A grease gun is a common workshop and garage tool used for
lubrication. The purpose of the grease gun is to apply lubricant
through an aperture to a specific point, usually on a grease
fitting or 'nipple'. The channels behind the grease nipple lead to
where the lubrication is needed. The aperture may be of a type that
fits closely with a receiving aperture on any number of mechanical
devices. The close fitting of the apertures ensures that lubricant
is applied only where needed. There are three types of grease
gun:1.Hand-powered, where the grease is forced from the aperture by
back-pressure built up by hand cranking the trigger mechanism of
the gun, which applies pressure to a spring mechanism behind the
lubricant, thus forcing grease through the aperture.2.Hand-powered,
where there is no trigger mechanism, and the grease is forced
through the aperture by the back-pressure built up by pushing on
the butt of the grease gun, which slides a piston through the body
of the tool, pumping grease out of the aperture.3.Air-powered
(pneumatic), where compressed air is directed to the gun by hoses,
the air pressure serving to force the grease through the aperture.
Russell Gray, inventor of the air-powered grease gun, founded Graco
based on this invention.[citation needed]The grease gun is charged
or loaded with any of the various types of lubricants, but usually
a thicker heavier type of grease is used.It was a close resemblance
to contemporary hand-powered grease guns that gave the nickname to
the World War II-era M3 submachine gun.
While anatomy is commonly associated with biology and medicine,
this article does not include the study of the human body. However,
the typical illustrative methods used for detailed examination and
analysis of bodily features have always been an effective learning
tool in the classroom. The anatomy lessons within Machinery
Lubrication will apply these same methods for various topics within
our industry.In this issue, the grease gun will be dissected to
uncover all of its component characteristics. In addition, several
other related topics will be discussed, such as common grease gun
disorders, symptoms of incorrect greasing volume or frequency and
best practices for using a grease gun.Types of Grease Guns
Types of Grease GunsIts fundamental that grease is used as a
lubricant because it clings to a machines moving surfaces without
easily leaking away like oil. For this reason, the filling and
refilling of grease in grease-lubricated machines must be treated
differently than that of oil-lubricated machines. Therefore, it is
essential that the proper grease gun operation is understood and
managed by lubrication technicians for bearing and machine
reliability. Simply knowing the signs of overgreasing and
undergreasing and how often to reapply can go a long way in
extending machinery life.Connectors, Adapters and Couplers
A grease gun may come with the standard connection adapter such
as a hydraulic coupler, but there are several variations depending
on the application. The standard hydraulic coupler is the most
commonly used and most applicable. A 90-degree adapter is ideal for
fittings in confined areas that require a 90-degree bend. A
needle-end adapter provides a thin, precise amount of grease for
tight places, while a three-jaw swivel coupler offers a variety of
locking positions for different applications.Flexible Hose vs.
Fixed TubeThe decision to use a flexible hose or a fixed tube
depends on the machines grease-fitting type and ease of location,
as well as the type of grease gun used. For example, a
hard-to-reach location would benefit from a flexible tube. On the
other hand, lever-style grease guns require both hands to pump the
grease and would favor the fixed-tube alternative.AccessoriesGrease
gun meters can be retrofitted onto a grease gun to help optimize
lubricant consumption. Plastic caps provide benefits such as
preventing corrosion and debris. They also can be color-coded so
that cross-contamination does not occur. Other accessories such as
sonic/ultrasonic devices are also available.Grease Fittings
Grease fittings have several names such as a Zerk fitting,
grease nipple or Alemite fitting. This is the lubrication point
where the grease connector is attached. The standard hydraulic
grease fitting is most commonly used for standard applications. It
can be either upright or angled. The button-head fitting is ideal
for good coupler engagement when large volumes of grease are being
added. A flush-type grease fitting is preferred when space is
limited for standard protruding fittings, while the pressure-relief
vent fitting helps prevent higher pressures that could lead to
damaged seals.Machine Health Risks Associated with Grease GunsHigh
Grease Gun PressureA high-pressure manual grease gun is designed to
deliver from 2,000 to 15,000 psi. Applying too much pressure while
greasing will damage the bearing seals, which rarely handle more
than 500 psi. Symptoms of high grease gun pressure include
collapsed bearing shields, damaged bearing seals, grease driven
into electric motor windings, and safety and environmental
issues.Regreasing FrequencyManaging regreasing frequencies to
optimal conditions is necessary to avoid long-term machine health
problems. If the frequency is too long, symptoms may include
lubricant starvation, which promotes wear, friction and grease
contamination. If the frequency is too short, excessive grease
consumption and safety and environmental issues may
occur.Overgreasing and UndergreasingIt is important to know the
exact amount of grease necessary for your greasing application to
avoid overgreasing or undergreasing. Symptoms of overgreasing
include damaged seals and motor windings, environmental issues, and
fluid friction, which leads to increased heat generation, higher
grease oxidation rates and higher energy consumption. Symptoms of
undergreasing include bearing starvation, which results in friction
wear and increased contamination.How Output is MeasuredIt is common
for maintenance departments to have a wide variety of grease gun
types, makes and models. This can cause grease-related disorders
due to cross-contamination and inaccurate knowledge of each grease
guns output per stroke. Grease guns are known to vary in the amount
of grease that is output from 0.5 grams to more than 3 grams. This
inconsistency depends on factors such as the type, model and age of
the grease gun.
