Just in Time Toyota Production System

LOGO

JUST IN TIME

Course of Production Management

2

Just-In-Time (JIT) Defined

JIT can be defined as an integrated set of activities designed to achieve high-volume production using minimal inventories (raw materials, work in process, and finished goods).

JIT also involves the elimination of waste in production effort.

JIT also involves the timing of production resources (e.g., parts arrive at the next workstation “just in time”).

ISE - Production Management

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JIT Definitions

elimination of waste in the production system remove non-value added activities from the

production activities improve quality minimize lead time reduce costs improve productivity


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The Japanese Approach to Productivity

Imported technologies Efforts concentrated on shop floor Quality improvement focus Elimination of waste Respect for people


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Waste in Operations

1. Waste from overproduction2. Waste of waiting time3. Transportation waste4. Inventory waste5. Processing waste6. Waste of motion7. Waste from product defects


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Minimizing Waste: Focused Factory Networks


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Minimizing Waste: Group Technology (Part 1)

Using Departmental Specialization for plant layout can cause a lot of unnecessary material movement.


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Minimizing Waste: Group Technology (Part 2)

Revising by using Group Technology Cells can reduce movement and improve product flow.


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Minimizing Waste: Uniform Plant Loading


Suppose we operate a production plant that produces a single product. The schedule of production for this product could be accomplished

using either of the two plant loading schedules below

Not uniform Jan. Units Feb. Units Mar. Units Total 1,200 3,500 4,300 9,000

or

Uniform Jan. Units Feb. Units Mar. Units Total 3,000 3,000 3,000

9,000

How does the uniform loading help save labor costs?

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Minimizing Waste: Just-In-Time Production


WHAT IT IS WHAT IT DOES

•Management philosophy•“Pull” system though the plant

•Attacks waste•Exposes problems and bottlenecks•Achieves streamlined production

WHAT IT REQUIRES WHAT IT ASSUMES

•Employee participation• Industrial engineering/basics•Continuing improvement•Total quality control•Small lot sizes

•Stable environment

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Minimizing Waste: Inventory Hides Problems


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Key Activities in JIT

Matching demand with product design

Define product families with specific manufacturing goals, then design manufacturing system to facilitate the flow based production of these families

Establish relationship with suppliers to ensure raw material delivery in a JIT manner


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Traditional Push SystemISE - Production Management

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Kanban Pull SystemISE - Production Management

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Minimizing Waste:Kanban Production Control Systems


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Determining the Number of Kanbans Needed

Setting up a kanban system requires determining the number of kanbans (or containers) needed.

Each container represents the minimum production lot size.

An accurate estimate of the lead time required to produce a container is key to determining how many kanbans are required.


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The Number of Kanban Card Sets

k = Number of kanban card sets (a set is a card) D = Average number of units demanded over some time period L = lead time to replenish an order (same units of time as demand) α = Safety stock expressed as a percentage of demand during lead

time C = Container size


C

DL

k

1container theof Size

stockSafety leadtime duringdemand Expected

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Example 1

If the lead time for a container is one hour and a container holds ten parts and the demand per hour is twenty, the minimum number of kanbans is then

n = DL(1+ α) / Cn = 20 * 1 * (1 + 0 ) / 10 = 2

Any positive α will force more kanbans to hold safety stock.


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Example 2

A switch assembly is assembled in batches of 4 units from an “upstream” assembly area and delivered in a special container to a “downstream” control-panel assembly operation.

The control-panel assembly area requires 5 switch assemblies per hour.

The switch assembly area can produce a container of switch assemblies in 2 hours.

Safety stock has been set at 10% of needed inventory.


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Example 2

Always round up!


375.2

4)1.1)(2(51

container theof SizestockSafety leadtime duringdemand Expected

orC

DL

k

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Example 3

Consider the following production process where the machine hours available for Work Centers A, B, and C are 16, 24, and 8 hours respectively.– Calculate the number of kanbans for the WIP between

stations A and C– Calculate the number of kanbans for the WIP between

stations B and C– If it is desired for station C to be able to handle variation

of up to 10 % of the plan production, what are the number of kanbans for both a) and b) in this case.


