Industrial automation systems: innovation moves away from bearings

In this article we will talk about how, in industrial automation systems, innovation passes from bearings (ceramic bearings, super-concrete bearings...).

Industrial automation is a discipline that, using mechanical, electronic and IT technologies for the control of production processes, allows to manage energy, material and information flows in order to obtain an efficient production process.

Leaving aside the electronic and IT aspects of industrial automation, in this article we focus on mechanical technologies and in particular on the influence that the choice of bearings can have on the ability to control production processes.

Of course, the definition of "efficient production process" depends on the type of automation and the field of application; the efficiency of a baggage conveyor belt at an airport cannot, in fact, be measured or evaluated in the same way asassessing the efficiency of a pick and place machine for electronic cards.

In any case, however, you can list some fundamental aspects of an automation:

1. Automation operation repeatability (i.e. with the same process input) outputs are constant over the life of the automation system or between two maintenance operations
2. Reduction in maintenance frequency and durability
3. Maximizing the energy performance of the system
4. Maximizing automation system performance

Let's look at these 4 aspects in more detail.

1. The repeatability of the automation operation.

Suppose you have to move an object from point A to point B. The automation system design could provide that an electric motor which controls the movement will allow the desired displacement to be obtained with a rotation of N rpm. Under ideal conditions the behavior of the automation system will always be the same; in reality there are multiple factors that will divert the system from the ideal behavior such as, for example, bearing games, wear of belts or chains, wear of joints, deterioration of engine functions, etc. This means that with the same input (number of engine rotations) the final position of theobject, i.e. the output, will not be B but around B with consequent potential negative effects: need for corrections, increase in the time it takes to complete the operation, increased power consumption, etc. Ultimately, effectiveness (understood as the ability to reach position B) remains unchanged but efficiency may decrease dramatically. Adopting components that maintain their efficiency for as long as possible is a good design and maintenance standard.

2. Reduction in maintenance frequency and durability

Maintenance operations stop the system and, therefore, affect total production capacity. For this reason it is important to reduce the frequency and duration of maintenance. This can be achieved by a careful choice of the various components of the automation system, balancing any increase in the costs of these components with increased productivity.

3. Maximizing the energy performance of the system

The energy performance of any mechanical system is measured by evaluating how much energy needs to be spent to achieve the desired operation. The higher the yield, the lower the energy expenditure. Since the main component of energy dispersion in a mechanical system is friction, adopting low friction solutions generally allows to increase the efficiency of the system.

4. Maximizing automation system performance

Normally, automation systems are implemented to increase productivity. It is clear, therefore, that reducing the time it takes the system to complete its operations is a primary objective of the design. Of course, it is not possible to define rules that can apply in any system since the objectives, modes and structure of automation systems can be very different depending on the scope. In any case, the reduction of time can be achieved by increasing the speeds (rotation, linear displacement, etc.) whereas, however, it can give rise to negative effects such as excessive vibration (noise and reduction of precision), increased wear of mechanical components with increased frequency of maintenance operations, increased temperature of components with possible faster deterioration of their functionality, etc.

Let's see now why ceramic bearings can be a valid response to the needs of the automation systems described above.

1. The repeatability of the automation operation

One feature of bearings that can affect repeatability is play.

Choosing the optimal game means finding a balance between conflicting needs and effects. Simplifying and excluding extreme situations, we can say that as the game increases, in general, the life of the bearing increases, internal friction, wear and temperature of the bearing as well as the deterioration of the lubricant are reduced. In the same way, however, the rigidity of the system is also reduced and this can lead to a reduction in accuracy and, therefore, repeatability. On the contrary, reducing the play of the bearing results in an increase in friction torque, wear and bearing temperature; the lubricant is used more with its faster deterioration. However, it gains the rigidity of the system and therefore the precision and repeatability of the automation operation.

Ceramic bearings have a lower friction torque for the same play than steel bearings. In addition, under the same conditions, they have lower wear as well as being less sensitive to temperature increases and lubrication conditions. This means that ceramic bearings can maintain their characteristics and operate optimally for much longer times than steel bearings.

2. Reduction in maintenance frequency and durability

Bearing maintenance operations are necessary when they lose their functions due to excessive wear or tear. In addition, it may be necessary to stop the system or machine to restore the correct lubrication conditions.

The ceramic bearings, thanks to the characteristics of the materials that compose them, have less wear than the steel bearings, thus lengthening the life of the bearing itself. In addition, they require less stringent lubrication conditions both in terms of lubricant type and quantity (under certain conditions they can work even in the absence of lubrication) thus allowing to avoid stops for relubrication or to reduce their frequency.

It should also not be forgotten that are not favourable operating conditions for steel bearings such as corrosive environments (presence of acids or bases) or that may cause oxidation (e.g. sanitization operations in the food sector) or environments with high temperatures (e.g. furnaces) or environments in which bearings may be subject to electrical discharges or magnetic fields (e.g. welding equipment or medical equipment). In all these situations steel bearings require frequent maintenance. Ceramic bearings, on the other hand, can withstand very effectively in these environments by drastically reducing the frequency of maintenance operations.

3. Maximizing the energy performance of the system

Frictional losses occurring inside a bearing lower the energy performance of the system in which the bearing is inserted. In addition to this, friction losses turn into an increase in bearing temperature with possible negative effects on the life of the bearing itself.

The friction torque of a bearing has the following elements:

• friction coefficient of the material with which the bearing is made
• bearing game
• track geometry
• type of bearing
• type of gaskets
• type and quantity of lubricant

Thanks to the characteristics of ceramic materials and the optimization of track geometry for these materials, ceramic bearings have a lower friction torque than steel bearings. In addition, requiring a smaller amount of lubricant, the component of the corresponding friction torque is lower than that of steel bearings. Theother seals of the ceramic bearings are made in such a way as to minimize, if not cancel, the creeping of the gasket on the rings by considerably reducing or cancelling the relative friction torque.

Ultimately, ceramic bearings have lower friction pairs than steel bearings, resulting in an increase in the system's energy performance.

4. Maximizing automation system performance

The tendency today in automation systems is to increase speed as much as possible in order to increase productivity. Sometimes this extremely fast research comes up against some structural problems that can affect the end result. Some problems may be caused by the onset of vibrations or deformations caused by the increase in inertia forces. Other problems can be caused by increased stresses on the bearings resulting in a reduction in the life of the bearing itself.

In these situations, ceramic bearings can help to overcome system limits thanks to reduced weights (reduction from 30% to 70% of weight depending on the type of ceramic material). The low weight of ceramic bearings allows not only to reduce moving masses with beneficial effects on vibrations and stresses on the structure of the plant or machine, but also to reduce the stresses inside the bearing allowing to achieve higher rotational speeds.

Follow the advice of our bearing experts to find the solution that best suits the specificities of your machines.