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FAQ Alignment
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Shaft Alignment |
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How accurate should rotating equipment be aligned?
This depends very much on the type of equipment and the speed it is running with. In general
rotating equipment has to be aligned within ±0,05mm for the parallel offset and within 0,05 mm
over the full coupling diameter. It is very important that accuracy is not mixed up with the
target alignment. For example: A diesel engine will grow parallel 0,2 mm over a generator
during operation. The target alignment should then be -0,2 mm ± 0,05mm
The coupling manufacturer indicates that his coupling can take more than
2 mm misalignment. What does this mean for the accuracy of the alignment?
Nearly nothing!! First of all it depends very much on the type of coupling which is used.
Some couplings can take parallel offset easier then angular offsets or vice versa.
A coupling in general is designed to transmit power and to allow for misaligned during start
up. Most couplings are designed to "absorb" loads due to misalignment but still there will
be forces going into the machinery and these will cause damages to seals, bearings
and other parts.
Over which distance can we align rotating equipment?
In general we can measure up to 15 meters distance
Is a Shaft system able to measure soft foot?
Yes, all Shaft systems have a software program to measure soft foot.
Do you always have to use a laser alignment system?
In most cases a laser alignment system can be used for performing an accurate and fast
alignment. However we must not forget that a laser alignment system is a tool and not a
magic box. An alignment engineer still has to use his brains and creativeness in order to
solve alignment problems. We choose the tool for each specific problem and situation and
sometimes we go back to use dial indicators. Sometimes there is from a practical point
of view no possibility to use a laser alignment system.
Will a laser alignment system be able to measure if we only can rotate the shafts
over an angle smaller then 180 degree?
It is always the most accurate to rotate the laser alignment system over 180 degrees. However,
in some situation this is physically impossible. Modern systems like our Shaft systems are able
to measure over an angle of minimum 60 degrees.
Do we need to align cardan-shafts?
The traditional cardan shafts (without hemokinetic device) need to be aligned with a zero angle.
An angular error results in a non linear movement which causes vibrations and extreme forces in
mainly bearings, couplings and seals.
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Geometric Alignment |
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How accurate is measuring with a geometric laser system?
The accuracy of a measurement with a laser system is depending on a number of factors
and influences like:
- The accuracy of the laser and it's detectors. Nowadays systems can measure up to 0,001mm;
- The type of measurement. A line bore measurement of a diesel engine will have an accuracy
of ± 0,005 m /pocket and the measurement of the rollers in a typical paper mill will be better
then ± 0,05 mm/roll;
- External Influences like temperature, moving air, dust, vibrations and distances can and
will negatively influence the accuracy. Very important is always that the alignment engineer
gives his opinion on how much the measurement is influenced by these external influences.
What is the difference between a geometric laser system and a traditional
optical instrument like a theodolite?
To select the most suitable measurement technique depends very much on the type of applications
you have. But there a few considerations:
- A laser system is for most applications more accurate. A theodolite can measure within
± 0,1 mm and a laser system can go even up to ± 0,001 mm;
- A laser system is more suitable for mechanical engineers;
- A laser system is for a number of applications much faster in taking the measurement and
interpreting the outcome;
- With a laser system it is possible to measure and to align the machinery simultaneously;
- A laser system requires less maintenance;
- Although Machine Support is recognised as the laser alignment specialist we also
sometimes use the latest 3D theodolites.
What kind of measurements can be done with a geometric laser system?
Typical measurements are: straightness, flatness, perpendicularity, parallelity and line bore.
What kind of measurements can not be done with a geometric laser system?
Although geometric laser systems are nowadays very versatile they have there limitations:
- They are not able to measure distance in an absolute way like the distance
between two machine parts;
- They are only able to measure 2D, otherwise we will use a 3D theodolite.
What about measuring when the machine is in operation?
This depends very much on the application but we are able to measure thermal growth when for
example a machine train is operation but we have our difficulties measuring the parallelity
of rolls when the paper mill is producing.
Over what distances is it possible to measure with a geometric laser system?
In general It starts with a few centimetres and it ends around 100 meters. It also
depends on the measurement procedure which is followed.
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