PROCESS ANALYTICS HANDBOOK
Problem 1: Three Step Process Assignment Questions Process 1 To begin, consider the three-step process model in the Process 1 tab. The process is staffed by three workers: Alice is assigned to step A, Bob is assigned to step B, and Charlie is assigned to step C. Please answer the questions below. 1. What is the bottleneck of this process?
Process B
2. What is the cycle time of this process?
5 mins
3. What is the capacity of this process?
12 per hour
4. What is the throughput time or a rush order (that is, an order arriving when the system is empty that is moved through the process without delay)?
10 mins
5. What is the labor utilization of each worker?
60%, 100%, 40%
6. What is the average labor utilization of the workers?
66.67%
Process 2 Now that you have finished Process 1, consider the same process, but assume we assign Betty, an additional worker, to a step B. Betty and Bob are equally qualified, and they are told to split the work of step B (working simultaneously complete the 5 minutes of work on a unit in half that time). 1.
Before doing any calculations, which process metrics would you expect to change relative to Process1
2.
What is the cycle time of this process?
3.
3 mins What is the capacity of this process?
4.
Cycle time, worker utilization
20 units/hour
What is the throughput time for a rush order (that is, an order arriving when the system is empty that is moved through the process without delay)?
5.
10 mins What is the labor utilization of each worker?
6.
100%, 83%, 83%, 67% What is the average labor utilization of the workers?
83%
7.
What have you learned?
Concepts like labour utilization rate and average labour utilization.
Process 3 Look at Process 3, a variant of Process 1 ( 3 workers, Alice does step A, Bob step B, and Charlie step C). However, assume that steps A and B can be completed in parallel, as shown in the process diagram. (“In parallel” means that Alice can work on her component at the same time as Bob works on his component. For example, Alice could be finishing a table top at the same time Bob is finishing the four legs, and Charlie could be assembling the table by attaching the legs to the table top.) 1. Before doing any calculations, which process metrics would you Process I?
Throughput time,
2. What is the bottleneck of this process?
Workstation B
3. What is the cycle time of this process?
5 mins
4. What is the capacity of this process?
12 units/hour
5. What is the throughput time for a rush order (that is an order arriving when the system is empty that is moved through the process without delay)?
7 mins
6. What is the labor utilization of each worker?
A=60% , B=100%, C=40%
7. What is the average labor utilization of the workers?
66.67%
8. What have you learned?
Calculate the utilization in terms of man minutes
Problem 2: Four Step Process Assignment Questions Process 1 To begin, consider the four – step process model in the Process 1 tab. 1. Calculate the amount of the time it would take to get a rush order through the process.
14.5 mins
2. Calculate the capacity of the process.
12/hour
3. Calculate the labor content of the process.
14.5 mins
4. Calculate the average labor utilization.
72.5%
Process 2 For the process 2, assume that you have hired an additional worker (i.e., a fifth for the process). This new worker is cross – trained at every step in process (can perform any of the 4 steps or any portion of any of the four steps). Inventory is permitted between steps so that the cross –trained worker can move around freely. Assume no transportation time in moving from one step to another. 1.
At which step (s) does the worker spend the majority of his or her time?
2.
A
What is the impact on performance?
Reduction in cycle time
Process 3 For Process 3, you have the opportunity to send each of your four specialists to get additional training in the other process steps. As a result of this training program, you will have five workers available to you, each one cross-trained at each of the four process steps. 1.
What benefits do you expect as a result of this additional training?
Bottle neck is being subordinated If a worker is absent then the other 3 can run still run the line but with more cycle time Equal division of work among the workers (basically line balancing)
Process 4 Go to Process 4, a variant of Process 1. Your analysis was done with the assumption that no inventory would be allowed to build up between steps. Answer these questions without that assumption. 1. How would performance change if this restriction were relaxed? That is, what would impact of allowing inventory to accumulate between steps?
If there is a breakdown the process will not stop.
Problem 3: Sub Assembly Assignment Questions Consider the following process in the Process 1 tab. All steps (A, B, C, D) are necessary to create each finished unit. Each step employs a single worker who is not cross-trained for any other processing times listed represent the amount of time each worker spends on a single unit. There is not variability in processing times. Process 1 1. What is the fastest that a rush order can go through the process?
