JUST IN TIME

• JIT is a production philosophy.•JIT uses the pull method of scheduling material flow.•Kanban- visual record (1950)•Where Kan means – Card•Ban means – signal •To produce goods and services as needed.•JIT systems are known by many different names including zero inventory, synchronous manufacturing, lean production, stockless production, material as needed and continuous flow manufacturing.

• Basically production can be considered in two categories:a) Produce on demand, pull system. • A pull system uses bottom up demand which it is driven by the

consumption rate of the parts in the production process. More materials in the production line when they are needed.

• Pull method in which customer demand activates production of the item

manufacturer Pull customer b) Push method. • In which the production of the item begins in advance of customer

need. • With this method management schedules the receipt of all materials

and authorizes the start of production. Manufacturer push customer• JIT refers to the production and supply of the required number of

parts/products when needed. Workers perform the required operation on the material/work part drawn from the preceding work station at the necessary time with the use of a Kanban (instruction card).

Raw material supplier Machining stage

K

Assembly stage

Material flow

Master production scheduleProduction Kanban

Withdrawl Kanban

FUNDAMENTAL CONCEPTS OF JIT PRODUCTION SYSTEM

1. Elimination of waste. Production of only the minimum necessary units in the smallest possible quantities (lot sizes) at the latest possible time.

2. Employee participation. Probably all management efforts have behavioural aspects because management is working through other people to accomplish the organization objectives.

Management plans and decisions only by the ground work. This is the resulting human behaviour that determines a company’s success or failure.

3. Integrated system. First and foremost a culture of mutual trust and team work must be developed in an organization, Manager and workers must see each other as co-workers committee to the company’s success. If an improvement is suggested and approved a new standard procedure will be adopted. This standardization prevents variations in product as services which can cause defects.

OBJECTIVES OF JIT• A JIT system of production management aims of achieving

the following major objectives or ideas.

I) Zero set up times

II) Zero inventory

III) Zero breakdown

IV) Zero defects

V) Zero waiting times for material/component

VI) Zero waste of any kind

AREAS OF IMPACT OF JIT

1. Production planning

2. Scheduling

3. Equipment set up

4. Layout of machine

5. Maintenance

6. Quality control

7. Purchasing

8. Receiving

9. Inventory control

CHARACTERISTICS OF JIT1. People involvement

2. Team work

3. Discipline

4. TQM

5. Pull method of material flow

6. Small lot sizes- variety of products

7. Short set up times

8. Uniform workstation loads

9. Standardized components and work methods

10. Close supplier ties

11. Flexible work force

12. Product focus

13. Automated production

14. Preventive maintenance

15. Production methods

COMPARISON OF THE JIT AND CONVENTIONAL PRODUCTION SYSTEMS

Characteristics JIT Conventional

Basic architecture Inflexible Flexible

Production runs Small lots Long runs

Inventory Zero inventory objective

Stock needed for flexibility

Planning Last stage first First stage first

Information cost Low High

Set up times Low and frequent High and infrequent

Operating control Decentralized Centralized

Workers Multi-skilled Mono-skilled

Quality control Managed by workers

Managed by quality control unit

IMPROVEMENT IN MANUFACTURING PROCESS IN JIT

• A basic focus of the JIT system is toward improving the flow of the work. This goal is sought to be achieved through physical changes in the manufacturing process. Trhese changes result in substantive process. Improvements toward efficiency cost reduction, flexibility, quality and the productivity.

• The process changes to be introduced take three main forms:

1. Reducing setup time

2. Preventive maintenance

3. Changing to flow lines

REDUCTION OF SET-UP TIMES1. Separating the internal from the external setup.

2. Converting as much as possible of the internal to the external setup.

3. Eliminating adjustment process.

4. Abolishing the setup step itself.

REDUCING SET UP TIME WILL

a) Increase machine efficiency

b) Decrease batch size

c) Decrease lead time

d) Decrease inventory levels

e) Create greater uniformity of the setup

f) Reduce the scrap associated with the set up activity.

