SKF TKGT 1 User manual

SKF Grease Test Kit
TKGT 1
Instructions for use

2SKF TKGT 1
Safety recommendations..........................................................................................4
1. Introduction .....................................................................................................5
1.1 Principle of operation.................................................................................................... 5
2. Content ............................................................................................................6
2.1 Technical data................................................................................................................. 8
3. Analysis Protocol ..............................................................................................9
3.1 Collecting information................................................................................................... 9
3.1.1 Application conditions .......................................................................................10
3.1.2 Grease in use .....................................................................................................10
3.2 Collecting grease samples ..........................................................................................11
3.2.1 Material ..............................................................................................................11
3.2.2 Sampling procedure .........................................................................................12
3.2.3 Recommendations.............................................................................................13
3.3 First Visual inspection ................................................................................................14
3.3.1 Examples ............................................................................................................14
3.4 Consistency test ...........................................................................................................15
3.4.1 Principle of operation ......................................................................................16
3.4.2 Material...............................................................................................................17
3.4.3 Test procedure ..................................................................................................17
3.4.4 Recommendations.............................................................................................19
3.5 Oil bleeding test ...........................................................................................................21
3.5.1 Principle of operation........................................................................................21
3.5.2 Material...............................................................................................................22
3.5.3 Test procedure ..................................................................................................22
3.5.4 Recommendations.............................................................................................26
3.6 Contamination test ......................................................................................................27
3.6.1 Principle of operation........................................................................................27
3.6.2 Material...............................................................................................................27
3.6.3 Test procedure ..................................................................................................28
3.6.4 Recommendations ...........................................................................................31
3.7 Reporting ......................................................................................................................32
3.7.1 Recommendations.............................................................................................32
4. Reference cases..............................................................................................33
4.1 Grease shelf life / Quality ...........................................................................................34
4.2 Grease life / trend analysis .........................................................................................35
4.3 Grease selection...........................................................................................................36
4.4 Contamination..............................................................................................................37
4.5 Summary......................................................................................................................38
Table of contents
Original instructions

3SKF TKGT 1
5. Maintenance...................................................................................................39
5.1 Cleaning ........................................................................................................................39
5.2 Spare parts...................................................................................................................39
6. Appendixes.....................................................................................................39
6.1 USB heater ...................................................................................................................39
6.2 USB adapter.................................................................................................................39
6.3 Microscope....................................................................................................................39
Original instructions

4SKF TKGT 1
Safety recommendations
• Always read and follow the operating instructions.
• Do not expose to high humidity, temperature exceeding 40 °C (105 °F) or
direct contact with water.
• Read single components instructions for use provided in appendixes
(USB heater, USB adaptor, Microscope).
• Read greases safety data sheets.
• Obey local regulations regarding handling of lubricants.
• Do not use the kit while food or drinks are standing around.
• Comply with machinery and local safety recommendations before sampling.
• Use provided nitrile, powder free disposable gloves to avoid direct skin
exposure with grease. Long term contact with greases may cause skin
allergic reactions.

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1. Introduction
Grease is used to lubricate around 80% of all rolling element bearings. Poor lubrication
methods account for around 50% of all premature bearing failures. Poor lubrication
methods include such things as:
• wrong lubricant selection
• wrong amount of lubricant (over and under greasing)
• wrong lubrication delivery (ingress of contaminants)
• and wrong lubrication intervals.
Monitoring grease condition in the field allows decisions to be made quickly. A quick
diagnosis of the grease condition can make a real difference to the bearing condition and
performance.
The SKF Grease Test Kit TKGT 1 has been especially designed to be used in the field
and offers a complete fast testing method. No special training is required and the tests
themselves are easy to perform. Compared to most laboratory type tests, the sample of
grease required for an analysis is very small (typically just 0,5 grams), allowing the tests to
be conducted on most sizes of bearings.
To further simplify procedures and safety, no harmful chemicals are required for any of the
testing methods.
Monitoring grease condition is very important. By being proactive, actions can be taken
before the lubrication contributes to deterioration of machinery condition such as an
increase in bearing temperature or vibration levels.
Monitoring grease condition gives valuable information on the application condition.
Changes in grease properties can be monitored and can help evaluating: grease shelf life,
grease quality, grease performance, trending to determine best re-lubrication interval and
colour changes.
Included in these instructions for use are a number of real application cases that show the
test results and the reporting of the grease condition.
1.1 Principle of operation
The kit allows many grease characteristics to be easily checked. However, the method
shown in this instructions for use must be followed to get good and effective results.
Chapter 3 gives detailed information on the method and procedures to be followed.

