Assignment Capacity

What is a Process A process is any activity or group of activities. Process analysis is the detailed understanding and documentation of how work is performed and how it can be redesigned and improved. Tools for documenting a process: Flowchart, service blueprint, process chart, Identify opportunity 1 Define scope 2 Document process 3 Implement changes 6 Redesign process 5 Evaluate performance 4

Flow Chart A flowchart is a diagram that traces the flow of materials, customers, information, or equipment through the various steps of a process E C A B B D C F Capacity-related metrics: Capacity, time to perform the process Quality-related metrics: Defective rate, customer satisfaction rate Efficiency-related metrics: Cost, productivity, utilization Flexibility-related metrics: Time to change the process from one type of product to another

Problem1: Single-Stage and Two-Stage Process Cycle time = Capacity = Theoretical Flow Time = Ip = 1 min Operation A Tp =1 min 1/1 per min, 60 per hour 1 min 1 Operation B Tp =8 min Operation A Tp =10 min Cycle time = Capacity = Theoretical Flow Time = Ip = IpA = IpB = 10 min 1/10 per min, 6 per hour 18 min OprA OprB 18 CT 38 28 48 1.8 1 0.8

Problem1: Two-Stage Process Cycle time = Capacity = Theoretical Flow Time = Ip = IpA = IpB = 10 min Operation B Tp =10 min Operation A Tp =5 min 6 per hr 15 min OprA OprB 11 CT 23 17 29 1.5 0.5 1 Operation A is Specialized and Fast Operation B is Specialized and Fast Process Capacity 6 per hour

Problem1d: Single-Stage Process Lets cross train them and reduce set up time of the operation. They are not fast anymore. Instead of 5+10=15 it takes 16 to complete a part Operation AB1 16 Operation AB2 Cycle time = Capacity = Theoretical Flow Time = 8 min 60(2/16) per hr 7.5 per hr 16 OprAB1 OprAB2 16 CT 48 32 64 Due to pooling and cross-training, capacity increased from 6 to 7.5. Therefore, throughput can go up. We will show that flow time will also goes down.

Problem 2. Problem 5.3 in the book Three hairstylists and a receptionist. On average it takes 10 minutes to shampoo, 15 minutes to style the hair and 5 minutes to bill a customer. The customer first checks in with the receptionist. This takes only 3 minutes. One of the three stylists then takes charge and performs all the three activities—shampooing, styling and billing—consecutively. Receptionist Hair Stylist a) How many customers can be serviced per hour in this salon? Check-in Sh-Sty-Bill 3 minutes 10+15+5=30 The capacity of each stylists is 60 /30 = 2 customers/ hour. Capacity of the stylist pool is 3(2) =6 customers/ hour. Capacity of the receptionist is 1* 60/3 = 20 customers per hour.

Problem 2. Problem 5.3 in the book The capacity of the process is min (6, 20) = customers per hour. The bottleneck is the stylist pool. Receptionist Hair Stylist 3+5 =8 10+15=25 ChinBill Sh-Sty b) What would be the impact on the theoretical capacity if the billing operation is transferred to the receptionist? The capacity of each stylists is 60 /25 = 2.4 customers/ hour. Capacity of the stylist pool is 3(2.4) =7.2 customers/ hour. Capacity of the receptionist is 1* 60/8 = 7.5 customers per hour. The capacity is min (7.2, 7.5) = 7.2 customers per hour. The bottleneck is still the stylist pool.

Problem 3 Eastern Coffee follows the flow chart below to serve its customers. It takes a worker two minutes to take order and receive payment, two minutes to prepare coffee, and three minutes to clean equipment. Take Order & Receive Payment Prepare Coffee Clean Equipment Eastern Coffee has two workers: worker A takes order and prepares coffee, while worker B handles the cleaning. a) How many customers can Eastern Coffee serve per hour? Capacity of the bottleneck is 15 customers/hour

Problem 3 TpA = 2+2=4, TpB = 3 Capacity of worker A: 60/4 = 15 customers/hour Capacity of worker B: 60/3 = 20 customers/hour   Western Coffee follows the same flow chart above, and each activity takes the same amount of time as Eastern. Western Coffee also has two workers: worker C only takes order and payment, while worker D handles the coffee preparation and cleaning. b) How many customers can Eastern Coffee serve per hour? TpC = 2, TpD = 2+3=5 Capacity of worker C: 60/2 = 30 customers/hour Capacity of worker D: 60/5 = 12 customers/hour Capacity of the bottleneck is 12 customers/hour

Problem 4. Problem 5.1 in the book A law firm processes (I) shopping centers and (II) medical complexes contracts. The time requirements (unit loads) for preparing a standard contract of each type along with some other information is given below. In November 2012, the firm had 150 orders, 75 of each type. Assume 20 days per month, and 8 hours per day. Capacity Waste factor at the three resource-s are 25%, 0, and 50%, respectively.