PREVENTIVE MAINTENANCE

• As the inventory levels are reduced in a JIT implementation unreliable machines become more of problem.

• The reduction in the buffer stocks means that if a machine should break down, subsequent machines quickly become started of the work.

• In order to prevent this happening the JIT implementation includes a preventive maintenance program to keep insure high process reliability in keeping with other aspects of JIT.

FLOW LINE CHANGES• The flow of work through the manufacturing systems can be

helped by replacing the more trained process layout with flow lines.

• Using flow lines, work can flow quickly from process to process.

• Since the flowing process will usually be adjacent in this way, lead times can be significantly reduced.

• Long lead time is wasteful not only because they: Increase inventory levels Increase the risk of obsolescenceReduce flexibility

PLANNING FOR JITi) Involvement from the top management is must.

ii) Identify all the elements of JIT as a part of the plan.

iii) The real goal can only be achieved when JIT is working throughout the length of the entire supply chain.

iv) Constant predictable quality levels hitherto considered impossible are also fundamental to the achievement of JIT.BASIC PRINCIPLES OF THE JIT

i) Cope with fundamental extent problems, capacity, bottleneck, machine breakdown.

ii) Eliminate waste in all forms- inspection, transport, wasting, inventory.

iii) Strive for simplicity- simple unidirectional and smooth flow of parts and products.

iv) Create system to identify and resolve problems at source.

ELEMENTS OF JIT There are six different internally focused elements and one

externally focused element.

i) The first internally focused element is the just-in –time philosophy itself.

ii) Quality at the source.

there are three manufacturing engineering elements:

iii) Uniform plant load.

iv) Over-lapping operations (machine cells or group technology).

v) Minimum setup time.

vi) Type of control system called, variously, a pull system, Kanban, or linking operations.

THE JIT PHILOSOPHY

JIT philosophy

Flow Employee involvement Quality

Uniform plant load

Reduced setup time

Overlapping operations

pull system

JIT purchasing

KEYS TO SUCCESSFUL JIT IMPLEMENTATION

PRODUCTION SMOOTH

1. Establish and level the MPs with uniform plant loading. • create a uniform load on all work centers through constant daily

production, establish freeze windows to prevent changes in the production plan for some period of time and mixed model assembly (produce roughly the same mix of products everyday) using a repeating sequence if several products are produced on the same line meet demand fluctuations through end items inventory rather through fluctuations in production level.

• Benefits:

a) Learning curve improvements

b) Increased mix flexibility

c) Reduced inventory

d) Shorter lead times

e) Quality improvements.

2. Reduced lot sizes.

• Aim for reducing setup times, allows economical products of smaller lots; close cooperation with supplies is necessary to achieve reductions in order lot sizes for purchased item since this will require more frequent deliveries.

3. Preventive maintenance.

• Use machine and worker idle time to maintain equipment and prevent breakdowns.

4. Flexibility workforce.

Worker should be trained to use several machines to perform maintenance tasks and to perform quality inspections.

5. Require supplier quality assurance. • Require supplier quality assurance and a zero defect quality program,

errors leading to defects item must be eliminated since there are no buffers of excess parts.

• A quality of source (JIDOKA) program must be implemented to give workers, the personal responsibility for the quality of the work they do, and the authority to stop production when something goes wrong.

6. Reduce or eliminate setup time.

7. Zero inventory

8. Systems to work on.

9. Small lot size (single unit).• Control system such as Kanban (cards)system to convey parts

between work stations in small quantity (ideally one unit at a time).

• In largest sense, JIT is not the something as a Kanban system is not required to implement a LKanban system and the two concepts are frequently equated with one another.

JIT CONCEPTS OF ELIMINATING OF WASTEDue to the difference in cultural, economic and logistic factors,

not all JIT practices are applicable to U.S. manufacturers.1. Focused factory (plant size). • Small specialized plants that make parts for a single major

manufacture.• Keiretsu large holding companies; maintained close

linkages but independent operations.2. Group technology (facility layout) • Process all parts with similar operations in the same

manufacturing cell that eliminate waiting and moving lines.3. Quality at the source (quality control).• “ quality is built in, not inspected in”.• Workers are responsible for their own works.• An operator can stop an assembly line if something goes

wrong.