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2. Content
Sampling tools Contamination test
Consistency test CD containing instructions for use, report
template and consistency test scale
Oil Bleeding test

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List of parts
Item number Quantity Description
1 1 Sampling syringe
2 1 Sampling tube
3 1 Permanent marker
4 10 Sample container
5 20 Disposable gloves
6 1 Set of disposable spatulas
7 1 250 mm spatula
8 1 150 mm spatula
9 1 Pair of scissors
10 1 Housing
11 1 Weight
12 1 Mask
13 4 Glass plates
14 1 USB Heater
15 1 USB/220V/110V adaptor
16 1 Blotter paper pack
17 1 Ruler
18 1 Microscope
19 2 AAA LR03 lithium batteries
20 1 CD
21 1 Carrying case

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2.1 Technical data
Item number Item Description
1Sampling syringe Material: polypropylene
2Sampling Tube Material: PTFE,
Length: approx. 1 meter
3Permanent marker Colour: black
4Sample container Material: polyethylene
5Disposable gloves Material: grease resistant nitrile
(synthetic rubber), powder free,
Size: XL, Colour: blue
6Set of disposable
spatulas
Material: plastic
7250 mm spatula Material: stainless steel
8150 mm spatula Material: stainless steel
9Pair of scissors Material: stainless steel
10 Housing Material: aluminum
11 Weight Material: stainless steel
12 Mask Material: plexiglas
13 Glass plates
14 USB Heater Refer to Appendix 6.1
15 USB/220V/110V
adapter
Refer to Appendix 6.2
16 Blotter paper pack Set of 50 sheets
17 Ruler Material: aluminum, graduated
0.5 mm
18 Microscope Refer to Appendix 6.3
19 AAA LR03 lithium
batteries
20 CD
21 Carrying case Dimensions:
530 × 110 × 360 mm
(20.9 × 4.3 × 14.2 in.)
Weight complete kit: 3,2 kg (7.05 lb)

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3. Analysis Protocol
The proposed protocol is shown in the table below. Information collected and test results
obtained in each part can be reported in the report template printable from the CD.
3.1 Collecting information 3.1.1 Application conditions
3.1.2 Grease in use
3.2 Collecting samples 3.2.1 Material
3.2.2 Sampling procedure
3.2.3 Recommendations
3.3 First Visual inspection 3.3.1 Examples
3.4 Consistency test 3.4.1 Principle of operation
3.4.2 Material
3.4.3 Test Procedure
3.4.4 Recommendations
+
3.5 Oil bleeding test 3.5.1 Principle of operation
3.5.2 Material
3.5.3 Test Procedure
3.5.4 Recommendations
3.6 Contamination test 3.6.1 Principle of operation
3.6.2 Material
3.6.3 Test Procedure
3.6.4 Recommendations
3.7 Reporting 3.7.1 Recommendations
3.1 Collecting information
The ability of grease to lubricate correctly depends on the grease itself linked with external
parameters. It is strongly recommended to collect as much information as possible on the
application conditions and grease type used. The information collected can greatly help in
interpreting the results.
For example:
A softening of grease can be caused by excessive vibrations, oil contamination, housing
overfilled, and so on.
Knowing vibration levels, finding an oil can nearby the application or revising the amount of
lubricant put at each relubrication interval can simplify analysis.

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3.1.1 Application conditions
Take a note of the application conditions. This includes such things as:
• Application type (electrical motor, crusher, railways axlebox, vibrating screens, …).
• Machine number or code (Pump 43).
• Last relubrication interval and quantity (date, amount in grams).
• Relubrication interval (hours).
• Bearing designation, type and size (deep groove ball bearing 6210, ….).
• Operating bearing temperature (70 °C).
• Load (C/P).
• Speed (n.dm).
• Ambient conditions (temperature, contamination, moisture, … ).
• Sealing type (mechanical seals, oil seals, ….).
• Operating bearing lifetime in hours.
• Vibrations (excessive, levels, …).
• and so on.
3.1.2 Grease in use
Record if possible full information on the grease in use such as:
• Grease name, type, batch and brand
• Find grease specifications –
Check NLGI grade or consistency value given by the manufacturer.
• Get if possible a fresh unused sample from the same can or batch
(See chapter 3.2 for sampling procedures)
• Sometimes, the grease used is the wrong grease for the application.
The suitability and relubrication intervals can be checked online*):
- SKF LubeSelect http://www.skf.com/portal/skf/home/aptitudexchange
- SKF LuBase http://www.skf.com/portal/skf/home/aptitudexchange
*) A subscription may be required to access these services.
Note all your collected information on the provided report template on section
3.1: Application & lubrication conditions.

