Just-In-Time Manufacturing:

JIT is a philosophy of continuous improvement in which non-value-adding activities (or wastes) are identified and removed for the purposes of:

JIT is not about automation.  JIT eliminates waste by providing the environment to perfect and simplify the processes.  JIT is a collection of techniques used to improve operations  It can also be a new production system that is used to produce goods or services.

The American Production and Inventory Control Society (APICS) has the following definition of JIT: 

"a philosophy of manufacturing based on planned elimination of all waste and continuous improvement of productivity.  It encompasses the successful execution of all manufacturing activities required to produce a final product, from design engineering to delivery and including all stages of conversion from raw material onward.  The primary elements include having only the required inventory when needed; to improve quality to zero defects; to reduce lead time by reducing setup times, queue lengths and lot sizes; to incrementally revise the operations themselves; and to accomplish these things at minimum cost."

When the JIT principles are implemented successfully, significant competitive advantages are realized.  JIT principles can be applied to all parts of an organization:  order taking, purchasing, operations, distribution, sales, accounting, design, etc.

Elimination of Waste:

JIT usually indentifies seven prominent types of waste to be eliminated:

Summary:

Material related costs are reduced by reducing the number of suppliers a company deals with and developing long-term contracts through creative supplier networking, eliminating the need to count individual parts, reducing order scheduling, eliminating expediting, simplifying receiving systems, eliminating receiving inspection, eliminating most unpacking, eliminating the stocking of inventory, and eliminating excess material spoilage.

Manufacturing related costs are reduced by design for manufacture and design for assembly techniques where unnecessary parts or processes are eliminated. They are also reduced through the elimination of excess material handling, inspections, and storage of parts.  The primary goal is to eliminate non-value adding tasks.  Quick change over techniques replace long set-up times.  Cells will replace traditional assembly lines.