To overcome this problem, it is necessary to calculate the
amount of grease that is released from a grease gun per stroke. To
do this, use a calibrated scale and consistently pull 10 strokes of
grease onto the scale. Once this value is known, divide by 10.
Grease Gun Best Practices Calculate the proper amount of grease
needed for the relubrication of bearings based upon the calibrated
delivery volume of the selected grease gun. Use a vent plug on the
relief port of the bearing to help flush old grease and reduce the
risk of too much pressure on the bearing. Use extreme caution when
loading grease into the grease gun to ensure that contaminants are
not introduced. If using a cartridge, be careful when removing the
metal lid so that no metal slivers are introduced into the grease.
Make sure the grease gun is clearly marked to identify the grease
with which it should be charged. Do not use any type of grease
other than that which is identified. Always make sure the
dispensing nozzle of the grease gun is clean before using. Pump a
small amount of grease out of the dispensing nozzle and then wipe
the nozzle off with a clean rag or lint-free cloth before attaching
it to the grease fitting. Clean the grease fitting of all dirt
before attaching the grease gun. Inspect and replace damaged
fittings. It is helpful to use grease-fitting caps to keep them
clean, but still wipe fittings clean before applying grease. Ensure
that the proper grease is used at every grease point. Applying the
wrong grease can cause an incompatibility problem, which can
quickly cause bearing failure. Lubrication points should be clearly
identified as to which grease is to be used. This can be done with
colored labels, adhesive dots or paint markers. Grease guns should
be stored unpressurized in a clean, cool and dry area and in a
horizontal position to help keep the oil from bleeding out of the
grease. Grease gun clamps make storage easy and organized. Also,
cover the coupler to keep it free from dirt and contaminants.
Calibrate grease guns regularly to ensure the proper delivery
volume.
Grease Gun Best PracticesWhen lubricating equipment with a
grease gun, it is important to know precisely how much lubricant
needs to be applied per cycle and how much lubricant the grease gun
will produce per shot. Grease guns can produce between 1 gram and
1.5 grams per shot. This can result in significant overlubrication
per point unless the output is known.Grease guns are capable of
producing several thousand psi per stroke. This kind of pressure
can certainly blow out bearing seals and shields. If a careless
approach is taken when using the grease gun, then it is highly
likely that the equipment will be overpressurized and
overlubricated. When this occurs, particularly with a bearing, then
the likelihood that the bearing can see its rated lifecycle is
greatly reduced.Whether the gun is filled with oil or grease, the
practitioner should be precise with the use of the gun, beginning
with an analysis of the bearing dimensions and calculation of the
required amount of grease per cycle, followed by an analysis of the
amount of output per cycle of the gun.When working the grease gun
lever arm, never hold the nozzle onto the grease fitting. Also,
when cycling the lever arm, be conscious of the risk of
overpressurization and do not force the lever arm if there is
strong back pressure.Use the following tips to maintain your grease
guns and fittings. Wipe the fitting before use to clear debris. Use
a clean shop rag or lint-free cloth to clear debris. Inspect the
grease fitting. Replace defective or damaged fittings. Where
possible, standardize on fitting type. Conspicuously mark the
grease fitting with the type of grease being used. Avoid changes
where possible. Learn the proper grease gun operation and know the
delivery volume per shot. Have grease guns calibrated occasionally
to ensure proper volume delivery. Some grease guns develop pressure
up to 15,000 psi. Exercise caution to avoid overpacking and/or seal
damage. Keep guns clean, avoiding laying them on dirty surfaces.
