MAIN MAINTENANCE FUNCTIONS IN THE CEMENT INDUSTRY
The maintenance task produces a wide variety of activities that will be carried out and those activities will require a group of relationships between the rest of the company’s functions, to be interconnected. The graph below shows a general aspect of the relationships that are required for the maintenance function to perform efficiently and effectively.
Explaining approximately the graph, it can be seen that the maintenance has been divided into:
Maintenance function, which represents with it the management part and the integrating part of it; maintenance process where the execution of tasks is carried out and the part of the equipment is repaired; maintenance engineering where all existing and potential techniques are executed to improve and develop maintenance; and outsourcing corresponding to the acquisition of human and technical resources to perform some maintenance tasks.
The management and maintenance portion is responsible for maintaining and improving relations with the rest of the organization of the company: the operations that represent the management part of the production function must maintain a close relationship with maintenance through the maintenance program that coordinates the availability of the equipment: production represents the execution of operations and is related to maintenance through availability and maintenance cost.
The plant manager, who represents the highest management position in the plant, grants maintenance objectives and resources to achieve these objectives.
Maintenance is highly related to the investment processes required by market conditions to keep the plant running. Specifically, participation in the maintenance of new projects and the acquisition of new or additional equipment is a matter of great importance for the success of the company.
Purchasing and human resources are two important providers of resources for maintenance. They must be in close contact to detect the need and even the possible need for maintenance to keep it at the forefront of technology and learning new technologies.
The entire maintenance function must be evaluated and measured in order to make appropriate improvements. This function is usually represented by administrative control where finance plays a fundamental role.
This graph below shows a synthetic approach to the main relationships that define the availability of the equipment. This availability is based on two separate blocks: a) reliability based on machine design and measured as MTBF; and b) maintainability based on the ability of the maintenance functions to decrease the measurement of repair time as MTTR. Both reliability and maintainability rest in the block called operative, which represents the total production cost.
The second graph shows the MTBF and MTTR relationships and an approximate definition of availability stands out from these relationships.
MEAN TIME BETWEEN FAILURES (MTBF)
Here these are statistics that can be represented mathematically by probabilities. This statistical behavior of machines creates complications to availability computing. Some additional specific techniques and programs are required to calculate the times.
The maintenance within the plants has undergone some changes in recent years and at present, the highly competitive market and the melting wave are forcing managers to act quickly and soon.
The 5 stages of maintenance
The objective of our maintenance is to increase the availability of the plant. To achieve this objective, we can classify the maintenance history in 5 stages that successively increase the availability of the plant:
The 5 stages in detail
As you can see here, the approach, attitude, problem solving, maintenance data and the use of maintenance resources are compared. The tendency is to make optimal use of resources (minimum waste) and increase plant availability as much as possible according to the stage at which each plant works.
5 Maintenance levels
This maintenance classification helps you understand how maintenance managers and staff face these activities.
- Regressive: where maintenance focuses on meeting the budget and taking a passive attitude. This level is useful when a company is deteriorating its business or is no longer interested in staying in it.
- Reactive: the approach is “fix after failure”. No measures are taken until the machine fails. This level is useful when there are machines that can make backup copies of those that work or when the importance of no working conditions is irrelevant to the company’s results. It can also be used when an emergency condition appears.
- Planned: Here some initial actions are taken to be prepared, intervene the machine when it fails or perform some activities that allow the moment of stopping. Every certain interval the machine is intervened or checked. Some initial preventive and predictive actions and concepts are taken within this level.
- Proactive: the motto here is “not only fix it, improve it”. The idea is to obtain as much of the machine’s availability as possible. Deep technical knowledge is required at this level and several advanced research tools such as RCA can be used.
- Strategic: this level aims to carry out maintenance activities within an integrated environment so that the results are economically optimal for the company. This level requires a culture focused on profits and should be understood throughout the company to maintain this integration and avoid the so-called “agent effect”, whose effect is to maximize the function of each company despite maximizing the profits or results of the company .
Evolution of the Maintenance Strategy
EFFECTS ON MAINTENANCE COSTS
This figure shows the effect over time of different maintenance strategies on direct maintenance costs.
What is expected to occur is an increase in the cost of the bow-wave during the initial implementation of the new techniques and methods. This is because investment is required to introduce the required equipment and personal training and the time required to carry out the entire change process.
The graph also shows that after this bow-wave passes, the slope in the decrease of the direct cost of the new technologies is greater than the slope produced by the maintenance techniques in use before implementation. The bow-wave is a real limitation: additional background. In a restrictive economy they are not easy to obtain.
There is also the risk of interpreting that the way forward is to implement each stage and time level for each team. In fact, this is not the truth. A careful study from the point of view of the criticality of production can give a sequence and a priority to carry out the implementation. Each stage and level can and will be present in each plant according to the need for real maintenance availability for each machine/equipment. We must be prepared to live with a combination of levels and stages of maintenance. The key element is the benefit of the company, without the application of the latest technique per se.
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