JIT is a management philosophy that strives to eliminate sources of manufacturing waste by
producing the right part in the right place at the right time. Waste results from any activity that
adds cost without adding value, such as moving and storing. JIT (also known as lean production or
stockless production) should improve profits and return on investment by reducing inventory
levels (increasing the inventory turnover rate), improving product quality, reducing production and
delivery lead times, and reducing other costs (such as those associated with machine setup and
We strongly believe that the implementation of this management philosophy in industries like the
automobile industry can bring about a see saw change in both quality & quantity since in a JIT
system, underutilized (excess) capacity is used instead of buffer inventories to hedge against
problems that may arise. JIT applies primarily to repetitive manufacturing processes in which the
same products and components are produced over and over again. The general idea is to establish
flow processes (even when the facility uses a jobbing or batch process layout) by linking work
centers so that there is an even, balanced flow of materials throughout the entire production
process, similar to that found in an assembly line. To accomplish this, an attempt is made to reach
the goals of driving all queues toward zero and achieving the ideal lot size of one unit.
We present here some ideas that we got from the study about this new trend in engineering
production, which originally refer to the production of goods to meet customer demand exactly, in
time, quality and quantity, whether the `customer' is the final purchaser of the product or another
process further along the production line. This new concept reduces wastage by nearly 55-75%.
"Waste" in this context is taken in its most general sense and includes time and resources as well
as goods. So, we firmly believe after this study that this concept can really change the phase of
industrial production of goods like car & other important utilities.
JIT – BACKGROUND AND HISTORY
JIT is a Japanese management philosophy, which has been applied in practice since the early
1980s in many Japanese manufacturing organizations. It was first developed and perfected within
the Toyota manufacturing plants by Taiichi Ohno as a means of meeting consumer demands with
minimum delays. Taiichi Ohno is frequently referred to as the father of JIT.
Toyota was able to meet the increasing challenges for survival through an approach that focused
on people, plants and systems. Toyota realised that JIT would only be successful if every
individual within the organisation was involved and committed to it, if the plant and processes
were arranged for maximum output and efficiency, and if quality and production programs were
scheduled to meet demands exactly.
JIT manufacturing has the capacity, when properly adapted to the organisation, to strengthen the
organisation's competitiveness in the marketplace substantially by reducing wastes and improving
product quality and efficiency of production.
There are strong cultural aspects associated with the emergence of JIT in Japan. The Japanese
work ethic involves the following concepts.
Workers are highly motivated to seek constant improvement upon that which already
exists. Although high standards are currently being met, there exist even higher standards
Companies focus on group effort, which involves the combining of talents and sharing
knowledge, problem-solving skills, ideas and the achievement of a common goal.
Work itself takes precedence over leisure. It is not unusual for a Japanese employee to
work 14-hour days.
Employees tend to remain with one company throughout the course of their career span.
This allows the opportunity for them to hone their skills and abilities at a constant rate
while offering numerous benefits to the company.
These benefits manifest themselves in employee loyalty, low turnover costs and fulfillment of
ELEMENTS OF JIT
There are some very important elements in just in manufacturing which makes it a successful
philosophy. They are
Attacking fundamental problems - anything that does not add value to the product.
Devising systems to identify problems.
Striving for simplicity - simpler systems may be easier to understand, easier to manage and
less likely to go wrong.
A product oriented layout - produces less time spent moving of materials and parts.
Quality control at source - each worker is responsible for the quality of his or her own
Poka-yoke - `foolproof' tools, methods, jigs etc. prevent mistakes
Preventative maintenance, Total productive maintenance - ensuring machinery and
equipment functions perfectly when it is required, and continually improving it.
Eliminating waste. There are seven types of waste:
Waste from overproduction.
Waste of waiting time.
Waste of motion.
Waste from product defects.
Good housekeeping - workplace cleanliness and organization.
