations to the company. The stacker is palletizing boxes of

powdered detergent $(20$x$16$x $8)$ weighing $23$ lbs at a rate of $5$ boxes$/$min for a full $8-$hour shift. There are

four layers of $12$ boxes per layer lying on pallet, the surface of which is $4$ from the floor. The boxes are

taken from a conveyor of height $30$ from the floor with minimum H distance. For simplicity, assume $45-$

degree twisting and that the laborer completes one layer before progressing to the next layer, otherwise a

stack may topple $($although the handler doesn$$t always do that$).$ Calculate H and V based on box sizes and level palletized.

$1.$ Calculate RWL based on NIOSH lifting guidelines for the lowest layer by hand for the origin

and destinations.

$$ Recommended Weight Limit

RWL $=$ LC $\backslash$times HM $\backslash$times VM $\backslash$times DM $\backslash$times AM $\backslash$times FM $\backslash$times CM

Where:

LC $=$ Load Constant $=51$lbs

HM $=$ Horizontal Multiplier $=10/$H

VM $=$ Vertical Multiplier $=10\mathrm{.}0075|$V $30|$

DM $=$ Distance Multiplier $=0\mathrm{.}82+$

$1\mathrm{.}8/$D AM $=$ Assymetry Multiplier $=1$

$0\mathrm{.}0032\backslash$times A

FM $=$ Frequency Multiplier $=$ refer to Frequency Multiplier Table

CM $=$ Coupling Multiplier $=$ refer to Coupling Multiplier Table

H $=$ Horizontal location of the load cg forward of the midpoint between the ankles, $(10<=$ H $<=25$

inches$)$

V $=$ Vertical Location of the load cg$,(0<=$V $<=70$ inches$)$

D $=$ Vertial travel distance between the origin and destination of the lift, $(10<=$ D $<=70$ inches$)$

A $=$ Angle of asymmetry between the hands and feet $($degrees$)$

$2.$ Calculate LI based on NIOSH lifting guidelines.

$3.$ Redesign the task to minimize the stress on the worker. Recalculate both RWL and LI values to

demonstrate that you have improved the task. Consider both expensive $($but very safe$)$ options that

eliminate lifting completely vs$.$ relatively inexpensive modifications that may not eliminate lifting.

Page $3$ of $11$

$$ Review the multipliers in the RWL formula: What can be improved?

$$ Review the measurements: What can be improved? $($H$,$V$,$ A$,$ F$)$

Limitations for the redesign

$$ Productivity should not change significantly.

$$ Can$$t fire the worker.

$$ Can$$t change the size of the box.

$4.$ Discuss the cost$-$benefits of your redesigns, i$.$e$.,$ the risk of injury vs$.$ the cost of redesign. Explain

why your redesign is better than the existing process. Also, don$$t forget productivity! Cost$-$benefits $-$

look on the internet for prices, estimate wages, increases in productivity, etc. Does not need to be exact,

but a fairly good analysis. Is there a high upfront cost? Will your redesigns save money in the long

run?

$5.$ Which method$($s$)$ would you recommend to Upstate Engineering Co$.$ to redesign the process for

loading the boxes?