Material Requirements Planning (MRP) is a material planning management model within an industrial manufacturing enterprise. According to the subordinate and quantity relationship of items at all levels of the product structure, it takes each item as the planning object, takes the completion period as the time benchmark to reverse the plan, and distinguishes the order of the planned time of each item according to the length of the lead time. MRP is a practical technology that formulates the production plan of the product according to the market demand and customer orders, and then generates the schedule based on the product, composes the material structure table and inventory status of the product, and calculates the demand and demand time of the required materials through the computer, so as to determine the processing progress of the material and the order schedule.
Most MRP systems are software-based, but MRP can also be performed manually. The MRP system is designed to meet three objectives simultaneously: ensuring that raw materials are available for production and products can be delivered to customers, maintaining the lowest possible material and product levels in the store for planned manufacturing activities, delivery schedules, and purchasing activities.
1. The preparation procedure of MRP material requirements plan is roughly as follows:
1. Calculate the gross demand of materials.
According to the master production plan and the bill of materials, the gross demand of the first-level material item is obtained, and then the gross demand of the next-level material item is calculated through the first-level material item, and the calculation is carried out in turn until the lowest level of raw material blank or purchased parts.
2. Calculation of net demand.
The net demand for each material is calculated according to the gross demand, available inventory, allocated quantity, etc., that is, the net demand = gross demand + allocated quantity - available inventory - in-transit quantity.
3. Batch calculation.
It is up to the relevant planner to make a decision on the batch strategy for the production of the material, regardless of the batch rule or not, the net requirement calculation should indicate whether there is a batch requirement.
4. Calculation of safety stock, scrap rate and loss rate.
It is up to the relevant planner to plan whether these three calculations are to be made for the net requirements for each item.
5. Place a planned order.
After passing the above calculations, the planned order is generated based on the lead time. The planned orders generated by the MRP must be confirmed by the capacity resource balance before the planned orders can be officially released.
5. Calculate again.
According to the actual situation, the planned orders that have been placed are calculated and adjusted again.
Second, the key points of MRP material requirements planning include:
1. Determine the master production plan: The master production plan is the basis of MRP, which determines the production plan of the final product, including product, quantity, time, etc.
2. Understand the bill of materials: The bill of materials is an important basis for calculating the gross demand in MRP, and it is necessary to understand the hierarchical relationship, quantity and time of each material.
3. Master inventory information: Inventory information includes existing inventory, in-transit volume, allocated quantity, etc., which will affect the calculation of net demand.
3. Select the appropriate batch rule: select the appropriate batch rule according to the actual situation to determine the net demand for the material.
4. Consider factors such as safety stock, scrap rate and attrition rate: these factors will affect the demand for materials and the placement of planned orders.
5. Confirm and adjust the planned order: confirm and adjust the planned order according to the actual situation to meet the needs of the actual production.
In addition, there are a few things to keep in mind when implementing MRP material requirements planning:
1. Accuracy of data: Ensure that the input data is accurate, including product structure documents, inventory files, production time and procurement time, etc.
2. Stability of the system: choose reliable MRP software and ensure the stability of the system to avoid problems in the calculation process.
3. Professionalism of personnel: Relevant planners need to have professional knowledge and skills, and be able to correctly understand and implement the calculation process and results of MRP.
4. Consider the actual situation: When implementing the MRP material requirement plan, it is necessary to consider the actual situation, such as production capacity, procurement cycle, transportation time, etc., in order to formulate a reasonable plan.
5. Continuous improvement: MRP material requirements planning is a process of continuous improvement, which needs to be continuously adjusted and optimized to meet the needs of actual production.