What Is Materials Requirement Planning?

Material Requirement Planning (MRP) refers to the inversion plan based on the affiliation and quantity relationship of items at different levels of the product structure, with each item as the planning object, and the time of completion as the time base. The items are released according to the length of the lead time. The sequence of planning time is a management model for material planning in industrial manufacturing enterprises. MRP is based on market demand forecasts and customer orders to formulate production plans for products, and then generate schedules based on the products, the material structure table and inventory status of the products, and calculate the required amount and time of the required materials through the computer to determine the material processing A practical technique for schedule and order schedule.

American Production and Inventory Control Society (APICS: American Production and Inventory Control Society) definition of material requirements planning: Material requirements planning is based on the master production plan (MPS), bill of materials, inventory records, and outstanding orders, etc. Calculate to obtain the demand status of various dependent demand materials, and propose various new order supplements, as well as a practical technique for amending various open orders.

Its main content includes customer demand management, product production planning, raw material planning, and inventory records. among them

1. Relevance of demand : In the circulation enterprises, various needs are often independent. In a production system, demand is relevant. For example, after the required product quantity is determined based on the order, the new product structure file

The following basic data must be available before making a material requirements plan:

The first data is the master production plan , which indicates the various products and spare parts that should be produced in a certain planning period. It is one of the most important data sources for material requirements planning.

The second item of data is the bill of materials (BOM) , which indicates the structural relationship between the materials and the quantity of each material requirement. It is the most basic data in the material requirements planning system.

The third item is the inventory record , which reflects the actual status of the current inventory and planned acceptance of each item.

The fourth item is the lead time , which determines when each material will start and finish.

It should be said that these four data are all vital and indispensable. Without any of them or the data in any of them is incomplete, the material requirements planning will be inaccurate. Therefore, these four data must be completely established before the material requirements plan is formulated, and it must be absolutely reliable and executable data.

Generally speaking,

The basic processing model of MRP mainly includes two aspects of basic condition data and expansion data.

(1) Obtain the raw materials and components needed for production in time to ensure the timely supply of products required by users.

(2) Guarantee the lowest possible inventory level.

(3) Plan the production and procurement activities of the enterprise, so that the requirements of parts and components, purchased outsourced parts and assembly in each department are precisely connected in time and quantity.

MRP is mainly used in the manufacturing of "assembled" products. When implementing MRP, a sales plan that is responsive to market needs is the most basic element of MRP success. However, MRP also has limitations, that is, the tendency of resources to be confined to enterprises and structured decisions is obvious.

(1) Regenerative MRP, which means that every calculation will overwrite the original MRP data and generate a new MRP. Regenerative MRP is a periodic computation MRP, and the usual computation cycle is one week.

(2) Net variant MRP, which means that it will only change according to the specified conditions, such as MPS change, BOM change, etc. Partial operations update part of the original MRP data. Net variant MRP is a continuous operation that needs to run immediately when the specified data changes.

(1) Based on market forecasts and customer orders, correctly prepare reliable production plans and production operations plans, and specify the types, specifications, quantities, and delivery dates of production in the plan. At the same time, the production plan must be compatible with the existing production capacity s plan.

(2) Correctly compile the product structure drawing and the material list of various materials and parts.

(3) Correctly grasp the actual inventory of various materials and parts.

(4) Correctly specify the date of purchase and delivery of various materials and parts, as well as the order cycle and order quantity.

(5) Determine the total demand and actual demand for various materials and parts through MRP logic operations.

(6) Issue a purchase notice to the purchasing department or issue a production instruction to the production workshop of the enterprise.

The operation logic of MRP basically follows the following process:

Decompose according to the product structure to determine the total demand for different levels of materials; determine the net demand for each material according to the inventory status; reverse the input production date of each component based on the final delivery date of the product and the relationship between the production processes; according to the order Lot and lead time finally determine the order date and quantity. MRP has two modes of operation, namely regeneration and net change. The regeneration method is to recalculate the MRP from the master production plan every certain period. This method is suitable for MTS (stock-oriented production) with relatively stable planning and little change in demand. The net change method is to process only the changed data when the demand method changes, and calculate the demand change part of those affected parts. The net change method can be processed at any time, or once at the end of each day. ^[1]

Manufacturing Resource Planning MRP (Manufacturing Resource Planning) is centered on production planning and organically links the activities of production, supply, sales, and finance related to material management to form a whole and coordinate them so that they can be used in production management Make the most of it. The ultimate goal is to maintain continuous and balanced production, minimize the consumption of inventory and funds, reduce waste, and improve economic efficiency.

The development of MRP from material requirements planning to manufacturing resource planning MRP is the result of continuous deepening of the essence of the production and management process, which reflects the continuous integration of advanced computer technology and management ideas. Therefore, the development of MRP into MRP is an inevitable process.

Enterprise Resource Planning ERP (EnterpriseResourcesPlanning) is a new generation developed from MRP

The development of a material requirements plan (MRP) requires three key pieces of information: MPS, BOM, and inventory records. MPS refers to the master production plan and BOM refers to the bill of materials. In the MRP formulation process, the calculation method of inventory records constitutes the basic calculation model of MRP. Therefore, we mainly introduce the form of inventory records in MRP, and how to calculate and use the inventory records of MRP.

The inventory records in MRP are also called MRP tables. The MRP form is similar in many ways to the MPS record form. It includes: planning factors, crude demand, estimated inventory, existing inventory, planned order inventory, and planned order quantity. It is similar to MPS. It divides the future demand into time periods. The unit of this time period is usually week, but sometimes it is also expressed by day or month. In order to facilitate understanding, the following describes the calculation process of the MRP table with an example.

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Let's first look at the contents of the inventory record and how to determine it.

In a large market with fiercely competitive manufacturing, whether it is discrete or process manufacturing, whether it is single-piece production in small quantities and multiple varieties, or standard product mass production, its internal management may encounter issues such as Unscheduled or inadequate supply of raw materials, serious backlog or unclear quantities of work in progress, decreased productivity cannot be delivered on time, and changing market planning and scheduling are difficult to adapt to. It is necessary to establish a set of modern enterprise management technology to overcome these problems, so that enterprises can be invincible in market competition.

The management information of a manufacturing enterprise refers to the relevant information of production, supply, sales, inventory, people, property, and goods throughout the entire production and operation process. Generally, the manufacturing MRP model can be decomposed into sales, planning, inventory, production, purchasing and parts data, product structure and

Although the development process of ERP has gone through five stages of order point method, MRP, closed-loop MRP, MRPII and ERP, the MRP method is still its core and foundation. The basic function of MRP is to realize the integration of material information, ensure the timely supply of materials, reduce inventory, and improve production efficiency. Material requirements information consists of the following four elements: (1) what is needed; (2) when is it needed; (3) how much is needed; (4) when is the order placed.

MRP is based on the known master production plan (MPS: scheduling of various products based on actual customer orders and market forecasts), based on product structure and material master data, processing processes, product delivery periods, and finished products Material purchase plan and material production plan prepared from inventory, semi-finished product inventory, in-transit quantity, in-process quantity, raw material inventory and other information. As shown below:

The application of MRP requires several clear guarantee conditions:

1. Relatively stable main production plan MPS.

2. Perfect material master data and BOM.

3. Strong ability to provide insurance.

4. Support flexible processing capabilities.

5. Clear order management process, especially order change management.

6. Reasonable production schedule.

The guarantee of these conditions requires the support of good comprehensive management capabilities of the enterprise. Failure to meet any one of these conditions may cause unsatisfactory production organizations.