importancia de la alineación del eje en bombas
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8/3/2019 Importancia de la alineacin del eje en bombas
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Premature shaft and coupling
failure.
Excessive seal lubricant
leakage.
Failure of coupling and
foundationbolts.
Increasedvibration and noise.
Shaft MisalignmentShaft misalignment is responsible
for as much as 50 percent of all
costs related to rotating machinery
breakdowns. Accurately aligning
shafts can prevent a large number
of machinery breakdowns and
reduce much of the unplanned
downtime that results in a loss of
production. In todays challengingenvironment of reducing costs and
optimizing assets, the necessity of
accurate shaft alignment has never
been greater.
Correct AlignmentMachines need to be aligned in
both the horizontal and vertical
planes. Misalignment can bedue to
parallel or angular misalignment, or
a combination of both.
Basically, there are two types of
misalignment: parallel (or offset)
misalignment and angular
misalignment.
With parallel misalignment, the
center lines of both shafts run
parallel to oneanother, but theyare
offset. With angular misalignment,
the shafts run at an angle to one
other.
Types of Shaft
MisalignmentParallel misalignment can be
further subcategorized as either
horizontal or vertical misalignment.
Correctly aligned shaft
A major part of keeping equipment
running smoothly involves regularmaintenance and upkeep and
ensuring that the machinery is kept
lubricated and properly aligned.
When shafts or belts on rotating
equipment are misaligned, the risk
of costly, unplanned machine
downtimerises dramatically.
Misalignment also damages sealsand couplings. Lubrication
problems often can be traced to
seals that have been compromised
by shaft or belt misalignment.
Simply replacing a seal will not stop
future seal failure and associated
loss of lubricant only correcting
the misalignment will solve the
problem.
Failure to align the shafts or beltsproperly will increase theamount of
stress on the units, resulting in a
range of potential problems that
ultimately can seriously impact a
companys bottomline:
Increased friction, resulting in
excessive wear, excessive
energy consumption, and the
possibility of premature
breakdown of equipment.
Excessive wear onbearings and
seals, leading to premature
failure.
by Dead Cat
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The straightedge is positioned ontwo bearings supporting one or
moreshafts, while themaintenance
inspector visually assesses
whether or not the components are
properly aligned. While such rough
alignment methods have the
advantage of being quick and
relatively easy, they are also highly
inaccurate and do not produce the
exacting degree of accuracy
required by today's precisionmachinery.
Dial indicators represent anothertraditional method of measuring
misalignment. But while dial
indicators do offer a higher degree
of accuracy, they also present
certain problems. Not only do they
require a high level of technical skill
to be used properly, but the effort is
also generally quite time-
consuming.
Furthermore, dial indicators do notprovide real-time values that
enable technicians to
simultaneously measure and attain
correct alignment.
Horizontal misalignment refers to
misalignment of the shafts in the
horizontal plane, while vertical
misalignment refers to
misalignment of the shafts in the
vertical plane. Parallel horizontalmisalignment results when the
motor shaft is moved horizontally
awayfromthe pump shaft, but both
shafts still operate in the same
horizontal plane and parallel.
Parallel vertical misalignment
occurs when the motor shaft is
moved vertically away from the
pump shaft, but both shafts still
operate in the same vertical plane
and parallel.
Similarly, angular misalignment can
be further subcategorized as either
horizontal or vertical misalignment.
Angular horizontal misalignment
occurs when the motor shaft is at
an angle with the pump shaft, but
both shafts still operate in the same
horizontal plane. Angular vertical
misalignment occurs when the
motor shaft is at an angle with the
pump shaft, but both shafts still
operate in the same vertical plane.
Serious instances of misalignment
can occur as a result of parallel
misalignment, angular
misalignment, or a combination of
thetwo.
Correcting Shaft
AlignmentTradit ional al ignment methods
still in common use today include
visual inspection combined with a
straightedge or ruler.
THE IMPORTANCE OF SHAFT ALIGNMENT
Overview of shaft alignment options -- (from left to right) straightedge, dial indicators, and
laser shaft.
by Dead Cat
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THE IMPORTANCE OF SHAFT ALIGNMENT
Shaft alignment laser-guided tools
typically consist of two units, each
capable of emitting a precise laser
beam and detecting a laser beam
from its mate, plus a handheld
control device.
The units securely mount to shafts
via magnetic brackets and/or amagnetic chain. To run them, the
operator activates the instrument
via thehandheld control device and
each unit emits a precise laser line
projected onto the other units
detector.