Set-up time reduction - increases flexibility and allows smaller batches. Ideal batch size is
1item. Multi-process handling - a multi-skilled workforce has greater productivity,
flexibility and job satisfaction.
Leveled / mixed production - to smooth the flow of products through the factory.
Kanbans - simple tools to `pull' products and components through the process.
Jidoka (Autonomation) - providing machines with the autonomous capability to use
judgement, so workers can do more useful things than standing watching them work.
Andon (trouble lights) - to signal problems to initiate corrective action.
CASE STUDIES BY ZENTEC
Zentec process consulting and management made 4 case studies on change of
(1) Process Improvement Through Offsite Warehouse Removal
(2) Processing Plant with Quality Control Problems
(3) Administration Areas in Large Processing Plant
(4) Heavy Engineering: Machine Tool Production
Before & after implementation of JIT philosophy.
We were lucky enough to get the final results of these case studies.
The results of the first was that there was a net saving of 35,000 pounds per annum, that of second
was that there was a net saving of 200,000 pounds per annum for client, that of third was that there
was a productivity improvement by 85% & cost reduction for administration by 55% and the result
of the fourth case study was that there was 50% productivity Improvement, 80% Lead-time
reduction, 40% space reduction after implementation of JIT Techniques.
Table comparing JIT with MRP
How Toyota's JIT philosophy differs from a typical Western company
Factors Toyota's JIT Western Philosophy
Inventory A liability. Every effort An asset. It protects against
must be extended to do away forecast errors, machine
with it. problems, late vendor
deliveries. More inventory is
Lot sizes Immediate needs only.A Formulas. Theyr’e always revising
minimum replenishment quantity the optimum lot size with
is desired for both some formula based on the trade-off
manufactured and purchased between the cost of inventories
parts. and the cost of set up.
Set ups Make them insignificant.This Low priority. Maximum output is
requires either extremely the usual goal. Rarely does
rapid changeover to minimize similar thought and effort go
the impact on production, or into achieving quick changeover.
the availability of extra
machines already set up. Fast
changeover permits small lot
sizes to be practical, and
allows a wide variety of parts
to be made frequently.
Queues Eliminate them. When problems Necessary investment. Queues
occur, identify the causes and permit succeeding operations to
correct them. The correction continue in the event of a
process is aided when queues problem with the feeding
are small. If the queues are operation. Also, by providing a
small, it surfaces the need to selection of jobs, the factory
identify and fix the cause. management has greater
opportunity to match up varying
operator skills and machine
capabilities, combine set ups
and thus contribute to the
efficiency of the operation.
Vendors Co-workers. They're part of Adversaries. Multiple sources
the team. Multiple deliveries are the rule, and it's typical
for all active items are to play them off against each
expected daily. The vendor other.
takes care of the needs of the
customer, and the customer
treats the vendor as an
extension of his factory.
Quality Zero defects. If quality is Tolerate some scrap. They usually
not 100%, production is in track what the actual scrap has
jeopardy. been and develop formulas for
Equipment Constant and effective. As required. But not critical
maintenance Machine breakdowns must be because we have queues
Lead times Keep them short. This The longer the better. Most
simplifies the job of foremen and purchasing agents
marketing, purchasing, and want more lead time, not less.
manufacturing as it reduces
the need for expediting.
Workers Management by consensus. Management by edict. New
Changes are not made until systems are installed in spite
consensus is reached, whether of the workers, not thanks to
or not a bit of arm twisting the workers. Then they
is involved. The vital concentrate on measurements to
ingredient of "ownership" is determine whether or not they're
achieved. doing it.
KEYS TO SUCCESSFUL JIT IMPLEMENTATION
The following are some of the keys for successful JIT implementation
1. Stabilize 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 each day, using a repeating sequence if several products are
produced on the same line). Meet demand fluctuations through end-item inventory rather
than through fluctuations in production level.
