ChII-ProcessAnalysisI

ChII-ProcessAnalysisI - MGMT 36100 Operations Management...

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Unformatted text preview: MGMT 36100 Operations Management (OM) Ch II: Process Analysis - I transforms outputs inputs Process takes inputs and transforms them into outputs that, that, it is hoped, are of greater value than the greater than original inputs. Operations Input Output A process is any part of an organization that process Process schematic Control Transactions go through a process, transactions can go be people, material, etc. people Operations require resources , these resources can resources these include people, machines, etc. people ChII-ProcessAnalysisI 1 ChII-ProcessAnalysisI 2 Process Flowcharting • Used to present the major elements of a process. • Basic elements can include tasks (operations), flows of materials or customers, decision points, and storage areas or queues. • Ideal methodology by which to methodology by w hich to begin analyzing a process. Process (Flow) Diagram, Value Stream Mapping, etc. Resource Buffer Decision Process Process types – Single Stage 1 2 Stations in parallel, separate queue St Stations in parallel, single queue In and above, there is a single stage stage with multiple stations. ChII-ProcessAnalysisI Process types – Multi Stage 1 2 Process with buffer Transaction Information Flow. Flow Fl 3 Operation Precedence 3 3 Hybrid Words Station and Stage will be used interchangeably when there is only one station at each stage. 4 For process design, we will use another diagram called Precedence Diagram. ChII-ProcessAnalysisI Process types Make Make to stock Process activated to meet expected or forecast demand. Customer orders are served from target stocking level. Make to order Only activated in response to an actual order. Both work-inwork-in-process and finished goods inventory kept to a minimum. Hybrid Make to order Wendy’s Raw Matl. Customer order Combines the features of both make-tomake-toorder and make-to-stock. make-to-stock Cook Assemble Chili Deliver Patties cooking for too long used for chili soup. Make to stock Old Process at McDonald’s Raw Mat. Customer Order Finished goods Hybrid Hybrid Burger King Raw Matl. Customer Order Assemble C WIP Custom or Standard? Finished goods Deliver Cook Assemble Deliver Cook S Assemble ChII-ProcessAnalysisI 5 ChII-ProcessAnalysisI 6 ChII-ProcessAnalysisI 1 Process design: 1. We first determine what operations involved and how long does it take to perform each operation. 2. We need to know precedence relationship between operations (what goes before what). 3. The first two steps will help us draw a precedence diagram. Process design: Example 1 Suppose the work involves envelope stuffing. We first determine operations involved (times in sec.) Operation 1 Get Material 2 Get envelop 3 Insert & seal 4 Paste label label 5 Drop in the box Time 30 s 2s 8s 5s 3s 1 3 5 4 We can perform operation (3) only after completing (1) and (2). (2). We can do (5) only after doing the other four operations. Precedence diagram. di We will use intuitive method for the time being to develop process designs. However, later we will see that we need to know the desired production capacity and any other constraints that we may have to consider. ChII-ProcessAnalysisI 7 ChII-ProcessAnalysisI 2 We will now look at several designs. 8 Ex Ex 1: Envelope stuffing 1 2 4 3 5 Operation 1 Get Material 2 Get envelop 3 Insert & seal 4 Paste label 5 Drop in the box Time (S) 30 2 8 5 3 Let’s assume that we use one worker at each station. Productivity: Productivity: Productivity = output / input Measure Total Partial Defined in many different ways Output Input Output Labor Goods Goods and services produced All resources used Output Output Capitol Output Output Materials Energy ______ ______ Output_________ Labor + capitol + Materials Process 1 1 30 30 2 2 3 8 4 5 5 3 Multifactor Process 3 1, 2 32 3, 4, 5 16 5 workers. Capacity ? 120 units/hour Process 2 1 30 2, 3, 4, 5 18 Output Labor + Capitol + Energy 1, 2 32 2 workers. Capacity? 120 units/ hour ChII-ProcessAnalysisI •Measuring in common units is difficult. •We will use output per labor hour as the output productivity measure in many examples. •Productivity is a relative measure – productivity increased from 2.7 units per labor hour to 3 units per labor hour. 9 ChII-ProcessAnalysisI 10 3 workers. Capacity? 