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Example 3

– Container Size for A is 10– Container Size for B is 8


Machine HoursA 16B 24C 8

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Respect for People

Level payrolls Cooperative employee unions Subcontractor networks Bottom-round management style Quality circles (Small group involvement

activities)


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JIT Requirements: Design Flow Process

Link operations Balance workstation capacities Relayout for flow Emphasize preventive maintenance Reduce lot sizes Reduce setup/changeover time


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JIT Requirements: Total Quality Control

Worker responsibility Measure SQC (Statistic Quality Control) Enforce compliance Fail-safe methods Automatic inspection


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JIT Requirements: Stabilize Schedule

Level schedule

Underutilize capacity

Establish freeze windows


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JIT Requirements: Kanban-Pull

Demand pull

Backflush

Reduce lot sizes


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JIT Requirements: Reduce Inventory More

Look for other areas Stores Transit Carousels Conveyors


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JIT Requirements: Improve Product Design

Standard product configuration

Standardize and reduce number of parts

Process design with product design

Quality expectations


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JIT Requirements: Work with Vendors

Reduce lead times

Frequent deliveries

Project usage requirements

Quality expectations


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JIT in Services (Examples)

Organize Problem-Solving Groups Upgrade Housekeeping Upgrade Quality Clarify Process Flows Revise Equipment and Process Technologies


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JIT in Services (Examples)

Level the Facility Load Eliminate Unnecessary Activities Reorganize Physical Configuration Introduce Demand-Pull Scheduling Develop Supplier Networks


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Key elements to successful JIT (1)

Housekeeping is the organizing of the workplace for higher productivity

Quality improvement through process improvement is necessary so that there are no interruptions in the flow due to defective material

Reduce setup times allow smaller lots Preventive maintenance is practiced to

avoid unexpected interruptions


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Key elements to successful JIT (2)

Incremental inventory is reduced to force problems into the open

Workers are cross-trained to allow higher efficiency for the workforce

A level schedule is maintained so that flow is easier to balance throughout the process

Operations are balanced to allow even flow and to prevent inventory between work centers


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Disadvantages & Limitations Kanban is intrinsically a system for repetitive manufacturing. It

will not succeed without modification in a non- repetitive environment

requires a leveled schedule, standard containers and strict discipline

inflexible and cannot easily respond to irregular changes requires great cooperation from outside suppliers it places emphasis on process technologies, such as product based

flow configurations and may require considerable investment in developing new methods, procedures, jigs and fixtures, etc., perhaps even new capital equipment


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Advantages

stimulate productivity improvements, reduces inventory and production lead time, and within the system constraints, allows the plant to respond to predictable small demand variations.

is a simple system of flow control with visible means of inventory control

minimum paperwork


LOGO

Toyota Production System (Lean Production)

Course of Production Management

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“We place the highest value on actual implementation and taking

action. There are many things one doesn’t understand and

therefore, we ask them why don’t you just go ahead and take

action; try to do something? You realize how little you know and

you face your own failures and you simply can correct those

failures and redo it again and at the second trial you realize

another mistake or another thing you don’t like so you can redo it

once again. So by constant improvement, or, should I say, the

improvement based on action, once can rise to the higher level of

practice and knowledge”

Fujio Cho, President, Toyota Motor Corporation, 2002


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Guiding Principle One-Piece Flow: make one unit at a time at the rate

of the customer demand or TAKT (German word for rhythm or meter). Using smaller buffers means that problems like quality defects become immediately visible.

