At Rockland Steel, we make steel coils that are ultimately used to form many common consumer products. One of our production facilities is a hot strip mill that turns steel slabs into coils of steel.
Operation Details
Production
The facility produces coils one at a time. A coil can be of varying weight according to the following distribution:
Coil Size % of Coils Rolling Mill Time
Small (100-200 pounds) 50 5 minutes
Medium (200-500 pounds) 30 10 minutes
Large (500 and above pounds) 20 22 minutes
A coil looks similar to a very large roll of toilet paper. A slab can produce one large coil, two medium coils or four small coils. An individual slab cannot be used to make multiple types of coils. (Hint: your Decide module will contain these percentages: 24.5% small, 34.5% medium, 41% large to achieve desired distribution of coils.)
Hot Strip Mill (HSM)
A hot steel slab is run through a sequence of rolling mills to reduce it to a long, thin strip of a given width and thickness. Slabs arrive according to an Exponential distribution with a mean of 20 minutes apart. (All slabs are the same size.) The strip is fed into one coiler at the end of the mill where the coil is formed. The coils are then removed by automated equipment and banded and placed in a common staging area. You can assume that the time to band and place the coils is included in the times given above.
After banding, the coil is staged for pickup/movement to the shipping dock. If it is a small or medium coil it is placed on a conveyor. If large, it must be moved by forklift. It is a type of non-accumulating conveyor that automatically transfers the coils forward toward the delivery end. Both small and medium coils can be assumed to take the same amount of space on the conveyor (15 feet). Each large coil must be transported by forklift(s) which runs at 30 feet per minute. The distance to be covered from the mill to the shipping area is 400 feet for the forklift and 300 feet for the conveyor.
The hot strip mill works continuously 24 hours per day, 7 days per week. Run your simulations for seven days.
Adjust the speed of the conveyor and the number of forklifts needed for this operation. This may affect your output number of coils for each size. Be sure to produce the right mix or coils for sale given in the table above. Discuss the impact of conveyor speed and number of forklifts for your best model. Make sure that your model shows conveyor and forklift animation. Put counters on the screen for coiler queue, conveyor queue, forklift queue and shipped count by coil size. Utilization of forklifts is desired to be as high as possible.