225 units/hour Ex 1: Envelope stuffing Process 1 1 30 2 2 3 8 Process Process 1 2 3 4 5 Productivity 24 Units per hour per worker 60 Units per hour per worker 75 Units per hour per worker 5 3 Example 2: 2: Task no., time (sec.) 1: 20 3: 10 2: 50 4: 40 6: 30 5: 30 7: 20 A 1 20 2 50 2: 50 M1 3 10 4 40 4: 40 P1 5 30 6 30 7 20 5 workers. Capacity: 120 units/hour Process 2 1 2, 3, 4, 5 30 18 1 3 5 4 B 1: 20 20 3: 10 10 5: 30 30 6: 30 30 7: 20 20 2 workers. Capacity: 120 units/ hour Process 3 1, 2 32 3, 4, 5 16 2: 50 M2 4: 40 P2 2 C 2 50 2, 3 60 1, 5 50 1, 4 60 3, 4 50 5, 6 60 6, 7 50 7 20 1 2 3 4 1, 2 32 ChII-ProcessAnalysisI D 11 Capacity 72 Units per hour 120 Units per hour 72 Units per hour 60 Units per hour Productivity? 12 3 workers. Capacity: 225 units/hour ChII-ProcessAnalysisI ChII-ProcessAnalysisI 2 Process parameters: indicate Design parameters indicate what a process can achieve. Run time parameters indicate what the current values are for a specific indicate schedule. These values change with the schedule. Example 3 M1 4 min Design Parameters Capacity = 15 [units /hr] Cycle time = 1/15 [hrs/unit] = 1/15 [hrs / unit] * 60 [min/hour] [hrs = 4 [min/unit] Minimum TPT = 4 [min] Design Run time Capacity: Capacity: Maximum rate Input Rate: transaction arrival rate Rate: of transaction processing. Output Rate: Current rate of Rate: Productivity processing = Capacity / labor Productivity = Output /labor (Design) Cycle Time = 1/( capacity). Minimum Throughput hroughp Time (TPT) – How fast a (TPT) transaction goes through the process when the process is empty. ChII-ProcessAnalysisI Part A: A new component is scheduled every 4 minutes. Calculate run time parameters for this schedule. Actual Cycle Time = 1 / (output rate) Average TPT: Avg. time for a TPT: Avg. transaction to go through a stable stable process. Average WIP: Avg. number of WIP: Avg. transactions in the process. 13 M1 Job 1 4 Job 2 Job 3 8 Job 4 12 16 Run time parameters Input rate Output rate Actual CT Avg. TPT Avg. WIP = 15 [units / hour] = 15 [units / hour] = 4 [min/unit] = 4 [min] = 1.0 [unit] 14 ChII-ProcessAnalysisI Example 3 M1 4 min Design Parameters Capacity = 15 [units /hr] Cycle time = 1/15 [hrs/unit] = 1/15 [hrs / unit] * 60 [min/hour] [hrs = 4 [min/unit] Minimum TPT = 4 [min] Example 3 M1 4 min Design Parameters Capacity = 15 [units /hr] Cycle time = 1/15 [hrs/unit] = 1/15 [hrs / unit] * 60 [min/hour] [hrs = 4 [min/unit] Minimum TPT = 4 [min] Part B: A new component is new scheduled every 10 minutes. Calculate run time parameters for this schedule. Part C: A new component is scheduled every 3 minutes. Calculate run time parameters for this schedule. Run time parameters M1 Job 1 4 10 Job 2 14 Input rate = 20 [units / hour] 20 Output rate = 15 [units / hour] …cannot exceed capacity. There is a problem! Queue will build up as time progresses. = 6 [units / hour] = 6 [units / hour] = 10 [min/unit] = 4 [min] = 0.4 [units] 15 Run time parameters Input rate Output rate Actual CT Avg. TPT Avg. WIP When the input rate is more than the capacity, number of transactions waiting to be processed will keep on increasing. The process will never become stable. ChII-ProcessAnalysisI 16 ChII-ProcessAnalysisI Example 4: M1, 10 M2, 16 M3, 20 Time in seconds (a) For the single stage process shown to the left, what is the cycle time? (b) If you need to produce 1165 units per hour, do you need an extra machine? If so, what should be the per unit processing time if this machine is used in parallel? Capacities add for = 3600 / 10 parallel machines = 360 [units / hour], hour], Capacity of M2 Capacity of M2 = 225 [units / hour], 225 hour Capacity of M3 = 180 [units / hour]. hour]. System capacity = 765 [units / hour]. hour]. Cycle time = 1 / (Capacity) = 3600 / 765 = 4.706 [sec / unit] Part (a): Capacity of M1 Part (b): Needed total capacity = 1165 units per hour. We need extra machine with capacity = (1165 – 765) = 400 [units / hr]. [units hr]. PerPer-unit processing time on this extra machine = 3600 / 400 = 9 sec. ChII-ProcessAnalysisI 17 ChII-ProcessAnalysisI 3 ...
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