A display on the handheld device
provides real-time coupling and
feet values during the alignment
process, avoiding the need toremove and reinstall the measuring
units after each alignment
adjustment.
In addition, the laser system tool
documents the values, which can
be downloaded to a computer and
used as a benchmark for future
alignment inspections. More
advanced laser-alignment systems
come with a built-in step-by-step
alignment process, from
preparation, inspection andevaluation through correction,
reporting and analysis. Some
models also offer a unique
database to store data regarding
visual inspectionsonoil leakage, oil
level, foundation bolt status, and
wear indications.
Laser-alignment methods represent
a marked improvement over
traditional methods. A laser-drivenshaft alignment device allows one
to adjust alignment with far more
speed and accuracy than either the
straightedge or dial method.
Instead, the dial indicators must be
removed and then reinstalled after
each alignment adjustment is
completed. As a result, the process
for obtaining critical measurements,
such as feet values and coupling
values, can belengthy. Feet values
indicate whether the pedestal or
footing on which the machine restsis loose or compromised in some
other way. Coupling values attest to
the integrity of a coupling
connecting two shafts.
Laser -gu ided tools, generally
speaking, are quick, accurate,
easy-to-use, and require only a
single installation. In addition, they
deliver consistently better accuracy
than dial indicators and they do notrequire special skills to obtain
accurate results virtually every
time.
Overview of shaft alignment options -- (from left to right) straightedge, dial indicators, and laser shaft
by Dead Cat
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THE IMPORTANCE OF SHAFT ALIGNMENT
Belt or Pulley
AlignmentBelt alignment or pulley alignment
is also an important maintenance
task and, when carried out
correctly, can prevent unplannedshutdowns and achieve
considerable cost savings.
Because belt alignment depends
on the correct alignment of the
pulleys on which the belt operates,
belt and pulley alignment are
generally considered one process.
Belt alignment involves aligning the
belts in a manner that results in the
least wear on the belts and lowestenergy loss for the machine or
driver unit. In practice this means
the grooves of the pulleys are in
linewith one another.
Consequences of Belt
MisalignmentLike shaft misalignment, belt
misalignment can result in a wide
range of detrimental and
sometimes dangerousconsequences, including:
Reduced efficiency of the
machine.
Increased wear on pulleys and
belts.
Increasedfriction.
Excessive energy consumption.
Increased noise and vibration
and Premature bearing and belt
failure
Types of misalignment
Measuring prallel and angular misalignment using a straightedge or a piece of string.
by Dead Cat
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THE IMPORTANCE OF SHAFT ALIGNMENT
Vertical angle or twisted
misalignment occurs when one of
the pulleys has an angular error
from the vertical angle plane. This
is usually caused by incorrect
positioning of the machine and canbe corrected by lifting either the
front or rear feet of the motor to
which the pulley is attached,
depending on the direction of the
vertical angle error. This differs
from shaft alignment in that one
never moves both feet in a vertical
direction to reach the desired
result.
Horizontal angle misal ignmentoccurs when the driver and the
driven unit are not positioned
parallel to each other. Incorrect
positioning of applications, such as
the motor, typically can cause this
type of misalignment. Horizontal
angle misalignment generally can
be corrected by moving the front or
rear feet forward or backward on
their guides, depending on thedirection of the horizontal angle
error, in order to twist the motor
around its center.
Parallel misalignment is the least
complex form of misalignment. It is
often caused by the incorrect
positioning of the motor along its
shaft axis, positioned either too far
forward or backward compared to
the other shaft. Or it can be causedby incorrect positioning of the
pulleys on their respective shaft,
where one of the pulleys needs to
beadjusted on the shaft.
Belt Alignment Methods
Belt alignment can be performed
by either traditional visual methods
or the laser method. Traditional
methods usually employ strings
and/or straightedges. Lasermethods utilize a laser beam,
which provides for a much higher
degree of accuracy. The main
advantage of these traditional
methods is the limited length of
time needed for adjustment,
although the use of a straightedge
takes more time than visual
assessment alone. The major
disadvantage is the lack of
accuracy. For example, some beltmanufacturers recommend a
maximum misalignment of 0.5
degrees or even 0.25 degrees,
which is difficult to accomplish by
using visual assessment. These
traditional low-tech methods
involve a good deal of trial and
error, naked eye approximation,
and rough estimates. All told, that
means a large margin for error,which is unacceptable for precision
pulley alignment.