35
2. Working 8 hours a day, what is the daily capacity? 32 Process 2 For the next two questions, consider a fifth step added to the process along with a fifth worker. The fifth step, Step E, is done after Step C, and before Ste D, as depicted Process 2. All steps (A, B, C, D, and E) are necessary to create each finished unit. Processing times are shown for each process step. 3. What is the fastest that a rush order can go through the process?
40
4. Working 8 hours a day, what is the daily capacity?
32
Problem 4: Batch Processing Assignment Questions Consider the following three-step worker- paced line in the Process 1 tab. Each step employs a single worker who is not cross- trained for any other step. The setup represents the amount of time the worker spends setting u e machine hatch. No units can be processed during setup. The run time represents the amount of time it takes the worker to process a single unit. When a worker completes a batch, he or she hands it off to the next stage. Process 1 1. If only 10-unit batches are produced, what is the average capacity of the process per 8hour
4 batches
2. At what batch size does the bottleneck move? That is, at what batch size are there two steps that are the bottleneck?
5 batches
Problem 5: Random Variation Assignment Questions Consider the six-step process in the Process 1 tab, where the processing time for each step is uniformly distributed. Processing times can range from 12 to 18 minutes (any value in that range is as likely to occur as any other in that range). Process 1 1. If inventory were permitted to accumulate throughout this process, what impact would you expect on capacity (as compared to the process without inventory)?
Capacity would improve if the inventory is allowed to accumulate in the process but it may have effect on the quality of the products being manufactured as if any defect is generated at any of the workstations then it will not be detected immediately.
2. If you could add one inventory buffer, where would you add it to maximize capacity?
As the cycle time for each of the workstation varies with each simulation we cannot determine exactly where to put the buffer in order to maximize the capacity. It will vary depending on the actual time taken by each of the workstation.
3. If you added a second unit of buffer to the same location as the first, what would be the incremental impact on capacity of the second unit as compared with the first unit?
Incremental impact of the second unit of buffer would be less as compared to the first unit ***************************************************************THE END
Problem 6: Inventory Assignment Questions consider the four-step worker paced line in the Process 1 tab. Each step employs a single worker who is not cross-trained for any other step. The processing times listed represent the amount of time each worker spends on a single unit. There is no variability in processing times. Assume that all workers begin to work on the next unit as soon as they can. Process 1 1. Assume that inventory is not permitted to accumulate - i.e., a unit cannot be passed to the next stage until the worker receiving the unit is ready for it. What is the capacity of the process?
3
2. If inventory were allowed to accumulate in this process, where would it accumulate?
Between A and B. Between C and D
3. If inventory were allowed to accumulate, how would capacity be affected?
No effect
4. If inventory were allowed to accumulate, how would average throughput time be affected?
Average throughput time would increase
From this point forward, assume that inventory is not permitted to accumulate, and that work cannot be passed to the next stage until the worker receiving the unit is ready. 5. If a fifth worker were added to the process, what would the maximum capacity be? Assume that you can add the fifth worker to anyone of the four tasks, that the worker is not cross trained to do any of the other tasks and that the fifth worker works at the same rate as the original worker doing that task.
4 per hour.
6. Instead, if a fifth worker who was cross – trained for all tasks were added to the process, what would the new capacity be? Assume that this fifth worker incurs no travel time in moving between Compare the labor utilization of the worker at Step 1 in the original situation (four workers, no inventory) and the situation with the addition of the cross-trained fifth worker from the Four Step Process problem. How does it change?
New capacity will be 5.14 per hour.
The utilization will improve to 85.71% from 62.5%
Problem 7: Krunchy Kreme Assignment Questions Krunchy Kreme, marking its famous doughnuts, begins with the three-step process shown in Process 1. One dedicated worker mixes the dough and creates the doughnut shape from it. Batches of doughnuts from the Shaping stage are processed in one of two identical machines in the third step, staffed by one worker each. (Ignore the remaining steps in the process, such as frying and packing, because they have ample capacity.) Assume that all setups are done by the workers. A setup must be performed in each step of the process before every batch. Also, assume that each worker is busy during the run time of his or her operation. Process 1 1. Suppose that the batch size is 50 doughnuts. What is the capacity in an eight – hour day? 7 batches 2. What is the average utilization of these four workers? 84% 3. If Krunchy Kreme decides to change batch sizes, for what range of batch sizes is mixing the bottleneck? 82 units
Problem 8: Random Variation with Long Chains Assignment Process 1 For the processes in this assignment, we will explicitly account for variability in process time with those process times distributed according to a uniform distribution. Thus, a process time of 5 ±1 minutes/unit indicates that there is equal probability that the process (machine or person) will have a process time of anywhere from four to six minutes/unit. There are no setups.
