Maintenance and Reliability

Every company, whatever stage of development it is in, sooner or later turns its attention to the relationship between its maintenance services and the level of reliability that this process represents. The maintenance function in a plant, although very necessary, is unfortunately, in cost terms, an additional expense for which the customer will not pay. It is a loss.

When discussing the level of reliability of a machine park, and its maintenance costs, whether variable or fixed, one cannot rely solely on a financial definition.

Why are reliability and maintenance important?

Maintenance involves resolving problems before and after they arise. Equipment needed for production is kept in optimal working order through maintenance. Nonetheless, reliability covers aspects of machines and equipment work output over time and interactions with environmental factors. Reliability seeks to establish a more comprehensive strategy that deals with the underlying causes of machine failure. Maintaining system capability while keeping costs under control is the goal of maintenance and reliability in just about any business with mechanical equipment.

The analysis of the reliability process requires a much more complex interpretation and analysis that will answer the question of whether the maintenance process, which is in principle a loss for added value to the company, can ultimately reduce the cost of manufacturing a product, by providing a stable and repeatable level of service that simply becomes cheaper.

This topic is always topical and, in the current geopolitical situation of the world, where many companies are affected by, higher energy and material costs, more expensive supply chains, and higher labor costs, is even more relevant. We will discuss this topic in a matter-of-fact manner and offer several solutions which can make your maintenance service a model for other departments in your company.

Maintenance Strategy

Maintenance, as a department and a key function in the plant, must have a strategy. 
What is a strategy in maintenance? What types are there? Which one should we choose for our company?
A strategy for maintenance is nothing more than how we will manage each department, what the objectives will be in the short, medium, and long term, and how to measure performance. You only manage what you can measure - this old principle is key here. 
In practice, companies use one of three maintenance strategies: 

1. Reactive or breakdown
2. preventive or predictive
3. a mixed solution

Breakdown (or Reactive) Maintenance Method

The first of these, often referred to as breakdown maintenance, is the oldest of the techniques and is rarely used on a larger scale. We can only talk about its cost-effectiveness if we have the luxury of having many of the same machines that can be replaced in the event of a breakdown. This is possible when our production process remains unchanged and stable and we do not have to keep an eye on storage costs and we have the possibility to produce for stock where the stock will last much longer than the potential removal of this failure. 
A breakdown or reactive strategy will not work when our production is governed by the Just In Time principle, when the customer base and product portfolio is large and changes frequently. Here, any delay generates huge logistical and financial problems. Failure to execute a production plan on time means that an order is not fulfilled and further orders are delayed. This is a double whammy: the customer who is affected by the delay may turn away from us, and our entire production plan will be postponed. This is the perfect recipe for getting bogged down in firefighting for days or even weeks. 

Preventive and Predictive Strategies

Preventive and predictive strategies were subsequently developed to meet the expectations of production companies. 

Preventive Strategy

The preventive strategy is a major step forward in maintenance systems and in improving the reliability of equipment.

It is a simple maintenance doctrine based on specific maintenance intervals. For example, after a certain duration of the production process, production tonnage has been reached, or number of cycles have been completed, etc., we stop our equipment and subject it to maintenance.
This requires companies to have a clear maintenance plan for the machines in the factory. It is mandatory to divide equipment according to its level of criticality and have a clear calendar set in advance for major shutdowns with the planning and production department. In the end, we are all playing to one goal and plans must be precisely set with the ultimate goal of fulfilling customer orders successfully.

In a perfect world, when we are not creating any added value and the costs of the spare parts warehouse are not a priority for us, we have the time to agree with the planning and production departments to complete maintenance activities. Here, the level of reliability will increase commensurate with the maintenance costs. The more time and effort we spend on prevention (ensuring higher reliability), the more it will cost us as a company.

However, a preventive strategy is not a bad investment for companies, rather it should be associated with profit in the long term. In this case, the costs will always be much higher at the beginning, as we have to acquire the right number of spare parts, optimize the production plan to ensure that the maintenance services can stop the machines, and sometimes sign service contracts for work that goes beyond the knowledge of our personnel. It will ensure stable and predictable operation, and this is the basis for operational excellence, to which most companies are constantly striving to win against the competition.

What is Reliability-Centered Maintenance (RCM)?

