Đang tải... (xem toàn văn)
Lecture 28 - JustinTime Manufacturing (Continued). The contents of this chapter include all of the following: JIT layout, distance reduction, increased flexibility, inventory, reduced variability, reduced setup cost, JIT scheduling, kanban, JIT quality tactics, lean operations.
Lecture 28 JustinTime Manufacturing (Continued) Books • Introduction to Materials Management, Sixth Edition, J. R. Tony Arnold, P.E., CFPIM, CIRM, Fleming College, Emeritus, Stephen N. Chapman, Ph.D., CFPIM, North Carolina State University, Lloyd M. Clive, P.E., CFPIM, Fleming College • Operations Management for Competitive Advantage, 11th Edition, by Chase, Jacobs, and Aquilano, 2005, N.Y.: McGrawHill/Irwin • Operations Management, 11/E, Jay Heizer, Texas Lutheran University, Barry Render, Graduate School of Business, Rollins College, Prentice Hall Objectives • • • • • • • • • • JIT layout Distance reduction Increased flexibility Inventory Reduced variability Reduced setup cost JIT scheduling Kanban JIT quality tactics Lean Operations JIT Layout Reduce waste due to movement JIT Layout Tactics Build work cells for families of products Include a large number operations in a small area Minimize distance Design little space for inventory Improve employee communication Use poka-yoke devices Build flexible or movable equipment Cross-train workers to add flexibility Distance Reduction Large lots and long production lines with single-purpose machinery are being replaced by smaller flexible cells ỵ Often U-shaped for shorter paths and improved communication ỵ Often using group technology concepts þ Increased Flexibility Cells designed to be rearranged as volume or designs change ỵ Applicable in office environments as well as production settings ỵ Facilitates both product and process improvement ỵ ImpactonEmployees Employees are cross trained for flexibility and efficiency ỵ Improved communications facilitate the passing on of important information about the process ỵ With little or no inventory buffer, getting it right the first time is critical ỵ ReducedSpaceandInventory With reduced space, inventory must be in very small lots ỵ Units are always moving because there is no storage ỵ Inventory Inventory is at the minimum level necessary to keep operations running JIT Inventory Tactics Use a pull system to move inventory Reduce lot sizes Develop just-in-time delivery systems with suppliers Deliver directly to point of use Perform to schedule Reduce setup time Use group technology Reduce Variability Inventory level Process downtime Scrap Setup time Quality problems Late deliveries Reduce Variability Inventory level Process downtime Scrap Setup time Quality problems Late deliveries More Kanban Usually each card controls a specific quantity or parts ỵ Multiple card systems may be used if there are several components or different lot sizes ỵ In an MRP system, the schedule can be thought of as a build authorization and the kanban a type of pull system that initiates actual production ỵ MoreKanban Kanban cards provide a direct control and limit on the amount of work-in-process between cells ỵ If there is an immediate storage area, a twocard system can be used with one card circulating between the user and storage area and the other between the storage area and the producer ỵ TheNumberofKanbanCards orContainers Need to know the lead time needed to produce a container of parts ỵ Need to know the amount of safety stock needed ỵ Demand during Safety lead time + stock Number of kanbans = Size of container (containers) Number of Kanbans Example Daily demand Production lead time (Wait time + Material handling time + Processing time) Safety stock Container size = 500 cakes = days = 1/2 day = 250 cakes Demand during lead time = 2 days x 500 cakes = 1,000 1,000 + 250 Number of kanbans = =5 250 Advantage of Kanban • • Small batches allow a very limited amount of faulty material Bad Aspects of Holding (Carrying) Inventory MPoor quality MIncreased insurance MObsolescene MIncreased material MDamage MOccupied space MCommitted assets Handling MIncreased accidents Advantages of Kanban Allow only limited amount of faulty or delayed material ỵ Problems are immediately evident ỵ Puts downward pressure on bad aspects of inventory ỵ Standardized containers reduce weight, disposal costs, wasted space, and labor ỵ Quality ỵ Strong relationship JIT cuts the cost of obtaining good quality because JIT exposes poor quality ỵ Because lead times are shorter, quality problems are exposed sooner ỵ Better quality means fewer buffers and allows simpler JIT systems to be used ỵ JIT Quality Tactics Use statistical process control Empower employees Build fail-safe methods (pokayoke, checklists, etc.) Expose poor quality with small lot JIT Provide immediate feedback ToyotaProductionSystem ỵ Continuous improvement Build an organizational culture and value system that stresses improvement of all processes þ Part of everyone’s job þ þ Respect for people People are treated as knowledge workers ỵ Engage mental and physical capabilities ỵ Empower employees ỵ ToyotaProductionSystem ỵ Standard work practice Work shall be completely specified as to content, sequence, timing, and outcome ỵ Internal and external customer-supplier connection are direct ỵ Product and service flows must be simple and direct ỵ Any improvement must be made in accordance with the scientific method at the lowest possible level of the organization ỵ LeanOperations Different from JIT in that it is externally focused on the customer ỵ Starts with understanding what the customer wants ỵ Optimize the entire process from the customers perspective ỵ BuildingaLeanOrganization Transitioning to a lean system can be difficult ỵ Lean systems tend to have the following attributes ỵ Use JIT techniques ỵ Build systems that help employees produce perfect parts ỵ Reduce space requirements ỵ BuildingaLeanOrganization Develop partnerships with suppliers ỵ Educate suppliers ỵ Eliminate all but value-added activities ỵ Develop employees ỵ Make jobs challenging þ Build worker flexibility þ JIT in Services þ The JIT techniques used in manufacturing are used in services Suppliers ỵ Layouts þ Inventory þ Scheduling þ End of Lecture 28 ... thought of as a build authorization and the kanban a type of pull system that initiates actual production ỵ More Kanban Kanban cards provide a direct control and limit on the amount of work-in-process... amount of safety stock needed ỵ Demand during Safety lead time + stock Number of kanbans = Size of container (containers) Number? ?of? ?Kanbans Example Daily demand Production lead time (Wait time + Material. .. is no storage ỵ Inventory Inventoryisattheminimumlevelnecessary tokeepoperationsrunning JIT Inventory Tactics Use a pull system to move inventory Reduce lot sizes Develop just-in-time delivery