The first operator on each line assembled the cabinet and fused the parts of the cabinet together using an

ultrasonic welder. One operator could assemble and weld nine cabinets per hour. The second operator

assembled the door for Parcel Guard. The door featured a complicated design, and a skilled operator could

complete one door sub$-$assembly in $6\mathrm{.}4$ minutes. The third operator installed the wiring harness and door

sub$-$assembly. Installing both the wiring harness and door sub$-$assembly took $8\mathrm{.}1$ minutes. The fourth

operator completed the wiring by connecting the power supply to the lock mechanism, siren, load cells, and

main control panel. One operator could install the various electrical components and complete the wiring

for $8\mathrm{.}5$ units in one hour. The fifth operator was responsible for the final inspection as well as testing the

electrical functions of Parcel Guard. The inspection took no more than $90$ seconds, and the electrical test

was automated through a dedicated software program designed to put Parcel Guard through a number of

authentication procedures. The electrical test took a total of $15$ minutes, including the labour to initiate the

test procedure and read the results. The technician could test three Parcel Guards at one time. The sixth and

final operation was packaging. One operator took a total of five minutes to package one unit; it then took

four minutes to stack six packaged Parcel Guards onto a pallet and prepare the pallet for shipping