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ME 482 - Manufacturing Systems Production Planning, Scheduling and Control by Ed Red.

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Presentation on theme: "ME 482 - Manufacturing Systems Production Planning, Scheduling and Control by Ed Red."— Presentation transcript:

1 ME Manufacturing Systems Production Planning, Scheduling and Control by Ed Red

2 ME Manufacturing Systems Objectives To review modern production control technologies - MRP - JIT - Shop floor control - Inventory control To review modern production control technologies - MRP - JIT - Shop floor control - Inventory control To study costs and complexity of manufacturing systems To study costs and complexity of manufacturing systems To consider application conditions (student presentations) To consider application conditions (student presentations) To test understanding of the material presented To test understanding of the material presented INMASS/MRP Modules MRP (Materials Requirements Planning) Inventory Control Bill of Materials Job Cost/Work in Process Purchasing Sales Order Entry General Ledger Accounts Receivable Accounts Payable Payroll Shop Floor Control Bar Coding Forecasting StarShip Shipping Module Customer Histories Vendor Histories Each module includes built-in reports and the INQUIRE Report Generator allows you to create customized reports and forms.

3 ME Manufacturing Systems Production planning, scheduling, and control Objective –...managing the details of what and how many products to produce and when, and obtaining the raw materials, parts, and resources to produce those products. (Groover) Four activities of production planning: Aggregate production planning – enterprise level planning for product lines and output levels.Aggregate production planning – enterprise level planning for product lines and output levels. Master production planning - Breaking down the enterprise product plans into a master production schedule (MPS) for producing models within each product line.Master production planning - Breaking down the enterprise product plans into a master production schedule (MPS) for producing models within each product line. Material requirements planning (MRP) – computer plan to convert MPS into a schedule of raw materials and parts used in the end products.Material requirements planning (MRP) – computer plan to convert MPS into a schedule of raw materials and parts used in the end products. Capacity planning – determine labor and equipment needed to achieve master schedule.Capacity planning – determine labor and equipment needed to achieve master schedule. 6 or more months months

4 ME Manufacturing Systems Production planning, scheduling, and control Four production activities: Shop floor control – compare progress and status of production orders to production plans (MPS) and release production orders to the factory as needed.Shop floor control – compare progress and status of production orders to production plans (MPS) and release production orders to the factory as needed. Inventory control - techniques for managing inventory.Inventory control - techniques for managing inventory. Manufacturing resource planning (MRP II) – integrates MRP, capacity planning, shop floor control and other production functions.Manufacturing resource planning (MRP II) – integrates MRP, capacity planning, shop floor control and other production functions. Just-in-time production systems (JIT) – scheduling discipline in which materials and parts are delivered to the next production station (cell, FMS, etc.) just prior to their being used.Just-in-time production systems (JIT) – scheduling discipline in which materials and parts are delivered to the next production station (cell, FMS, etc.) just prior to their being used.

5 ME Manufacturing Systems Shop floor control Three phases: Order release – soft (modern factory) and/or hard (manual factory) documentation needed to process a production order through the factory.Order release – soft (modern factory) and/or hard (manual factory) documentation needed to process a production order through the factory. Order scheduling - assigns production orders to the plant work centers...often referred to as a dispatch list.Order scheduling - assigns production orders to the plant work centers...often referred to as a dispatch list. Order progress – monitors the status of the orders in the plant, WIP (work- in-progress), and any other characteristics which can be used to measure progress and performance. May depend on a factory data collection system for information.Order progress – monitors the status of the orders in the plant, WIP (work- in-progress), and any other characteristics which can be used to measure progress and performance. May depend on a factory data collection system for information.

6 ME Manufacturing Systems Shop floor control – order release Documentation consists of: Route sheet – documents process plan for part to be produced.Route sheet – documents process plan for part to be produced. Material requisition - draw necessary materials from inventory.Material requisition - draw necessary materials from inventory. Job cards – report labor required to produce part.Job cards – report labor required to produce part. Move tickets – authorize parts to be transported between work centers.Move tickets – authorize parts to be transported between work centers. Parts list – needed if the product requires an assembly of component partsParts list – needed if the product requires an assembly of component parts

