1. Operations Management
Chapter 16 –
JIT and Lean Operations
PowerPoint presentation to accompany
Heizer/Render
Principles of Operations Management, 7e
Operations Management, 9e

2. Outline Global Company Profile: Toyota Motor Corporation
Just-in-Time, the Toyota Production System, and Lean Operations
Eliminate Waste
Remove Variability
Improve Throughput

3. Outline – Continued Just-in-Time JIT Layout JIT Partnerships
Concerns of Suppliers
JIT Layout
Distance Reduction
Increased Flexibility
Impact on Employees
Reduced Space and Inventory

4. Outline – Continued JIT Inventory JIT Scheduling Reduce Variability
Reduce Inventory
Reduce Lot Sizes
Reduce Setup Costs
JIT Scheduling
Level Schedules
Kanban

5. Outline – Continued JIT Quality Toyota Production System
Continuous Improvement
Respect for People
Standard Work Practices
Lean Operations
Building a Lean Organization
Lean Operations in Services

6. Learning Objectives
When you complete this chapter you should be able to:
Define just-in-time, TPS, and lean operations
Define the seven wastes and the 5 Ss
Explain JIT partnerships
Determine optimal setup time

7. Learning Objectives
When you complete this chapter you should be able to:
Define kanban
Compute the required number of kanbans
Explain the principles of the Toyota Production System

8. Toyota Motor Corporation
Largest vehicle manufacturer in the world with annual sales of over 9 million vehicles
Success due to two techniques, JIT and TPS
Continual problem solving is central to JIT
Eliminating excess inventory makes problems immediately evident
Toyota Motor Corporation, with $250 billion in annual sales of over 9 million cars and trucks, is one of the largest vehicle manufacturers in the world. Two Lean techniques, just-in-time (JIT) and the Toyota Production System (TPS), have been instrumental in its growth. Toyota, with a wide range of vehicles, competes head-to-head with successful, long-established companies in Europe and the U.S. Taiichi Ohno, a former vice president of Toyota, created the basic framework for two of the world’s most discussed systems for improving productivity, JIT and TPS. These two concepts provide much of the foundation for Lean operations:

9. Toyota Motor Corporation
Central to TPS is a continuing effort to produce products under ideal conditions
Respect for people is fundamental
Small building but high levels of production
Subassemblies are transferred to the assembly line on a JIT basis
High quality and low assembly time per vehicle
Central to JIT is a philosophy of continuous problem solving. In practice, JIT means making only what is needed, when it is needed. JIT provides an excellent vehicle for finding and eliminating problems because problems are easy to find in a system that eliminates the slack that inventory generates. When excess inventory is eliminated, shortcomings related to quality, layout, scheduling, and supplier performance become immediately evident—as does excess production. ◆ Central to TPS is employee learning and a continuing effort to create and produce products under ideal conditions. Ideal conditions exist only when management brings facilities, machines, and people together to add value without waste. Waste undermines productivity by diverting resources to excess inventory, unnecessary processing, and poor quality. Respect for people, extensive training, cross-training, and standard work practices of empowered employees focusing on driving out waste are fundamental to TPS.

10. Just-In-Time, TPS, and Lean Operations
JIT is a philosophy of continuous and forced problem solving via a focus on throughput and reduced inventory
TPS emphasizes continuous improvement, respect for people, and standard work practices
Lean production supplies the customer with their exact wants when the customer wants it without waste
Lean operations supply the customer with exactly what the customer wants when the customer wants it, without waste, through continuous improvement. Lean operations are driven by workflow initiated by the “pull” of the customer’s order. Just-in-time (JIT) is an approach of continuous and forced problem solving via a focus on throughput and reduced inventory. The Toyota Production System (TPS) , with its emphasis on continuous improvement, respect for people, and standard work practices, is particularly suited for assembly lines.

11. Just-In-Time, TPS, and Lean Operations
JIT emphasizes forced problem solving
TPS emphasizes employee learning and empowerment in an assembly-line environment
Lean operations emphasize understanding the customer
In this chapter we use the term Lean operations to encompass all the related approaches and techniques of both JIT and TPS. When implemented as a comprehensive operations strategy, Lean sustains competitive advantage and results in increased overall returns to stakeholders.

