What kind of materials need to be reserved for production and maintenance, how much to reserve, and how to manage inventory, procurement and consumption are the main contents of enterprise maintenance materials management. Inventory control and management of maintenance materials are the core and foundation. This paper discusses the factors affecting the inventory of maintenance equipment, four inventory control management methods and the importance of establishing inventory benchmark.
Maintenance substance; Inventory management; stock control
Discussion on Inventory Management of Maintenance Materials
Abstract: This is the main content of maintenance materials management in enterprises. Managing the types and quantities of maintenance materials, and managing the inventory, purchase volume and consumption are the core and foundation of maintenance materials inventory control management. This paper discusses the influencing factors of inventory maintenance, four management methods of inventory and the importance of establishing inventory benchmark.
[Keywords:] material maintenance, inventory management, inventory control 1
There is no denying that our company's inventory of maintenance materials is on the high side for a long time. By the end of 2008, the inventory of maintenance materials was about 900 million yuan, and the inventory of maintenance materials per ton of steel was about 170 yuan, which did not reach the average level of iron and steel enterprises. In particular, the existence of a large number of spare parts beside the machine shows that there is still much room for improvement in our maintenance material inventory management. High inventory is the result of long-term accumulation. It is not only related to inventory management methods, but also related to management methods. To sum up, there are four main factors that lead to high inventory: first, there are no standards to evaluate the rationality of inventory, such as the benchmark of maintenance material inventory control, replacement cycle and procurement cycle of replacement parts, and the basis of inventory control is not clear; Second, secondary units have long attached importance to the safe storage of maintenance materials, ignoring economic rationality. In order to minimize the possibility of affecting production, they adopted the strategy of storing more, and did not control the inventory from the perspective of company capital operation; Third, long-term mixed management of equipment, spare parts, tooling and tools. As a result, the reserve structure is unreasonable, and the rationality of the reserve structure is not analyzed, especially the reasonable inventory management of spare parts beside the machine, which is generally based on the requirements of on-site management; Fourth, there are many kinds of non-standard parts. Due to the long-term management practice of directly linking with its installation equipment, it is difficult to effectively control the phenomenon of repeatedly storing the same or interchangeable spare parts. Although the relevant management departments of the company have done a lot of work in recent years to reduce the variety of non-standard parts, there is still some potential to be tapped. These four factors show that there is still a lot of room for improvement in the ways and means of maintenance material inventory management. The first problem is to determine and implement the basic principles of maintenance material inventory management. The reason why the inventory management principle is the primary problem is that it has the following two functions: first, the inventory of various maintenance materials can be compared and approved according to the inventory management principle, so that the inventory of various materials can be controlled at an appropriate level; The second is to provide a management benchmark for controlling the maintenance material inventory in the future. Inventory exceeding the inventory benchmark will be regarded as unqualified management behavior, which is restrained by the company's management system.
2 factors affecting the inventory of maintenance materials
2. 1 There are obvious differences between maintainable materials and productive materials. In our company, maintainable materials can usually be divided into four categories: standard parts, non-standard parts, large tools and equipment, maintenance materials and replacement parts. Of course, it can also be divided into production and maintenance materials, engineering materials and management consumables (such as labor insurance supplies and office supplies). Different types of maintenance materials have different procurement methods, uses, consumption characteristics and management requirements, and the procurement difficulty and ordering cycle are also different. These factors will affect the evaluation of inventory, and it is very important to keep the inventory of various materials to meet the requirements of safe inventory and economic inventory at the same time, which will be affected by understanding and concepts. As far as the management practice of our company is concerned, there are two cognitive tendencies, which are not conducive to objectively and reasonably analyzing the influencing factors of inventory. One tendency is that more spare parts need to be prepared in order to ensure production safety. This tendency mainly considers the safety of production, because compared with the loss caused by not having this spare part when needed, the funds occupied by storing one or two more spare parts are negligible. When this practical and reasonable opinion becomes a consensus, the inventory of maintenance materials will increase year by year, and the economic reserve will be damaged; Because we lack the means to verify the actual usage and purchase of maintenance materials in practical work, we can't find out in time that the actual inventory has far exceeded the reserves needed for safe production. At present, the backlog of spare parts next to the machine belongs to this situation. Another tendency is to think that maintenance materials are in the form of objects, even if there are many, they will still be there and will be used all the time. For example, some high-consumption, low-value maintenance materials, labor insurance supplies, spare parts, tools, etc., often keep a large inventory because of this understanding. If we consider the capital operation and cost efficiency of the company, we will find that this understanding is not enough. First, it will occupy part of the working capital; Second, long-term storage of materials will reduce their applicability, and problems such as outdated quality, damage caused by improper storage, and inability to use after adjustment of production technology will objectively cause unnecessary waste of these materials.
