Just in TimeBy Dr. Pritpal Singh BhullarB.Tech(Mechanical) MBA(Finance) UGC NET , Phd (Finance)

Just in Time

• JIT is a management system for productivity and efficiency improvement.

• JIT philosophy means getting the right quantity of goods at the right place and the right time

• Just in time is processing the exact information, materials, services and products in the required or ordered quantity, when required by downstream processes or customers.

• This means that stock levels of raw materials, components, work in progress and finished goods can be kept to a minimum.

Elements of JIT

1. Stabilized and uniform plant loading-Create a uniform load on all work centers through constant daily, production 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 setup time-Setup time should be very less so that quick demands can be met. Company must aim for single digit set up time .

Set up time < 10 Minutes This can be done through better, planning, process redesign and product

redesign.

For Uniform plant loading a “level” schedule is developed so that the same mix of products is made every day in small quantities

Monday Tuesday Wednesday Thursday FridayAAAAA BBBBB BBBBB DDDDD EEEEEAAAAA BBBBB BBBBB CCCCC EEEEE

Monday Tuesday Wednesday Thursday FridayAABBBB AABBBB AABBBB AABBBB AABBBBCDEE CDEE CDEE CDEE CDEE

5 units5 units10 units

Weekly Production Required

Traditional Production Plan

JIT Plan with Level Scheduling

ABCDE

10 units20 units

Elements of JIT

3. Reduce lot sizes— Small lots mean less average inventory and shorten manufacturing lead time

Reducing set up 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 deliveries.

4. Preventive maintenance—Use effective machines but the key is to use machine and worker idle time to maintain equipment and prevent break downs.

5. Flexible work force—Workers should be trained to operate several machines, to perform maintenance tasks, and to perform quality inspections. In general JIT requires teams of competent, empowered employees who have more responsibility for their own work. The Toyota production system concept of “respect for people” contributes to a good relationship between workers and management.

Plant Layout of JIT

• The layout in JIT manufacturing is often in the form of product focus and manufacturing cells. This type of layout is necessary because lot size production requires that the layout to be compact and efficient to ensure smooth flow of materials.

• A pull production system requires close communication between work stations, unlike traditional manufacturing. The flow in a JIT system is in two directions, material is pulled forward, but information flows backward to provide feedback on material

requirements. 

Plant Layout in JIT

1. Lot size - In contrast to the traditional manufacturing, JIT manufacturing requires production of small lot sizes.

Production of small lot sizes is made possible by drastically reducing set-up times. Production of small lot sizes leads to improved quality, reduced inventory, easier delivery and other market responsiveness.

2. Employee and supplier involvement - Employee involvement leads to high level of activity coordination and information sharing among team members. It also helps in better decision making and in developing innovative ideas of production.

In JIT involvement of suppliers leads to improve quality, shorten delivery time and offer ideas towards new design.

Plant Layout in JIT

3. Quality—Under JIT manufacturing organizations are often positive and quality means getting it right the first time.

In JIT, because of small lot sizes ,small setup time and continuous improvement quality of product can be improved.

4. Just in time purchasing—JIT is an approach with the objective of producing the right part in the right place at the right time. This obviously means that purchasing the raw material should also beat the right time or just in time. It helps in reducing inventory that further leads to reduction in various losses to company.

Plant Layout in JIT5. Technology—In a JIT manufacturing system technology comes after

simplification and understanding of the entire system. Effective use of technologies and tools in a coordinated and logical manner, dramatically shorten setup time,  reduce the number of prototypes, cut costs and improve quality of the design.

6. Just in time production—JIT production is closely related to the practices of designing.

Focused factories – These are small specialized manufacturing plants that are dedicated to the production of a small number of products

Cellular manufacturing - It is the practice of organizing a factory into manufacturing cells that are dedicated to the production of a single product, or a few similar products

Such layout leads to obtaining more accurate product costs and less product

diversity within a cell.

Plant Layout in JIT JIT production also emphasizes continuously reducing the time required to

perform the needed machine set-ups and operation, thus reducing down time and production lead time to a minimum correcting defects as they occur and emphasizing on small or zero inventories

7. Fail proof devices and preventive manufacturing— Fail proof devices such as warning bells times electric eyes and alignment

templates are also used to prevent from occurring off. JIT also helps in excessive manufacturing. In JIT production is done as per the demand of customers for products.