Problem 4. Problem 5.1 in the book What is the effective capacity of the process (contracts /day)? Paralegal: Unit Load (50%Sh 50% Med): 0.5(4)+0.5(6) = 5 hrs Capacity Waste Factor (CWF) = 0.25 Total Unit Load = Tp = 5/(1-0.25) = 20/3 hrs Theoretical Capacity = 1/5 per hr Effective Capacity = Capacity = 1/(20/3) = 3/20 per hr Tax Lawyer: Unit Load 0.5(1)+0.5(3) = 2 hrs CWF = 0 Total Unit Load = Tp = 2 hrs Theoretical Capacity = 1/2 per hr Effective Capacity = Capacity = 1/2 per hr

Problem 4. Problem 5.1 in the book Senior Partner: Unit Load 0.5(1)+0.5(1) = 1 hrs CWF = 0.5 Total Unit Load = Tp = 1/(1-0.5) = 2 hrs Theoretical Capacity = 1/1 = 1 per hr Effective Capacity = Capacity = 1/2 per hr b) Compute the cycle time? 4.8 units in 8 hours. Cycle time = 8/4.8 = 1.67 hours

Problem 4. Problem 5.1 in the book c) Compute the flow time. Vey Theoretical Flow time = 5+2+1 = 8 !!!!!! Theoretical Flow Time 6.67+2+2 = 10.67 Flow Time = 10.67 + Waiting times d) Compute the average inventory. RT=I  R= 4.8 per 8 hours or 0.6 per hour T =10.67 hours I = 0.6(10.67) = 6.4 e) Can the company process all 150 cases in November? 150/20 = 7.5. The effective capacity of 4.8 /day is not sufficient. f) If the firm wishes to process all the 150 cases available in November, how many professionals of each type are needed?

Problem 4. Problem 5.1 in the book Demand per day = 150/20 = 7.5 # of paralegals required = 7.5/1.2 = 6.25 # of tax lawyers required = 7.5/4 = 1.875 These could be rounded up to 7, 2 and 2 We need 7, 2, 2. We have 4, 4,4. We may hire 3 additional paralegals. Alternatively, we may hire just 2 and have 6 paralegals. They need to work over time for 0.25 paralegal who works 8 hrs /day. That is 1.5 hours  1.5/8 = 22.5 minutes over time.

Problem 5. Problem 5.4 in the book A company makes two products, A and B, using a single resource pool. The resource is available for 900 min per day. The profit margins for A and B are $20 and $35 per unit respectively. The unit loads are 10 and 20 minutes. a) The company wishes to produce a mix of 60% As and 40% Bs. What is the effective capacity (units per day)? An aggregate product will need 0.6(10) + 0.4(20) = 14 minutes Capacity is 1/14 per minute or 900(1/14) = 64.29 per day b) What is the financial throughput per day? Financial throughput is the rate at which a firm is generating money. An aggregate product will generate 0.6(20) + 0.4(35) = $28 64.29(28) = $1671.5 per day

Problem6 Angels Inc. fabricates garage doors. Roofs are punched in a roof punching press (10 minutes per roof) and then formed in a roof forming press (5 minutes per roof). Bases are punched in a base punching press (10 minutes per base) and then formed in a base forming press (15 minutes per base), and the formed base is welded in a base welding machine (5 minutes per base). The base sub-assembly and the roof then go to final assembly where they are welded together (10 minutes per garage) on an assembly welding machine to complete the garage. Assume one operator at each station. Draw a flowchart of the process. What is the minimum time required to produce a garage (from starting an order to finishing it)? What is the capacity of the factory in terms of garages per hour? If you want to increase the capacity, what is the stage that you would put some additional resource?

Problem 7. Capacity: Cost Vs. Flow Time Product Mix: 50%-50% Set-up time 30 min per product Working hours 8 hours/day 10 min/unit A Operation B 20 min/unit 1 machine 100% available Compute the capacity under min cost strategy. Two set-ups each for 30 min = 60 mins An aggregate product takes (10+20)/2 = 15 Production time = 8*60-60 = 420 mins Capacity = 420/15 = 28 aggregate units Each aggregate unit is 0.5 A and 0.5 B (total of 14A and 14B)

Problem 7. Capacity: Cost Vs. Flow Time Compute the capacity under min inventory strategy. In a minimum inventory strategy, we produce one product at a time then switch to the other. 10 min/unit A Operation B 20 min/unit 1 machine 100% available Product A: 10+30 = 40 Product B: 20+30 = 50 An aggregate product takes (40+50)/2 = 45 Production time = 8*60 = 480 mins Capacity = 480/45 = 10.66 aggregate units. Each aggregate unit is 0.5 A and 0.5 B (total of 5.33 A and 5.33B)

Problem 8 The following graph shows a production process for two products AA and BC. Station D and E are flexible and can handle either product. No matter the type of the product, station D can finish 100 units per day and station E can finish 90 units per day. Station A works only for Product A and have a capacity of 60 units per day. Station B and C are only for Product BC and have capacity of 75 and 45 units per day, respectively. The demands for each product is 50 units per day. Which station is the bottleneck? Stations A and C Station B and C Stations C and D Stations D and E Station C and E A: 60 D: 100 E: 90 B: 75 C: 45

Problem 8 Which of the following is NOT true? The utilization of machine A is at least 75% The utilization of machine B at least about 53% The utilization of machine B is at most 60% The utilization of machine D is 90% None of the above. E  We can produce at most 90 AA and BC. C  We can produce at most 45 BC We may produce all combinations from 50AA and 40 BC to 45AA and 45 BC A: 60 We produce at least 45 AA: 45/60 = 75% We produce at least 40 BC: 40/75 = 53.33% 45/75 = 60% 90/100 = 90% D: 100 E: 90 B: 75 C: 45

Problem 9 A company has five machines and two products. Product X will be processed on Machine A, then J, then B. Product Y will be processed on Machine C, then J, then D. The demands for both products are 50 units per week. The capacities (units/week) of the machines are marked in the graph on the right. Which machine is the bottleneck? A B C D J

Problem 9 Which of the following is NOT true? The utilization of machine A is at least 80% The utilization of machine B at least about 66% The utilization of machine D is at least 50% The utilization of machine C is at most about 72% None of the above. We can produce at most 90 X and Y. We may produce all combinations from 50 X and 40 Y to 40 X and 50Y We produce at least 40 X: 40/50 = 80% We produce at least 40 X: 40/60 = 66.67% 40/80 = 50% 50/70 = 71.43%