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3.2 Collecting grease samples
Grease sampling is an important step of the analysis. Care should be taken when
performing this step. Proper tools and good practices will improve accuracy of the tests.
Note: - It is not always easy to have a representative grease sample.
- To perform all the tests, just 0.5 gram (0.02 oz) of grease is needed.
3.2.1 Material
A
9
7
55
6
4
4
4
1
2
3
8

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3.2.2 Sampling procedure
1. Ensure that the tools are clean and tidy.
2. Wear gloves.
3. Take a sample container. Using the pen provided, mark it with date of sampling and
machine number/bearing position or with a unique identification referring to the
report template.
Mark both lid and container to avoid mismatch
(Grease quantity in the picture is 0.5 gram, 0.02 oz)
4a If bearing is accessible, use provided stainless steel spatulas - Best sampling areas
are on the cage bars, on the raceways or just besides the roller set.
Put the grease sample directly in the marked sample container and do not fill it
completely. 0.5 gram is sufficient for one analysis.
If sample will also be used later, for trend analysis for instance, take a bigger sample.
4b If the bearing is not accessible, use tube (cut 10-15 cm, 4-6 in.) and syringe to suck
grease through the housing by removing grease nipples. In case of sampling through
grease escape holes, clean hardened and dirty grease before operation. On slewing
bearings, inspection screw can be removed and tube inserted to collect sample.
Pump grease. 4 to 5cm (1.5 - 2 in.) of tube should be filled with grease and put it in
the sample container waiting for analysis. Be sure to keep half a centimeter (1/4in.) of
tube clean to pump it back in the container!
The grease should not reach the syringe. These samples are less representative than
the ones taken directly from the bearing, but can still help to spot some issues.
Tube in sample container
Fill in the provided report template section 3.2: Collecting samples.
lid container

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3.2.3 Recommendations
• Get an additional fresh unused sample whenever possible. Make sure
to sample it in a clean way from the original grease can or cartridge.
• If housing is dismounted or bearing accessible, look where the grease is before
sampling. Look at filling level as well as colour differences. Take samples of extreme
colours.
• Grease can be taken from the seals with the supplied stainless steel spatulas.
• Avoid taking samples too close to the filling point.
• Look at the grease at the filling point – Is the grease very different from the one in the
bearing?
• Do not use wooden spatulas (oil sucked through the wood fibres can influence results
or wood fibres can contaminate the grease).
• Do not mix greases from different bearings and/or housings in the same container!
• Do not use transparent containers. Use containers provided.
• Look around the machines – such things as wrong grease cartridges, wrong lube type
and so on can give indications on mistakes.
• For trend analysis, take the sample always at the same sampling position.
• Take application photos if possible.
Example of bad sampling methods
Bad marking Broken sample container Transparent container
Inappropriate Inappropriate container Too much grease

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3.3 First Visual inspection
After the sample has been taken, a visual inspection should be first carried out.
This gives a first indication on grease status. Use the unused fresh grease sample as a
reference.
These are some grease aspects to look at:
• Grease should have a shiny, oily appearance. If not, the base oil has been probably
used up
• Darkening of the grease can result from high bearing temperature (oxidation,
carbonization) or solid contaminants. Note that some greases are originally black, e.g.
those containing MoS2or graphite
• Change in smell often results from oxidation
• Various aspects in colour, transparency, smell can result from mixing lubricants
or from lubricants incompatible with the material used for surrounding machine
components, for instance a brass cage
• General grease texture may be an indicator of bearing operating conditions. Normally,
the texture of a grease should change very little during service. It should be smooth
with no grit or lumps. If either is present, the grease can be contaminated
• Note all these changes.
Note: A blackening of the grease does not necessarily mean that the grease is not good.
Fill in the provided report template section 3.3: First visual inspection
3.3.1 Examples
Darkening Various aspects in colour -
grease contamination
Dryness - extreme case