Advantages of Just in Time

• Lower stock holding means a reduction in storage space which saves rent and insurance costs

• As stock is only obtained when it is needed, less working capital is tied up in stock

• There is less likelihood of stock perishing, becoming obsolete or out of date• Avoids the build-up of unsold finished product that can occur with sudden

changes in demand• Less time is spent on checking and re-working the product of others as the

emphasis is on getting the work right first time

Advantages of JIT

• As just-in-time production works on a demand-pull basis, all goods made would be sold, and thus it incorporates changes in demand with surprising ease.

• Just-in-time manufacturing encourages the right first time concept, so that inspection costs and cost of rework is minimized.

• High quality products and greater efficiency can be derived by just-in-time production system.

• Close relationships are established along the production chain under a just-in-time manufacturing system.

• Constant communication with the customer results in high customer satisfaction.

• Over production is eliminated, when just-in-time manufacturing is adopted.

Disadvantages of Just in Time

• Just-in-time manufacturing provides zero tolerance for mistakes, as it makes re-working very difficult in practice, as inventory is kept to a bare minimum.

• There is a high dependency on suppliers, whose performance is generally outside the purview of the manufacturer.

• Due to there being no buffers for delays, production downtime and line idling can occur, which would bear a detrimental effect on finances and on the equilibrium of the production process.

• The organization would not be able to meet an unexpected increase in orders, due to the fact that there are no excess finish goods.

• Transaction costs would be relatively high, as frequent transactions would be made.

Role of Management in JIT

• Responsible for culture of mutual trust• Serve as coaches & facilitators• Support culture with appropriate incentive system including non-monetary • Responsible for developing workers• Provide multi-functional training• Facilitate teamwork

Kanban System

Kanban is a Japanese noun which means “visible record”. ”. Kanban refers to cards used to control flow of production through a factory. Kanban signal (communicate) some or all of the following:what parts to manufacture, when to start manufacturing, when to stop manufacturing, how many to manufacture, andwhere to deliver them to.

“KANBAN IS A FORM OF JIT-SYSTEM or PULL SYSTEM

Operating Rules of Kanban

1.Each container must have a card.2.The assembly line always withdraws materials from fabrication

(pullsystem).3.Containers of parts must never be removed from a storage area without a

kanban being posted on the receiving post.4.The containers should always contain the same number of good parts. The

use of nonstandard containers or irregularly filled containers disrupts the production flow of the assembly line.

5.Only non defective parts should be passed along.6.Total production should not exceed the total amount authorized on the

kanbans in the system

Kanban

• A Kanban system is a means to achieve just in time (JIT) production. It works on the basis that each process on a production line pulls just the number and type of components the process requires, at just the right time.

• The mechanism used is a Kanban card. This is usually a physical card but other devices can be used. Two types of such cards are usually used.

• One card is used as a signal for the need to deliver more parts whereas the other card is used as a signal for the need to produce more parts.

• Withdrawal KANBAN• Production KANBAN

Kanban

Withdrawal Kanban : • It Specifies the kind and quantity of product which a manufacturing

process should withdraw from a preceding process. • This card (following card) shows that the preceding process which makes

this part is forging, and the person carrying this card from the subsequent process must go to position B-2 of the forging department to withdraw drive pinions.

• Each box of drive pinions contain 20 units and the shape of box is “B”. This Kanban is the 4th of 8 issued. The item back number is an abbreviation of the item.

Withdrawal Kan ban System

• The main function of a withdrawal Kan-ban is to pass the authorization for the movement of parts from one stage to another.

• Once it gets the parts from the preceding process and moves them to the next process, remaining with the parts until the last part has been consumed by the next process.

• The withdrawal Kanban then travels back to the preceding process to get parts thus creating the cycle.

Withdrawal Kanban

A withdrawal Kanban usually carries the following information:o part numbero part nameo lot sizeo routing processo name of the next processo location of the next processo name of the preceding processo location of the preceding processo container typeo container capacityo number of containers released

Kanban

Production Kan ban System (Single Card Kanban)• The primary function of the production Kan-ban is to release an order to

the preceding stage to build the lot size indicated on the card.

The production Kan-ban card should have the following information :

o materials required as inputs at the preceding stageo parts required as inputs at the preceding stageo information stated on withdrawals Kan-ban

Kanban

Production ordering Kanban :

• Specifies the kind and quantity of the product which the preceding process must produce.

