Preventive Replacement: a Main Preventive Maintenance Strategy

 

 

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Preventive Replacement is Economically More Interesting Than a Corrective Repair

By keeping equipment and machinery safe and reliable, regular maintenance ensures long-term profitability and competitiveness for an organization. Nowadays, the role of maintenance reaches far beyond simply keeping assets in a good condition. Scheduled, predictive, and highly effective, maintenance is at the core of smart manufacturing. Advanced maintenance became a pre-condition for a company’s access to industry 4.0 and as such demands the involvement of all departments.

We, at Mobility Work, believe that a properly carried-out maintenance starts with good communication and data input into a user-friendly solution. Our next-gen CMMS helps you to eliminate inadequate maintenance actions that can lead to accidents, excessive costs and production downtimes.

 

Preventive Maintenance

The main objective of preventive maintenance is to ensure the rebuild, repair or replacement of a piece of equipment before its expected failure point defined by the manufacturer or expected life statistics. Preventive interventions are regularly performed on specific schedules. Preventive maintenance includes various actions (as equipment checks, oil changes, lubrication, etc.) aiming at improving the availability and reliability of an asset by reducing the overall rate of occurrence of system failures.

 

Replace or Repair: When Should a Component Be Replaced Preventively?

There are some predefined candidate assets for which replacement is better than repair as for example certain critical assets, assets subject to fatigue and wear-out failure and those with a high utilization index. For all the rest, whether a preventive replacement is appropriate or not and the best time to proceed with it should be precisely determined. There are two basic requirements that should be fulfilled in favor of preventive replacement vs. corrective repair:

1. The condition of the component, respectively all important measurements as operating time, dimensional control, thickness measurements, clogging index, thermography, oil analysis and vibratory analysis should get worse over time (increasing failure rate). Thanks to the Mobility Work CMMS, all this data can be continuously stored, tracked and analyzed. The team will get immediately notified as soon as the critical threshold has been reached.

2. The preventive replacement (CP) should cost less than a possible corrective (unplanned) maintenance action (CU).

 

If these both conditions are met, then the optimum preventive replacement time for the component can be computed and the total cost can be represented. According to the “strategy T” a component or a piece of equipment needs a corrective action if it fails before time t and a preventive action if it does not fail by time t. The total cost will be the sum of the corrective replacement costs that will increase as time increases and the preventive replacement costs that will decrease as the time interval increases. This means that the less often you perform preventive maintenance, the higher your corrective costs will be. The longer you wait to perform a preventive maintenance intervention, the less important the corrective maintenance costs will be. Nevertheless, if you plan preventive maintenance interventions too often, your costs will increase too. It is only by combining relevant data that an optimum replacement time interval can be calculated and a balance between the associated costs and risks can be found.

 

Computing the Optimum Replacement Time

● CPUT is the Cost Per Unit Time;
● R(t) is the reliability of the component at time t;
● t is the optimum preventive replacement time for the component.

 

 

There are a couple of other factors that can be considered as well when choosing between preventive and corrective maintenance actions. If a component is a brand new, still under warranty and it shows signs of defects, a replacement is definitely the best decision. Depending on the cost and the availability of the component, a comparison with the labor cost is crucial when making decisions to repair or replace. Sometimes a component that keeps braking after several repairs and obviously needs to be replaced can be a good reason to upgrade to more recent technology.

Most of the maintenance professionals agree that preventively replacing a component or a piece of equipment is economically more interesting than waiting for the moment it breaks and replacing it. Some of the evident benefits of preventive replacement include optimization, cost efficiencies and reduced accident risks.

 

Preventive Replacement Model Based on Age

This type of preventive model, where the age of each part is known and the part is changed as soon as it has reached the defined age is widely used in industrial manufacturing.

The lifetime of a component spans three important stages:

1. Decreasing failure rate (DFR) or the early stage of an asset;
2. Constant failure rate (CFR) or the useful stage of an asset;
3. Increasing failure rate (IFR) or the wear-out stage of an asset, known as well as the most critical or deteriorate condition which increases the frequency of failures.

Preventive replacement occurs always in the third stage of component’s lifetime and its main objective is to reduce maintenance cost and production losses. It is obvious that if not preventively replaced a component in a deteriorating condition will lead to a critical unexpected machine downtime.

Next-gen CMMS and 1st maintenance social network helps you optimize your preventive maintenance schedule. The solution delivers most accurate data analytics, spare parts management information and connects all organization’s departments. Mobility Work supports you in critical decision-makings by providing you with 360-degree insights into your assets condition.

 

Direct Benefits of Preventive Maintenance for Your Business

● Preventive maintenance is more cost-efficient compared to corrective maintenance, especially in the long term;
● Preventive Maintenance reduces unscheduled equipment breakdowns and thus optimizes production time;
● Preventive Maintenance enhances system service life and equipment reliability;
● Preventive Maintenance improves spare parts inventory management.

 

If a spare part has an increasing failure rate, replacing it preventively under certain circumstances is much more cost efficient than replacing it when it fails (correctively). The challenge is to determine whether an expensive replacement is the best possible decision and if so, to identify the optimum replacement time based on the optimum age replacement model, mentioned before.

Mobility Work stores all sensors collected data, equipment readings and intervention history to evaluate the deterioration rate of a certain asset when necessary. The precise data analytics additionally support the established preventive maintenance program by minimizing the overall costs and meeting the desired reliability objective.

 

 

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