12. Eliminate Waste
Waste is anything that does not add value from the customer point of view
Storage, inspection, delay, waiting in queues, and defective products do not add value and are 100% waste
Lean producers set their sights on perfection: no bad parts, no inventory, only value-added activities, and no waste. Any activity that does not add value in the eyes of the customer is a waste. The customer defines product value. If the customer does not want to pay for it, it is a
waste.

13. Ohno’s Seven Wastes Overproduction Queues Transportation Inventory
Motion
Overprocessing
Defective products
◆Overproduction: Producing more than the customer orders or producing early (before it is demanded) is waste.
◆ Queues: Idle time, storage, and waiting are wastes (they add no value).
◆ Transportation: Moving material between plants or between work centers and handling it more than once is waste.
◆ Inventory: Unnecessary raw material, work-in-process (WIP), finished goods, and excess operating supplies add no value and are wastes.
◆ Motion: Movement of equipment or people that adds no value is waste.
◆ Overprocessing: Work performed on the product that adds no value is waste.
◆ Defective product: Returns, warranty claims, rework, and scrap are wastes.

14. Eliminate Waste
Other resources such as energy, water, and air are often wasted
Efficient, ethical, and socially responsible production minimizes inputs, reduces waste
Traditional “housekeeping” has been expanded to the 5 Ss

15. The 5 Ss Sort/segregate – when in doubt, throw it out
Simplify/straighten – methods analysis tools
Shine/sweep – clean daily
Standardize – remove variations from processes
Sustain/self-discipline – review work and recognize progress
For over a century, managers have pursued “housekeeping” for a neat, orderly, and efficient workplace and as a means of reducing waste. Operations managers have embellished “housekeeping” to include a checklist—now known as the 5Ss. 1 The Japanese developed the initial 5Ss. Not only are the 5Ss a good checklist for Lean operations, but they
also provide an easy vehicle with which to assist the culture change that is often necessary to bring about Lean operations.

16. The 5 Ss Sort/segregate – when in doubt, throw it out
Simplify/straighten – methods analysis tools
Shine/sweep – clean daily
Standardize – remove variations from processes
Sustain/self-discipline – review work and recognize progress
Two additional Ss
Safety – build in good practices
Support/maintenance – reduce variability and unplanned downtime

17. Remove Variability
JIT systems require managers to reduce variability caused by both internal and external factors
Variability is any deviation from the optimum process
Inventory hides variability
Less variability results in less waste
Managers seek to remove variability caused by both internal and external factors. Variability is any deviation from the optimum process that delivers a perfect product on time, every time. Variability is a polite word for problems. The less variability in a system, the less waste in the system. Most variability is caused by tolerating waste or by poor management.

18. Sources of Variability
Incomplete or inaccurate drawings or specifications
Poor production processes resulting in incorrect quantities, late, or non-conforming units
Unknown customer demands

19. Sources of Variability
Incomplete or inaccurate drawings or specifications
Poor production processes resulting in incorrect quantities, late, or non-conforming units
Unknown customer demands
Both JIT and inventory reduction are effective tools in identifying causes of variability

20. Improve Throughput
The time it takes to move an order from receipt to delivery
The time between the arrival of raw materials and the shipping of the finished order is called manufacturing cycle time
A pull system increases throughput
Throughput is the rate at which units move through a process. Each minute that products remain on the books, costs accumulate, and competitive advantage is lost. Time is money. The time that an order is in the shop is called manufacturing cycle time . This is the time between the arrival of raw materials and the shipping of finished product. For example, phone-system manufacturer Nortel had materials pulled directly from qualified suppliers to the assembly line. This effort reduced a segment of the manufacturing cycle time from 3 weeks to just 4 hours, the incoming inspection staff from 47 to 24, and problems on the shop floor caused by defective materials by 97%. A pull system pulls a unit to where it
is needed just as it is needed. Pull systems are a standard tool of Lean. Pull systems use signals to request production and delivery from supplying stations to stations that have production capacity available.

21. Improve Throughput
By pulling material in 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

22. Just-In-Time (JIT) Powerful strategy for improving operations
Materials arrive where they are needed when they are needed
Identifying problems and driving out waste reduces costs and variability and improves throughput
Requires a meaningful buyer-supplier relationship
Just-in-time (JIT), with its focus on rapid throughput and reduced inventory, is a powerful component of Lean. With the inclusion of JIT in Lean, materials arrive where they are needed only when they are needed. When good units do not arrive just as needed, a “problem” has been identified.

