Process selection


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Process selection

  1. 1. PROCESS SELECTION Chapter 4INTRODUCTION to Operation Management4e, SchroederMcGraw-Hill/Irwin Copyright © 2008 by The McGraw-Hill Companies, Inc., All Rights Reserved.
  2. 2. Product-Flow CharacteristicsTypes of Product Flow – Continuous process – Job shop – Assembly Line – Batch – Project 4-2 4-2
  3. 3. Continuous ProcessIts name derives from how materials movethrough the process. Usually one primarymaterial, such as a liquid, gas, wood fibers, orpowder, moves without stopping through thefacility.Example: Oil refinery 4-3 4-3
  4. 4. Product-Flow Characteristics Continuous ProcessProcess industries (beer, paper, oil, etc.)Highly standardized and automatedHigh volumes of productionFlexibility limited 4-4 4-4
  5. 5. Assembly Line FlowMaterials move linearly from one operation tothe next according to a fixed sequence, withlittle inventory held between operations.Each operation performs the same processover and over with little variability in theproducts or services provided. Productionorders arent directly linked to customerorders, as is the case with project and jobprocesses.Example: Automobile production line 4-5 4-5
  6. 6. Assembly Line FlowManufacturers with line flow processes oftenfollow a make-to-stock strategy, with standardproducts held in inventory so that they areready when a customer places an order. Thisuse of a line flow process is sometimes calledmass production. 4-6 4-6
  7. 7. Product-Flow Characteristics Assembly Line FlowLinear sequence of operationsDiscrete products (autos, appliances, etc.)High-volume, standardized productsInflexibility in product and volumeVery efficientLarge capital investment 4-7 4-7
  8. 8. Assembly Line Flow (metal bracket, see fig. 4.1)cut drill bend paint Task or work station Product flow 4-8 4-8
  9. 9. Batch ProcessA batch process is similar to a job shop,except that the sequence of activities tends tobe in a line and is less flexible.Products are produced in batches, for example,to fill specific customer orders.Example: Bakery 4-9 4-9
  10. 10. Batch ProcessA batch of one product or customer group isprocessed, and then production is switched tothe next one.Eventually, the first product or service isproduced again.A batch process is similar to a job shop,except that the sequence of activities tends tobe in a line and is less flexible. The activities,while in-line, are disconnected from oneanother. 4-10 4-10
  11. 11. Product-Flow Characteristics Batch FlowProduction of batches or lotsBatches flow from one work center to anotherLow volume productsMany different types of productsFlow is jumbled and intermittentFlexible labor and equipment 4-11 4-11
  12. 12. Batch Flow(three metal brackets, see fig. 4.2) Bend Batch A Cut Paint Batch B Batch C Drill Task or work station Product flows 4-12 4-12
  13. 13. Job ShopA job shop is a flexible operation that hasseveral activities through which work canpass. In a job shop, it is not necessary for allactivities to be performed on all products, andtheir sequence may be different for differentproducts.Example: Printing and Machine shop 4-13 4-13
  14. 14. Job Shop, continuedTo illustrate the concept of a job shop,consider the case of a machine shop. In amachine shop, a variety of equipment such asdrill presses, lathes, and milling machines isarranged in stations. Work is passed only tothose machines required by it, and in thesequence required by it. This is a very flexiblearrangement that can be used for wide varietyof products. 4-14 4-14
  15. 15. Job Shop, continuedCompanies choosing a job process often bidfor work. Typically, they make products toorder and dont produce them ahead of time.The specific needs of the next customer areunknown, and the timing of repeat orders fromthe same customer is unpredictable. Each neworder is handled as a single unit--as a job. 4-15 4-15
  16. 16. ProjectIn a project, the inputs are brought to theproject location as they are needed; there is noflow in the process.The firm brings together the resources asneeded, coordinating them using projectmanagement techniques.Since there is no flow of product - the quantityproduced usually is equal to one.Example: building construction 4-16 4-16
  17. 17. Factors Affecting Process Choice Market conditions and competition Capital requirements Labor supply and cost State of technology 4-17 4-17
  18. 18. PRODUCT-PROCESS MATRIX (Figure 4.5) Low volume, Unique, one of Low volume, Higher volume High volume, high Multiple a kind low few major standardization, products product standardization products commodityProject Building NONEJob Shop Printing HeavyBatch Equipment AutoAssembly assemblyline SugarContinuous NONE Refinery 4-18 4-18