5 industrial predictive maintenance technologies that improve your machines and plants

Industrial predictive maintenance technologies improve the performance of rotating machines and can be applied from the mechanical point of view as in the case of:

• Vibration analysis.
• Line-up.
• Balancing of machines.
• Lubricant analysis.
• Thermography.

Having defined these industrial predictive maintenance technologies, let's look at each of them in detail and find out how they can help you improve your machines and facilities.

1. Vibration Analysis

Most machine failures, regardless of whether the failure is mechanical or electrical in nature, generate vibration at a specific frequency. This vibration can correspond to faults such as misalignment, cavitation, belt defects or loose belts, foundation or base looseness, bearing damage, gear damage and many other defects.

Just as a doctor examines his patients, this is how the vibration specialist should present himself to the machine when its condition worsens. The first symptoms are manifested in excessive vibration characteristic values, which are recorded by condition monitoring. With powerful analysers and suitable methods, the cause of the high characteristic values can be effectively detected and the problem can be solved in time.

A vibration analysis programme allows a machine and its components to be inspected, through the study and calculation of frequencies in the vibration spectra, without the need to stop or dismantle it. This analysis helps to detect all these problems before failures occur.

Keep in mind that each component vibrates in a different way and generates characteristic signals, leaving a typical trace in the spectrum in the form of a line pattern. If there is a deterioration, the pattern shows it from variation in the characteristic signals. This technology allows you to detect whether it is, for example, an imbalance, alignment failure or bearing damage. In addition to an accurate diagnosis, you can generally also specify whether you need to act quickly or can wait until the next scheduled overhaul.

2. Alignment

The second of the industrial predictive maintenance technologies is alignment, which is the process by which the shaft centreline of a piece of machinery, e.g. an engine, is matched to the extension of the shaft centreline of another machine coupled to it, e.g. a pump.

Rotating shafts must be aligned to achieve optimum machine performance. Misalignment occurs when the centres of rotation of two (or more) shafts are not collinear with each other.

The aim of shaft alignment is:

• Increasing the availability of the rotating machine, allowing components to reach the end of their service life: bearings, seals, couplings, shafts.
• Extend machine availability and increase MTBF.
• Reduce long-term operation and maintenance costs. The rotating machine alignment technologies cut energy costs by up to 10%.
• Protecting assets, increasing product quality and reducing vibrations.

Alignment aims to position the machines so that these deviations are within certain tolerance values.

You can recognise a misalignment when you observe:

• Excessive radial and axial vibration.
• Premature failure of bearings, seals, shafts and couplings.
• Oil leakage at bearing seals.
• High temperatures in bearings and couplings.
• Cracked or fractured shafts.
• Loose screws in the base of the machine.
• Increase in energy consumption, which avoids the energy savings on rotating machines using alignment technologies.

¿How to integrate machine alignment systems into the plant's technical culture? Conventional measurement methods have too low a resolution for the adjustment of modern machines. Ruler/gauge alignment methods depend on the limited resolution of the human eye. The resulting resolution of 1/10 mm, for most machines, is inadequate.

Dial gauges are another form of alignment, typically with a resolution of 1/100 mm, but the calculations tend to be complicated, require experienced users, and take a long time to complete. These methods are prone to human error when reading dial indicator values or calculating alignment status.

The most accurate method of achieving perfect shaft alignment is the one that uses laser alignment equipment for predictive maintenanceThis has great advantages over the conventional method of alignment with dial gauges in terms of ease, speed, accuracy, precision and flexibility, as the measurement can be taken with the coupling installed and the interpretation or reading errors that normally occurred when measurements were taken with dial gauges are completely eliminated.

3. Machine balancing

Balancing, the third of the industrial predictive maintenance technologies, defines the determination and compensation of an imbalance, i.e. the centring of the masses of a rotating body so that the axis of rotation coincides with the axis of inertia, thus achieving concentric rotation.

Every day, machines and equipment are built faster, lighter and more powerful; if they are not correctly balanced, they present centrifugal forces and moments and cause vibrations that can loosen screws, nuts and rivets, as well as cause pressure on bearings, bushings and bearings, often leading to their breakage due to material fatigue. Vibrations also cause annoying and disturbing noises in the working environment.

The faster the machines are, the more precise the balancing must be, as the centrifugal forces increase in proportion to the square of the speed; balancing is especially necessary to avoid problems when passing through the resonance zone of parts and elements that make up the machine, such as the machine anchorage, housings, guards, clamps, etc.

Unbalances cause much of the damage in rotating machines. They are frequently found in coolers, fans, pulleys or couplings. The enormous centrifugal forces of the uneven mass distribution generate high vibrations during rotation that affect the entire machine construction. As a result, bearings, seals and couplings wear out prematurely or even fail completely.

