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This 44 page Class Notes was uploaded by Samantha on Friday April 24, 2015. The Class Notes belongs to OM 300 at University of Alabama - Tuscaloosa taught by William Petty in Winter2015. Since its upload, it has received 120 views.
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Date Created: 04/24/15
Learning Objectives When you complete this chapter you should be able to 1 NPP PPP Define justintime TPS and lean operations Define the seven wastes and the 5 Ss Explain JIT partnerships Determine optimal setup time Define kanban Compute the required number of kanbans Explain the principles of the Toyota Production System TPS Elements Anidon Assembly Components Enfl em d39spliaytboard Pu il System placed in cab tor easy a mgmigca 95 units produced oniy access rather than on i shelio39es adjacent to the assembliy line when more production is needed Kantian signai that indicates w 7 r production otsrnaii t 39 I r quot 39 y 39 batches ot E39 quot components Respect for People employees treated as knowiedge workers Standard Work Practices Empowered Employees 1 can stop production iideas 39 quot solicited quality circles etc rigorous agreed upon documented procedures ior production JilT parts and supplies l deiiyered iust as needed in the quantity needed I Minimal machines Proprietary machines designed tor speciiiic Toyota appiicatiions Leyei Schedules models mixed on 39 production iines to meet customer orders Kaizen Area an area where suggestions are tested and evaluated Jiidoka machines with builtin devices tor monitoring pertormance and making judgements 0 sec Automotive Amciricss to Hana Assemblieirs ILLP G PPG Industries Inc a Tokai Flika Glass assemblies Assembly of tire onto wheel Glass assemblies Functional parts 399 AHK Inc 9 HEFio Logistics ILILP 9 Hayes Automotive Group 39 industrial waste management recycling 39 Logistics 39 interioirfexterior parts JlTTPSLean Operations Good production systems require that managers address three issues that are pervasive and fundamental to operations management eliminates waste remove variability and i prove thrOUQhQUt JustlnTime TPS and Lean Operations 9 JIT is a philosophy of continuous and forced problem solving via a fOCUS on throughput and reduced inventory 9 TPS emphasizes continuous improvement respect for people and standard work practices 9 Lean production supplies the customer with their exact wants when the customer wants it without waste JustlnTime TPS and Lean Operations O JIT emphasizes forced prOblem SOIVing O TPS emphasizes employee learning and empowerment in an assemblyline environment 9 Lean operations emphasize understanding the CUStomer Eliminate Waste 9 Waste is anything that does not add value from the customer point of view 9 Storage inspection delay waiting in queues and defective products do not add value and are 100 waste Ohno s Seven Wastes Overproduction Queues Transportation Inventory unnecesary inventory should be removed Motion create a tighter space for workers Overprocessing Defective Products Eliminate Waste Other resources SUCh as energy water and air are often wasted 9 Efficient sustainable production minimizes inputs reduces waste 9 Traditional housekeeping has been expanded to thess39s The 5 Ss SortSegregate When in dOUbt thrOW Itout gt SimplifyStraighten methOdS analysis tools gt ShineSweep Clean daily gt Standardize remove variations from processes V SustainSeIfDisoipline FGVieW work and recognize progress Remove Variability O JIT systems require managers to reduce variability caused by both internal and external factors is any deviation frOm the optimum process 9 Inventory hides variability 9 Less variability results in less waste Sources of Variability 1 imcomplete or inaccurate drawings or specifications 2 Poor production processes resulting in incorrect quantities late or nonconforming units 3 Unknown customer demands Improve Throughput O The time it takes to move an order from receipt to delivery 9 The time between the arrival of raw materials and the shipping of the finished order is called manufacturing cycle time 9 A pull system increases throughput Improve Throughput 9 By pulling material in small lots inventory cushions are removed exposing problems and emphasizing continual improvement 9 Manufacturing cycle time is reduced 9 Push systems dump orders on the downstream stations regardless of the need JustlnTime JIT gt Powerful strategy for improving operations gt Materials arrive where they are needed when they are needed gt Identifying problems and driving out waste reduces costs and variability and improves throughput gt Requires a meaningful buyersupplier relationship JIT Partnerships O JIT partnerships exist when a supplier and purchaser work together to remove waste and drive down COStS 9 Four goals of JIT partnerships are Q Removal of unnecessary activities 9 Removal of inplant inventory 9 Removal of intransit inventory 9 Improved quality and reliability Concerns of Suppliers Q Diversification ties to onIy one customer increases risk 9 Scheduling don t believe customers can create a smooth schedule 9 Lead time short lead times mean engineering or specification changes can create problems 9 Quality limited by capital budgets processes or technology 9 Lot sizes small lot sizes may transfer costs to suppliers Distance Reduction 9 Large lots and long production lines with singlepurpose machinery are being replaced by smaller flexible cells 9 Often uShaped for shorter paths and improved communication 9 Often using group technology concepts Increased Flexibility 9 Cells designed to be rearranged as volume or designs change 9 Applicable in office environments as well as production settings 9 Facilitates both and improvement Impact on Employees 9 Employees may be cross trained for flexibility and efficiency 9 Improved communications facilitate the passing on of important information about the process 9 With little or no inventory buffer getting