Just in Time is one of the core philosophies and drivers in Lean. It involves changing the production process, so that you produce the right amount of product ‘just in time’ for the customer’s needs. It involves high efficiency, low waste and well coordinated production processes.
Why use Just in Time?
If you manage to move to a Just in Time system, you will:
- reducing the amount of money tied up in finished goods stock
- reduce the risk of finished goods stock becoming obsolete
- less material around which can be lost / damaged
- increased flexibility, as production and materials can be easily changed to other outputs
- improved quality, leading to lower cost of quality and greater customer satisfaction
- less space required, reducing rent and rates costs
When not to use Just in Time?
There are situations when it’s not a good idea to put JIT in place, at least not until these issues are solved
- If you have supplier reliability issues, a delivery failure may cause you to let down your customer
- If you have long lead times for your suppliers (e.g. if you have bespoke parts and/or they are made a long distance away) you will not be able to order ‘when required’
- If you have a high (or fluctuating) defect rate, you might end up with not enough finished goods of a good enough quality to fulfil your order
Push vs pull manufacturing
Just in time involves changing from a traditional ‘push’ production method, where your production line pushes out stock at a consistent rate into a finished goods warehouse, where your customer then can buy what they need, in a ‘supermarket’ type method. It moves to ‘pull’, where customer demands mean that just the right amount is produced at just the right time, and no permanent finished goods stock is required, reducing inventory waste.
It uses the ‘kanban’ system to make this happen, and also requires there to be very little if any waste.