Repack on a clean bench using a gun loader fitting. Keep grease
guns covered when not in use. Exercise caution to ensure safety.
Make changes such as piping out the fitting to avoid danger. When
repacking grease guns from a pressure line, wipe down the fitting
and the pressure line to prevent contamination. When repacking with
tubes, move to an environmentally controlled area, such as a
control room, to replace the tube.
Greasing with AccountabilityMost grease-lubricated bearings fail
to reach their life expectancy. This statistic is due to a number
of reasons, one of which is the manual grease route, which
unfortunately has properties similar to human beings. Man is not
faultless either as an individual or as a group and makes errors
regularly. Automatic Greasing
To date, one of the objectives of maintenance departments has
been to replace all manual greasing with automatic lubrication
systems. Automatic systems offer several advantages: Greasing with
the correct amount of lubricant significantly reduces the
consumption of grease when compared to traditional manual greasing.
Several cases have reported grease consumption was reduced by 30 to
50 percent. Not only has this been documented by various automatic
systems manufacturers, but an article in the Swedish magazine
Underhll and Driftskerhet (Maintenance and Reliability, February
2000) and a case study from VTT (Technical Research Center of
Finland) carry convincing evidence. Automatic grease lubrication
that provides reliable cycles and correct lubricant discharge may
reduce the number of bearing failures by approximately 50 percent,
which is supported by the VTT report. The automatic systems are
closed, ensuring grease is isolated from the environment when it
transfers from the lubricant reservoir to the bearings (no
contaminated zerks). Automatic lubrication that is correctly
designed, installed and maintained is reliable; therefore the
impact of the human factor is virtually eliminated. Unfortunately,
the cost of implementing the system may be a hindering issue. When
installed in process industries, automatic lubrication is costly -
roughly estimated between 380 to 760 USD (300 and 600 EUR) per
lubrication point. Current Manual Greasing
Manual greasing is a daily task performed in process industries
worldwide. It is carried out with simple tools, as a low-priority,
routine task without status. This is industrys standard practice to
date! Unfortunately, the problem with manual greasing is the
frequency of faults. Manual lubrication is performed by human
beings and humans make mistakes. Aviations View of Mistakes
In some human activities, such as aviation, mistakes cannot be
tolerated. Aviation demands specific routines and systems, which
are created to increase safety and eliminate (or minimize) the
human element where possible. Aviation has adapted to the following
conclusions: Human beings make mistakes; and mistakes cost money
and may cost lives. What are the similarities between the aviation
industry and lubricating with grease? Both are large-scale routine
activities performed daily by various people. In both activities,
mistakes result in expensive consequences ruled by natural law.
What are the differences between the aviation industry and
lubricating with grease? In the aviation industry, the potential
consequences of human mistakes are obvious, immediate and may risk
lives. In greasing, the consequences are costly and lives are very
seldom at risk when we fail to lubricate. Unfortunately, they are
not immediately obvious. Hidden Mistakes Lead to Costly
Consequences
The grease in a rotating bearing works only for a limited time
and must be replenished while the lubrication film in the bearing
is still in good condition. If the grease in a bearing is not
replenished in time, heat, oxygen in the air and mechanical
stresses will degrade the oil and adversely affect the strength of
the lubricating film. This will result in the initiation of a
bearing failure, which will reduce the life of the bearing. An
obvious problem is that one is never aware that he may have missed
lubricating a bearing. A working bearing that has not been
lubricated for more than a month can still function without
problems, and may not show any obvious symptoms of deterioration.
When the bearing finally fails, it will be filled with good grease
and no signs of a missed lubrication event will be present. Since
the bearing was missed, several successful relubrication events
have been made. Therefore, the life of the bearing was reduced and
acceptance of the shortened life becomes the norm.Being unaware of
the mistake prevents corrective actions to manual greasing from
being implemented, which leads to the following conclusions: Human
beings make mistakes, and mistakes cost money. The mistakes made by
the lubrication technician are not immediately apparent. The
mistakes unfortunately remain; otherwise a large difference would
not be evident when manual greasing is replaced by automatic, as
outlined in the VTT report. The lubricating film must remain
perfect around the clock to prevent breakdowns in the bearings. In
the past, manual greasing was inferior to automatic lubrication
when attempting to maintain uninterrupted production of a mill.
