JIT vs MRP

JIT and MRP are completely unlike, but are complementary concepts used in material planning and control. MRP stands for Manufacturing Resource Planning, while JIT is Just in Time. MRP is a resource and planning tool that is forward-thinking, and time-phased. The philosophy of JIT, on the other hand, is based on the riddance of waste. One important feature of JIT is known as ‘kanbas’, which is a method of performance based on restoring used material that has no forward visibility.

While operating a manufacturing business, it is possible to operate only with MRP, but the case isn’t the same with JIT, because it does allow for forward planning, which is a vital planning requirement when running a manufacturing operation. There is a need to ensure that materials which cannot be replaced by ‘kanbas’, can be availed when needed. This makes MRP a tool that gives more control, while JIT increases the value of your processes.

There is a mistaken analysis of referring to JIT as a ‘pull’ system, and to MRP as a ‘push’ system. This analysis can be greatly misleading. MRP is a system which focuses on satisfying the requirements of the ‘projected’ usage in a determined time frame. JIT is very much focused on the current, ‘real’ usage, where parts of the production system are ‘connected’ with the use of Kanban’s, while the system runs. It is this kind of linkage that is the main distinguishing feature between JIT and MRP. The JIT system is dynamically linked, whereas MRP is not. This means that JIT is most applicable when lead times are short, whereas MRP is suited for longer lead times. To add to that, for computerized operations, you are better off implementing MRP, than JIT.

Generally, in MRP, there are two basic information types that are required: Structural and tactical. Structural information includes the information about the components used by the company, and the relationship between the different items. Things such as the lead time and batch size rule are included in structural information. The essential point about this information, is that it does infrequently vary.

Tactical information includes such things as the current state of the operation, for instance, pending sales orders, master production schedules, inventory levels, and purchase orders. Obviously, the fundamental point about this information, is that it frequently varies.

Summary:
JIT is Just in Time, while MRP refers to Manufacturing Resource Planning.
MRP is a resource planning system that focuses on the future, and is time phased, while JIT does not provide for forward-thinking.
The JIT system is a dynamically linked system, that is better applied for short lead times, while MRP is not linked, and is better suited for long lead times.
Whereas the JIT system enhances the value of processes, MRP will give you more control.

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