1. Consider an eight-workstation in-series line, with all workstation processing time at 5 ±1 minutes per unit. Allocate 22 units of buffer capacity to this line so as to maximize average output. What is the best such allocation?
To maximize the average output we would allocate 3 units before each orkstation starting from workstation 2 and the left out will be allocated randomly to any workstation.
For the rest of this part, consider four different production ,lines consisting of inseries workstations with no buffers between stations. The numbers under e workstation represent the process time per unit, in minutes.
2. Assuming that Line A has been operating for a while, the expected capacity of Line A is a. Less than 6 units per hour a. Less than 6 units per hour b. Greater than 6 units per hour c. 6 units per hour d. Cannot be determined 3. Comparing the utilization of Machine A2 of Line A to that of Machine B3 of Line B, e. A2 has the same utilization as B3 f. A2 has a lower utilization than B3 g. A2 has a higher utilization than B3 h. Cannot be determined 4. Comparing the capacity of Line B to that of Line C, i. Line C has a higher output than Line B’s j. Line C has a lower output than Line B’s k. Line C has an output equal to that of Line B l. Cannot be determined 5. Comparing the capacity of Line C to that of Line D, m. The output of Line D is lower than line D, n. The output of Line D o. The output of Line D is higher than Line C’s p. Cannot be determined
Problem 9: Rework and Scrap Assignment Questions Imagine a three-workstation worker-paced line with task times 7, 6, and 8 minutes, respectively. In the previous problems, a 100% yield was assumed - i.e., no defects. The present problem will explicitly consider the impact of nonzero defect rates. In particular,
assume that the first workstation has an 8% defect rate and that the second workstation has a 12% defect rate. The third workstation, in contrast, generates no defects. For problems 1 to 4, assume that all defective units are scraped. Part A 1. What is the capacity of this process?
5.8
2. Where is the bottleneck?
A is the bottle neck
3. Is the utilization of the bottleneck step 100%? If so, why? If not, why not?
No. Because of the scrap the process utilization decreases.
4. What is the yield of the process (the ratio of good process)?
93.7%
Part B Now assume that the second workstation feeds its defects to a rework station that performs a delicate and lengthy task of disassembling the product and repairing it. Thus, it requires a relatively long time (here, 40 minutes on average) to fix defects. There is an inventory buffer in front of this rework step to accommodate for the unlikely case that there are several defects in a row. While time- consuming, it still is successful only 90% of the time. When rework is successful, the rework station passes the now- good unit to the third workstation in the line. If it is not successful, the product is scrapped.
The third workstation, receiving reworked units, now has an average task time of 9 minutes. 1. What is the capacity of this process?
6
2. Where is the bottleneck?
Work station C
3. Is the utilization of the bottleneck step 100%? If so, why? If not, why not?
No. Because of the rework of the scrap material generated.
4. What is the yield of the process (the ratio of good finished product to items started in the process)?
72%
Name of Group Members
Ankit Bhatnagar Gurneet KaurBhatia Pankaj Dhiman Rohit Suri Vineet Chauhan
GENERAL QUESTIONS 1.0
What were the major learning’s from this simulation We learned new various new concepts. The concepts like yield of the process, labour utilization, average labour utilization. In addition the learning were to utilize the simulations for use of project analysis.
2.0
Formulate a problem (like the ones you have done in this simulation) which you would like to assign to the BM Juniors if you are the instructor of Operations I. Also provide the answer and the logic of giving the question
The above mentioned diagram shows a process flow consisting of total of 7 processes. Processes A,B and C work in parallel. Similarly process D&E. In addition work time is also given. Calculate the following. A. Bottleneck of the process? Ans. As the maximum time is taken by D/E both D and E are bottlenecks. B. What is the cycle time of the process? Ans. 6 mins C. What is the capacity of the process.? Ans. Capacity would be 60/6 which is 10 per hour. D. What is throughput time for a rush order? Ans. 14 mins. E. If one additional worker is assigned to both D&E what will be the new bottleneck? Ans. The new bottleneck would be either B/C/F as they would take the maximum time. F. What is the average labour utilization? Ans. 26/42 =62%
