ChIII-ProcessSelection_II-Sp10

ChIII-ProcessSelection_II-Sp10 - 2/2/2010 MGMT 36100...

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Unformatted text preview: 2/2/2010 MGMT 36100 Operations Management (OM) III: Process Selection – Part II Example 1 Part (b): LPT rule Target CT = 60 [sec/unit] Total task time = 200 [sec] Lower bound: 4 stations LPT order Station Station 1, 20 3, 10 2, 50 6 1 7 3 4, 40 6, 30 5, 30 7, 20 2 4 5 Effective CT: 60 [sec./unit]. 60 Efficiency: (100 * 200) / (4 * 60) = 83.3%. Selected Cum. Time Eligible I II III IV V 2 ,3 5 ,1 4 6 ,7 50 , 60 30 , 50 40 30 , 50 2,1 / 5, 1, 3 / 5,1 5,1 / 1 / 4 4 /6 6 /7 ProcessSelection-Sp10 1 ProcessSelection-Sp10 2, 3 60 5, 1 50 4 40 6, 7 50 16 MGMT 361000 MGMT 361000 Assembly Line Balancing (ALB) Objective: To get a layout with minimum number of minimum stations for a specified target cycle time. Procedure: Start with the precedence diagram. Determine target CT. Select a priority rule (SPT, LPT, RPW) and a tie-breaking rule. tieStart with work station 1. Include as many eligible tasks as possible in each work station without exceeding target cycle time. If a task cannot be selected, skip and try the next one. If no eligible task can be selected, create a new station. If all tasks have been included, stop. Example 2 - SPT Need 1800 units in 7.5 hours. Target CT = 15 [sec. /unit] Total task time = 74 sec. Need at least 5 stations. St Selected C. Time Eligible I II 2, 6 1, 4 , 5 5 , 10 01 6 04 4 5 5 8 09 05 02 5 06 5 10 12 2,1,3 / 6,1,3 /1,3 6 ,10,15 1, 3 / 4,5,3 / 5,9,3 / 10,9,3 5 10, 9, 3 10 03 5 07 9 III 10 08 6 6 11 Eligible task: A task is eligible if all tasks that precede this task have been selected and there are no other restrictions. We will show the remaining solution in one click. SPT order 4 2 5 6 7 10 1 8 11 9 12 3 18 ProcessSelection-Sp10 17 ProcessSelection-Sp10 MGMT 361000 MGMT 361000 Example 2 – SPT, continued 01 6 04 4 5 5 8 09 Target CT = 15 [sec. /unit] /unit] St Select Cum. T Eligible I 2,6 5,10 2,1,3 / 6,1,3 / 1,3 6,1,3 1,3 II 1,4,5 6,10,15 1, 3 / 4,5,3 /5,9,3 12 01 6 04 4 5 5 09 8 Example 2 - SPT Target CT = 15 [sec. /unit] /unit] St Selected C. Time Eligible I II 2, 6 1 , 4, 5 5, 10 2,1,3 /6,1,3 /1,3 02 05 05 5 06 5 10 What if tasks 2 & 6 cannot be done in the same station? 02 5 06 5 10 12 9 07 5 10 6,10, 15 1, 3 / 4,5,3 / 5,9,3 5, 13 10, 15 6, 12 9 10, 9, 3 / 9, 3 / 3 9, 3 / 7, 8 / 8 7, 8 / 11 / 12 11 12 9 Efficiency: 100*[ 74/ (6*15)] = 82.2% 3, 7 15 MGMT 361000 III 10, 9 IV 3, 7 V 8, 11 VI 12 5 07 10 6 11 9 We make task 6 temporarily tem ineligible for the current station. 03 03 08 6 08 6 11 6 St Select Cum. T Eligible I 2 1 4 5 11 15 2, 1, 3 / 6,1,3 / 4,5,6,3 / 5, 6, 9, 3 6,1,3 4,5,6 II SPT order 19 Effective CT: 15 sec /unit. 2, 6 10 1, 4, 5 15 10, 9 13 5,6,9,3 8, 11 12 12 9 4 2 5 6 7 10 1 8 11 9 12 3 20 ProcessSelection-Sp10 ProcessSelection-Sp10 MGMT 361000 ProcessSelection‐Sp10 1 2/2/2010 Back to Ex. 1 Part (c): RPW rule 110 1, 20 3, 10 4, 40 90 50 6, 30 20 7, 20 Ex. 1 Which layout do you prefer? 1, 20 3, 10 2, 50 5 30 4 40 5, 6 60 3, 4 50 4 40 6, 7 50 7 20 6, 7 50 6, 7 50 4, 40 6, 30 5, 30 7, 20 180 Target CT = 60 [sec/unit] Total task time = 200 [sec] 2, 50 Lower bound: 4 stations RPW order Station Selected Cum. Time Eligible 100 5, 30 80 4 5 6 7 2 1 3 1 20 2, 3 60 2, 3 60 2 50 2, 3 60 5, 1 50 1, 4 60 1, 5 50 I II III IV 2 ,3 1,4 5 ,6 7 50 , 60 20 , 60 30 , 60 20 2, 1 / 1, 3, 5 / 1, 5 1, 5 / 4, 5 / 5 5 /6 /7 7 2, 3 60 1, 4 60 5, 6 60 After getting After getting RPW RPW order, do not use weights. Use only task times. Effective CT: 60 [sec./unit]. Efficiency: 100 * 200 / (60 * 4) = 83.3% . 7 20 How about this one? 22 ProcessSelection-Sp10 21 ProcessSelection-Sp10 MGMT 361000 MGMT 361000 Example 2 R.P.W. method: 01 6 4 04 8 21 5 09 17 Example 2 Target C.T.= 15 [sec. /unit ]. 