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3.4 Consistency test
Grease consistency is an important grease parameter that determines stiffness
of the grease. The choice of a certain consistency for a certain application depends on
many operating conditions such as temperature, speed, shaft alignment, pumpability and
so on.
For example:
• Vertical shaft arrangements calls for stiff greases
• Low operating temperatures calls for low consistency greases in general
• and so on
Grease consistency is classified according to a scale developed by the NLGI (National
Lubricating Grease Institute). This is based on the degree of penetration achieved by
allowing a standard cone to sink into the grease, which has been worked for 60 strokes in
a grease worker, at a temperature of 25 °C (80 °F) for a period of 5 seconds. The depth of
penetration is measured on a scale of 10-1 mm and the softer greases allow the cone to
penetrate further into the grease, hence the higher penetration number. The test method is
in accordance to ISO 2137.
NLGI Number ASTM 60 strokes worked
penetration (10-1 mm)
Appearance at room temperature
000 445-475 Very fluid
00 400-430 Fluid
0 355-385 Semi-fluid
1 310-340 Very soft
2 265-295 Soft
3 220-250 Medium hard
4 175-205 Hard
5 130-160 Very hard
6 85-115 Extremely hard
Note: Greases for bearing applications have generally a NLGI value between 1 and 3.

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Once a certain consistency has been chosen for a certain application, it should
not change drastically during the advised relubrication interval or storage time.
This is related to grease mechanical stability. These are some possible causes for a
consistency change:
Softening (Lower NLGI value) of the grease can be caused by:
• Grease with too soft consistency or poor mechanical stability used in vibrating
application.
• Bearing housing filled too much for the speed used. This creates churning and
excessive grease shearing.
• Excessive temperature for the grease used.
• Rotating outer ring application filled too much and/or unsuitable housing design.
• Water in grease.
• Leakage of oil from neighbouring systems.
• Mixing of incompatible greases.
• Shelf life exceeded.
Hardening (Higher NLGI value) of the grease can be caused by:
• Grease has lost base oil due to exceeded relubrication interval (see oil bleeding test),
or because of evaporation due to continuous use at high temperature/poor grease
quality if changes happen fast.
• Certain grease can harden after extensive mechanical working.
• Mixing of incompatible greases.
• A large amount of solid contaminants (carbonized particles for instance).
• Shelf life exceeded.
3.4.1 Principle of operation
Under field conditions, it is virtually impossible to determine consistency using the
ISO 2137 method.
Instead, the grease test kit allows a suitable method to perform this test in the field.
A fixed grease volume is spread between two glass plates for 15 seconds by means of the
weight. By comparing the grease stain obtained with the calibrated measuring scale, the
consistency of the grease can be evaluated.
DiameterWeightGrease sampleGlass plates15 seconds

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3.4.2 Material
Preparation before test:
• Print the calibrated measuring scale with right printer settings. Do not scale to page!
To check if the print out is the correct one, the outside diameter of the housing should
be the same as the circle drawn on the calibrated measuring scale.
• Grease samples should be at temperature between 15 °C and 30 °C (59 °F and 86 °F).
• Wristwatch or clock to measure 15 seconds (not provided).
NLGI Grade
000
00
0
12
3
4
5
13
12
10
11
B
3.4.3 Test procedure
1. Ensure all components are clean
2. Wear gloves
3. Place weight in the housing
4. Place one glass plate on top of the
weight
5. Place mask on top of the glass plate 6. Take the grease sample to analyze from the
sample container using a disposable spatula
7. Apply the grease in the mask. Make sure that hole is full with grease and wipe off excess on the top.

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8. Remove carefully mask. Grease should stay on the glass plate.
9. Remove glass plate (with grease) and the weight from the housing.
10. Put the housing on the calibrated scale, insert glass plate containing grease face up in the
housing (grease should not be on the paper side!) – Align the grease spot with the centre of
the scale.
11. Take the weight and the second glass plate together with the glass plate beneath the weight,
lower gently on the housing. The weight should not touch the grease!

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12. Wait 15 seconds. 13. Remove the weight gently from the housing.
14. Read consistency number by looking at which zone is located the under grease stain –
Use the colour code to determine NLGI class.
Fill in the provided report template section 3.4: Consistency test.
Note: Keep the sample for test D!
3.4.4 Recommendations
It is good practice to test both a used and fresh/unused sample of the same grease. By
comparing the two stains obtained, differences in stiffness within the same NLGI grade can
be observed.
fresh used fresh used

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When fresh samples are used, stir them for 30 seconds with a spatula prior testing.
When used samples are tested, it can happen that the stain obtained is not very round.
This might be due to several reasons such as non homogeneity of the sample and/or
contaminants blocking the spreading in some directions. In this case, take an average.
When a stain is exactly in between two grades, grease could be classified as a
NLGI 1-2 for example.
Reminder: The test is meant to be performed at 15-30 °C (60-85 °F). If temperature is
different, the NLGI grade will be given at this temperature.
NLGI 1-2