Statistics of Manual Greasing
Manual greasing is performed so often it must be looked upon as
a statistical phenomenon. At our mill, we perform approximately
100,000 grease replenishments of bearings through zerks per year.
If our team of lubrication technicians exhibit superior performance
and do not miss more than one nipple per 1,000 nipples,
statistically there will be 100 missed bearings per year. These
missed bearings are expected to cost the mill 126,000 USD (100,000
EUR) in increased maintenance costs and lost production. So, there
is definitely a problem! If the error level is decreased by a
factor of 10, the mistakes will cost 12,586 USD (10,000 EUR) per
year. Furthermore, if the level is decreased 100 times, the cost
comes down to 1,259 USD (1,000 EUR) per year, which is acceptable.
How can the error level be decreased by 100 times? Overgreasing: A
Solution or Problem?If bearings are unnecessarily greased twice as
often, some nipples can be missed without any perceived problem,
because the missed bearings will, in all probability, be greased
the next time. If one bearing per 1,000 is randomly missed, the
risk of the same bearing being missed consecutively is one in a
million. Greasing at half the optimum intervals offers a solution
to the problem of randomly missed zerks. But will equipment then be
overgreased? Overgreasing is considered to be one of the main
causes of grease-lubricated bearing failures. Greasing at half the
required interval demands a great deal of work and is bad practice.
Electronic Greasing Aids: A Better Solution?The lubrication
technician is provided with a handheld aid to use during the
greasing route that indicates how much grease each lubrication
point needs. As greasing occurs, the aid automatically reads the
lubrication point number and registers the amount of grease pumped
into the bearing. It also stores all of the data. If the lube tech
should miss one or more lubrication points, he will be alerted to
this when the greasing route data is downloaded to a computer. He
can then return and finalize the greasing route by lubricating the
missing points. Not a single lubrication point will be missed. A
professional lubrication technician using the new aid will
guarantee this! The correct procedure no longer depends on the
skills of specific individuals. It can be accomplished by
substitute lube techs, who may be standing in due to sickness or
holidays. During a greasing route, the new handheld tool will
automatically register which lubrication points have been greased,
when they were greased and the quantity they were greased with. At
the base, the computer will show which lubrication points need to
be greased to finalize the lubrication route. Guaranteed
lubrication cycles will be achieved with statistic certainty,
providing higher profit margins for the mill. The SystemThe system
that met our requirements was a radio frequency identification
(RFID)-based manual greasing system, where each lubrication point
is equipped with a special grease nipple combined with a
transponder. With a built-in antenna, the grease meter communicates
with the transponder (Figure 1).
Figure 1. Grease Nipple with Transponderand Hydraulic Coupling
with AntennaIn addition to the RFID unit and its antenna, this
system has a metering module that calculates the grease quantity
pumped into the grease nipple. The grease meter is also equipped
with intelligence and storing capacity (Figure 2).
Figure 2. The Grease MeterThe entire system is controlled by a
computer managed by lubrication technicians (Figure 3). The grease
meter is connected to the computer via a communication and loading
unit.
Figure 3. A Lubrication TechnicianControls the SystemHow Does it
Work?When its time to lubricate, the lubrication technician loads
the current grease route into the grease meter, then walks his
route and performs the necessary tasks. For each lubrication point,
the meter displays the amount of grease the bearing needs and how
much it receives. The lube tech returns to the base and connects
the grease meter to the computer. The stored information is
downloaded to the computer, and the time of the download operation
is simultaneously registered. The computer display immediately
shows the status of the lubrication points in the grease route. It
appears as a list with different colors for greased and nongreased
lubrication points. The Economic BenefitsThe economic impact of
greasing efficiently depends on three factors: 1. The number of
mistakes made by lubrication technicians. 2. The physical
consequences of missing a lubrication point. The more accurate
greasing intervals, the greater the impact will be. 3. How much
overgreasing is reduced when the correct amount of grease is
applied at optimal intervals. The first factor is difficult to
estimate and depends on the organization and its personnel. The
author estimates it to be one in 1,000, but likely more for most
mills. With the electronic aid, this could decrease by at least a
power of 100; meaning that the number of missed points will be less
than one in 100,000. The second factor is more easily estimated
because it depends only on those powers of nature which have a
degradable effect on lubricants. The author estimates it to be a
ratio of 1:3, assuming a defective lubrication film will appear in
one-third of the missed bearings. These bearings will have to
operate on the defective lubrication film until the next
lubrication route. This figure is presumably conservative. If the
current number of missed bearing is one in every 1,000, then it
would be expected that 100 would be missed in every 100,000. By
applying the electronic aid, this can be reduced from 100 to one.