7 ME Manufacturing Systems Shop floor control – order scheduling Concerned with machine loading and job sequencing: Machine loading – allocating orders to work centers.Machine loading – allocating orders to work centers. Job sequencing - determining the order in which parts are processed through a given work center.Job sequencing - determining the order in which parts are processed through a given work center. Priority control – maintains the proper priority for the production orders under the dispatching rules: first-come-first-serve – jobs are processed in order received earliest due date – orders with earlier due dates have higher priority shortest processing time – those finished faster have higher priority least slack time – jobs with least slack time have higher priority critical ratio – ratio of time remaining until due date divided by remaining process time. Orders with lowest ratio given higher priority.Priority control – maintains the proper priority for the production orders under the dispatching rules: first-come-first-serve – jobs are processed in order received earliest due date – orders with earlier due dates have higher priority shortest processing time – those finished faster have higher priority least slack time – jobs with least slack time have higher priority critical ratio – ratio of time remaining until due date divided by remaining process time. Orders with lowest ratio given higher priority.

8 ME Manufacturing Systems Shop floor control – order progress Concerned with progress reports: Work order status reports – status of production orders.Work order status reports – status of production orders. Progress reports - report performance of shop during a time period, including orders completed, orders not completed, etc.Progress reports - report performance of shop during a time period, including orders completed, orders not completed, etc. Exception reports – deviations from the production schedule and other exceptions.Exception reports – deviations from the production schedule and other exceptions.

9 ME Manufacturing Systems Shop floor control – software

10 ME Manufacturing Systems Shop floor control software

11 ME Manufacturing Systems Shop floor control – software

12 ME Manufacturing Systems Inventory control Concerned with minimizing cost of holding inventory and maximizing customer service. These seem to conflict. Types of inventory: Raw materialsRaw materials WIPWIP ComponentsComponents Finished productsFinished products Inventory costs: Investment costsInvestment costs Storage costsStorage costs Possible obsolescence costsPossible obsolescence costs Spoilage costsSpoilage costs Inventory as a function of demand: Independent demand (order point inventory method) – demand for a product is unrelated to demand for other items (e.g., final product and spare parts)Independent demand (order point inventory method) – demand for a product is unrelated to demand for other items (e.g., final product and spare parts) Dependent demand (MRP method) – demand for an item is directly related to demand for some other item (e.g., product component, raw material)Dependent demand (MRP method) – demand for an item is directly related to demand for some other item (e.g., product component, raw material)

13 ME Manufacturing Systems WIP inventory costs Concerned with minimizing costs of processing materials before the final product can be released to the consumer. Costs considerations: Production consists of a series of operationsProduction consists of a series of operations Time is consumed in each operation (and time is cost)Time is consumed in each operation (and time is cost) Time and costs are consumed between each operation (e.g., material handling with no value added)Time and costs are consumed between each operation (e.g., material handling with no value added) WIP represents money expended for material and processing, still considered inventory because goods are not yet delivered to the customer!

14 ME Manufacturing Systems WIP inventory cost analysis - terms C m – material cost T p – average production time (setup plus operation time) T pk – production time for process k (setup plus operation time) T su – average machine setup time for a batch process T no – average non-operation time for a machine T c – average operation cycle time for a machine T a – average operation cycle time for a machine including setup and non-operation times Q – average batch quantity for batches of parts being processed

15 ME Manufacturing Systems cost WIP inventory cost analysis - terms C o – production costs rate C ok – operational costs for process k C no – average non-operational costs (material handling, inspection, etc.) C nok – non-operational costs for process k (material handling, inspection, etc.) C su = setup costs and/or ordering costs for an order($/setup or $/order)

16 ME Manufacturing Systems WIP inventory cost analysis - terms C pc – part costs accumulated through all processes, inspections, and material handling n o – total number of operations/processes MLT – manufacturing lead time (the longer the MLT, the greater the WIP) t – time of part spent in process sequence h – holding cost rate C h = holding costs HC pc – holding cost per part TC pc – total cost per part including WIP carrying costs

17 ME Manufacturing Systems WIP inventory cost analysis graphs Linear approximation of part costs as function of time in factory Part/product costs as function of time in factory

18 ME Manufacturing Systems WIP inventory cost analysis graphs Linear approximation with WIP holding costs

19 ME Manufacturing Systems WIP inventory cost analysis Equations: avg batch operation cycle time T a = T su + Q T c + T no MLT (batch process) MLT = n o T a cost per operation C ok = C o T pk + C nok total cost after all operations C pc = C m + k C ok ( k = 1,.. n o ) total cost after all operations* C pc = C m + n o ( C o T p + C no ) * assuming T pk and C nok are the same for each operation