• The one illustrated below shows that the machining process SB-8 must produce the crankshaft for the car type X5OBC-150. The crankshaft produced should be placed at store F26-18. The production ordering Kanban is often called an in-process or simply a production Kanban.

Kanban

Advantages of Kanban System

• Low costs associated with the transfer of information.• • Provides quick response to changes.• • Delegates responsibility to line workers.• • It is a simple technique not involving computers so its cost is low.• • Lead times are reduced.

Disadvantages of Kanban

• It is less effective in shared-resource situations. Suppose the upstream station made several parts. Then a request to make more of the part needed by the downstream station will have to wait if other parts have to be made. A buffer is needed to ensure the downstream station doesn’t run out mean while. And, because each part needs a separate signaling card, the system becomes more complex than if the resources were dedicated.

• Surges in mix or demand cause problems because Kanban assumes stable repetitive production plans. It is less suited to industries where mix and volumes fluctuate. • Kanban in itself doesn’t eliminate variability, so unpredictable and lengthy down times could disrupt the system; poor quality in terms of scrap and rework also affect its good functioning.

Disadvantages of Kanban

• Kanban systems are not suited for manufacturing environments with short production runs, highly variable product demand, poor quality products, and a multitude of product types.

• A breakdown in the Kanban system can result in the entire line shutting down.

• The throughput of a Kanban system is not managed but is instead a result of controlled WIP and known cycle times.

Kanban System

JIT Cause & Effect Chain

• The cause-and-effect diagram, also called “fishbone” or the “Ishikawa diagram” (named after its inventor),

• It permits identification and organization of a list of factors thought to cause a problem or affect variation in a desired outcome.

• The cause-and-effect diagram is essentially a pictorial display of a list.  • Each diagram has a large arrow pointing to the name of the problem or

issue. 

• The branches off the large arrow represent main categories of potential causes.  Smaller branches, representing sub-categories (can be a list of items) are then drawn off of each major branch.

JIT Cause & Effect Chain

• These main categories ("Bones") may be customized to fit the process under study, however, typical categories of major causes used with the cause-and-effect diagram are:

• Equipment, Methods, Materials, People, Environment/Measurements/Procedures

• Steps of Process (Block Diagram)• Who--What--When--Where• People, Provisions (Supplies), Procedures, Place, Patrons (Patients)

JIT Cause & Effect Chain

Cause-and-Effect DiagramsCause-and-Effect Diagrams

MaterialMaterial MachineryMachinery

MethodsMethods ManpowerManpower

InadequateInadequate

supply of supply of magazinesmagazines

Inadequate Inadequate

special meals special meals

on-boardon-board

Insu

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ient

In

suff

icie

nt

clea

n cl

ean

pillo

ws

pillo

ws

& b

lank

ets

& b

lank

ets

on-b

oard

on-b

oard

Broken Broken

luggage luggage

carouselcarousel

Mechanical Mechanical

delay on planedelay on plane

Dei

cing

D

eici

ng

equi

pmen

t eq

uipm

ent

not

not

avai

labl

eav

aila

ble

Overbooking policiesOverbooking policies

Bumping policiesBumping policies

Mis

tagg

eM

ista

gge

d ba

gsd

bags

Poo

r ch

eck-

Poo

r ch

eck-

in p

olic

ies

in p

olic

ies Understaffed Understaffed

ticket ticket

counterscounters

UnderstaffeUnderstaffe

d crewd crew

Poo

rly

Poo

rly

trai

ned

trai

ned

atte

ndan

tsat

tend

ants

Dissatisfied Dissatisfied Airline Airline CustomerCustomer

Waste

• Waste is non value added activities in the company which consumes time, money and resources.

• It is important for every company to eliminate these non value added activities (waste) for an efficient production system.

• There are mainly seven types of wastes –1) Overproduction 5) Waiting2) Defects 6) Motion3) Inventory 7) Over - processing4) Transportation

Types of Wastes

1. Overproduction - Overproduction is regarded as the most serious waste. Overproduction is producing more than demanded or producing it too early before it is needed.

This increases the risk of obsolescence, increases the risk of producing the wrong thing and increases the possibility of having to sell those items at a discount or discard them as scrap.

Overproduction also tends to lead to excessive lead and storage times. As a result, defects may not be detected early, products may deteriorate and artificial pressures on work rate may not be generated

Types of Wastes

2. Defects - Defects waste is a direct cost. When defect occurs, rework may be required otherwise the product will be scrapped.