From this, it is apparent that the electronic aid could prevent 99
bearings from being missed. Of these 99, it is estimated that
one-third would have premature wear resulting from the missed
relubrication event. This means that we can prevent at least 30
premature bearing breakdowns yearly by decreasing the human factor.
The improved reliability and the decreased maintenance costs can be
estimated to several hundred thousand USD per year. This will also
result in an improved environment (decreased grease consumption and
waste handling). Profits will also increase from reducing
overgreasing which SKF Reliability Systems estimates as one of the
main causes of bearing failures in this type of industry. According
to SKF, we can also save another hundred thousand USD per year from
reducing overgreasing. The investment for the whole mill amounts to
approximately 204,508 USD. The described system (LubeRight) has
been invented and developed by the Swedish company Assalub. to
Operate a Grease Gun Safely
All machinery must be lubricated to ensure smooth operation and
to maximize equipment life. From manufacturing to farming to wind
energy applications, grease guns are one of the most common ways to
achieve proper lubrication. Although use of grease guns is
widespread, these tools deserve respect and should be used in
accordance with the manufacturers safety guidelines to avoid
injury.There are four main types of grease guns on the market:
manual, battery-operated, air-powered and AC electric. Each type
has its own specific set of guidelines, but many general rules are
applicable to all, such as training, proper tool use and care, work
area safety and personal safety.Manual Grease GunsManual grease
guns include lever-action and pistol-grip models. These popular
tools are widely used and are the most economical type of grease
gun. Manual grease guns can achieve pressures up to 10,000 pounds
per square inch (psi), while plug-valve sealant guns can reach
15,000 psi.Battery-operated Grease GunsBattery-operated grease guns
are ideal for speeding up routine lubrication tasks. Using this
type of grease gun can also help to minimize operator fatigue.
These grease guns are rated anywhere from 6,000 to 10,000 psi,
depending on the model.Air-powered Grease GunsAir-powered or
pneumatic grease guns use compressed air to apply pressure to an
air piston, which drives the grease piston and forces lubricant out
of the coupler into a grease fitting. By depressing the guns
trigger, a steady flow of lubricant is dispensed. Typically,
pneumatic grease guns are rated up to 6,000 psi.AC Electric Grease
GunsAC electric or corded grease guns provide a consistent flow of
grease and are often used as an alternative to air-powered tools.
AC electric grease guns generally are rated up to 7,000
psi.TrainingEffective lubrication requires specific training,
ranging from the actual physical activity of applying the lubricant
to the effects of misapplication, including spills and damage to
machinery. The operator should be trained on each piece of
equipment to be lubricated, as well as each grease gun that will be
used to accomplish the task.
Some general rules of lubrication also should be considered,
said Alemite senior product manager Americo dos Santos. Do not
apply lubricants to a machine in operation unless the fittings are
located in a safe place. Never reach over, under, through or past
moving parts of the equipment to complete your task. You should
maintain proper footing and balance at all times to facilitate
better control of the tool in unexpected situations.Proper Tool Use
and CareWhether you are using a manual, battery-operated,
air-powered or AC electric grease gun, the high pressure developed
by the tool should be considered. High pressure can develop in
different ways. A common situation when high pressure is created
involves what is known as a frozen fitting. When a fitting is not
lubricated for an extended period of time, the grease in the line
may cake. Mineral or vegetable oil in the grease gets consumed and
leaves a waxy, soap-like base. This soap thickener is what makes
grease a semi-solid. Common soaps include calcium stearate, sodium
stearate and lithium stearate, as well as mixtures of these
components.High-pressure injection injuries may be caused by
accidental injection of grease through the skin and into the
underlying tissue. Generally, fingers or hands experience this type
of injury, which is most likely to occur when a hose ruptures.
