Presentation on theme: "Chapter 7s Class 1."— Presentation transcript:

1 Chapter 7s Class 1



2 Design and Effective Capacity

Design capacity is the maximum theoretical output of a system Normally expressed as a rate Effective capacity is the capacity a firm expects to achieve given current operating constraints Often lower than design capacity This slide can be used to frame a discussion of capacity. Points to be made might include: - capacity definition and measurement is necessary if we are to develop a production schedule - while a process may have “maximum” capacity, many factors prevent us from achieving that capacity on a continuous basis. Students should be asked to suggest factors which might prevent one from achieving maximum capacity.



3 Utilization and Efficiency

Utilization is the percent of design capacity achieved Utilization = Actual output/Design capacity Efficiency is the percent of effective capacity achieved Efficiency = Actual output/Effective capacity



4 Bakery Example Actual production last week = 148,000 rolls

Effective capacity = 175,000 rolls Design capacity = 1,200 rolls per hour Bakery operates 7 days/week, hour shifts Design capacity = (7 x 3 x 8) x (1,200) = 201,600 rolls It might be useful at this point to discuss typical equipment utilization rates for different process strategies if you have not done so before.



5 Bakery Example Actual production last week = 148,000 rolls

Effective capacity = 175,000 rolls Design capacity = 1,200 rolls per hour Bakery operates 7 days/week, hour shifts Design capacity = (7 x 3 x 8) x (1,200) = 201,600 rolls It might be useful at this point to discuss typical equipment utilization rates for different process strategies if you have not done so before. Utilization = 148,000/201,600 = 73.4%



6 Bakery Example Actual production last week = 148,000 rolls

Effective capacity = 175,000 rolls Design capacity = 1,200 rolls per hour Bakery operates 7 days/week, hour shifts Design capacity = (7 x 3 x 8) x (1,200) = 201,600 rolls It might be useful at this point to discuss typical equipment utilization rates for different process strategies if you have not done so before. Utilization = 148,000/201,600 = 73.4% Efficiency = 148,000/175,000 = 84.6% © 2011 Pearson Education, Inc. publishing as Prentice Hall



7 Bakery Example Actual production last week = 148,000 rolls

Effective capacity = 175,000 rolls Design capacity = 1,200 rolls per hour Bakery operates 7 days/week, hour shifts Efficiency = 84.6% Efficiency of new line = 75% It might be useful at this point to discuss typical equipment utilization rates for different process strategies if you have not done so before. Expected Output = (Effective Capacity)(Efficiency) = (175,000)(.75) = 131,250 rolls © 2011 Pearson Education, Inc. publishing as Prentice Hall



8 Problem S7.7 southeastern Oklahoma State University’s business program has the facilities and faculty to handle an enrollment of 2,000 new students per semester. However, in an effort to limit class sizes to a “reasonable” level (under 200, generally), Southeastern’s dean, Tom Choi, placed a ceiling on enrollment of 1,500 new students. Although there was ample demand for business courses last semester, conflicting schedules allowed only 1,450 new students to take business courses. What are the utilization and efficiency of this system?



9 Solution: Design capacity = 2,000 students

Effective capacity = 1,500 students Actual output = 1,450 students



10 Problem S7.8 under ideal conditions, a service bay at a fast lube can serve 6 cars per hour. the effective capacity and efficiency of a fast lube service bay are known to be 5.5 and 0.880, respectively. what is the minimum number of service bays fast lube needs to achieve an anticipated production of 200 cars per 8-hour day



11 To do 200 cars per day it requires,

Solution: Actual or expected output = Effective capacity*Efficiency 5.5 cars  = 4.84 cars. In one 8-hour day, one bay accommodates (8 hr * 4.84 cars per hr) = cars To do 200 cars per day it requires, (200 cars) / (38.72 cars/bay) = 5.17 or 6 bays



12 Process Times for Stations, Systems, and Cycles

The process time of a station is the time to produce a unit at that single workstation The process time of a system is the time of the longest process in the system … the bottleneck The process cycle time is the time it takes for a product to go through the production process with no waiting



13 A Three-Station Assembly Line

2 min/unit 4 min/unit 3 min/unit A B C Figure S7.4



14 Capacity Analysis Two identical sandwich lines

Lines have two workers and three operations All completed sandwiches are wrapped Wrap 37.5 sec/sandwich Order 30 sec/sandwich Bread Fill Toast 15 sec/sandwich 20 sec/sandwich 40 sec/sandwich



15 Capacity Analysis Wrap 37.5 sec Order 30 sec Bread Fill Toast 15 sec 20 sec 40 sec Toast work station has the longest processing time – 40 seconds The two lines each deliver a sandwich every 40 seconds so the process time of the combined lines is 40/2 = 20 seconds At 37.5 seconds, wrapping and delivery has the longest processing time and is the bottleneck Capacity per hour is 3,600 seconds/37.5 seconds/sandwich = 96 sandwiches per hour Process cycle time is = seconds



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17 Problem S7.11 Solution: Stat.1_A 0.05 hr/unit Stat.2 0.2 hr/unit Stat.3 hr/unit Stat.1_B 0.05 hr/unit (a) System process time = bottleneck time = 0.2 hr/unit (b) Bottleneck time = 0.2 hr/unit (c) Process cycle time = 0.05 hr+0.2 hr hr = hr = 20 min (d) Weekly capacity= total time in a week/bottleneck time = (10hr*5days)/0.2 = 250 units/week



18 Capacity Analysis Standard process for cleaning teeth

Cleaning and examining X-rays can happen simultaneously Check out 6 min/unit Check in 2 min/unit Develops X-ray 4 min/unit 8 min/unit Dentist Takes X-ray 5 min/unit X-ray exam Cleaning 24 min/unit



19 Capacity Analysis All possible paths must be compared

Check out 6 min/unit Check in 2 min/unit Develops X-ray 4 min/unit 8 min/unit Dentist Takes X-ray 5 min/unit X-ray exam Cleaning 24 min/unit All possible paths must be compared Cleaning path is = 46 minutes X-ray exam path is = 27 minutes Longest path involves the hygienist cleaning the teeth Bottleneck is the hygienist at 24 minutes Hourly capacity is 60/24 = 2.5 patients Patient should be complete in 46 minutes



20 Problem S7.14 Klassen Toy Company, Inc., assembles two parts (parts1 and 2): Part 1 is first processed at workstation A for 15 minutes per unit and then processed at workstation B for 10 minutes per unit. Part 2 is simultaneously processed at workstation C for 20 minutes per unit. Work stations B and C feed the parts to an assembler at workstation D, where the two parts are assembled. The time at workstation D is 15 minutes. a) What is the bottleneck of this process? b) What is the hourly capacity of the process?



21 Problem S7.14 Solution: Station A 15 min/unit Station B 10 min/unit Station D 15 min/unit Station C 20 min/unit (a) System process time = bottleneck time = 20 min/unit (b) Hourly capacity = time in an hour/bottleneck time = 60min/20 = 3 units/hr * Process cycle time = 25 min + 15 min = 40 min

