Manufacturing and Service Processes
Chapter 06 Learning Objectives Understand what a production process is.
Understand the idea of production process mapping. Define Littles law. Demonstrate how production processes are organized. Describe the product-process matrix. Provide an overview of how the different types ofproduction processes are designed. Understand how to design and analyze an assemblyline. Types of Firms Make-to-Stock
Serve customers from finished goods inventory Make-to-Stock Combine a number of preassembled modules to meet a customers specifications Assemble-to-Order Make the customers product from raw materials, parts, and components Make-to-Order Work with the customer to design and then make the product Engineer-to-Order Make-to-Stock Examples of products
Televisions Clothing Packaged food products Essential issue in satisfying customers is to balance the levelof inventory against the level of customer service Easy with unlimited inventory but inventory costs money Trade-off between the costs of inventory and level of customerservice must be made Use lean manufacturing to achieve higher service levels fora given inventory investment Assemble-to-Order A primary task is to define a customers order in terms ofalternative components since these are carried in inventory An example is the way Dell Computer makes their desktop computers One capability required is a design that enables as muchflexibility as possible in combining components There are significant advantages from moving the customerorder decoupling point from finished goods to components Make-to-Order/Engineer-to-Order
Boeings process for making commercial aircraft isan example Customer order decoupling point could be in eitherraw materials at the manufacturing site or thesupplier inventory Depending on how similar the products are it mightnot even be possible to pre-order parts Production Process Mapping
Develop a high-level map of a supply chain process Useful to understand how material flows and whereinventory is held First step in analyzing the flow of material througha production process Inventory Measures Total average value of inventory -the sum of the value (atcost) of the raw material, work-in process, and finishedgoods inventory Commonly tracked in accounting systems and reported in financialstatements Inventory turns -the cost of goods sold divided by theaverage inventory value Not particularly useful for evaluating the performance of a process Days of supply -the inverse of inventory turns scaled todays Organization of Production Processes
Project the product remains in a fixed location, equipment is moved to the product Workcenter (job shop) - similar equipment or functions are grouped together Manufacturing cell - a dedicated area where products that are similar in processing requirements are produced Assembly line - work processes are arranged according to the progressive steps by which the product is made Continuous process - assembly line only the flow is continuous such as with liquids Production System Design
The product remains in a fixed location A high degree of task ordering is common A project layout may be developed by arranging materials according, to their assembly priority Project Layout Most common approach to developing this type of layout is to arrange workcenters in a way that optimizes the movement of material Optimal placement often means placing workcenters with large interdepartmental traffic adjacent to each other Sometimes is referred to as a department and is focused on a particular type of operation Workcenter Production System Design
Formed by allocating dissimilar machines to cells that are designed to work on similar products (shape, processing, etc.) Manufacturing Cell Designed for the special purpose of building a product by going through a series of progressive steps Assembly Line and Continuous Layout Manufacturing Cell Development
Group parts intofamilies that followa commonsequence of steps. Identify dominantflow patterns foreach part family Machines and theassociatedprocesses arephysicallyregrouped intocells Workcenter layout similar machines grouped together Regrouped Machines Manufacturing cell layout dissimilar machines grouped together by product Assembly Line Design Workstation cycle time - a uniform time interval in which amoving conveyor passes a series of workstations Also the time between successive units coming off the line Assembly-line balancing - assigning tasks to a series ofworkstations so that the required cycle time is met and idletime is minimized Precedence relationship - the order in which tasks must beperformed in an assembly process Mixed-Model Line Balancing
Most factories produce a number of differentproducts Inventory can be reduced by building some of eachproduct during every period (e.g. day, week, etc.) Mixed-model line balancing is one means ofscheduling this varied production