23. JIT and Competitive Advantage
By driving out waste and delay, JIT reduces inventory, cuts variability and waste, and improves throughput. Every moment material is held, an activity that adds value should be occurring. Consequently, as Figure 16.1 suggests, JIT often yields a competitive advantage.
Figure 16.1

24. JIT and Competitive Advantage
Figure 16.1

25. JIT Partnerships
JIT partnerships exist when a supplier and purchaser work together to remove waste and drive down costs
Four goals of JIT partnerships are:
Removal of unnecessary activities
Removal of in-plant inventory
Removal of in-transit inventory
Improved quality and reliability

26. JIT Partnerships Figure 16.2
Supplier partnerships exist when a supplier and a purchaser work together with open communication and a goal of removing waste and driving down costs. Trust and close collaboration are critical to the success of Lean. Figure 16.2 shows the characteristics of supplier partnerships.
Figure 16.2

27. 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
Lean layouts reduce another kind of waste—movement. The movement of material on a factory floor (or paper in an office) does not add value. Consequently, managers want flexible
layouts that reduce the movement of both people and material. Lean layouts place material directly in the location where needed. For instance, an assembly line should be designed with delivery points next to the line so material need not be delivered first to a receiving department Lean layouts reduce another kind of waste—movement. The movement of material on a factory floor (or paper in an office) does not add value. Consequently, managers want flexible layouts that reduce the movement of both people and material. Lean layouts place material directly in the location where needed. For instance, an assembly line should be designed with delivery points next to the line so material need not be delivered first to a receiving department
Table 16.1

28. Distance Reduction
Large lots and long production lines with single-purpose machinery are being replaced by smaller flexible cells
Often U-shaped for shorter paths and improved communication
Often using group technology concepts
Lean layouts reduce another kind of waste—movement. The movement of material on a factory floor (or paper in an office) does not add value. Consequently, managers want flexible
layouts that reduce the movement of both people and material. Lean layouts place material directly in the location where needed. For instance, an assembly line should be designed with delivery points next to the line so material need not be delivered first to a receiving department

29. Increased Flexibility
Cells designed to be rearranged as volume or designs change
Applicable in office environments as well as production settings
Facilitates both product and process improvement
Modern work areas are designed so they can be easily rearranged to adapt to changes in volume and product changes. Layout flexibility aids the changes that result from product
and process improvements that are inevitable at a firm with a philosophy of continuous improvement.

30. Impact on Employees
Employees are 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
When workers produce units one at a time, they test each product or component at each subsequent production stage. Work processes with self-testing poka-yoke functions detect defects automatically. Before Lean, defective products were replaced from inventory. Because surplus inventory is not kept in Lean facilities, there are no such buffers. Employees learn that getting it right the first time is critical.

31. Reduced Space and Inventory
With reduced space, inventory must be in very small lots
Units are always moving because there is no storage
When there is little space, inventory travels less and must be moved in very small lots or even single units.

32. 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
Inventories in production and distribution systems often exist “just in case” something goes wrong. That is, they are used just in case some variation from the production plan
occurs. The “extra” inventory is then used to cover variations or problems. Lean inventory tactics require “just in time,” not “just in case.” Lean inventory is the minimum inventory
necessary to keep a perfect system running. With Lean inventory, the exact amount of goods arrives at the moment it is needed, not a minute before or a minute after.
Table 16.2

33. Reduce Variability Inventory level Process downtime Scrap Setup time
Late deliveries
Quality problems
Inventories in production and distribution systems often exist “just in case” something goes wrong. That is, they are used just in case some variation from the production plan
occurs. The “extra” inventory is then used to cover variations or problems. Lean inventory tactics require “just in time,” not “just in case.” Lean inventory is the minimum inventory
necessary to keep a perfect system running. With Lean inventory, the exact amount of goods arrives at the moment it is needed, not a minute before or a minute after.
Figure 16.3

34. Reduce Lot Sizes Q1 When average order size = 200
200 –
100 –
Inventory
Time
Q1 When average order size = 200
average inventory is 100
Q2 When average order size = 100
average inventory is 50
Lean also reduces waste by cutting the investment in inventory. A key to slashing inventory is to produce good product in small lot sizes. Reducing the size of batches
can be a major help in reducing inventory and inventory costs. As we saw in Chapter 12 , when inventory usage is constant, the average inventory level is the sum of the maximum inventory plus the minimum inventory divided by 2.
Figure 16.4

