Discussion of Results
Conclusions from these results will be difficult to obtain because not all of the relevant factors were given. For example, since it is impossible to factor in cost of material and cost of labor, our results should be considered incomplete or perhaps inadequate to draw conclusions from.
For the paced lines, the third line has the best performance. Even though it had a dismal rejection rate (50%), the throughput was so high (180 items per hour) that we would still get overall production of 90 switchboxes per hour, which was much higher than the other 2 paced lines which had longer cycle times. However, there is some relevant data that is missing. What is the cost of the material? It could perhaps be said that this line is grossly inefficient because we are, in effect, throwing away half of our raw materials. If our material cost is high, this would adversely impact our company. Also, what about the morale of the workers? It was quite visible that they were under much stress working with such a low cycle time. Could they keep this pace up for hours and hours? Would they quit? Would the rejection rate of the switchboxes increase? These are all relevant criteria in which to judge the efficiency of our line.
Out of the two unpaced lines, experiment 4 is more efficient. Even though it has a higher idle time, it has a higher throughput and a lower line imbalance. In retrospect, it could be said that a higher idle time is an advantage for experiment 4 because even though the workers are idle for longer, they get more work done. A high idle time would probably be helpful in alleviating feelings of being overworked.
Comparing the best unpaced line (experiment 4) and the best paced line (experiment 3), it is clear that the unpaced line has a clear advantage. Even though the paced line had a higher throughput (180 versus 120), its 50% rejection rate means that only 90 units will be produced every hour. Also, the paced line has a higher idle time and only a slightly better line balance.
For experiment four, starving occurred at station 4 and 5. This was probably because the employees at those stations were underworked. While the first three stations were balanced, stations 4 and 5 had much quicker tasks, which left them idle as they waited for station 3 to finish his task. Conversely, in experiment 5, the first three stations were blocked, the fourth was OK, and last one was starved. This was obviously because station 1 was underworked (enabling him to finish his task very quickly and place his switchboxes in the queue), station 2 was fine, but since station 3 was overworked, this blocked both station 2 and station 1. The line was terribly unbalanced and inefficient.
Even though our results show that an unpaced line is better suited for this kind of production, there are some instances where a paced line would be preferred. If the nature of the assembly line was inherently unbalanced (one station had a lot more work to do), a paced line would be better because even though one employee would have lots of idle time, this would prevent the others from being blocked. Also, for very diligent and difficult work, a paced line (with adequate time) might be preferred to prevent the workers from feeling rushed.
Conclusion:
This experiment clearly showed that the unpaced lines had better performance than the paced lines. Their idle times were lower, their throughputs were higher, and they had a nonexistent rejection rate. Also, the value of balancing lines and reducing idle times were shown, to increase efficiency and profits for the company producing the materials.
However, in this laboratory setting, there is only so much that this type of experiment could teach us. As discussed above, some crucial factors were omitted and ignored for the sake of expediency. For example, worker morale, cost of material, and cost of labor were all ignored. So, while experiment 4 may have seemed the best in theory, there is no way of knowing whether human workers can make 120 switchboxes every hour without making any costly errors or being overcome with fatigue or apathy. Also, this experiment ignored specialization of skills, which would undoubtedly become important in an assembly line manufacturing something more complicated than a switchbox.
In the final analysis, this experiment was very useful in showing the many important criteria that an efficient assembly line must meet.