Within the vibration spectrum it is easy to detect an imbalance, since it vibrates in synchronisation with the shaft speed. Its energy is concentrated in the first harmonic spectral line. This can be remedied by balancing the rotor in the mounted state, so-called in-situ balancing, with a mobile balancing instrument.

The balancing instruments from manufacturers are perfectly tuned to detect an unbalance and eliminate it in a few steps. Whether unbalance vibration is acceptable or not depends basically on whether its values are within the quality tolerances set in the standards for the characteristics and speeds of the rotor in question.

Keeping the imbalance within tolerances will allow you to:

• Avoid fatigue failure of structures and elements associated with the rotating element.
• Increase the service life of the machine.
• Energy saving.
• Prevent excessive bearing loads due to overloading.

4. Lubricant analysis

Lubricant analysis techniques are the fourth of the industrial predictive maintenance technologies and are essential for determining lubricant deterioration, contaminant ingress and the presence of wear particles.

These are implemented on an ad hoc basis:

• Routine AnalysisThey apply to equipment considered as critical or of high capacity, in which a sampling frequency is defined, the main objective of the analysis being the determination of the state of the oil, level of wear and contamination, among others.
• Emergency AnalysisThese are carried out to detect any anomaly in the equipment and/or Lubricant, according to: 1) Water contamination, 2) Solids (defective filters and seals), 3) Use of an unsuitable lubricant.

Workshop equipment for oil analysis is now available that allows the setting up of a mini laboratory for rapid oil analysis in the industrial plant, which allows:

• Obtain immediate results on analysis.
• Reduce the cost of analysis per sample.

This, among the industrial predictive maintenance technologies, ensures that we will have:

• Maximum reduction of operating costs.
• Maximum component life with minimum wear.
• Maximum utilisation of the lubricant used.
• Minimal effluent generation.

In each sample we can obtain or study the following factors that affect the machines:

• Wear elements: Iron, Chromium, Molybdenum, Aluminium, Copper, Tin, Lead.
• Particle counting: Determination of cleanliness, ferrography.
• Contaminants: Silicon, Sodium, Water, Fuel, Soot, Oxidation, Nitration, Sulphates, Nitrates.
• Lubricant additives and conditions: Magnesium, Calcium, Zinc, Phosphorus, Boron, Sulphur, Viscosity.
• Historical: For the assessment of trends over time.

5. Thermographs

Thermal imaging cameras for predictive maintenance inspections are powerful, non-invasive tools for monitoring and diagnosing the condition of electrical and mechanical components and installations. With a thermal imaging camera, you can identify problems at an early stage, so they can be documented and corrected before they become more serious and costly to repair.

This is the fifth of the industrial predictive maintenance technologies:

• They are as easy to use as a camcorder or digital camera.
• They provide a complete picture of the situation.
• They allow inspections to be carried out while the systems are loaded.
• They identify and find the problem.
• They measure temperatures.
• They store information.
• They indicate exactly what needs to be corrected.
• They help to find faults before real problems occur.
• They save valuable time and money.

Thermal imaging with accurate temperature data provides the maintenance manager with important information about the condition of the equipment being inspected. These inspections can be carried out while the production process is in full operation and, in many cases, the use of a thermal imaging camera can even help to optimise the production process itself.

Thermal imaging cameras are such a valuable and versatile tool that it is impossible to list all possible applications. New and innovative ways of using the technology are being developed every day. In many industries, mechanical systems are the backbone of all operations.

Thermal data collected with a thermal imaging camera can be a very valuable source of complementary information for vibration studies and monitoring of mechanical equipment.

Mechanical systems overheat if there are misalignments at certain points in the system. Conveyor belts are a good example. If a roller is worn, it will show up clearly on the thermal image, indicating that it needs to be replaced.

When mechanical components wear out and become less efficient, they tend to dissipate more heat. As a result, faulty equipment or systems quickly become hotter before they break down.

By regularly comparing readings from a thermal imaging camera with the temperature profile of a machine under normal operating conditions, it is possible to detect a large number of different faults.

Other mechanical systems that are monitored with thermal imaging cameras are connections, transmissions, bearings, pumps, compressors, belts, turbines and conveyor belts.

Examples of mechanical failures that can be detected by thermography:

• Lubrication problems.
• Alignment errors.
• Overheated engines.
• Suspicious rollers.
• Pumps overloaded.
• Overheated engine shafts.
• Hot bearings.

These and other problems can be detected at an early stage using a thermal imaging camera. This will help to prevent costly damage and ensure continuity of production.

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