A methodology of preventative maintenance is reliability-centered maintenance (RCM). RCM aims to fulfill user requirements in the framework of a business's current equipment operating environment. Some of the benefits include

• less equipment uptime
• increase in cost-effectiveness 

The idea of the RCM method is based on the rules contained in the so-called seven RCM questions:

1. What are the functions of the technical object (functions)? 
2. How can an object lose its ability to perform certain functions (functional failures)?    
3. What causes each functional damage (damage symptoms)?
4. What happens when damage occurs (damage consequences)?    
5. What are the consequences of each damage (consequences of damage)?   
6. What should be done to anticipate damage and eliminate it in advance or minimize its consequences (preventive actions and frequency)?   
7. What should be done if appropriate preventive actions are not selected?

Work scheduling using this method is characterized by a smaller number of tasks than those developed using classic methods, leaving only those tasks that are necessary and give the greatest maintenance efficiency to the maintenance staff. Its aim is rationality, which is to justify the execution of maintenance activities.

Predictive Maintenance Strategy

The last of the maintenance strategies is the predictive strategy, a strategy based on mathematical and statistical calculations. They are the driving force behind maintenance activities and based on extensive analyses, we can even analyze the technical condition of the equipment in a continuous manner, predict its reliability (useful life), and plan its repairs in advance. Here, we try to prevent a breakdown situation from occurring and react in advance to its first symptoms.

To speak of a fully implemented predictive strategy, as a company, we need to make substantial investments. We are investing in modern technologies: 

• thermal imaging
• ultrasound
• Tribology
• and wide-ranging information technologies for online data collection from our equipment

Furthermore, we need to create an appropriate base for collecting and analyzing these data and fully develop the skills of our maintenance staff who must be able to use these technologies in a conscious manner.

There is no doubt that this strategy will work in modern factories, as well as in those that, despite many years of operation, have very complex and therefore expensive machinery. A machinery park without redundant equipment or one that requires costly repairs if its equipment breaks down - for example, several meters of connecting rod systems in presses with automatic lubrication and temperature measurement - provides a cheaper solution by having continuous online monitoring of the key performance parameters of these components rather than having them repaired over a long and costly period. A machinery park in which we do not have replacement equipment, and in which the equipment we own is of a complex design or technology, is a very failure-sensitive environment. Here, every stoppage means losses and costs running into hundreds of thousands of dollars if failure occurs.

So, what can we do to ensure high availability of the machinery (reliability) and keep our manufacturing costs under control?
The best solution is a hybrid approach that incorporates elements of all the strategies above. This approach should also include the role of an experienced maintenance manager. It is incumbent upon them to perform an in-depth analysis of the current state of the machinery. 

The analysis should include:

• the number of identical pieces of equipment
• criticality for the customer, i.e., for production (can the process be transferred to other lines in the event of a breakdown?)
• current technical condition of the equipment, its age, signed service contracts, level of know-how of local maintenance services, etc.
• availability of spare parts
• historical data on downtimes and failures

Having a factual analysis can guide us in the choice of a particular strategy, and not another, for a group of machines in the fleet. This means that to be successful in the field of maintenance reliability and to maintain reasonable costs in the company, some machines will be covered by a reactive maintenance strategy, as their potential failures will not jeopardize the realization of our production plan and will have very little impact on our costs.

A preventive strategy will cover our key machines, which still have occasional breakdowns but are costly and time-consuming. In this case, we will "blow the cold", based on the principle that it is better to do something extra and more expensive (replace a component with a new one, even if its condition may not yet require it, rather than wait for it to fail), but it will be more efficient, ultimately increasing our level of reliability.

The last predictive strategy, whose main task is to anticipate potential failures and dysfunctions of our equipment, is a step further than the preventive strategy. It assumes that we 'know' about a failure before it occurs. With this strategy, we will always have a safety buffer in the form of time to plan a repair or overhaul. It will not force us to keep large quantities of expensive spare parts in stock, allowing us to plan the downtime needed for the repair at a convenient time for production and other departments. Often, we will be able to combine the repair with planned downtime. An additional benefit of this strategy is the capacity building of our maintenance department, where, with each analysis performed, the technical awareness of our associates will increase.

How do you build the perfect hybrid of all these strategies? How do you analyze the machinery and the level of competence of the maintenance department before selecting it? What should be considered when choosing the criteria for this analysis?

Such questions are certainly not easy to answer, which is why Performance Solutions by Milliken Practitioners are here to help you with their expert, empirically acquired knowledge, as many have managed maintenance and engineering departments in the past. It is worthwhile to make use of such knowledge condensed in one place and to learn from ''others'' rather than your own mistakes.

We have been building on our unique approach to maintenance management since 1996, within the framework of our MPS philosophy (Milliken Performance System), whereby reliable maintenance is one of the pillars of our group's success and development. We have many successes and international awards in this field, and we are happy to share this knowledge with you.