ECO Note.doc

Session 1：Planning, execution, and control overviewClosed-loop systemThe MPC system is a closed-loop system. A close-looped system is a system that monitors accomplishment against the plan. It has an internal control and replanning capability. It typically includes: Sales and operations planning Master production scheduling Material requirements planning Capacity planningThe execution functions include the manufacturing control functions of Input-output capacity Detailed scheduling Dispatching Anticipated delay reports from both the plant and suppliers Supplier schedulingThe planning and control process consists of the following steps: establish a plan, execute the plan, measure performance, and take corrective actions.Primary object of planning and control process Maximizing customer service Limiting inventory investment Maintaining high operating efficiencies.Interface is a point of interaction between two systems or work groups.Planning interfaces Interactions that facilitate the planning and control of production activity Communication channels that transfer the following information to the production organizationo Production plano Master production scheduleo Material requirements plano Capacity requirements plan1. Business planningBusiness planning, while outside of the MPC boundaries, is considered part of the MPC system because it has d direct impact on the subsequent planning activities. The plan must be consistent with strategic plans, departmental budgets, and the firms capabilities. The business plan is typically prepared annually and updated on a quarterly basis. A business plan is usually accompanied by supporting financial statements, such as budgets and a projected balance sheet or cash flow statement. A business plan is a statement of long-range: Strategy Revenue Cost profitA business plan is usually stated in terms of dollars and grouped by product family. The business plan, the production plan, the master schedule, the material requirements plan, and the capacity requirements plan, although frequently stated in different terms, must agree with each other.2. Sales and operations planningSales and operations planning, establishes the overall level of manufacturing output by creating the production plan. Sales and operations planning focuses on Meeting business goals and objectives Establishing production quantities Confirming resource availabilityThe production plan is the primary input to resource requirements planning. The resource requirement planning is used to confirm that critical resources with long lead times can be made available. Resources that should be checked include: facilities long-lead-time equipment critical materials technology labor skillsSales and operations planning provide a direct and consistent dialogue between manufacturing and top management. The production plan is a primary output of sales and operation planning.3. Master schedulingMaster scheduling is the process where the master production schedule is created, reviewed, and approved. The MPS is the planned build schedule for manufactured end products or product options. It interfaces with rough-cut capacity planning.At an operational level, master scheduling focuses on: processing transactions maintaining records and reports performing a periodic review-and-update cycle processing and responding to exceptions and conditions measuring effectiveness on a routine basisThere are four master scheduling approaches: make-to-stock engineer-to-order make-to-order assemble-to-orderRough-cut capacity planning is a process used to ensure that potential bottleneck resources are available to accomplish the MPS.4. Material requirements planningMRP explodes the MPS into a detailed, time-phased set of component and raw material requirements. MRP uses the product bills of material, inventory data by part number, and part production or procurement lead times to calculate the net material requirements for each part number required to calculate the MPS. The material requirements planning process begins with the MPS and determines: the quality of all components and materials required the date that the components and material are requiredThis is accomplished by exploding the bill of material adjusting or netting for inventory quantities on hand or on order offsetting the net requirements by appropriate component or raw material lead timesWhile MRP can be run frequently to reflect a timely material s requirements plan, it has weak points especially when viewed from JIT perspective. If deliveries are expected to be late, safety stock can be used; if production may be late, safety time can be built into item lead times; and if poor yields are typical, scrap and yield factors can be used for planning. JIT addresses these exceptions differently.In addition, the traditional MRP manufacturing approach to production scheduling has been to minimize change. This makes reacting in a JIT environment extremely difficult.JIT and MRP are not mutually exclusive, but rather, complementary. While they are different in terms of how the integration and coordination are performed, they both emphasize the integration and coordination of manufacturing and the various interfacing activities. Many JIT-based companies have implemented MRP, not necessarily for production scheduling but for planning production over large periods of time. The three characteristics described below further depict the relationship between the two concepts: informational versus physical planning versus execution bills of materialRouting data, work center parameters, planned orders, and open orders is the input data for CRP.Capacity requirements planning refer to the process of determining in detail the amount of labor and/or machine resources