it right the first time iS critical Reduced Space and Inventory 9 With reduced space inventory must be in very small lots 9 Units are always moving because there is no storage Reduce Inventory gt Reducing inventory uncovers the rocks Problems are exposed gt Ultimately there will be virtually no inventory and no problems says inventory is evil Inventory Reduce Lot Sizes gt Ideal situation is to have lot sizes of one pulled from one process to the next gt Often not feasible gt Can use EOQ analysis to calculate desired setup time gt Two key changes necessary Q 205 gt Improve material handling 0 lib Wm gt Reduce setup time Lot Size Example Annual demand 400000 units Daily demand 400000250 1600 per day Daily production rate 4000 units EOQ desired 400 Holding cost 20 per unit Setup cost to be determined 9 2DS Q2 2DS P HL1 d 19 HL1 d 19 Q H1 d p 4002201 16004000 240 21 2400000 Mm amp S Setup time 24030hour 008 hr 48 minutes Reduce Setup Costs 9 High setup costs encourage large lot sizes 9 Reducing setup costs reduces lot size and reduces average inventory 9 Setup time can be reduced through preparation prior to shutdown and changeover JIT Scheduling O Schedules must be communicated inside and outside the organization Level schedules 9 Process frequent small batches O Freezing the schedule helps stability Kanban O Signals used in a pull system O Level Schedules gt Process frequent small batches rather than a few large batches gt Make and move small lots so the IEVEI SChedUIG is economical gt Jelly bean scheduling Freezing the SChEdUIE closest to the due dates can improve performance Kanban gt Kanban is the Japanese word for card gt The card is an authorization for the next contain39 er of material to He produced gt A sequence of kanbans pulls material through the process gt Many different sorts of signals are useq but the s stem IS stlil called a kan an Kanban Material Parts Supplier Final Finished Customer assembly goods order Kanban Kanban I More Kanban 9 When the producer and user are not in visual contact a card can be used 9 When the producer and user are in visual contact a light or flag or empty spot on the floor may be adequate 9 Since several components may be required several different kanban techniques may be employed More Kanban 9 Usually each card controls a quantity or parts 9 card systems may be used if there are several components or different lot sizes 9 In an system the schedule can be thought of as a build and the kanban a type of pull system that initiates actual production More Kanban O Kanban cards provide a direct control and limit on the amount of workin process between cells 9 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 The Number of Kanban Cards or Containers gt Need to know the lead time needed to produce a container of parts gt Need to know the amount of safety stock needed Demand during Safety Number of kanbans lead time stock containers 39 Size of container Number of Kanbans Example Daily demand 500 cakes Production lead time 2 days Wait time Material handling time Processing time Safety stock 12 day Container size 250 cakes Demand during lead time 2 days x 500 cakes 1000 Safety stock 12 x Daily demand 250 1000 250 250 5 Number of kanbans Computing the Number of Kanbans an aspirin manufacturer has converted to JIT manufacturing using kanban containers They wish to determine the number of containers at the bottle filling operation which fills at a rate of 200 per hour Each container holds 25 bottles it takes 30 minutes to receive more bottles safety stock is 10 of demand during LT S 10demandt 102005 10 bottles N 20011025 44 Kanban containers N DT 80 Advantages of Kanban gt Small containers require tight schedules smooth operations little variability gt Shortages create an immediate impact gt Places emphasis on meeting schedules reducing lead time and setups and economic material handling gt standardized containers reduce weight disposal costs wasted space and labor JIT Quality 9 Strong relationship 9 JIT cuts the cost of obtaining good quality because JIT exposes poor quality 9 Because lead times are shorter quality problems are exposed SOOHGF 9 Better quality means fewer buffers and allows simpler JIT systems to be used Toyota Production System gt Continuous improvement gt Build an organizational culture and value system that stresses improvement of all pro cesses kaizequot gt Part of everyOne s job gt Res ect for people gt People are treated as knowledge workers gt Engage mental and physical capabilities gt Empower employees I Toyota Production System gt Standard work practice gt Work shall be completely specified as to content sequence timing and outcome gt Internal and external customer supp er connection are direct gt Product and service flows must be simple and direct gt Any improvements must be made in accordance with the scientific method at the lowest possible level of the organization Lean Operations 9 Different from JIT in that it is externally focused on the customer Starts underestimating What the customer wants 9 optimize the entire process from the customer s perspective Building a Lean Organization 9 Transitioning to a lean system can be difficult 9 Lean systems tend to have the following attributes 9 Use JIT techniques 9 Build systems that help employees produce perfect parts 9 Reduce space requirements Building a Lean Organization gt Lean systems tend to have the following attributes gt Develop partnerships with suppliers gt Educate suppliers gt Eliminate all but Value added activities gt Develop employees gt Make jobs challenging gt Build worker flexibility Lean Sustainability gt Two sides of the same coin gt Maximize resource use and economic efficiency gt Focus on issues outside the immediate firm gt Driving out waste is the common ground Lean Operations in Services gt The JIT techniques used in manufacturing are used in services gt Suppliers gt Layouts gt Inventory gt Scheduling
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