Just-In-Time (JIT) Approach

JIT, in manufacturing industry, is attributed largely to Taichi Ohno, of Toyota. He was inspired by his first visit to an American supermarket where he saw customers getting just what they wanted, when they wanted it. Of course the concept was not new - for example, in the catering trade and where goods are perishable, the nature of the product imposes similar demands. We are increasingly familiar with JIT in the High Street where items such as photographs, spectacles, cosmetics and music CDs are customised to order.
Behind the scenes, in manufacturing industry, the same principles are being applied. With technology and fashion changing so rapidly, it makes little sense to hold stocks which may ultimately not be wanted. Even if we can be assured of eventually selling them, stock holding costs money, so we need to minimise stocks and add value which differentiates them as late as possible.
Why do we hold stocks at all if they are so costly? Well, customers can be fickle, so we need to assure them that they can have whatever they need whenever they want it - and it also takes time to make the product, transforming it from raw materials and sub-components into the finished article. If we actually take a look at the lead time - the time it takes for a product to pass through the entire process - we find that most of this time is actually waiting time. 

It takes seconds to form a piece of metal; seconds to weld it to another; seconds to paint it, minutes to stove the paint, and perhaps a few minutes to assemble it to other components and package it. Yet that piece of metal will days - probably weeks or even months passing through the various manufacturing stages. Why? Because there is waste in the process - waste being anything that does not add value as far as the customer is concerned.
Waste Our main targets are 'WID'. we find these in all sorts of jobs - on and off the shop floor. If there is difficulty - physical or mental - there is a likelihood of somebody or something failing. We need to remove the problem. People know what they are and are happier to get  known problems out of the way before others are identified to them.
Irregularity
Difficulty

Then  we need to get the process under control - this is, after all one of the fundamental tenets of GK. Discover the causes of variation and iron out the irregularities. In our experience 95% of these are simply because people are not following standard procedures and methods.
We now have the system under control - we have established a regular flow of product. We can now start to drain away the waste!
The Seven Deadly Wastes

Taking away the waste means that we are closer to our customers, We need to 'turn on the tap' when they want product, rather than filling buffers. A pull system, such as kanban helps us do this.

Finally, we need to match the rate of production with the rate of consumption. This is known as the tact. For example, if the customer requires 60 pieces an hour, the tact will be one minute.

Flow

 Pull Tact

The main elements of JIT
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