SCM 302 OPERATIONS MANAGEMENT JIT

Transcription

1 SCM 302 OPERATIONS MANAGEMENT JIT

2 2 Agenda for this Module 1. Define just-in-time, TPS, and lean operations 2. Define the seven wastes and the 5Ss 3. Explain JIT partnerships 4. Determine optimal setup time 5. Define kanban 6. Compute the required number of kanbans 7. Explain the principles of the Toyota Production System

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4 4 JIT/TPS/Lean Operations Good production systems address 3 fundamental issues 1) Eliminate waste 2) Remove variability 3) Improve throughput Just-In-Time (JIT) Materials arrive where they are needed and when they are needed Continuous problem solving Focus on improving throughput and reducing inventory. Identify problems, drive out waste to reduces cost and variability Requires a meaningful buyer-supplier relationship Toyota Production System (TPS) Continuous improvement Build organizational culture and value system on kaizen Part of everyone s job Respect for people Treat as knowledge workers Mental & physical capabilities Empower employees Standard work practice Work specified as to content, sequence, timing, and outcome Internal and external customersupplier connection are direct Product and service flows must be simple and direct Scientific-method based improvement Lean Operations What does customer want? Optimize entire process from the customer s perspective Transition to lean can be difficult Attributes Use JIT to eliminate inventory Build systems that help employees produce perfect parts Reduce space, minimizing travel distance Develop partnerships with suppliers, help them understand end-customer needs Educate suppliers to accept responsibility for shared customer needs Eliminate all but value-added activities Develop employees by constantly improving job design Push responsibility to lowest level Build worker flexibility, cross-training and reduced job classifications Terms often used interchangeably little difference in practice

5 5 JIT/TPS/Lean Operations

6 6 Eliminate Waste Waste: anything that does not add value from the customer point of view 100% Waste: Storage, inspection, delay, waiting in queues, and defective products Wasted resources such as energy, water, and air Efficient, sustainable production minimizes inputs, reduces waste Ohno s 7 Wastes 1. Overproduction 2. Queues 3. Transportation 4. Inventory 5. Motion 6. Overprocessing 7. Defective products

7 7 The 5Ss Sort/segregate when in doubt, throw it out Set in Order a place for everything and everything in its place. Mise en place Shine/sweep clean and inspect regularly Standardize remove variations from processes, establish benchmarks Two Additional Safety built in good practices Support/maintenance reduce variability and unplanned downtime Sustain/self-discipline review work and recognize progress, make habits of best practices

8 8 Variability: Root of All Evils Variability: any deviation from optimum process Sources of variability Poor production processes resulting in improper quantities, late, or non-conforming units Unknown customer demands Incomplete or inaccurate drawings, specifications, or bills of material Reduce variability caused by both internal and external factors Inventory hides variability Less variability results in less waste

9 9 Improve Throughput Throughput: rate at which units move through process Receipt of order to delivery of order Manufacturing cycle time: time between the arrival of raw materials and the shipping of the finished order How does a pull system increase throughput? Small lots: inventory cushions are removed, exposing problems and emphasizing continual improvement Manufacturing cycle time is reduced Push systems dump orders on the downstream stations regardless of the need

10 High water hides rocks: High levels of inventory hid problems 10 Inventory level Scrap Setup time Quality problems Process downtime Late deliveries

11 Reduce inventory, problems exposed Reducing inventory uncovers the rocks 11 Inventory level Scrap Setup time Quality problems Process downtime Late deliveries Figure 16.3

12 Smoother sailing: After reducing inventory and removing problems 12 Inventory level No scrap Setup time reduced No late deliveries Quality problems removed Process downtime removed Figure 16.3

13 JIT and Competitive Advantage 13

14 14 JIT Tactics Layout Inventory Scheduling Quality Work cells Large # operations in small area Minimize distance Little space for inventory Employee communication Flexible equipment Cross-train workers U-shaped lines Increased Flexibility Reduce lot sizes Just-in-time delivery systems with suppliers Deliver directly to point of use Perform to schedule Reduce setup time Reduced storage space Units always moving because there is no storage Communicate schedules to suppliers Level schedules Freeze part of the schedule Perform to schedule Eliminate waste Use kanbans: signals Make each operation produce a perfect part Internal & external communication Frequent small batches rather than few large batches JIT exposes poor quality & sooner Better quality: fewer buffers SPC Empower employees Provide immediate feedback

15 15 Reduce Setup Costs High setup costs encourage large lot sizes Reducing setup costs reduces lot size and reduces average inventory Setup time can be reduced through preparation prior to shutdown and changeover

16 16 Reduce Setup Costs Figure 16.6 Initial Setup Time 90 min Step 1 Step 2 Separate setup into preparation and actual setup, doing as much as possible while the machine/process is operating (save 30 minutes) Step 3 Move material closer and improve material handling (save 20 minutes) Step 4 Standardize and improve tooling (save 15 minutes) Step 5 Step 6 Use one-touch system to eliminate adjustments (save 10 minutes) Training operators and standardizing work procedures (save 2 minutes) Repeat cycle until subminute setup is achieved 60 min 45 min 25 min 15 min 13 min

17 17 Kanban = card or signal Kanban system moves parts through production via a pull signal Card is authorization for the next container of material to be produced A sequence of kanbans pulls material through the process Many types of signals used: Light or flag or empty spot on the floor Multiple card systems used if there are several components Two-card system can be used when there is intermediate storage. Kanban cards provide a direct control and limit on the amount of work-inprocess between cells Small containers require tight schedules, smooth operations, little variability Shortages create an immediate impact Emphasis on meeting schedules, reducing lead time and setups, and economic material handling Standardized containers reduce weight, disposal costs, wasted space, and labor

18 18 Kanban Signal marker hanging on post for part Z405 shows that production should start for that part. The post is located so that workers in normal locations can easily see it. Signal marker on stack of boxes Part numbers mark location of specific part Material/Parts Supplier Final assembly Finished goods Customer order Work cell Kanban Kanban Kanban

19 19 JIT Impact on Employees How will JIT impact employees? Employees may be cross trained for flexibility and efficiency Improved communications facilitate the passing on of important information about the process With little or no inventory buffer, getting it right the first time is critical

20 20 JIT Partnerships Supplier and purchaser work together to remove waste and drive down costs 4 Goals: Remove unnecessary activities Remove in-plant inventory Remove in-transit inventory Improve quality and reliability Supplier Concerns Diversification: ties to only one customer increases risk Buyer cannot create a smooth schedule Short Lead times mean engineering or specification changes can create problems Quality limited by capital budgets, processes, or technology Small lot sizes may transfer costs to suppliers

21 21 Lean Sustainability Two sides of the same coin Maximize resource use and economic efficiency Focus on issues outside the immediate firm Driving out waste is the common ground

22 22 Lean Operations in Services Video: JIT at Arnold Palmer Hospital