37 01 6 21 19 04 4 5 8 09 37 29 02 19 05 17 Need 1800 units in 7.5 hours. Target CT = 15 [sec. /unit] Total task time = 74 sec. Need at least 5 stations. stations. 5 19 5 06 14 5 10 9 9 12 05 Station Selected Cum. Time 29 02 I 1, 2, 4, 6, 11, 15 5 19 5 06 14 10 5 9 12 14 36 03 10 5 10 6 11 07 5 9 14 21 08 9 12 07 5 6 15 11 Weight 6 36 03 10 08 6 Time Task 6 1 5 2 10 3 4 4 5 5 5 6 5 7 6 8 8 9 21 11 6 15 1 2 3 ProcessSelection-Sp10 37 37 29 36 23 RPW order: 01 03 02 04 08 05 06 09 11 07 10 12 ProcessSelection-Sp10 24 MGMT 361000 MGMT 361000 Example 2 Target C.T.= 15 [sec. /unit ]. Station Selected I II III IV V VI 1, 2, 4 3, 5 8, 6 9, 11 7, 10 12 37 01 6 21 19 04 4 5 8 09 Ex. 2: Solving by inspection. Target CT = 15 sec/unit inspection. 17 I 1,2,4 II 5,6,10 III 3,7 IV 8,9 V 11,12 05 Cum. Time 6, 11, 15 10, 15 6, 11 8, 14 5, 10 9 29 02 5 19 5 06 14 10 5 9 12 01 6 04 4 5 5 8 09 IV I 02 05 9 14 36 03 10 07 5 5 II 06 5 10 12 9 98.7% 08 6 21 12 9 11 6 15 Effective CT = 15 sec /unit. Efficiency = 100 *74 / (6 * 15) = 82.2% 1, 2, 4 15 3, 5 15 8, 6 11 9, 11 14 MGMT 361000 III 03 25 07 5 V 6 26 7, 10 10 10 08 6 11 ProcessSelection-Sp10 ProcessSelection-Sp10 MGMT 361000 ProcessSelection‐Sp10 2 2/2/2010 Various layouts Line flow, flow shop / product layout Job shop: • New products. • Shifting bottlenecks. • Capacity? • Need skilled operators. Layout: the configuration of departments, work centers, and equipment, with particular emphasis on movement of work (customers or materials) through the system. 1: Product layout: Layout uses standardized processing operations to achieve smooth, rapid, high-volume flow. highAdvantages: • High rate of output • Low unit cost • Labor specialization • Low material handling cost • High utilization of labor and equipment • Established routing and scheduling • Routing accounting and purchasing 27 ProcessSelection-Sp10 Hybrid A B 1: A - C - D 2: C - B 3: B - D – C - A Job Shop C ProcessSelection-Sp10 D MGMT 361000 MGMT 460 Disadvantages: • Creates dull, repetitive jobs • Poorly skilled workers may not maintain equipment or quality of output • Fairly inflexible to changes in volume • Highly susceptible to shutdowns • Needs preventive maintenance • Individual incentive plans are impractical 28 MGMT 361000 2. Process layout: Layout that can handle varied processing requirements. Dept. A Dept. B Dept. C Dept. D Dept. E Dept. F 3. Fixed Position layout: Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed. Airplanes. Ships, PrePrefabricated homes Advantages: • Can handle a variety of processing requirements • Not particularly Not particularly vulnerable vulnerable to equipment failures • Equipment used is less costly • Possible to use individual incentive plans Disadvantages: • WIP inventory costs can be high • Challenging routing and scheduling • Equipment utilization rates are low utilization rates are low • Material handling slow and inefficient • Complexities often reduce span of supervision • Special attention for each product or customer • Accounting and purchasing are more involved 29 4. Cellular Production: Layout in which machines are grouped into a cell that can process items that have similar processing requirements 5. Group Technology: The grouping into part families of items with similar design or manufacturing characteristics with similar design or manufacturing characteristics Service Layouts Warehouse and storage layouts Retail layouts Office layouts Service layouts must be aesthetically pleasing as well as functional ProcessSelection-Sp10 ProcessSelection-Sp10 30 MGMT 361000 MGMT 361000 ProcessSelection‐Sp10 3 ...
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This note was uploaded on 12/14/2010 for the course MGMT 361 taught by Professor Panwalker during the Spring '10 term at Purdue University-West Lafayette.

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