TAKT is the rate of customer demand: the rate at which the customer is buying product. TAKT can be used to set the pace of production and alert workers whenever they are getting ahead or behind


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Basic Approach

1. Go and see2. Analyze the situation3. Use one-piece flow and andon to surface the

problems4. Ask “why?” five times5. Andon: light signal for help: fixed- position

line stop system


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Benefits of One-piece flow

1. Built-in quality2. Create real flexibility3. Create higher productivity4. Free up floor space5. Improve safety6. Improve morale7. Reduce cost of inventory


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Just-In-Time JIT is a set of principles, tools, and techniques that allows a

company to produce and deliver products in small quantities, with short lead times, to meet specific customer needs. Simply put, JIT delivers the right items and the right time in the right amounts. It allows you to be responsive to the day- by-day shifts in customer demands.

JIT means removing, as much as possible, the inventory used to buffer operations against problems that may arise in production.

Shortening lead time by eliminating waste in each step of a process leads to best quality and lowest cost, while improving safety and morale.


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The process of continuous improvement (1)

Deming’s principle: “The next process is the customer”

Kaizen is the process of making incremental improvements, no matter how small, and achieving the lean goal of eliminating all waste that adds cost without adding value.

Kaizen teaches individual skills for working effectively in small groups, solving problems, documenting and improving processes, collecting and analyzing data, and self-managing within a peer group.


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The process of continuous improvement (2)

Kaizen pushes decision making (or proposal making) down to the worker and requires open discussion and group consensus before implementing any decisions

Need to view workers as intelligent, capable employees


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Waste (Muda)

1. Overproduction2. Waiting3. Unnecessary transport or conveyance4. Overprocessing or incorrect processing5. Excess inventory6. Unnecessary movement7. Defects8. Unused employee creativity


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Value Stream MappingISE - Production Management

• Identify all of the steps currently required to create value• Decide what the future should look like• Challenge every step: Why is this necessary?• Many steps are only necessary because of the way firms are organized

and previous decisions about technology.(Not because the customer want it)

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Jidoka halts production process when there is a problem. Workers must resolve problems immediately and urgently to resume production.

Heijunka: leveling out the production schedule in both volume and variety.

A level schedule or heijunka is necessary to keep the system stable and to allow for minimum inventory.

Genchi genbutsu: Problem solving is at the actual place to see what is really going on


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Benefit of level workload

Flexibility to make what the customer wants when they want it. (reduce inventory)

Reduced risk of unsold goods Balanced use of labor and machines Smoothed demand on upstream processes

and the plant’s suppliers


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5S (seiri, seiton, seiso, seiketsu, shitsuke)

Sort: clean out rarely used items by red tagging

Straighten: organize and label a place for everything

Shine: clean it Standardize: create rules to sustain the first 3

S’s Sustain: use regular management audits to

stay disciplined


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5S (seiri, seiton, seiso, seiketsu, shitsuke)


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3M

Muda – Non value-added

Muri – overburdening people or equipment

Mura – unevenness


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Taiichi Ohno 1988

“The slower but consistent tortoise causes less waste and is much more desirable than the speedy hare that races ahead and then stops occasionally to doze. The Toyota Production System can be realized only when all the workers become tortoise.”


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14 principles of the Toyota way1. Base your management decisions on a long-term

philosophy, even at the expense of short-term financial goals

2. Create continuous process flow to bring problems to surface

3. Use pull systems to avoid overproduction4. Level out the workload (Heijunka)5. Build a culture of stopping to fix problems, to get

quality right the first time (jidoka)


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14 principles of the Toyota way6. Standardized tasks are the foundation for continuous

improvement and employee empowerment7. Use visual control so no problems are hidden8. Use only reliable, thoroughly tested technology that

serves your people and processes9. Grow leaders who thoroughly understand the work,

live the philosophy, and teach it to others10.Develop exceptional people and teams who follow

your company’s philosophy


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14 principles of the Toyota way

11. Respect your extended network of partners12. Go and see for yourself to thoroughly understand

the situation (Genchi Genbutsu)13. Make decisions slowly by consensus, thoroughly

considering all options; implement rapidly14. Become a learning organization through relentless

reflection (Hansei) and continuous improvement (Kaizen)


Documents

Just in Time Toyota Production System