2.2. Other factors affecting the inventory of maintenance materials
2.2. 1 procurement mode and procurement difficulty
We are located in the mountainous area of western Sichuan, with inconvenient transportation and purchasing conditions. Therefore, from the perspective of transportation costs and the workload of procurement business, the procurement of some materials is regarded as a normal business behavior. In fact, the rationality of batch is related to consumption and consumption rhythm (frequency); In the case of clear consumption and consumption rhythm, due to the certainty of procurement cycle, the rationality and time advance of batch can be judged in advance.
2.2.2 Influence of production load
Most of our production processes are stable. Generally speaking, the production load is relatively stable. Even if there is an unstable state, it is mainly affected by market changes rather than internal management problems. It can be said that the production load mainly affects the replacement parts and materials that are consumed periodically.
2.2.3 The use and consumption characteristics of materials are the key factors affecting inventory management.
Spare parts for maintenance tasks are the materials with the largest variety and inventory among maintenance materials, and the management requirements for such materials are to meet the needs of maintenance work plan. Generally, maintenance plans can be divided into planned maintenance plans, annual maintenance plans, zero maintenance plans and other types. Therefore, in addition to the spare parts used in the zero maintenance plan, the spare parts used in the planned maintenance and annual maintenance plan can be given a consumption schedule according to the annual maintenance plan, and the procurement of spare parts can be organized according to this consumption schedule, which is a matter needing attention in the inventory evaluation of such spare parts. The procurement of engineering materials has its specific project schedule, and its inventory can be arranged accurately in advance. There is an important relationship between large tooling materials and production rhythm, which is generally clear, so the inventory can be properly estimated according to the annual overall production plan; Experience may play a key role in tooling that may need to be considered in advance due to product adjustment, but the types and quantities of such materials are few after all. For Panzhihua Iron and Steel Company, the reserve of rollers is restricted by the variety and low output of some products. At present, it is mainly centralized bulk procurement, and the general procurement cycle is about half a year. As long as the procurement progress is determined, the inventory can be reduced appropriately. Of course, it is necessary to consider the characteristics of special rail beam technology, with many product specifications, and some products are produced in small batches for comprehensive judgment. As for the consumption of labor insurance supplies and office supplies, most of them are stable consumption, as long as the inventory can meet the needs.
2.2.4 Non-standard parts inventory
From the characteristics of standard parts and non-standard parts, the main difference lies in the different relationship between these two types of materials and equipment. Standard parts have a one-to-many relationship, and non-standard parts have a one-to-one relationship. For standard parts, because they can usually be used in multiple processes or the same equipment, the total installed capacity and the maintenance characteristics of different process equipment are the main factors affecting inventory evaluation. Non-standard parts are only related to specific processes or equipment, so it is easy to determine the inventory, but it also makes the non-standard parts present a huge inventory problem as a whole. The key to reducing inventory is to find interchangeable and replaceable relationships for these non-standard parts. This work is often difficult, mainly because the establishment of interchangeable and replaceable relationships requires both certain technical literacy and meticulous and professional organization.
2.2.5 Imported maintenance materials
Inventory management imported maintenance materials, due to the limitation of order cycle, it is difficult to make emergency procurement arrangements, so a certain amount of safety inventory is generally used to ensure the needs of production and maintenance. However, it is not completely limited by the order cycle. The alternative is cooperation between peer enterprises, which requires efforts to establish a cooperative relationship of spare parts to maintain a low inventory. The cooperation between external companies such as Pangang, Pangang and Xichang Preparatory Group and the company headquarters is the foundation and convenience.
2.2.6. Inventory management of important and uncertain maintenance materials.
For some important and uncertain maintenance materials, inventory should be reserved on the premise of ensuring production safety, but due to its importance, there should be no inventory control requirements. In order to control the inventory, it is necessary to conduct a comprehensive study on the production maintenance cycle and production rhythm, try to determine a relatively safe inventory control level, and take the inventory level as the basis of inventory control.
