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Production Activity Control

Production Activity Control

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Production Activity Control

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  1. Production Activity Control “The time comes when plans must be put into action”

  2. Production Activity Control • Responsible for executing the: • Master Production Schedule (MPS) • Materials Requirements Plan (MRP) • At the same time: • Make good use of labor, machines and materials • Minimize work-in-process inventory • Maintain customer service

  3. Production Activity Control • Release work orders to the shop for manufacturing • Control work orders to complete on time • Control detailed the flow of orders through • manufacturing • Carrying out the plan • Controlling the work as it progresses to completion • Manage day-to-day activity and provide support

  4. Production Planning Master Production Scheduling Planning Material Requirements Planning Input/ Output Control Implement and Control Production Activity Control Purchasing Operation Sequencing Figure 6.1 Priority planning and production activity control

  5. Planning • To meet delivery dates • Ensure: • The required materials, tooling, personnel and information • Schedule: • Start and completion times for each shop order • Develop load profiles for the work centres`

  6. Implementation • Gather information needed to make the product • Release orders to the shop floor • MRP authorized “Dispatching”

  7. Control • The production order has been released • Is corrective action necessary? • Rank the orders by priority • Establish a dispatch list • Track performance to planned schedule • Replan, reschedule, adjust capacity • Monitor and control WIP, lead times, queues • Report work center effciency, scrap, times

  8. PRODUCTION ACTIVITY CONTROL PLAN Schedule Replan EXECUTE Work Authorization CONTROL Compare Decide Feedback Dispatch MANUFACTURING OPERATIONS Figure 6.2 Production control system

  9. Manufacturing Systems • Flow manufacturing • Intermittent manufacturing • Project manufacturing

  10. Flow Manufacturing • High volume • Standard products • Repetitive or • Continuous (production of high volume standard product) = repetitive manufacturingeg. Cars and appliances, if the goods are made in a continuous flow (eg. Gasoline) : continuous manufacturing

  11. Flow Manufacturing • Routings are fixed • Work centers arranged according to the routing • Dedicated to a limited range of products • specifically designed equipment • Use of mechanical transfer devices • Low WIP and throughput times • Capacity is fixed by the line

  12. Flow Manufacturing • Production Activity Control • Plans the flow of work • Planned schedule of materials to the line • Implementation and control are relatively simple

  13. Intermittent Manufacturing • Many variations in: • product design • process requirements • order quantities

  14. Intermittent Manufacturing • Flow of work is varied - work flow not balanced • Machinery and workers must be flexible • Usually grouped according to function • Throughput times are generally long • Capacity required depends on product mix

  15. Intermittent Manufacturing • Production Activity Control is complex: • number of products made • variety of routings • scheduling problems • PAC is a major activity • Controlled through shop orders for each batch

  16. Project Manufacturing • One or a small number of units • Usually in one place • Close coordination between: • Manufacturing, Marketing, Purchasing, Engineering • Examples: • Shipbuilding • House construction

  17. Data Requirements • Need to know: • What and how much to produce • When parts are needed • What operations and times are required • Work center capacities • Organized into databases: • Planning or Control

  18. Planning Files • Item master file • Product structure file • Routing file • Work center master file

  19. Part number Part description Manufacturing lead time Lot size quantity Quantity on hand Quantity available Allocated quantity already assigned to other work orders On-order quantities Item Master File

  20. Product Structure File • Bill of material file • A listing of single-level components to make an assembly • Forms a basis for a ‘pick list’

  21. Routing File • Step-by-step instructions on how to make the product • Operations and their sequence • Operation descriptions (brief) • Equipment tools and accessories • Operation setup times • Operation run times • Lead times for each operation

  22. Work Center Master File • Details on each work center • Work center number • Capacity • Shifts, machine hours and labor hours per week • Efficiency • Utilization • Average queue time • Alternative work centers

  23. Control Files • Shop order master file • Summarized data on each shop order • Shop order detail file • Current record of each operation

  24. Shop order number Order quantity Quantity completed Quantity scrapped Quantity of material issued to the order Due date Priority Balance due Cost information Shop Order Master File

  25. Shop Order Detail File • Operation number • Setup hours planned and actual • Run hours planned and actual • Quantity complete (at this operation) • Quantity scrapped (at this operation) • Lead time remaining

  26. Order Preparation • A check for available: • Tooling • Materials • Capacity - when it is needed

  27. Scheduling • To meet delivery dates • Make the best use of resources • Need information on: • Routing • Capacity • Competing jobs • manufacturing lead times