A laser belt alignment system
enables one to adjust alignment
with far more speed and accuracy
than with traditional methods.
Systems available on the market
can be categorized according to
the way the devices are attached to
the pulley and the way they align.Generally, there are two groups,
one that aligns the face of the
pulleys and one that aligns the
grooves of thepulleys.
Unless the misalignment is
corrected, a new replacement belt
will likely wear out quickly.
Continuous operation in a
misaligned state also will increase
wear on the pulleys themselves, aswell as their axles, shafts and
bearings.
Maintaining belts in proper
alignment is just as important as
aligning shafts. For that reason,
laser-guided belt aligning devices
are an essential part of an up-to-
date maintenance operators tool
kit.
Belt alignment laser-guided tools
consist of two components, a laser
emitting unit and a 3-D receiver.
The tool uses V-guides along with
powerful magnets that quickly
attach in the pulley groove to
facilitate alignment of pulleys even
if they have unequal widths or
dissimilar faces.
Nature of
MisalignmentAs with shaft misalignment, there
are various types of belt
misalignment. In practice, a
combination of different
misalignments is oftenencountered
simultaneously. For thisreason, it is
important that an alignment
instrument both diagnoses and
details the nature of the machine's
misalignment. The following
illustrations depict the three
different typesof belt misalignment.
by Dead Cat
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Bearings out of square with their
housings are another common
cause of misalignment. Often a
condition of wear, the out-of-square
bearing and/or its housing will need
to becorrected or replaced in orderto bring machines back into
alignment.
Maintaining Correct
AlignmentOnce misalignment is detected,
analyzed and corrected, an
ongoing alignment maintenance
program is important to keep
operations running smoothly. Aspart of this maintenance, alignment
checks should be performed to
document alignment conditions
before a machine is removed from
service. This gives users the ability
to install new or rebuilt machines
with the same proper alignment
values. In addition, a maintenance
program should include periodic
checks to verify conditions are still
within tolerance.
Taking these simple steps to
detect, correct and maintain proper
shaft and belt alignment can
prevent costly, unplanned
downtime. Fortunately, there is a
range of modern laser-alignment
options available to make this
processeasier than ever before.
Mark Ely is currently based inHolland as a product marketing
manager at SKF Maintenance
Products. He is a Marine Engineer
graduate and served in cruise ships
for a few years, where he quicklylearned the real world, hands-on
side of engineering. With nearly 25
years of service within SKF, Mr. Ely
has extensive experience in
maintenance applications and shaft
alignment, as well as product
development and product
marketing. Mr. Ely can be reached
at mark.ely@skf.com.
Karl Vietsch has worked for theSKF Condition Monitoring Centre,
Livingston, for almost three years.
During this time, Mr. Vietsch has
served as a Business Engineer
(BSc), and provided alignment
support service by telephone. In his
role as a project manager for
gearbox repair, he called SKF to do
the alignment job for a gearbox that
he and his team had repaired. Karlhas significant mechanical hands-
on experience and has strived to
make the lives of the alignment
engineer and management easier.
The result of his efforts is the
development of the SKF TKSA 60
and TKSA 80 shaft alignment
systems. Reach Mr. Vietsch at
Karl.Vietsch@skf.com.
Most products on the market use
the face or side of the pulley as a
reference for aligning the pulleys
and belts. The advantage of this
method is that it can be used for
belt types other than V-belts, suchas timing belts. V-belts, however,
comprise themajority of belts found
on the market, especially in
industrial applications. The main
disadvantage is that the face of the
pulley is the only reference point.
This means that only the faces of
the pulleys are aligned with each
other. This method results in
varying degrees of accuracy when
the pulleys are of differentthickness, brands or kinds(e.g. one
single-belt pulley and one multiple-
belt pulley) or when the faces are
not well finished.
Products that align using the
grooves of the pulleys in which the
belt runs tend to provide
substantially higher levels of
accuracy regardless of thethickness, brand or type of pulleys.
Soft FootSoft foot is a condition in which
one of the feet of a machine does
not sit flat on the baseplate. Soft
foot is among the most common
causes of misalignment.
Accordingly, one of the first steps to
take in an alignment check is to
assess the equipments foundationand employ a suitable shaft
alignment tool to identify and
correct potential soft foot
conditions.
THE IMPORTANCE OF SHAFT ALIGNMENT
by Dead Cat
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