Also, some lubrication applications require needle-type accessories
that can lead to an injury if used improperly.An injection injury
may be very small and essentially painless, and the injured person
may be tempted to continue working, explained dos Santos. However,
if you receive any type of injection injury, you should seek
medical attention immediately. The lubricant will need to be
removed and treatment initiated to prevent infection. If possible,
provide the medical technician with the brand of grease or oil
involved so that the manufacturer can be contacted regarding the
possible toxicity of the lubricant.Safety features are available
and precautions can be taken to minimize the risk involved in using
high-pressure grease guns. The key is to use the right tool for the
job. Do not improvise or change the grease gun configuration for
any purpose other than that which it was intended.It is critical
that all of the components utilized are rated for the amount of
pressure being applied, so you should use only hoses specified by
the grease gun manufacturer. For example, if your grease gun is
rated at 10,000 psi and your hose is only rated at 1,500 psi, the
situation can become hazardous very quickly.It also is essential
that you inspect the hose between the grease gun and the coupler
before each use, dos Santos stressed. If there are any signs of
wear or damage on the hose, do not use it.When a grease cartridge
is loaded into the grease gun, the follower rod should be securely
latched to the end cap so it doesnt spring back unexpectedly. Use
care when removing the pull-tab on the cartridge to prevent getting
cut by the tabs sharp edges. In addition, always aim the grease
coupler away from your body when loading and priming the grease
gun. You dont want to take any chances that grease may get into
your eyes.
Battery-operated grease guns have a few safety guidelines of
their own. For instance, the power switch should be in the off
position before inserting the battery pack. The battery pack should
always be disconnected from the grease gun before changing
accessories or unscrewing the grease cylinder from the gun. Never
attempt to open the battery pack or expose it to water.When not in
use, keep the battery pack away from metal objects such as paper
clips, coins, keys, nails, screws or other small items that can
make a connection from one terminal to another. Under abusive
conditions, liquid may escape from the battery and should be
avoided. If contact with this liquid occurs, flush with water. If
the liquid contacts your eyes, seek medical attention.When using a
battery charger, use only the charger specified by the
manufacturer. Ensure that the cord is situated so it will not be
stepped on, tripped over or otherwise subjected to stress. Do not
operate the charger with a damaged cord or plug, or if it has
received a sharp blow or been dropped. You should also refrain from
charging batteries or using any electrical (corded) grease gun in
damp areas.Other workplace practices involve operating, caring for
and servicing your grease gun, dos Santos noted. Always read and
follow the manufacturers instructions before using your grease gun.
Avoid kinking hoses, as this can weaken them and make them more
susceptible to ruptures. Be sure to label your grease gun so that
you can identify the type of grease in that particular gun. Also,
you should wipe grease fittings and the grease coupler clean before
connecting to prevent contamination.Battery-operated, air-powered
and AC electric grease guns can build extreme pressures, which may
not be evident to the user. Therefore, extra caution should be
taken with these tools. Never exceed the maximum input air pressure
on pneumatic tools. Most of these grease guns run at a 40-to-1
grease pressure to air ratio, so substantial pressure is created
with a relatively low input air pressure.Keep grease guns clean and
avoid placing them on dirty surfaces. All repairs should be
performed by a qualified technician who uses only original
replacement parts. Finally, when lubrication tasks are performed,
grease often gets on your hands, so be sure to wash them to remove
any chemical residue.Work Area Safety
Regardless of the type of grease gun you choose, it is important
to keep your work area clean and well lit. Cluttered and dark areas
invite accidents of many kinds. Oil or grease spills on floors,
catwalks and ladders can cause serious falls and fire hazards. Wipe
up lubricant spills immediately or use absorbent drying pads or
granules. Sources of lubricant leaks should be repaired to maintain
a safe environment.If you are using a power tool, make sure that
the area is free of flammable liquids, gases or dust, which may be
ignited if the tool creates a spark, dos Santos added. In addition,
power tools should not be exposed to rain or wet conditions, and
care should be taken to prevent cord damage, as this can increase
the risk of electric shock.Minimize distractions, such as
bystanders, while operating your grease gun, as they may divert
your attention from the task at hand. Never play around with or use
a grease gun for practical jokes.Personal SafetyIt is recommended
that you wear personal protective equipment including safety
glasses, gloves and non-skid shoes or boots to help prevent injury.
Refrain from wearing jewelry or loose or torn clothing that could
become caught in moving parts.Stay alert while using a grease gun.
You should never operate any tool if you are tired or impaired by
alcohol or medication, as a moment of inattention may result in
serious personal injury.By utilizing sound procedures, training and
appropriate tool use and care, you can maximize potential
bottom-line benefits received from proper grease gun lubrication
techniques while maintaining worker safety.The Dangers of
OvergreasingWhen it comes to regreasing bearings, more is not
always the better option and actually can be a costly mistake.
