SPM BC100 User Manual
SPM Instrument AB • Box 504 • SE-645 25 Strängnäs • Sweden
Technical data are subject to change without notice.
Tel +46 152 225 00 • Fax +46 152 15075 • info@spminstrument.se • www.spminstrument.com
ISO 9001 certified. © Copyright SPM 2008-06. 71796 B
User Guide
Contents
Instrument Overview ........................................................................2
Instrument parts ................................................................................ 2
General description ...........................................................................2
Displays and icons ............................................................................. 3
Start up ..............................................................................................4
Batteries ............................................................................................5
Settings .............................................................................................. 6
Battery type ....................................................................................6
Unit for temperature measurement ..................................................6
Unit for bearing diameter setting .....................................................6
Accessories ................................................................................... 7
Shock Pulse Measurement ...................................................... 8
The Shock Pulse Method ................................................................... 8
Carpet value dBc .............................................................................8
Maximum value dBm .......................................................................8
dBm/dBc.........................................................................................8
Normalized shock pulse values with dBi ............................................9
Unnormalized readings............................................................................9
The dBm/dBc technique................................................................... 10
Rules for measuring points................................................................ 11
Measuring points, examples ............................................................. 12
Measuring range .............................................................................14
Creating acceptable measuring conditions ....................................... 15
Measuring intervals .........................................................................16
Shock pulse transducers.................................................................... 17
Bearing Measurement ............................................................... 19
Input data .......................................................................................... 19
Entering shaft diameter and rpm for dBi calculation ..........................19
Entering dBi manually ...................................................................... 19
Shock pulse measurement ................................................................20
Transducer Line Test ..........................................................................21
Storing measurement results ............................................................ 21
Listening to the shock pulse pattern ................................................22
Evaluating the Bearing Condition ........................................... 23
Identifying the shock pulse source ...................................................24
Shock pulse patterns – condition codes ........................................... 25
Typical shock pulse patterns from rolling bearings ..........................26
Confirming bearing damage ............................................................. 30
Evaluation flow chart .........................................................................32
Temperature Measurement ...................................................... 34
Using the Stethoscope Function ............................................. 35
Technical Specifications ............................................................. 36
Maintenance and calibration .............................................................37
1
Document Outline
This User Guide contains useful information about the Bearing Checker, beginning with general information about instrument parts, user interface, batteries and settings.
A chapter explaining the theories of shock pulse measurement follows. It is advisable that you read this
as it is valuable in order to understand measurement results and to evaluate them correctly.
The shock pulse theories chapter is followed by chapters describing the hands-on use of the instrument
and how to confirm and evaluate measurement results.
References to icons, displays and modes in the instrument are in bold text. References to instrument
keys are in capital letters.
2
Instrument parts
1 Measuring probe
2 Temperature IR sensor
3 Condition indicators
4 Graphical display
5 Navigation keys
6 Measuring key and power on
7 Output for headphones
8 Transducer input
9 Measuring LED
10 Battery compartment
11 Serial number label
Instrument Overview
1
3
4
7 9
2
5
6
8
General description
The Bearing Checker is a shock pulse meter based on the well proven SPM method for quick and easy
identification of bearing faults. The instrument has a built-in microprocessor programmed to analyze
shock pulse patterns from all types of ball and roller bearings and display evaluated information on the
operating condition of the bearing.
Bearing Checker is battery powered and designed for use in harsh industrial environments. The graphic
display (4) gives the condition readings and the LED indicators (3) give an immediate evaluated bearing
condition in green-yellow-red.
The shock pulse transducer (1) of probe type is built-in. All types of SPM shock pulse transducers for adapters and permanent installation can also be used, connected to the transducer input (8). The dBi value is
programmed into the instrument and the measurement is started with key (6). The actual condition reading
is displayed on the graphical display (4) as a carpet value “dBc” and a maximum value “dBm”. The condition indicators (3) indicate the evaluated bearing condition in green-yellow-red. Headphones for listening
to the shock pulse pattern can be connected to the output (7).
The Bearing Checker can also be used for measuring surface temperature via the IR sensor (2), and for
detecting machine sound irregularities via headphones using the stethoscope function.
Internal or external probes can be used for listening.
11
10
3
Displays and icons
Bearing measurement
Temperature
measurement
Stethoscope
function
General settings
Bearing measurement
Input data Measurement
Input dBi
MemoryTLT test Listening
Back/Return
Main display
Temperature measurement Stethoscope function
Measure (or press the probe tip)
Back/Return
Back/Return
Volume (1– 8)
Back
to main menu
Battery Unit
About
Temperature
General settings
4
Pressing the measuring key (6) switches on the instrument.
Set up and measuring modes are selected with the arrow keys (5).