35. Reduce Lot Sizes
Ideal situation is to have lot sizes of one pulled from one process to the next
Often not feasible
Can use EOQ analysis to calculate desired setup time
Two key changes necessary
Improve material handling
Reduce setup time

36. Lot Size Example D = Annual demand = 400,000 units
d = Daily demand = 400,000/250 = 1,600 per day
p = Daily production rate = 4,000 units
Q = EOQ desired = 400
H = Holding cost = $20 per unit
S = Setup cost (to be determined)
Q =
2DS
H(1 - d/p)
Q2 =
2DS
H(1 - d/p)
Crate Furniture, Inc., a firm that produces rustic furniture, desires to move toward a reduced lot size. Crate Furniture’s production analyst, Aleda Roth, determined that a 2-hour production cycle would be acceptable between two departments. Further, she concluded that a setup time that would accommodate the 2-hour cycle time should be achieved.
S = = = $2.40
(Q2)(H)(1 - d/p) 2D
(3,200,000)(0.6)
800,000
Setup time = $2.40/($30/hour) = 0.08 hr = 4.8 minutes

37. 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
Both the quantity of inventory and the cost of holding it go down as the inventory-reorder quantity and the maximum inventory level drop. However, because
inventory requires incurring an ordering or setup cost that is applied to the units produced, managers tend to purchase (or produce) large orders; the larger the order the less the cost to be absorbed by each unit. Consequently, the way to drive down lot sizes and reduce inventory cost is to reduce setup cost, which in turn lowers the optimum order size.

38. Lower Setup Costs Holding cost Sum of ordering and holding costs Cost
Lot size
Holding cost T1 S1
Sum of ordering and holding costs T2 S2
Setup cost curves (S1, S2)
The effect of reduced setup costs on total cost and lot size is shown in Figure Moreover, smaller lot sizes hide fewer problems. In many environments, setup cost is highly correlated with setup time. In a manufacturing facility, setups usually require a substantial amount of preparation. Much of the preparation required by a setup can be done prior to shutting down the machine or process.
Figure 16.5

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

40. JIT Scheduling
Schedules must be communicated inside and outside the organization
Level schedules
Process frequent small batches
Freezing the schedule helps stability
Kanban
Signals used in a pull system
Effective schedules, communicated to those within the organization as well as to outside suppliers, support Lean. Better scheduling also improves the ability to meet customer orders, drives down inventory by allowing smaller lot sizes, and reduces work-in- process. For instance, many companies, such as Ford, now tie suppliers to their final assembly schedule.

41. JIT Scheduling Better scheduling improves performance
JIT Scheduling Tactics
Communicate schedules to suppliers
Make level schedules
Freeze part of the schedule
Perform to schedule
Seek one-piece-make and one-piece move
Eliminate waste
Produce in small lots
Use kanbans
Make each operation produce a perfect part
Table 16.3

42. Scheduling Small Lots JIT Level Material-Use ApproachB C
JIT Level Material-Use Approach A C B
Large-Lot Approach
Level schedules process frequent small batches rather than a few large batches. Figure 16.7 contrasts a traditional large-lot approach using large batches with a level
schedule using many small batches. The operations manager’s task is to make and move small lots so the level schedule is economical.
Time
Figure 16.7

43. Kanban Kanban is the Japanese word for card
The card is an authorization for the next container of material to be produced
A sequence of kanbans pulls material through the process
Many different sorts of signals are used, but the system is still called a kanban
One way to achieve small lot sizes is to move inventory through the shop only as needed rather than pushing it on to the next workstation whether or not the personnel there
are ready for it. As noted earlier, when inventory is moved only as needed, it is referred to as a pull system, and the ideal lot size is one. The Japanese call this system kanban . Kanbans allow arrivals at a work center to match (or nearly match) the processing time. the Japanese use systems that “pull” inventory through work centers. They often use a “card” to signal the need for another container of material—hence the name kanban. The card is the authorization for the next container of material to be produced.