Following losses happen to company due to defects – a) Wastage of materials b) Wastage of labour resources c) Create material shortages, d) Hinder meeting schedules, e) Create idle time at subsequent workstations and f) Increase manufacturing lead time

Types of Wastes

3. Inventory - Inventory waste means having unnecessarily high levels of raw materials, works-in-process and finished products.

Extra inventory leads to following losses to company due to high inventory –

a) Higher storage cost b) Higher defect rates c) Prevent rapid identification of problems d) Increase space requirement e) Increase lead time f) Additional requirement of material handling resources.

Types of Wastes

4. Transportation - Transportation includes any movement of materials that does not add any value to the product, such as moving materials between workstations.

Transportation waste leads to following losses – a) Multiple storage locations b) Extra material racks c) Complex inventory management d) Extra facility space e) Incorrect inventory counts f) Damaged materials

Types of Wastes

5. Waiting Time - When time is being used ineffectively then the waste of waiting occurs. This waste occurs whenever goods are not moving or being worked on.

Waiting is idle time for workers or machines due to inefficient production flow on the factory floor or small delays between processing of units.

Waiting leads o following losses – a) unbalanced operations b) lack of operator concern for equipment breakdown, and c) unplanned equipment downtime

Types of Wastes

6. Motion - Motion includes any unnecessary physical motions or walking by workers which divert them from actual processing work.

Motion waste involves following losses to company – a) Poor ergonomics of production where operators have to stretch, bend and pick b) poor productivity c) quality problems d) Excessive reaching or bending, e) Tools missing f) Poor managerial control.

Types of Wastes

7. Over processing - Over-processing is unintentionally doing more processing work than the customer requires in terms of product quality or features- such as polishing or applying finishing in some areas of product that will not be seen by the customer

Over-processing leads to following losses in company – a) Lack of clear customer specifications, b) redundant approvals c) extra copies d) excessive information

Elimination of waste

Steps in waste elimination 1) Find the waste – Company must find the waste in the system. Waste may

be in the form of Profits, Sales, Cost of quality, Lead time, Waiting time etc.

2) Measure the waste - The objective is to accurately define the magnitude of waste that currently exists.  Numerous tools are available to measure the waste like fish-bone diagrams, process analysis flow charts etc.

3) Pareto analysis - This charting technique is used to visually apply the “80/20 rule” to identify the larger areas of waste.

4) Assign root causes – Try to fin the main root or origin of waste.

Elimination of waste

5. Brainstorming – Formulate the group of experts of different areas and try to find out best feasible alternative for waste elimination. Sessions should be short and lively, and absolutely no criticism of ideas is allowed.  The objective is to generate and document a huge quantity of ideas.

6. Select action items – Evaluate each brainstorming idea and select which idea/ alternative one is best and effective to implement.  

Prioritize the list by weighing the benefit of each idea/ alternative against its difficulty of implementation.  Keep the list short and powerful.

Elimination of waste

7. Action plan – Adopt a standardize plan to implement the alternatives. 8. Monitor the plan – Stick to the plan and avoid “starts and stops.”  Status

The team of experts must review the progress and effectiveness of plan and try to remove any distraction in plan.

9. Measure the results – Record all the results. Measure the actual results against the expected results.

10. Use check sheets to record all identified waste and sum up all eliminated wastes in terms of profits and benefits the company gains from it.

Implementation of JIT

1. Review of segmentation of inventory by item types2. Ensure that all items are classified3. Ensure that unit cost is stated for each item.4. Establish anticipated annual demand quantity for each item.5. Establish purchase order, purchasing agreement or contract for selected

items with qualified vendors6. Establish inventory policy code for each item based on method of

inventory control and method of transaction reporting and recording7. Review and establish minimum economical order quantities and safety

stocks required by JIT production8. Measure inventory performance to determine effectiveness of Just in

time production and inventory management.

JIT Philosophy

• Just in Time is a philosophy which believes that waste can be eliminated by cutting unnecessary inventory and removing non- value added activities in operations. The goals are to produce goods and services as specifications and continuous improvement through value additions.

• Job scheduling systems are also known as optimisers. Working out the optimum way to allocate jobs amongst field workers so that the jobs can be carried out in the most efficient way and at the least cost to the business.