Measuring is started automatically whenever the internal
probe is pressed in. When using external probes, measuring is started manually by pressing the measuring key
(6) while in the Bearing mode.
The blue measuring LED (9) stops blinking when an SPM
measuring cycle is completed.
The green, yellow and red LEDs (4) beside the display
indicate the bearing condition after an SPM measurement.
If not used, the instrument will automatically shut off
after 2 minutes. It can also be shut off by simultaneously
pressing the LEFT and RIGHT arrow keys.
When switched back on, the instrument will resume its
last mode.
Start up
1
3
4
7 9
2
5
6
8
Serial number and software version
To check which software version is in your instrument
and find out the instrument serial number, go to the
Main display. Press the DOWN arrow key to enter the
General Settings mode. Use LEFT/RIGHT arrow keys
to highlight the Information icon (i), then press the UP
arrow key to see the software version and serial number.
To return to the General Settings mode, press the LEFT
arrow key.
To return to the Main display, use LEFT/RIGHT arrow
keys to highlight the Return icon, then press the UP
arrow key.
General
settings
Software version
and serial number
Back/Return
Main display
5
The instrument is powered by two batteries type MN 1500 LR6. Alkaline
or rechargeable batteries can be used. Please note that rechargeable
batteries must be removed from the instrument before recharging. The
battery compartment is located at the back. Press and push the lid to
open the compartment.
The battery test on the setup menu shows the present battery voltage.
The battery status icon will show when the batteries are low and have
to be replaced or recharged.
The battery life depends on how the instrument is used. Full power is
only consumed while a reading is in progress: from pressing the measuring key until a measured value is displayed.
Before long-time storage of the instrument, keep in mind to remove
the batteries.
Batteries
Battery check
For exact battery voltage, go to the battery setup menu:
From the Main display, press the DOWN arrow key to enter the General
Settings folder. Use LEFT/RIGHT arrow keys to highlight the battery icon,
then press the UP arrow key to enter battery type setup. The present battery voltage is shown in the upper left corner.
To return to the General Settings menu press the LEFT arrow key.
General
settings
Battery type
Battery
voltage
Back/Return
Main display
6
Battery type
Alcaline or rechargeable batteries can be used in Bearing Checker. The
battery type has no influence on instrument functionality or operation, but
should be set for the battery status icon to correctly show battery level.
From the Main display, press DOWN arrow key to enter the General Set-
tings folder. Use LEFT/RIGHT arrow keys to highlight the Battery icon,
then press the UP arrow key to enter battery type setup. Use UP/DOWN
arrow keys to set the battery type of your choice (1.2 V for rechargeable,
1.5 V for alcaline batteries). To save and return to the General Settings
menu press the LEFT arrow key.
To return to the Main display, use LEFT/RIGHT arrow keys to higlight the
Return icon, then press the UP arrow key.
Unit for temperature measurement
Temperature can be displayed in either Celsius or Fahrenheit. To choose
your unit of measurement, use the DOWN arrow key in the Main display
to enter the General Settings mode. Use the LEFT/RIGHT arrow keys
to highlight the Temperature icon, then press the UP arrow key. Use the
UP/DOWN arrow keys to set the measurement unit of your choice. To save
and return to the General Settings menu press the LEFT arrow key.
To return to the Main display, use the LEFT arrow key to highlight the
Return icon, then press the UP arrow key.
Unit for bearing diameter setting
Bearing diameter can be displayed in either mm or inch. To choose your
unit of measurement, use the DOWN arrow key in the Main display to
enter the General Settings mode. Use the LEFT/RIGHT arrow keys to
highlight the Measurement icon, then press the UP arrow key. Use the
UP/DOWN arrow keys to set the measurement unit of your choice. To save
and return to the General Settings menu press the LEFT arrow key.
To return to the Main display, use the LEFT arrow key to highlight the
Return icon, then press the UP arrow key.
Settings
Unit for temperature
General
settings
Select
type
Battery type
Back/Return
Main display
Select
inch or
mm
Unit for diameter
Select
°F or °C
Back/Return
Back/Return
7
Accessories
Accessories
EAR12 Headphones with ear defenders
TRA73 External transducer with probe
TRA74 Transducer with quick connector for adapters
CAB52 Measuring cable with slip-on connector for permanently installed transducers, 1,5 m
15286 Belt holder for external probe transducer
15287 Belt case for accessories
15288 Protective cover with wrist strap
15455 Protective cover with belt clip and wrist strap
93363 Cable adapter, LEMO-BNC
93062 Cable adapter, BNC-TNC, plug-jack
Spare parts
13108 Rubber sleeve for probe tip, chloroprene, maximum 110 °C (230 °F)
15288
15455
15287 15286
EAR12
TRA74
TRA73
8
The Shock Pulse Method
The Bearing Checker is based on the Shock Pulse Method. Measurements with the SPM method give an
indirect measure of impact velocity, i.e. the difference in velocity between two bodies at the moment of
impact. At the point of impact, a mechanical compression wave (a shock pulse) arises instantly in each
body. The peak value of the shock pulse is determined by the impact velocity and is not influenced by
the mass or the shape of the colliding bodies. Shock pulses in rotating ball and roller bearings are caused
by impacts between raceways and rolling elements. From the points of impact the shock pulses travel
through the bearing and the bearing housing. Extensive experience proves that there is a simple relationship between the bearing’s operating condition and the value of the shock pulses.