44. Kanban User removes a standard sized container
Signal is seen by the producing department as authorization to replenish
The system has been modified in many facilities so that even though it is called a kanban , the card itself does not exist. In some cases, an empty position on the floor is sufficient indication that the next container is needed. In other cases, some sort of signal, such as a flag or rag ( Figure 16.8 ), alerts that it is time for the next container.
Signal marker on boxes
Figure 16.8
Part numbers mark location

45. Purchased Parts Supplier
Kanban
Work cell
Kanban
Finished goods
Customer order
Final assembly
Raw Material Supplier
Ship
Kanban
Kanban
Sub-assembly
Kanban
Kanban
Purchased Parts Supplier
Kanban
Figure 16.9

46. More Kanban
When the producer and user are not in visual contact, a card can be used
When the producer and user are in visual contact, a light or flag or empty spot on the floor may be adequate
Since several components may be required, several different kanban techniques may be employed

47. More Kanban Usually each card controls a specific quantity or parts
Multiple card systems may be used if there are several components or different lot sizes
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

48. The Number of Kanban Cards or Containers
Need to know the lead time needed to produce a container of parts
Need to know the amount of safety stock needed
Number of kanbans
(containers)
Demand during Safety lead time + stock
Size of container =
The number of kanban cards, or containers, sets the amount of authorized inventory. To determine the number of containers moving back and forth between the using area and the producing areas, management first sets the size of each container. This is done by computing the lot size, using a model such as the production order quantity model. Setting the number of containers involves knowing: (1) lead time needed to produce a container of parts and (2) the amount of safety stock needed to account for variability or uncertainty in the system.

49. Number of Kanbans Example
Daily demand = 500 cakes
Production lead time = 2 days
(Wait time +
Material handling time +
Processing time)
Safety stock = 1/2 day
Container size = 250 cakes
Demand during lead time = 2 days x 500 cakes = 1,000
Hobbs Bakery produces short runs of cakes that are shipped to grocery stores. The owner, Ken Hobbs, wants to try to reduce inventory by changing to a kanban system. He has developed the following data and asked you to finish the project.
Number of kanbans = = 5 1,
250

50. Quality Strong relationship
JIT cuts the cost of obtaining good quality because JIT exposes poor quality
Because lead times are shorter, quality problems are exposed sooner
Better quality means fewer buffers and allows simpler JIT systems to be used
There is no Lean without quality. And Lean’s “pull” production, smaller batch sizes, and low inventory all enhance quality by exposing bad quality. Savings occur because scrap,
rework, inventory investment, and poor product are no longer buried in inventory. This means fewer bad units are produced. In short, whereas inventory hides bad quality, Lean
exposes it.

51. JIT Quality Tactics Use statistical process control Empower employees
Build fail-safe methods (poka-yoke, checklists, etc.)
Expose poor quality with small lot JIT
Provide immediate feedback
Table 16.4

52. Toyota Production System
Continuous improvement
Build an organizational culture and value system that stresses improvement of all processes
Part of everyone’s job
Respect for people
People are treated as knowledge workers
Engage mental and physical capabilities
Empower employees
Continuous improvement under TPS means building an organizational culture and instilling in its people a value system stressing that processes can be improved—indeed, that improvement is an integral part of every employee’s job. This process is formalized in TPS by kaizen , the Japanese word for change for the good, or what is more generally known as continuous improvement. Toyota, like other Lean organizations, recruits, trains, and treats people as knowledge workers. Aided by aggressive cross-training and few job classifications, Lean firms engage the mental as well as physical capacities of employees in the challenging task of improving operations. Employees are empowered. They are empowered not only to make improvements, but also to stop machines and processes when quality problems exist. Indeed, empowered employees are an integral part of Lean.

53. Toyota Production System
Standard work practice
Work shall be completely specified as to content, sequence, timing, and outcome
Internal and external customer-supplier connection are direct
Product and service flows must be simple and direct
Any improvement must be made in accordance with the scientific method at the lowest possible level of the organization
Building effective and efficient processes requires establishing what Toyota calls standard work practices. The underlying principles are:

54. Lean Operations
Different from JIT in that it is externally focused on the customer
Starts with understanding what the customer wants
Optimize the entire process from the customer’s perspective

55. JIT in Services
The JIT techniques used in manufacturing are used in services
Suppliers
Layouts
Inventory
Scheduling
The features of Lean apply to services—from hospitals to amusement parks and airlines— directly influencing the customers’ received value. The Lean attributes of respect for people,
efficient processes with rigorous standard practices that drive out waste, and a focus on continuous improvement are pervasive vehicles for consistently generating value for all stakeholders. If there is any change in focus of Lean between manufacturing and services, it may be that the high level of customer interaction places added emphasis on enabling people through training, motivation, and empowerment to contribute to their fullest.