selected topics of quality control 2

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SELECTED TOPICS OFSELECTED TOPICS OF

QUALITY CONTROLQUALITY CONTROL

Just In Time (JIT)



1. Introduction.

2.History of JIT.

3.Objectives of JIT.

4.Tools used in JIT.

5.Benefits and drawbacks of JIT.

6.Case study.



1.Introduction



Just-In-time or JIT, is a managementphilosophy aimed at eliminatingmanufacturing wastes by producing

only the right amount of parts at theright place at the right time.

‘Just in Time (JIT)’ enforces ‘ContinuousImprovement’ by continual reduction of

non-value-added inventory stocks tolower levels.



JIT will result in shorter throughput times

Ø better on-time delivery performance.

Ø higher equipment utilization.

Ø less space requirement.

Ø lower costs.

Ø greater profits.



Each activity is identified as either ‘Value-Added’ or ‘Non-Value-Added’.

The reduction of ‘Non-Value-Added’

activities is achieved mainly throughincreasing manufacturing flexibility andimproved quality.

JIT is the use of a 'pull' system to moveinventories through the production line.

In short, JIT means making what themarket wants, when it wants it.



2. History of JIT



JIT finds its origin in Japan, where it hasbeen in practice since the early 1950’s.

It was developed and perfected by Taiichi

Ohno of Toyota, who is now referred toas the father of JIT. Before the introduction of JIT, there were

a lot of manufacturing defects for the

existing system at that time. Thisincluded inventory problems, productdefects, risen costs, and large lotproduction and delivery delays.



Although many elements of JITmanufacturing were present in Ford'sassembly line in the 1930s, JIT as a

manufacturing process was not refineduntil the 1950's by Toyota Motors

After World War II, Japanesemanufacturers focused on improving

the production process. Their aim wasto increase product quality and reducethe costs.



Tai-ichiOhio established Toyota as leadersin quality and delivery time through theimplementation of JIT.

This position was gained due to acommitment to two philosophies:elimination of waste and respect forpeople.



3. Objectives of JIT



The Objective of JITThe Objective of JIT

The prime goal of JIT is the achievementof zero inventories.

There are three main objectives.

Increasing the organization’s ability tocomplete co-operate with others andremain competitive over the long run.

Increasing efficiency within theproduction process.

Reducing wasted materials, time andeffort. It can help to reduce the costs.



The Objective of JITThe Objective of JIT

Other objectives of JIT:

Identify and response to consumersneeds.

Optimal quality/ cost relationship. Plant design for maximizing efficiency.

Reduce unwanted wastes.



4.Tools of JIT



1.Kanban: The Japanese word “Kanban” can be translated

as "card" or "sign.“ A Kanban system is a material control system

where work centres use visible, physicalsignals to initiate manufacturing andmovement of material.

Signals used in a Kanban system can be

i. quite simple, such as an empty containerii. a card or a message at a workstation in a

computerized system

iii. an EDI message from a customer to a supplier.



2. Jidoka :

Transferring human intelligence toautomated machinery so machines are

able to detect the production of asingle defective part and immediatelystop themselves while asking for help.

one operator can oversee many machineswith no risk of producing large amountsof defectives.



3. Andon:

Andon is an electronic device: audioand/or color-coded visual display.

Andon unit has three color zones (red,green, and orange) and when theorange zone flashes with a distinctivesound, it calls for an attention of and issignaling operator to provide certainmaterial.



5.The Benefits and Drawbacksof JIT



The main benefits are: Reduced levels of in-process inventories, purchased

goods, and finished goods. Reduced space requirements.

Increased product quality and reduced scrap andrework. Reduced manufacturing lead times. Greater flexibility in changing the production mix. Pressure to build good relationships with vendors.

Increased productivity levels and utilization of equipment. Reduction in the need for certain indirect labour.



Drawbacks of Just In Time Although the great benefits of JIT, it has its

drawbacks.

a)Culture Differences: There are some cultures that tie to JITsuccess but it is difficult for an organizationto change its cultures within a short time.

b)Traditional Approach: companies which rely on safety stocks may

have a problem with the use of JIT.



c) Difference in implementation of JIT: Because JIT was originally established in

Japanese, it is somehow different forimplementing in western countries.

d)Loss of individual autonomy: due to the shorter cycle times which adds

pressures and stress on the workers.

e)Loss of method autonomy:

It means the workers must act some waywhen problems occur, this does not allowthem to have their own method to solve aproblem.



6.Case study



General Motors (GM) in the USA has (approximately) 1700suppliers who ship to 31 assembly plants scatteredthroughout the continental USA. These shipments total about30 million metric tons per day and GM spends about 1,000million dollars a year in transport costs on these shipments(1990 figures).

When GM moved to JIT there were simply too many (lightlyloaded) trucks attempting to deliver to each assembly plant.GM's solution to this problem was tointroduce consolidation centers at which full truckloadswere consolidated from supplier deliveries.

This obviously involved deciding how many consolidation centersto have, where they should be, their size (capacity) andwhich suppliers should ship to which consolidation centers(suppliers can also still ship direct to assembly plants).

As of 1990 some 20% by weight of shipments go throughconsolidation centers and about 98% of suppliers ship atleast one item through a consolidation centre.

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