Instead, greasing should be set on a frequency with proper
calculations used to determine the amount of grease needed at each
relubrication. The determining factor for the amount required is
based on the dimensions of the bearing or the bearing
housing.Overgreasing can lead to high operating temperatures,
collapsed seals and in the case of greased electric motors, energy
loss and failures. The best ways to avoid these problems are to
establish a maintenance program, use calculations to determine the
correct lubricant amount and frequency of relubrication, and
utilize feedback instruments.
Too much grease volume (overgreasing) in a bearing cavity will
cause the rotating bearing elements to begin churning the grease,
pushing it out of the way, resulting in energy loss and rising
temperatures. This leads to rapid oxidation (chemical degradation)
of the grease as well as an accelerated rate of oil bleed, which is
a separation of the oil from the thickener. The heat that has been
generated over time along with the oil bleed eventually will cook
the grease thickener into a hard, crusty build-up that can impair
proper lubrication and even block new grease from reaching the core
of the bearing. This can result in accelerated wear of the rolling
elements and then component failure.Seal damage is another negative
side effect of overgreasing. Grease guns can produce up to 15,000
psi, and when you overgrease a bearing housing, the lip seals can
rupture, allowing contaminants such as water and dirt to gain
access into the bearing housing. Keep in mind that lip seals
usually fail around 500 psi. This excessive pressure can also
damage single and double-shielded bearings, causing the shields
facing the grease supply to collapse into the bearing race and
leading to wear and eventually failure. When too much pressure is
generated from a grease gun due to overgreasing, it is easy for the
hard, crusty grease formed from heat (high operating temperatures)
to be broken apart and sent directly into the bearing
track.Overgreasing electric motor cavities has the same effect as
with any bearing application except that grease can reach the motor
windings. When filled completely with grease, an electric motor
bearing will generate excessive heat due to churning. This results
in energy loss as well as an accelerated rate of oil bleed and
hardening of the grease thickener. Again, the high pressure applied
from a grease gun can result in grease finding its way between the
shaft and inner bearing cap and pressing into the inside of the
motor. The result over time is the coating of the electric motor
windings with grease, which leads to both winding insulation and
bearing failures.Setting up a maintenance program is key to solving
the problem of overgreasing. Each lube point, whether it be a
bearing housing or electric motor, should be tracked as an asset,
and records kept for scheduling planned maintenance or inspections
of the asset. While the initial setup of a maintenance system may
take some time and hard work, the end results will have a major
impact.Once you have planned the scheduling of the assets, you will
need to determine the timing and amount of grease (volume) that
should be applied at each point. The volume can be calculated with
a simple equation (ref. SKF):G = 0.114 x D x BWhere G = the amount
of grease in ouncesD = the bore diameter in inchesB = the bearing
width in inchesNext, calibrate all grease guns in use and train the
technicians on the proper procedures of usage. Calibrating a grease
gun is very simple. All you need are the grease gun and a postal
scale. Determining the weight in ounces per full stroke (shot) of
the grease gun will allow you to identify the number of shots it
takes to equal 1 ounce of grease. This will help you establish the
right volume needed to ensure you are delivering the precise amount
at each use.After you have determined the correct volume, its time
to establish the proper frequency. There are several methods for
estimating a regreasing frequency, including multiple calculators,
tables and charts. The major factors in determining frequency are
load, operation time, type of bearing, speed, temperature and
environment.Feedback tools can also be beneficial for fine-tuning
your frequency. For example, ultrasonic instrumentation is one of
the best ways to optimize the correct frequency and help you set up
your maintenance program.Establishing appropriate procedures and
inspections during relubrication is another important part of a
maintenance program. Some basic steps include: Cleaning areas
around the fill and relief fittings. Ensuring the grease relief
valve moves freely or the drain plug is removed. Checking to be
sure the relief passage is clean from any hardened grease that may
be blocking grease from exiting. Greasing the bearing cavity with
the correct calculated volume of grease while slowly adding each
shot to minimize excessive pressure build-up. Allowing the motor to
run during and after greasing to expel any excess grease. This
should be done before re-installing the purge port or bottom grease
relief valve and cleaning the area of any excess grease.Tips to
Control Overgreasing Discontinue greasing when you feel abnormal
back pressure. Always make sure exhaust ports are cleaned out from
any debris or old, hard crust that could be blocking the
passageway. Consider installing grease guns with pressure gauges,
shut-off grease fittings or relief-type vent plugs. Slowly pump
grease into bearings every few seconds. Using a quick-lever action
could cause seal damage and not allow the grease to distribute
throughout the bearing correctly.10 Lubrication Best Practices for
Improved Equipment ReliabilityLubrication has a direct effect on
equipment reliability. If you have a good lubrication strategy, you
will improve your plant and equipment uptime. For any given plant,
there are a number of important steps that, if implemented, will
increase equipment reliability. The following 10 lubrication best
practices can help companies achieve the optimal result in
maintenance costs compared to production reliability. 1.