2. Reduce or eliminate setup times: aim for single digit setup times (less than 10 minutes) or
"one-touch" setup -- this can be done through better planning, process redesign, and
3. Reduce lot sizes (manufacturing and purchase): reducing setup times allows economical
production of smaller lots; close cooperation with suppliers is necessary to achieve
reductions in order lot sizes for purchased items, since this will require more frequent
4. Reduce lead times (production and delivery): production lead times can be reduced by
moving work stations closer together, applying group technology and cellular
manufacturing concepts, reducing queue length (reducing the number of jobs waiting to be
processed at a given machine), and improving the coordination and cooperation between
successive processes; delivery lead times can be reduced through close cooperation with
suppliers, possibly by inducing suppliers to locate closer to the factory
5. Preventive maintenance: use machine and worker idle time to maintain equipment and
6. Flexible work force: workers should be trained to operate several machines, to perform
maintenance tasks, and to perform quality inspections. In general, the attitude of respect for
people leads to giving workers more responsibility for their own work.
7. Require supplier quality assurance and implement a zero defects quality program: errors
leading to defective items must be eliminated, since there are no buffers of excess parts. A
quality at the 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. Techniques such as "JIT lights" (to indicate line slowdowns or
stoppages) and "tally boards" (to record and analyze causes of production stoppages and
slowdowns to facilitate correcting them later) may be used.
8. Small-lot (single unit) conveyance: use a control system such as a kanban (card) system to
convey parts between workstations in small quantities (ideally, one unit at a time). In its
largest sense, JIT is not the same thing as a kanban system, and a kanban system is not
required to implement JIT (some companies have instituted a JIT program along with a
MRP system), although JIT is required to implement a kanban system and the two concepts
are frequently equated with one another.
Kanban Production Control System
A kanban is a card that is attached to a storage and transport container. It identifies the part number
and container capacity, along with other information. There are two main types of kanban (some
other variations are also used):
1. Production Kanban (P-kanban): signals the need to produce more parts
2. Conveyance Kanban (C-kanban): signals the need to deliver more parts to the next work
center (also called a "move kanban" or a "withdrawal kanban")
A Kanban system is a pull-system, in which the kanban is used to pull parts to the next production
stage when they are needed; a MRP system (or any schedule-based system) is a push system, in
which a detailed production schedule for each part is used to push parts to the next production
stage when scheduled. The weakness of a push system (MRP) is that customer demand must be
forecast and production lead times must be estimated. Bad guesses (forecasts or estimates) result in
excess inventory and the longer the lead-time, the more room for error. The weakness of a pull
system (kanban) is that following the JIT production philosophy is essential, especially concerning
the elements of short setup times and small lot sizes.
Dual-card Kanban Rules
1. no parts made unless P-kanban authorizes production
2. exactly one P-kanban and one C-kanban for each container (the number of containers per
part number is a management decision)
3. only standard containers are used, and they are always filled with the prescribed (small)
Productivity Improvement with Kanban
1. deliberately remove buffer inventory (and/or workers) by removing kanban from the
2. observe and record problems (accidents, machine breakdowns, defective products or
materials, production process out of control)
3. take corrective action to eliminate the cause of the problems
From this study we were able to conclude, that in this modern competitive world, where only those
industry which provide maximum customer satisfaction at attracting prices can succeed, the JIT
system plays an important role as it reduces time for manufacturing & the wastage during
production and also at the same time increases the amount of goods produced and cost of
production of these goods. We would like to summarize this study by a flow chart showing how to
implement JIT technique in Automobile industries &other modern industries where large-scale
production takes place.
We could understand from the study that by the implementation of JIT techniques there has been a
rapid acceleration in quality & quantity of products and also reduction in production &
The schematic below shows how Lean system (JIT manufacturing technique) can accelerate ones
business as the familiarity and understanding of the Lean Principles grows within the organization.
So in short we believe that JIT philosophy should be implemented in all modern industry where
large-scale production takes place.