Homework 1 due: 08/26/16 before class 50 points

1. Capacity Analysis (25 points)

Abrasives Corp. manufactures industrial diamonds for use in the cutting, machining and drilling industries. They produce the highest quality diamonds in the industry, and can sell any amount they can produce for $6 per carat. Abrasive Corp runs 24 hours per day, 7 days per week.

Abrasive Corp.’s production process has six steps:

Graphite Core Manufacturing: There are two machines, each capable of producing 14 cores per hour.

Ceramic Tube Manufacturing: There are three machines, each capable of producing 12 tubes per hour.

Ceramic End Cap Manufacturing: There are four machines, each capable of producing 20 end caps per hour.

Cell Assembly. A complete cell is produced by placing the graphite core in the ceramic tube and closing each end of the ceramic tube using an end cap, i.e., two end caps in total per cell. One person can assemble a cell in 4 minutes. There are 2 people working in cell assembly.

Pressing. Each cell is placed in a single machine, where it is subjected to high pressures and temperatures. Each cell produces 50 carats of diamond. A machine can process one cell per hour. There are 22 pressing machines.

Separation. The diamonds produced during pressing need to be separated from the graphite. This requires a special chemical treatment in a reactor. A reactor (a type of machine) processes the cells in batches of 100. It takes 35 seconds per cell to load the reactor. Regardless of how many cells are processed, the reactor must be run for 8 hours after being loaded. At that point, the reactor is unloaded. It takes 20 seconds per cell to unload the reactor. There are two reactors.

(a) (13 points) What is the capacity (in carats per hour) of each of the six steps?

(b) (2 points) How many carats per hour can Abrasives Corp. produce?

(c) (10 points) There are two alternative reactor technologies that Abrasives Corp. could alsouse. These alternative reactor technologies both have faster load/unload times. (The run time is 8 hours for these technologies, and both technologies use a batch size of 100 cells).

Technology A: This type of reactor costs $500,000 but can do the loading in 25 seconds per cell and the unloading in 13 seconds per cell.

Technology B: This type of reactor costs $550,000 but can do the loading in 15 seconds per cell and the unloading in 5 seconds per cell.

Abrasives Corp can dispose of current reactors at no cost. What investments, if any, would you make in new reactors? Why?

2. Waiting Line Management (25 points)

During the busy lunch period at Café McColl, customers arrive at the rate of 200 customers/hour. Studies have indicated that 30% of the customers order their lunch from the Grill, and 50% of customers get lunch from the Deli (the remaining 20% just get self-service items). All customers pay for their food at the cash register. On average, the grill-chef takes 40 seconds to serve a customer, the deli-chef takes 30 seconds, and the register-clerk takes 12 seconds. (Assume that all service time and interarrival times are distributed exponentially, and that there is one employee at each of the three stations.)

(a) (10 points) What is the average throughput time (including both waiting and service time) atthe Grill? The Deli? The Register?

(b) (5 points) How long does the average customer spend acquiring their meal at CaféMcColl (don’t count the time walking from one spot to another or getting self-service items)?

(c) (10 points) As manager of Café McColl, you have been authorized by the state legislature (all salary increases must be approved by this body) to give a performance bonus to one of your employees. This bonus will cause the employee to work 10% faster. Which employee -- grill-chef, deli-chef, or register-clerk -- should receive this bonus (in addition to any calculations you perform, please give a one sentence justification for your choice)?