Assessment/BenchmarkingIn this process, you assess the things that
you do right as well as the things you need to do better.2.
Organization and PlanningThis step is about ensuring that all
lubrication tasks in the plant are completed at the right time with
the right lubricant and the right quantity while using the right
processes. For this, most companies use software to control and
report the activity.3. IdentificationTo ensure that the right
lubricant is added to a piece of equipment, a labeling system is
needed. This is driven by the fact that in large plants multiple
types of lubricants are used. Lubricants are complex chemical
compositions and are often very incompatible, so to avoid errors of
mixing lubes and to support industry standards, particularly in the
food-grade industry, a good labeling system is necessary.
A good labeling system can help ensure that the right lubricant
is added to a piece of equipment.4. Cleanliness ControlOil
contamination is a major source of component wear and equipment
failure. Therefore, it is important that only clean lubricants are
used in the equipment operation. Cleanliness-control centers ensure
that the lubricant is stored safely, is clean and is transferred in
a contamination-free environment.Best practices for cleanliness
control include: Only use fully sealed containers. Fit air
breathers to all containers to prevent the ingress of water and
contaminants from the atmosphere. Filter all oil to get it very
clean. Only use contamination-free containers, i.e., containers
that will not generate contaminants.An example of a
cleanliness-control center.5. In-plant DispensingOpen and dirty
dispensing containers can be a source of contamination entering the
machine. Dispensing equipment must be safe, clean and closed. It
also should be efficient, easy to use and adapted to the
applications being filled. Make sure the containers are
well-identified so no mistakes occur, regardless of who uses
them.
These multi-colored dispensing containers are fully sealed, easy
to use and rust free.6. Grease Lubrication ToolsAdding grease to a
machine accounts for the majority of lubrication jobs. Therefore,
its essential to have tools that are efficient and practical.
Grease guns should be color-coded to ensure that the right lube
gets in the right application. Color-coded grease guns, with one
color for each different grease, can help in this regard.7.
Contamination ControlControlling the contamination of oil inside
the equipment is also critical. The international standard for
measuring this is ISO 4406. Online and offline filtering systems
are used to clean up the oil, while breathers or air conditioners
are utilized to protect the lubricant.
An example of a small mobile filter cart.8. Oil
AnalysisAnalyzing the oil in an application is an important part of
a lubrication strategy. By measuring against ISO 4406 standards,
the oil can be kept at the right cleanliness levels. Additionally,
chemical analysis of the oil will determine if it is fit for
further use.9. Environmental ControlIf spilled, lubricants can
contaminate the environment. Therefore, most maintenance strategies
today work to prevent such contamination from occurring. This is
also a key ingredient in world-class manufacturing standards.10.
Knowledge ManagementManagement of knowledge is becoming critical in
industry today, particularly within the maintenance sphere.
Maintenance workers must be skilled in the benefits of good
lubrication practices. Additionally, with the growing awareness of
the benefits of employing reliability-based maintenance strategies,
the basic training of personnel should be raised to that of the
reliability techniques employed by best-practice
organizations.Dangers Associated with Implementing Best
PracticesImplementing reliability-based strategies that are
successful over the long term is not an easy task. Many strategies
fail because they are seen as projects and not as processes to
change the work culture of those involved.
Effective implementation requires the existing culture within a
plant to be changed so the processes are accepted, followed and
sustained.While cultures can be changed, to achieve this requires
an understanding of the causes of failure and how to prevent these
factors from coming into play during the implementation
process.Addressing the need to change the way employees work will
provide a higher success rate for any project and ensure the new
way of working will be sustainable over the long term.