Homework 6

mines to extinguish the blaze. The cost for this method would be on the order of $100 million. Relocation may be necessary.

R Do nothing. Arrange a federally funded relocation of the entire area and allow the fire to burn unchecked. Approximately $50 million would be required to relocate the town.

This problem was developed by Greg Bennethum, A. Craig Bushman, Stephen George, and Pablo Hendler, University of Michigan, 1990.

8.11. "Solvent Body Wipe Problem": When painting a new automobile it is essential that the exterior surface is clean. Any impurities present when the paint is applied will severely degrade the quality of the paint finish. Consequently, line operators use solvent-moistened wipes to clean the surface of each vehicle body before it enters the paint booth.

Current body wipe operations at one of the Big Three auto companies can be sum- marized as follows. The operator soaks a new, dry body wipe (a white synthetic cloth about 1 foot square) in an open bath of solvent. There is a small amount of spillage and evaporative solvent loss from the bath. After wringing out any excess solvent, the operator wipes down the exterior of the vehicle body. The operator then disposes of the wipe in a drum and moistens a new wipe for the next vehicle. Because the wipes in the drum still contain significant amounts of solvent—a hazardous and possibly toxic substance--the drum is sealed when it becomes full and is sent to a hazardous waste landfill. The safety officer has expressed concern about the level of operator exposure to the toxic solvent fumes.

This cleaning operation must be applied to each vehicle body as it moves along a conveyor belt from the assembly shop into the paint booth. Depending on demand, the production rate may require painting up to 80 bodies per hour. When defects in the paint job are found, the body must be taken offline for spot repairs or complete repainting. If a large percentage of bodies have paint defects, then production of the entire plant can be diminished as repaint jobs backup at the paint shop.

Upper-level management has decided to open another plant that will also require body wipe operations. Due to more stringent environmental, health, and safety regulations for new plants, the liquid hazardous waste must be reduced without slowing production. If possible, management would also like to make other improvements to the current method of cleaning.

Problem: What is the best body wipe method to adopt in the new plant? Engineering proposed four alternative methods which are summarized below:

1. Use each wipe on more than one vehicle. This alternative requires less effort by the operators since they do not need to moisten a wipe as often. Less solvent is applied per vehicle. Not only are the additional operational costs of this alternative

..".."w ,.."...," mow, W.I. solvent, and waste wipes are also sigma-

candy decreased. However, there is a small chance that reusing wipes would leave

impurities on the vehicle and cause the paint coat to crater. While a few vehicles

with impurities would not slow production, many vehicles would.

2. Recycle. This option requires expensive additional equipment to wash the wipes and

recover solvent. The amount of solvent applied to each vehicle would remain the

same but consumption of virgin raw materials would be decreased moderately.

Disposal of waste wipes and solvent would be decreased moderately as well.

However, this process should be monitored closely as recycled wipes would likely

deteriorate after a number of washings and leave lint on the vehicle, thereby causing

paint defects.

3. Incinerate used body wipes. With this option, the energy value of the spent wipes can

be partially recovered. In addition, the need for disposing of hazardous waste is

totally eliminated. It is possible, but unlikely, that the ash will need to be sent to a

landfill as nonhazardous waste. With incineration, there are no changes in the actual

wiping process; the option is completely "end-of-pipe." Therefore, solvent usage

will be unaffected. Incineration is moderately expensive.

4. Use a closed-top bath. The solvent bath would be covered with a lid that the operator

would remove each time he soaks a rag. This option would cut down on solvent

evaporative losses and spillage from the bath, both of which management desires.

However, the amount of solvent applied to each vehicle would stay the same.

Management gives only moderate weight to the actual amount of hazardous waste

diverted from the landfill and to decreasing raw material usage and minimizing

operator effort. The degree of workplace safety hazards (an extremely important

consideration) is influenced weakly by the amount of solvent stored on-site, which

in turn is influenced by the amount of solvent applied to each vehicle. The addi-

tional operating cost of the new method would also be a major consideration.

Finally, management wants the adverse consequences of the top two options to be

addressed, especially the negative impacts on product quality—a very serious issue.

Carry out a K.T. decision analysis to select a method to wipe the cars.

8.12. You need energy for an upcoming sports competition. You have the following

candy bars available to choose from: Snickers, Milky Way, Mars Bar, Heath Bar,

and a granola bar. Which do you choose? Prepare a K.T. decision analysis table.

8.13. Prepare a K.T. decision analysis table on selecting an apartment to move into next

year. Consult your local newspaper to learn of the alternatives available.

Potential Problem Analysis

8.14. "Sandy Beach": There was a minor oil spill on a small sandy resort beach. The CEO

of the company causing the beach shoreline to be soiled with oil said, "Spare no

expense, use the most costly method, steam cleaning, to remove the oil from the sand."