JUST IN TIME

Just-in-time (JIT) manufacturing, also known as just-in-time production or the Toyota Production System (TPS), is a methodology aimed primarily at reducing times within the production system as well as response times from suppliers and to customers. Its origin and development was mainly in Japan, largely in the 1960s and 1970s and particularly at Toyota.

Alternative terms for JIT manufacturing have been used. Motorola's choice was short-cycle manufacturing (SCM). IBM's was continuous-flow manufacturing (CFM), and demand-flow manufacturing (DFM), a term handed down from consultant John Constanza at his Institute of Technology in Colorado.

Still another alternative was mentioned by Goddard, who said that "Toyota Production System is often mistakenly referred to as the 'Kanban System'", and pointed out that kanban is but one element of TPS, as well as JIT production.

But the wide use of the term JIT manufacturing throughout the 1980s faded fast in the 1990s, as the new term lean manufacturing became established as "a more recent name for JIT". As just one testament to the commonality of the two terms, Toyota production system (TPS) has been and is widely used as a synonym for both JIT and lean manufacturing.

What is Just in Time ?

Just in Time (JIT), as the name suggests, is a management philosophy that calls for the production of what the customer wants, when they want it, in the quantities requested, where they want it, without it being delayed in inventory. So instead of building large stocks of what you think the customer might want you only make exactly what the customer actually asks for when they ask for it. This allows you to concentrate your resources on only fulfilling what you are going to be paid for rather than building forstock. Within a Just in Time manufacturing system, each process will only produce what the next process in sequence is calling for.

Elements involved in JIT

Continuous improvement:

• Attacking fundamental problems and anything that does not add value to the product.
• Devising systems to identify production and allied problems.
• Simplicity:  Simple systems are simple & easy to understand, easily manageable and the chances of going wrong are very low.
• A product: oriented layout for less time spent on materials and parts movement.
• Quality control at source to ensure every worker is solely responsible for the quality of their own produced output.

Eliminating waste: There are seven types of waste:

1. Waste from product defects.
2. Waste of time.
3. Transportation waste.
4. Inventory waste.
5. Waste from overproduction.
6. Processing waste.

Waste minimization is one of the primary objectives of Just In Time system. This needs effective inventory management throughout the whole supply chain. Initially, a manufacturing entity will seek to reduce inventory and enhance operations within its own organization. In an attempt to reduce waste attributed to ineffective inventory management, SIX principles in relation to JIT have been stated by Schniededans and they are:

1.       Reduce buffer inventory.
2.       Try for zero inventory.
3.       Search for reliable suppliers.
4.       Reduce lot size and increase the frequency of orders.
5.       Reduce purchasing cost.
6.       Improve material handling.

How does JIT differ from traditional manufacturing?

• In traditional manufacturing we try to predict what the customer will want and we will create a forecast (or guess) against which we will produce our products. We will also try to produce those products in large batches as the belief is that will make machines and processes more efficient, especially if those machines require a long time to setup. This will typically result in long lead times through our processes, huge amounts of Work In Process (WIP) stocks and also large quantities of finished goods stocks that have not yet been ordered by our customers. This is what many now call “Just in Case”manufacturing.
• If the customer does order something that is not in our current stocks they will either have to wait many weeks or even months for the product to be manufactured or work will be hurried through the system by progress chasers causing a huge amount of disruption to the production schedule.
• These systems are often run by Manufacturing Resource Planning (MRP2) programs that will try to schedule each and every process within the facility. These software packages will seek to control every step and everything requires careful and often complex planning.
• A Just in Time system on the other hand will seek to use simple visual tools known as Kanbans to pull production through the processes according to what the customer actually takes. It massively reduces the amount of stock held and will reduce lead times by a significant amount, often from weeks to just a few hours or days.

The Advantages and disadvantages of a JIT system

The following are some of the many benefits that you could gain through the implementation of just in time

• Order to Cash :The Order to Cash Timeline; as you reduce your lead time the quicker you get your cash. Reduction in the order to payment timeline; cash, as they say is king in business. Many businesses will suffer with cash flow problems as they will often have to purchase large amounts of raw materials prior to manufacturing and subsequent payment by the customer. Often this gap is many months. Through implementing JIT you are able to considerably reduce that time period.
• Reduction in Inventory costs; one of the main aims with any JIT implementation is to improve stock turns and the amount of stock being held. Personal experience has seen reductions of more than 90% stock in some industries. Along with the reduction in the stock come many other associated benefits.
• Reduction in space required; by removing large amounts of stock from the system and moving processes closer together we will often see a significant reduction in the amount of floor space being used. Results from 100’s of projects run within companies in the UK through the Manufacturing Advisory Service saw average reductions of 33% for simple 5 day implementation projects.
• Reduction in handling equipment and other costs; if you don’t have to move large batches there is less need for complex machinery to move them and all of the associated labor and training.
• Lead time reductions; one of the most significantly impacted areas is that of the time it takes for products to flow through the process. Instead of weeks or months most JIT implementations result in lead times of hours or a few days.
• Reduced planning complexity; the use of simple pull systems such as Kanban, even with your suppliers, can significantly reduce the need for any form of complex planning. With many implementations the only planning is the final shipping process.
• Improved Quality; the removal of large batch manufacturing and reduction in handling often results in significant quality improvements; often in the region of 25% or more.
• Productivity increases; to achieve JIT there are many hurdles that must be overcome with regards to how the process will flow. These will often result in productivity improvements of 25% upwards.
• Problems are highlighted quicker; often this is cited as being a negative aspect of JIT in that any problems will often have an immediate impact on your whole production process. However this is the perfect way to ensure that problems are highlighted and solved immediately when they occur.
• Employee empowerment; one requirement of JIT as with most other aspects of Lean manufacturing is that employees are heavily involved in the design and application of your system.
• Inventory Hides Problems : Many definitions of Just in Time and Lean itself will state that waste reduction is the aim; waste reduction, however, is actually something that you achieve through trying to implement the flow and other improvements required to achieve just in time and not an end in itself.

Disadvantages of Adopting JIT Systems

• JIT approach states ZERO tolerance for mistakes, making re-work difficult in practice, as inventory is kept to a minimum level.
• A successful application of JIT requires a high reliance on suppliers, whose performance is outside the purview of the manufacturer.
• Due to no buffers in JIT, production line idling and downtime can occur which would have an unfavourable effect on the production process and also on the finances.
• Chances are quite high of not meeting an unexpected increase in orders as there will be no excess inventory of finished goods.

Requirements for implementing Just in Time

• Just in Time is just one of the pillars of a lean manufacturing system and as such it cannot be implemented in isolation and without a firm foundation on which to build. Trying to reduce batch sizes without tackling setup times for instance cannot be done. The following are some of the things that must be implemented  for JIT to be able to work:
• Reliable Equipment and Machines; if your machinery is always breaking down or giving you quality problems then it will frequently manifest in big issues with any JIT flow. The implementation of Total Productive Maintenance is required to ensure that you can rely on your equipment and to minimize the impact that any failures have on your processes.