required to accomplish the production schedule. The detailed material plans drive the capacity requirements planning process.Planned and released shop orders in the MRP system are primary input to CRP. CRP translates these orders into ours of work. Although rough-cut capacity planning may indicate that sufficient capacity exists to execute the MPS, CRP may show that capacity is insufficient during specific time periods. Scheduled workload and capacity must be kept in balance.Execution interfaces Execution interfaces facilitate production activity control. Support the systems, plans and methods of communicating and executing activities on the shop floor. Offer feedback and facilitate production activities. Execution interfaces occur in the back end of the system.1. Production activity controlProduction activity control (PAC) embodies the execution of material and capacity plans. It comprises the execution part of the MPC system. Shop floor scheduling and control, typically referred to as shop floor control (SFC), and supplier control systems are the major parts of PAC. The objectives of execution systems are to Communicate detailed shop floor schedules to manufacturing and suppliers Identify bottleneck resources Highlight behind-schedule situations Provide feedback to the front-end systems (using manufacturing performance measures)o Identify and resolve problems and delayso Provide status informationo Track costso Update inventory balanceso Measure workloado Adjust work-center prioritiesPAC and MPCThe primary connections between PAC and the rest of the MPC system are the material and capacity plansThe capacity requirements plan Determines the amount of capacity required to execute the materials requirements plan Allows achievable shop floor schedules to be established Reflects current and future resource availabilityThe material requirements plan Provides detailed, time-phased material requirements information to the CRP, operations scheduling and supplier scheduling systems Establishes manufacturing schedule performance objectivesThe link between PAC, CRP and MRP are bi-directional. Feedback is of two types: status information, warning signals.PAC and JITPAC传统上一般是批次生产，the primary characteristic of batch manufacturing is that all components are completed at a workstation before they move to the next one. Under JIT, order release is still part of PAC, but typical shop orders are not used; therefore, the PAC functions are largely simplified. Detailed scheduling becomes unnecessary because work in process is pulled through the manufacturing cells Work is completed fast enough to eliminate the need for detailed operations scheduling Detailed scheduling of workers and equipment is not an issue because the JIT system design determines schedules Data collection, monitoring, and other status are not needed since work in process inventory is not tracked Receipts of finished goods are used to backflush raw materials, components, and labor Use of Kanbans eliminates the need for order authorizationThe essential inputs to a PAC system are routing and lead-time data.The schedules represent loading a particular job onto a particular work center for a particular time period. After loading, the job is added into the queue for the work center. Facility layoutThe objectives of a production layout are Reduced costs Reduced time Increased quality Inventory reductionThe layout of the shop floor is the physical arrangement of resources or centers of economic activity within a facility. Layouts include linear, functional, cellular, and fixed-positionIf JIT is implemented, a disconnected flow will eventually become like a connected-flow process. Every time the disconnected flow is simplified, it moves closer to being a connected flow.1. Functional layoutA functional layout is a shop floor configuration characterized by locating machine tools that perform a similar function in the same area or department. Disadvantages: Geographical distances Excessive materials transport Time separation Possible alienation2. Improper layout Birdcage layout Isolated island layout Linear layout3. Job shopA job shop process is characterized by the organization of similar equipment by function. Job shop operations, like repetitive flow operations, are characterized by batches. A job shop design is chosen for one or more of the following purposes: Providing flexibility for the customer Making small batches for test marketing or early in the production of a product Ensuring quality whenever highly skilled labor is required to meet specifications Making unique or low-volume products, such as machines, tools, and fixtures used to produce other products Making prototypes of new products.4. FlowThere are three types of flow designs: Continuous flow Dedicated repetitive flow Batch flowObjectives of flow design One-piece flow Lower inventory Minimized space requirements Attainment of operational requirements Flexibility to meet changes in output ratesA focused factory is a plant in which the entire manufacturing systems is focus on a limited, concise, manageable set of products, technologies, volumes, and markets precisely defined by the companys competitive strategy, technology, and economics. This enables the operation to approach a flow-like condition, thus achieving the objectives of the JIT philosophy more effectively. For large scale operations, a common approach is to have a number of focused factories under one roof.5. Cellular manufacturingCellular manufacturing is a manufacturing process that produces families of parts within a single line or cell of machines operated by operators who work only within the line or cell. Usually, the most functional arrangement is not a straight line, but rather a U-line.A cell is a manufacturing