3. Belonging.
4. Security.
5. Basic Needs.
During the early stages of development, MRP meant material requirements planning. It was a systematic way to determine the time-phased needs for components and raw material ("dependent" items) in a job shop environment. It was driven by a detailed master schedule for end products and took into account actions already taken. Later, it was recognized that a higher level of input, the production plan, was needed to make the system effective so MRP was broadened in scope and renamed manufacturing resource planning. Despite all the educational and promotional efforts during the last two decades, less than five percent of the MRP installations in America ever reached and maintained "Class A" status, which means they delivered what was expected when the systems were authorized. There are three major reasons for that disappointing record:.
1. The environment was too complicated. We tried to make the systems manage existing complex processes instead of simplifying the processes first it resulted in the same confusion, only at the speed of light.
2. In some cases, we distorted the businesses to fit the system. Since discrete order MRP was the "only game in town" we tried to turn naturally repetitive flow shops into pseudo job shops to utilize the system. Rate-based MRP systems have appeared recently but conversion costs have detected many companies from switching to them.
3. We tried to make MRP do too much. It was conceived as a planning system but we tried to use it for execution control as well. In truth, what we did was record events and when things got out of hand, we made a new plan. Frequent replanning created a "nervous" environment which disenchanted the users. They responded by ignoring the system.
Strengths of MRP are:.
Database organization.
Integrated planning capability.
Interactive information .
Updating and Time Phasing.
JIT adds process simplification.
