Traditionally, manufacturers have predicted future demand for their products and then tried to smooth production to meet that predicted demand. At the same time, they also tried to keep everyone as busy as possible, producing results in a way that maximized “efficiency” and (hopefully) reduced costs. Unfortunately, this approach has a number of important disadvantages, including large inventories, long production times, high defect rates, production obsolescence, inability to meet delivery schedules, and (ironically) high costs. None of this is obvious – if it were, companies would have abandoned this approach a long time ago.
JIT is a production and inventory control system in which materials are purchased and units are produced only as needed to meet actual customer demand. In just in time, stocks in production systems are reduced to a minimum and, in some cases, reach zero.
JIT operates in three types of inventories:
a) Raw materials: stocks provide insurance in case suppliers delay deliveries.
b) Work in progress: stocks are maintained in case a workstation cannot operate due to a breakdown or other reason.
c) Finished goods: Inventories are maintained to accommodate unforeseen fluctuations in demand.
on the right timeJust in Time Advantages
- Right quantity at the right time
- Higher quality - the elimination of large batch manufacturing and reduced handling often results in significant quality improvements; often in the region of 25% or more.
- Improve customer service
- Minimum Inventory and Waste One of the main objectives of any JIT implementation is to improve inventory turnover and the amount of inventory held. Personal experience has seen inventory reductions of over 90% in some sectors. Along with reducing stock, there are many other associated benefits.
- Reduced space requirements - By removing large amounts of inventory from the system and bringing processes closer together, we will often see a significant reduction in the amount of space used. Results from hundreds of projects carried out in companies across the UK through the Manufacturing Advisory Service have seen average reductions of 33% for simple 5-day implementation projects.
- Reduced lead time - One of the most impacted areas is 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.
- Increase equipment utilization
- Simplicity- Using simple pull systems like 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.
- More workforce participation - A requirement of JIT, as well as most other aspects of lean manufacturing, is that employees are heavily involved in the design and application of your system.
- Continuous improvement
- Better problem solving
- Reduce costs
Only in time limitation
- Requires a high degree of delegation
- Requires change in philosophy and culture
- Collapsing vulnerability
- Only work on regular products
- Requires highly reliable and flexible suppliers
- Requires super coordination between workforce and managers