unit consisting of A number of workstations Material transporting mechanisms Storage buffers that interconnect the cellsThe purpose of cellular manufacturing is to streamline production Functional clusters are broken up into cells, enabling improved material flow, visibility, and continuous manufacturing Families of parts are produced within a line or group of cells Floor space is minimized Direct handoff of parts is emphasized.6. HybridPure production design processes are rarely found. Most production processes combine two or three of these designs.The process for determining which production layout to use is to first document the existing flow and, second, to understand why a new flow may be needed. Session 2: Scheduling production and process operationsScheduling conceptScheduleSchedule is a plan that defines the sequence and time allocation for each operation necessary to complete a task. The detailed schedule includes: Sequence constraints Sequence of operations Time estimates Resource utilization and capacity.Objectives of Scheduling Establish due dates Determine throughput times Keep the shop floor running smoothlyThe goal of scheduling is to balance these objectives in order to provide timely and cost effective delivery of products.Establishing a Schedule1. Selection of Scheduling ApproachesMaster Scheduling is the final activity of the front end of the manufacturing planning and control (MPC) system. It is the process in which the master production schedule (MPS) is created, reviewed, and approved. The manufacturing environment determines which of the master scheduling approaches should be used. The manufacturing environment could be any of the following: Make-to-stockThe competitive strategy of make to stock emphasizes immediate delivery of standard items. MPS is the anticipated build schedule of the items required to maintain the finished goods at the desired inventory level. Quantities are scheduled based on manufacturing economics and forecasted demand as well as desired safety stock levels. Items may be produced either on a repetitive line or in batch production. Assemble-to-orderThe competitive strategy is to supply a large variety of final product configurations from standard components and subassemblies within a relatively short lead time. There is a schedule for options, accessories, and common components as well as a final assembly schedule(FAS).Forward scheduling is typically used to establish promise dates in this environment. However, backward scheduling is used to actually schedule the work after commitment (许诺) is made. Make-to-order or Engineer-to-orderThe final configuration of the end product is determined after receiving specifications and an order from the customer. In this case, a company is capable of producing a large range of potential finished units from a relatively small number of component and raw materials.2. Inputs Necessary for Effective Scheduling: What to make When to make it Where to make it How to make it How much to make Time needed to make it Due date Raw material availability Machine maintenance and failure schedules Rework or scrap percentages Other demands on the facility3. Scheduling Guidelines Business Priorities Targetso Minimum and maximum inventory levelso Production run lengthso Capacity utilizationo Production sequences Rules Procedures, must specify the following:o Scheduling frequencyo Schedule time intervalso Scheduling horizonso Responsibilitieso Sources for updating the scheduleo Techniques for linking the production plan with the production schedule.4. Production SchedulingThe purpose of scheduling in production environment is control. Assists in gaining control over production materials and processes by determining and authorizing production rates and levels. Servers as a performance measure Utilizes capacity and material plans. Detailed production scheduling occurs in the back end of the MPC system. Its a form of shop floor control. It is responsible for scheduling the activities required to execute the planned production. Capacity and material plans provide input for production scheduling and determine where can and should be scheduled.Capacity plansThe importance of capacity planning for production scheduling is illustrated by considering two extremes.Capacity plans are based on the results of backward and forward scheduling.Backward Scheduling It calculates start dates by starting with the MRP order due date and working backward to determine the required start date for each operation on the shop floor.Forward Scheduling Is a convenient method for establishing a schedule, providing that the order completion date is consistent with the master schedule and customers required date. Is often used to give customers promise dates May focus on critical or bottleneck operations Does not work well for complex product structures because of the timing interrelationships.Material plansMaterial plans provide information to production scheduling and set performance objectives.Scheduling production and process operationsThree methods of Production Scheduling:1. Mixed-Model SchedulingMixed-model scheduling facilitates making several different components in varying lot sizes. The goal is to build every item every day, according to daily demand in order to minimize work in process and control costs.Mixed-model scheduling affects operations scheduling by forcing it to facilitate the production of each of the different components.2. Rate-Based SchedulingWhich is used in either push or pull system, is a method for scheduling and producing based on a time period, such as daily, weekly, or monthly this method traditionally has been applied to high-volume an process industries; however, it can be applied within job shops using cellular layou