ProcessAnalysis Practice Problem

PorthosBakery Exercise

#1. Calculate the cycle time and theoretical capacity for each step inthe process.


Cycle time (average in minutes/lb. &amp lbs./minute)

Theoretical capacity (#lbs. hour &amp #lbs. daily)

1. Mixing

10lbs/10min*3 machines = 30lbs/10min = lbs./min &amp 0.33min/lb.

lbs./min* 60 min = 180lbs/hour

180lbs/hour*8 hours = 1,440lbs/day

2. Proofing

10lbs/30min * 7 machines =70lbs/30min = 2.33/min &amp 0.429min/lb.

2.33lbs/min * 60 = 140lbs/hour

140lbs/hr.*8 = 1120lbs/day

3. Baking

40lbs/60min * 4 machines = 160lbs/60min = 2.67lbs/min &amp 0.375min/lb.

2.67lbs/min * 60min = 160lbs/hr.

&amp 160lbs/hr. * 8 = 1280lbs/day

4. Packaging

75lbs/hr. * 3 machines = 225lbs/hr./60 min = 3.75lbs/min

&amp 0.267min/lb.

225lbs/hr. * hours = 1,800lbs/day

  1. Identify the bottleneck step, the system cycle time and the capacity of the system in an 8-hour day?

  • Cycle time for mixing = 1440lbs/8hrs, 1lb/0.006hrs, therefore the cycle time is 0.36 min.

  • Cycle time for proofing = 1120lbs/8hrs, 1lb/0.007hrs, therefore, cycle time is 0.43 min.

  • Cycle time for baking = 1280lbs/8hrs, 1lb/0.00625hrs, therefore, cycle time is 0.38 min.

  • Cycle time for packaging = 1800lbs/8hrs, 1lb/0.004hrs, therefore, cycle time is 0.27 min.

  • System cycle time is the cycle time for the bottleneck step = 0.43 min.

  • The bottleneck step is the step with the longest cycle time, which is Proofing.

  • Capacity of system = 8hrs.*60/0.43 = 1,116.3lbs.

  1. What is the throughput time for the average sized order? Assume that just one machine or resource is used at each process step.

  • Throughput time = lbs. produced/time = 50/8 hrs. = 6.25 lbs. / hour.

  1. What is capacity utilization given average current demand?What is the utilization when the proposed additional demand is included?

  • Capacity utilization at current demand = demand/capacity available = 1000/1116.3*100 = 89.6%

  • Capacity utilization when additional demand is included: 1250/1116.3*100 = 112%

  1. Will the purchase of an additional proofing oven add sufficient additional capacity to allow Porthos to accept the additional restaurant business? If not, what changes do you propose Porthos make to create the additional capacity.

  • Yes. Purchasing an additional proofing oven can add to adequate additional capacity to allow Porthos to accept the restaurant orders. This is because the new oven will reduce the cycle time at the proofing step, thus increasing the average capacity of the entire system. This will enable them to accommodate additional demand.


Krajewski,L. J., Ritzman, L. P., &amp Malhotra, M. K. (2013).&nbspOperationsmanagement: processes and supply chains.New York: Pearson.