
Mittwoch 19.12.2018 







AeroLas GmbH
Grimmerweg 6
D82008 Unterhaching
Tel.: +49 8966 60 890
Fax: +49 8966 60 8955
info@aerolas.de




AeroLas´ competence for exact calculations 

Undoubtedly, air bearings have outstanding features in many applications. Rarely, however, and because of a wrong or inadequate interpretation, an air bearing’s potential is completely made use of. Way too often, air bearings are assessed as unsuitable even though there would have been developed a superior system with a right calculation.
At AeroLas, we make use of our own simulation software, especially developed for the calculation of air bearings. This software has been developed based on exact, theoretical physical models. Thus, we are able to solve problems which would have not been solved otherwise with previous formulas and calculations.
Calculation opportunities at AeroLas tremendously increase the trustiness and quickness of developments for our customers. No matter whether our team should simulate single air bearings or complete drive systems: our simulations already offer a perfect image of the given circumstances. By doing so, we have been able to solve
our customer’s problems with conventional air bearings within a short time period.
In the following, we show you AeroLas’ calculation competence by means of some examples:


    air pressure characteristics in the gap of a flat air bearing     Theoretical modeling
When calculating the air bearing behaviors, we simulate the fluid flow within the gap and micro nozzles. As a result we get the pressure characteristics within the gap. Given this pressure, we are able to calculate all static properties. At AeroLas we do not use any parameters – as commonly made use of for air bearings. Thus, the result we get relies, indeed, only on descriptions of given physical effects and a clear imagination of the real circumstances in the later application.


    air pressure characteristics in the gap of a tilted flat air bearing ring     Tilt Stiffness
For many applications, the tilt stiffness of an air bearing or a complete guidance is fundamental. For this, our simulations offer exact mathematical values. When comparing the air bearing technology of AeroLas with conventional air bearings, our air bearings only produce their air cushion where it is forceful necessary.


    air pressure characteristics of a moved flat air bearing     Speed
Moved air bearings are tilting due to the aerodynamic effects within the gap. Depending on the tilt stiffness, an air bearing’s force capacity decreases with an increasing velocity until it reaches a limit at which it totally fails. Air bearings with the technology of AeroLas have a velocity limit which can reach, depending on the customizing, dozens of m/s. However, for air bearings with chambers and variable canal structures, an velocity only of a few m/s is already harmful.


    characteristics of an air bearing (red: real body; blue: inelastic body)     Deformation
Usually, the mechanical stiffness of an air bearing’s body is overestimated in comparison to the stiffness of the air cushion. The diagram shows the characteristics of an flat air bearing unit (height 20 mm, diameter 80 mm) in comparison to the theoretical characteristics of an inelastic bearing body with the same geometry. Based on such simulations, we determine both the material of the air bearing as well as the distribution and number of micro nozzles such that it is perfectly adjusted to deformation.


    structural analysis (finite element calculation)     The deformation of an air bearing’s surface due to the force of the cushion is calculated on the basis of a structural analysis, calculated with Pro/MECHANICA. The result obtained becomes a geometric parameter for the calculation of an air bearing’s simulation. With an iterative process, each point on the characteristics can be calculated. In doing so, we obtain an exact calculation of the deformation and air pressure profile.


    air pressure characteristcs in the gap of a loaded spindle     Spindles and cylindrical air bearings
AeroLas’ simulation software also allows calculations of symmetric, rotating systems. We are able to calculate load, stiffness, tilt stiffness, and air consumption of a complete spindle guidance, both at a standstill and highest rotary speed (including dynamic effects). With this method, we are able to give a prediction about the maximum rotary speed and natural frequencies. This is an indispensable requirement for a perfect spindle.
With this calculation technique, we also optimize cylindrical air bearings’ stiffness and air consumption on manufacturing tolerances.


    air pressure characteristics in the gap of a spherical air bearing     Spherical air bearings
AeroLas has a particular software for the calculation of spherical air bearings.


    comparison between calculation (red) and measurement (blue)     Accuracy
Many times, the calculation models have been validated by measurements. Typically, results and reality match by 5% of the load and 10 % of the stiffness. Deviations do not result from incorrect calculations but only because of the condition of an air bearing’s surface (form deviation, roughness, etc.).