20 ME Manufacturing Systems WIP inventory cost analysis Equations: part cost function line* C(t) = C m + n o (C o T p + C no )]t/ MLT *using average T p and C no total cost per part including WIP TC pc = C pc + (C m + C p )t/MLT)h dt where C p = n o (C o T p + C no ) where C p = n o (C o T p + C no ) thenTC pc = C pc + HC pc where HC pc = holding cost for WIP HC pc = (C m + C p /2) h (MLT) where HC pc = holding cost for WIP HC pc = (C m + C p /2) h (MLT)o MLT

21 ME Manufacturing Systems WIP inventory example Problem: Inventory Holding Cost for WIP During Manufacturing The cost of the raw material for a certain part is $100. The part is processed through 20 processing steps in the plant, and the manufacturing lead time is 15 wk. The production time per processing step is 0.8 hr, and the machine and labor rate is $25.00/hr. Inspection, material handling, and other related costs average to $10 per processing step by the time the part is finished. The interest rate used by the company i = 20%, and the storage rate s = 13%. Determine the cost per part and the holding cost.

22 ME Manufacturing Systems WIP inventory example Problem: Inventory Holding Cost for WIP During Manufacturing Solution: The material cost, operation costs, and non-operation costs are from C pc = C m + C p = C m + n o ( C o T p + C no ) = $ ($25.00/hr x.8 hr + $10) = $100 + $600 = $700/pc = $100 + $600 = $700/pc Next, determine the holding cost rate h = 20%+13%=33%. Expressing this as a weekly rate, h = (33%)/(52 wk) = %/wk = /wk. The holding cost/pc: HC pc = (C m + C p /2) h (MLT) = ( /2)( )(15 wk) = $38.08/pc This gives a total cost of TC pc = C m + C p + HC pc = = $738.08/pc

23 ME Manufacturing Systems JIT production systems Problem - to reduce inventory costs by delivering the correct components to the manufacturing operation exactly when needed, minimizing WIP and MLT. JIT is the solution.

24 ME Manufacturing Systems JIT production systems JIT must have: Pull system of production control – Kanban (card) system is often used to implement a pull system. The cards authorize 1) parts production (P-kanban) and 2) parts transport (T- kanban). A P-kanban authorizes an upstream process to produce only the parts that will fill a batch container, no more. A T-kanban authorizes the transport of the batch to a downstream station. These procedures are duplicated in sequence, eliminating much of the paperwork, but uses more labor, although said to promote teamwork among stations.

25 ME Manufacturing Systems JIT kanban examples The withdrawal Kanban shows that the preceding process which makes this part is forging, and the person carrying this Kanban from the subsequent process must go to position B-2 of the forging department to withdraw drive pinions. Each box of drive pinions contains 20 units and the shape of the box is B. This Kanban is the 4th of 8 issued. The item back number is an abbreviation of the item.

26 ME Manufacturing Systems JIT kanban examples The production ordering Kanban to the right shows that the machining process SB-8 must produce the crankshaft for the car type SX50BC-150. The crankshaft produced should be placed at store F The production-ordering Kanban is often called an in-process Kanban or simply a production Kanban.

27 ME Manufacturing Systems JIT production systems JIT must have: Small batch sizes and reduced setup times – uses improvements in fixturing, part handling, group technology, automation, etc. to minimize batch size and setup.

28 ME Manufacturing Systems JIT production systems JIT must have: Stable and reliable production operations – also includes a stable supplier base, good relationships, committed workforce, defect free materials and components (in other words, you must have your act together from A – Z)

29 ME Manufacturing Systems Lean versus agile production systems Lean production Agile manufacturing Enhancement of mass productionEmphasis on mass customization Flexible production for product varietyFlexibility for customized products Focus on factory operationsScope is enterprise wide Emphasis on supplier managementFormation of virtual enterprises Emphasis on efficient use of resourcesThriving environment with continuous change Relies on smooth production scheduleResponsive to change Minimize change! Embrace change!

30 ME Manufacturing Systems What have we learned? Production planning, scheduling and control


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