2.3 Management level and management methods of repairable materials
The factors affecting the inventory level of maintenance materials are very complicated. Considering only a single influence will often make inventory management unreasonable, which needs to be corrected according to specific conditions, such as the technical status of process equipment, the cyclical characteristics of production, the importance of maintenance materials and other factors. I won't go into details here. Perhaps another problem that must be considered is the influence of the management level and method of maintenance materials on inventory. This influence can be large or small, such as the degree of refined management, the management mode of material consumption cost control, and the introduction of modern management technologies and methods. Generally speaking, enterprises with a high degree of refined management can effectively curb the problem of low hit rate of demand planning and effectively reduce inventory because of accurate control of quantity and funds. Using modern management means is also an effective means to reduce inventory, that is, writing off inventory data, incoming data, outgoing data and actual consumption data in real time through information means will also promote inventory compression and improve demand planning rate.
3 maintenance materials inventory control management model
Here, according to the results of equipment management consulting activities carried out by our company in recent two years, we will put forward some views on inventory control management of maintenance materials, with the aim of improving our understanding of inventory control management methods on the basis of reform results.
3. 1 The company determines four inventory control management methods.
At present, the inventory control management determined by the company is divided into four ways according to the material category and actual management needs: quota control, reasonable inventory control, on-demand purchase control and expense consumption control. Quota control: for materials with basically stable consumption frequency and little influence by production load, purchasing conditions and maintenance, set consumption quota and reserve quota, implement quota management, keep the inventory quota to meet the needs of production operation and maintenance, and make the inventory conform to the principle of saving. Reasonable inventory control: For materials whose inventory is greatly affected by production load, maintenance demand and purchasing conditions, reasonable inventory methods should be adopted for inventory control and management. The inventory of this part of materials shows the characteristics of dynamic change with the changes of production load, maintenance demand and purchasing conditions, and the inventory should be controlled according to the concept of reasonable inventory. The analysis of reasonable reserve level can be carried out by establishing a computerized analysis model. On-demand procurement control: For materials (such as grates) that are easily affected by the production cycle and need to be used in large quantities at one time, the quantity and time of purchasing in advance should be determined, and the inventory quantity including reserve time should be approved accordingly. Cost control: For materials that cannot be controlled by the first three methods, cost control can be adopted, that is, the annual consumption quota of this part of materials is determined, and the inventory of materials is controlled through cost accounting. In practical application, the annual inventory consumption budget should be made according to the secondary factories and mines.
3.2. Determine the inventory control methods of various materials according to the classification of materials.
Generally speaking, materials can be divided into three categories according to their importance: A, B and C, and the inventory control methods of each category of materials are as follows: Class A materials refer to materials that will have a direct or significant impact on production, safety and environment when needed. According to the actual situation of important materials and large tools, the list of materials that need quota control, reasonable inventory control and on-demand procurement control can be listed respectively. Its initial consumption quota, reserve quota and reasonable reserve level are formulated by the material planning management personnel of each equipment department; Materials purchased on demand shall be formulated by the Equipment Department and the production unit. Class B materials: refers to the materials that will not have a significant or direct impact on production, safety and environment when needed, or materials that can be met with substitute spare parts. Among them, common parts (standard parts) and materials with large consumption (including spare parts with large consumption in non-standard parts) should be controlled reasonably; Non-standard parts with small usage or spare parts with small installation should be subject to quota control and management. The initial consumption quota and reserve quota shall be formulated by the secondary factories and mines and submitted to the Equipment Department for approval; Reasonable reserves are proposed by the equipment departments of factories and mines and the warehousing and distribution center, and submitted to the equipment department for approval. Class C materials: refer to materials other than Class A and B, in which standard parts with large usage should be controlled and managed reasonably, non-standard parts and materials with small usage should be controlled and managed, and spare parts for non-production (maintenance) can be controlled and managed according to actual conditions. The reasonable storage of Class C materials can be proposed by the warehousing and distribution center and submitted to the Equipment Department for approval.
3.3 Importance of establishing inventory control benchmark
After evaluating the inventory control according to the above principles and methods, the obtained inventory control data will be used as the benchmark for inventory management of maintenance materials, published in the standard way of the company, and included in the relevant management departments or secondary units as the annual assessment content of the company. Because this benchmark is influenced by many factors and may change, it is necessary to organize a benchmark examination and approval every year to adjust the benchmark to adapt to the changed market, production and maintenance tasks.
4 conclusion
Maintainability materials mainly serve production maintenance and tooling replacement, and are essential material support for the normal operation of enterprise production. How to ensure the production of qualified products with the minimum cost and equipment capital occupation, and pursue the maximum asset benefit is an important goal of maintenance material management. What kind of materials need to be reserved for production and maintenance, how much to reserve, and how to manage inventory, procurement and consumption are the main contents of enterprise maintenance materials management. Inventory control and management of maintenance materials are the core and foundation.