Reliable operation of fans and blowers is often critical to
production or process operations.Here, Phil Burge,marketing
manager at SKF, looks at how the uptime of such equipment
can be increased through integrated bearing, seal and
lubrication technologies

It is essential that fans and blowers can
withstand demanding environments,
while providing high performance, often
at their limit, and low cost operation. The
typical high rotational speeds equate to high
operating temperatures and as fans are often
used to evacuate hot gases, these temperatures
can range from 100 to 600°C. Naturally, some
of this heat is transferred to the systems’
components via radiation and conduction in
the fan shaft, in particular bearings.

Operating under such high temperatures can
lead to bearing failure, causing unplanned
stops and production losses.

In addition, high operating temperatures
can have a negative impact on
bearing lubrication, reducing
the service life of the base oil.

Degradation of lubricate
results in increased friction in
the bearings, increasing the
risk of potential bearing
failure still further. Indeed,
more than a third of all
premature bearing failures
are caused by lubrication
problems.

Despite these factors, the
maintenance of industrial
fans and blowers is
frequently neglected,
leading to inefficient
operation, faster wear, greater
energy consumption and, potentially,
unexpected failure.Maintenance is often an
area that is delayed until absolutely essential;
however, it cannot be delayed forever and
one option is to consider upgrading fans and
blowers, to improve their performance and
functionality and to extend maintenance
intervals.

An effective upgrade typically includes
higher specification bearings and seals;
combined with an improved self-lubricating
system and, depending on the nature of the
production operation, condition monitoring
devices so that future maintenance can be
accurately predicted.

Some manufacturers have developed a
complete solution for upgrading industrial
fans and blowers, making it possible to
standardise the procedure. For example, SKF
has devised an upgrade to reduce operating
temperatures by utilising optimised bearings
and housings and a new circulating oil
lubrication system, resulting in increased
reliability, extended service life, lower
maintenance costs and reduced
environmental effects.

A complete industrial fan upgrade typically
starts with a functional analysis of the
equipment to evaluate problems and identify
how an upgrade should be carried out. This
will determine which parts are most suited
to the application, allowing an engineer to
specify the necessary components to improve
performance. These could include a new
circulating oil lubrication system to reduce
operating temperatures and the need for
maintenance, a self-aligning bearing system
that generates less friction, and specially
designed housings, which are optimised for
use with circulating oil lubrication. A
condition monitoring system may be
recommended to warn of bearing failure.

As the bearing system in industrial fans has
to accommodate shaft deflections and thermal
expansion of the shaft, a self-aligning bearing
system is often used, eliminating the
problem of axial displacement, reducing the
cost of operating industrial fans and resulting
in more consistent and efficient rotation.

SKF’s bearing system has an SKF Explorer
spherical roller bearing in the locating
position and a CARB toroidal roller bearing
in the non-locating position. The CARB
bearing is a self-aligning radial bearing with
an inner ring that moves independently of
the outer ring, similar to a cylindrical roller
bearing. This lets the system accommodate
shaft elongation within the bearing without
inducing internal axial loads, resulting in less
friction and lower operating temperatures. It
operates with reduced vibration and noise
and enables safer, more efficient designs.This
leads to extended relubrication intervals and
extended bearing service life.

Alongside the self-aligning bearing system,
a range of sealing and lubricating solutions
can be used to further increase system
performance and reliability. Lubrication is an
essential part of preventative maintenance,
providing cool, clean oil for each bearing to
help reduce operating temperatures. It can
be handled in different ways, to suit the
application, including manual grease
lubrication and centralised grease
lubrication. It can also include automated
lubrication systems, which ensures bearings
are correctly lubricated at all times, without
the need for manual checking and
application procedures.

To ensure optimum performance of
industrial fans over extended service lives,
condition monitoring and predictive
maintenance can also be used. One such
system is SKF’s Copperhead which enables
early detection of unbalance, mechanical
looseness, bearing faults or high
temperatures. This allows remedial action to
be taken promptly before performance is
degraded. Furthermore, handheld analysers
are available for simple analysis and reporting.

It is vital that industrial fans and blowers
consistently perform to the highest standards.

Introduction of this new generation of total
fan solutions can optimise performance,
increase reliability, reduce maintenance and
extend service life.