  28. Manufacturing Lead Time • Queue - time spent waiting before operation • Setup - time to prepare the work center • Run - time to make the product • Wait - time spent after the operation • Move - transit time between work centers

  29. Move Queue Setup Run Wait Manufacturing Lead Time Queue Setup Run Wait Need a lift truck here Move

  30. Cycle Time • “The length of time from when material enters a production facility until it exits” • APICS Dictionary 11th Edition • Synonym - throughput time

  31. Example Problem

  32. Forward Scheduling Start when the order is received May finish early Used to determine the earliest completion date Determine promise dates Builds inventory Backward Scheduling Uses MRP logic Schedule last operation to be complete on the due date Schedule previous operations back from the last operation Reduces inventory Scheduling Techniques

  33. Material Ordered Material Ordered 3rd Operation 3rd Operation 1st Operation 1st Operation 2nd Operation 2nd Operation Forward and Backward Scheduling:Infinite Load Order Recieved Due Date 1 2 3 4 5 6 7 8 9 Forward Scheduling Backward Scheduling Figire 6.4 Infinite load profile

  34. Capacity Infinite Load Profile Capacity Overload Capacity Underload Figure 6.5 Infinite load profile

  35. Forward and Backward Scheduling:Finite Load Order Recieved Due Date 1 2 3 4 5 6 7 8 9 Forward Scheduling Material Ordered 3rd Operation 1st Operation 2nd Operation Backward Scheduling Material Ordered 3rd Operation 1st Operation 2nd Operation Figure 6.6 Forward and Backward scheduling: finite load

  36. Finite Load Profile Capacity Smoothed Load Figure 6.7 Finite load profile

  37. X A B Example Problem Backward Scheduling • A company has an order for 50 brand X to be delivered on day 100 • Only one machine is available for each operation • The factory works one 8 hour shift 5 days a week • The parts move in one lot of 50

  38. Example Problem Answer Part A OP 10 OP 20 X Assembly Part B OP 10 85 90 95 100 Working Days

  39. Operartion A SU Lot 1 Lot 2 T T Operation Overlapping • The next operation is allowed to begin before the entire lot is completed • Reduces the manufacturing lead time • Order is divided into at least two transfer lots Transfer Time SU Lot 1 Lot 2 Operation B

  40. Operation Overlapping • Costs involved: • Handling costs between work centers • May increase queue and wait for other orders • Idle time if the second batch doesn’t arrive in time

  41. Size of the Transfer Batch SUA = Set up time operation A SUB = Set up time operation B RTA = Run time per piece operation A RTB = Run time per piece operation B QT = Total order size T1 = size of the first transfer batch T1 = QT x RTA - SUB T2 = QT - T1 RTA + RTB

  42. Size of the Transfer Batch • If the second operation is slower than the first make the first transfer batch small • i.e. get the slower machine started early • If the second machine is faster than the first make the first transfer batch large • i.e. the second machine will be able to catch up

  43. T T Example Problem Operation A 0 30 730 1,000 (Minutes) 30 70 x 10 = 700 30 x 10 = 300 Transfer Time 1,010 50 70 x 5 = 350 30x5 = 150 740 790 1140 1290 Operation B Stores 1305

  44. Operation Splitting • Reduces manufacturing lead time • The order is split into at least two lots • Similar machines are run simultaneously • Setup time is low compared to run time • Operators can run more than one machine

  45. SU SU SU Run Run Run Operation Splitting One Machine Two Machine Operation Splitting Reduction in Lead Time Figure 6.9 Operation splitting

  46. Load Leveling • Load Report • Tells PAC the current and upcoming load on a work center • Based on standard hours of operation for each order

  47. Load Report Figure 6.10 Work centre load report

  48. Scheduling Bottlenecks • Some workstations are overloaded and some are underloaded • Bottlenecks • “a facility, function, department, or resource whose capacityis equal to or less than the demand put upon it.” APICs Dictionary 11th Edition

  49. Throughput • The total volume of product passing through a facility • Bottlenecks control the throughput • If Work centers feeding bottlenecks produce more than the bottleneck can process, excess WIP inventory is built up. Therefore, work should be scheduled through the bottleneck at the rate it can process the work • Work Centers fed by bottlenecks have their throughput controlled by the bottleneck, and their schedules should be determined by that of bottleneck

  50. Example Problem - Bottlenecks • Wagon Wheel Assembly - 1200 sets (2) per week • Handle Assembly - 450 per week • Final Assembly - 550 wagons per week a. What is the capacity of the factory? b. What limits the throughput of the factory? c. How many wheel assemblies should be made each week? d. What is the utilization of the wheel assembly? e. What happens if utilization is 100%