4. Just in time production (inventory management).• Maintain minimum inventory level and small lot sizes

and make no allowance for contingency.

5. Uniform plant loading (level production schedule). • Setup a firm production plan with the output rate is

frozen for the nearest future.

6. Kanban system (production control tool).

7. Minimized setup times (work method improvement).

• Separate setup times into internal and external setup procedures. Apply the time and motion studies and practice.

JIT MEANS ELIMINATING WASTE

• Eliminating waste of all kinds ii the deep seated ideology behind JIT. Shigeo, a JIT authority at Toyota , identified 7 waste in production that should be eliminated.

TOWARD ELIMINATING WASTE IN MANUFACTUING• A recognized JIT authority and engineer at the Toyota

motor company identifies 7 waste:

1. Overproduction: make only what is needed now.

2. Waiting: Coordinates flows between operations and balance load imbalances by flexible workers and equipments.

3. Transportation: Design facility layouts that reduce or eliminates materials handling and shipping.

4. Unneeded Production: Eliminate all unneeded production steps.

5. Work in process inventories: eliminate by reducing setup times, increasing production rates and better coordination of production rates between work stations.

6. Motion and effort: improve productivity and quality by eliminating unnecessary human motions, make necessary motions more efficient, mechanize, then automate.

7. Defective products: eliminate defects and inspection. Make perfect products.

BENEFITS OF JIT MANUFACTURING1. Inventory levels are drastically reduced.

2. The time it takes for products to get through the factory is greatly reduced, thus enabling factories to engage in time based competition, using speed as a weapon to capture share.

3. Product quality is improved and the cost of scrap is reduced. Product quality improves because of worker involvement in solving the causes of production problem and with smaller lots, defective parts are discovered earlier.

4. With less in process inventory less space is taken up with inventory and materials handling equipment together so that they can see each other, communicate more efficiently, learn each other’s jobs, and switch job as needed. Team work among workers and flexibility in work assignments.

5. Because the focus in manufacturing is on finding and correcting the causes of production problems, manufacturing operations are steamlined and problem free.

DIRECTIONS FOR THE POSSIBLE RESOLUTION OF JIT PROBLEMS

1. Weak commitment of the top management towards the JIT [program may be based on their inadequate understanding of large potential benefits resulting from the adoption of the JIT system. This situation may be rectified if the management is presented with empirical evidence regarding the result of successful JIT implementation in other firm of a comparable nature.

2. Everyone associated with JIT implementation should be educated and trained effectively with the help of outside experts, if necessary the education and training program should be continued regularly even after the initial phase for deliberating on the problems, their solutions and ways of containing improvement.

3. Inadequate understanding of the nature of improvements/ changes required by the workers and supervisors. This may be due to inadequate education and training and/ or lack of experience.

4. Understanding the tasks of implementation. JIT is not a soft or easy technique.

5. long/short period of implementation. This problem requires a balanced approach if the implementation period is long, loss of motivation and enthusiasm among the workers may be engendered.

6. For dealing with customer schedule changes JIT links with customers should be established and fostered.

7. JIT links with vendors should be fostered along with the lines of partner in profit’ concept.

8. Shortage of critical parts. This may require recourse to contingency plans or measures.

9. Workers fears and anxieties concerning their jobs security and status need to be alleged.

10. Inability to reduce setup time. This may require engineering research to be undertaken intentionally or through R&D firms.

11. The operation of a JIT flow line relies on what process improvement and control improvements. They need to be integrated .the problem may be investigated by a study team of industrial engineering and experienced workers/ operators.

12. This can have serious implication for the success of JIT program in near future. The primary requirements here is the regular contributions of the JIT education program. This needs to be critically supplemented by establishing the quality circle or productivity teams of workers.