A transducer detects the shock pulses in the bearing. The transducer signals are processed in the bearing
detector’s microprocessor and the measured shock pulse values are shown on the display. An headphone
can be connected to the instrument for listening to the shock pulse pattern. Please note that this instrument cannot be used for plain bearings.
Shock pulses are short duration pressure pulses which are generated by mechanical impacts. Mechanical
impacts occur in all rotating rolling bearings because of irregularities in the surfaces of the raceways and
the rolling elements. The magnitude of the shock pulses depends on the impact velocity.
Carpet value dBc
Surface roughness (small irregularities) will cause a rapid sequence of minor shock pulses which together
constitute the shock carpet of the bearing. The magnitude of the shock carpet is expressed by the carpet
value dBc (decibel carpet value). The carpet value is affected by the oil film between rolling elements and
raceways. When the film thickness is normal, the bearing’s carpet value is low. Poor alignment and installation as well as insufficient lubrication will reduce the thickness of the oil film in the whole or parts of the
bearing. This causes the carpet value dBc to rise above normal.
Maximum value dBm
Bearing damage, i.e. relatively large irregularities in the surfaces, will cause single shock pulses with higher
magnitudes at random intervals. The highest shock pulse value measured on a bearing is called its maximum value dBm (decibel maximum value). The maximum value dBm is used to determine the operating
condition of the bearing. The carpet value dBc helps to analyze the cause of reduced or bad operating
condition.
Shock Pulse Measurement
dBi = Initial value of a bearing
dBc = Carpet value (weak pulses)
dBm = Maximum value (strong pulses)
dBn = Unit for normalized shock level
dBsv = Unit for absolute shock level
rpm
d
The initial value dBi
depends on rpm and
shaft diameter d.
2 seconds
9
Normalized and unnormalized readings
The Bearing Checker measures impact velocity over a large dynamic range. In order to simplify readout
and evaluation, a logarithmic measuring unit is used: decibel shock value (dBsv).
dBsv is the general measuring unit for shock pulses. By measuring the shock pulses from a bearing in dBsv
a value for their magnitude is obtained, for instance 42 dBsv. However, this value is only part of the information needed to judge the operating condition of the bearing. We also need a standard of comparison,
i.e. a norm value for identical or similar bearings.
Such norm values have been obtained empirically, by measuring the shock pulses from a large number of
new, perfect ball and roller bearings. They are called “initial values” dBi (decibel initial). The dBi value can
be set manually or calculated by the instrument after input of rpm and shaft diameter (see chapter “Input
data”). The highest dBi value that can be entered is +60, the lowest -9. Any attempt to enter values below
this will result in dBi “- -” and an unnormalized shock pulse reading (see below).
By subtracting the dBi from the dBsv value we obtain the “normalized” shock pulse value or dBn (decibel
normalized) of the bearing, for example: 42 dBsv–10 dBi = 32 dBn”. The normalized shock pulse value dBn
is the measuring unit for the operating condition of bearings. A maximum value of 32 dBn means “32 dB
above normal”, which implies “reduced operating condition” for the measured bearing. By programming
the Bearing Checker with the dBi before taking a reading, the bearing condition will be indicated directly
on the condition display in green-yellow-red for “good”, “reduced” or “bad” operating condition for the
measured bearing. “Bad operating condition” can be synonymous with “bearing damage”, but the term
also includes a number of other “bearing faults” which can be detected by shock pulse measurement. The
initial value dBi of a bearing is directly related to its rotational speed and shaft diameter.
The absolute shock pulse level of a bearing, measured in dBsv (decibel shock value), is both a function of
rolling velocity and of bearing condition. The dBi value of the bearing must be entered in order to neutralize the effect of rolling velocity on the measured value.
The Bearing Checker takes a sample count of the shock pulses occurring over a period of time and displays:
• the maximum value dBm for the small number of strong shock pulses.
• the carpet value dBc for the large number of weaker shock pulses.
• a lit-up LED on the condition scale (for normalized readings only): green for dBn up to 20 dBn =
good condition, yellow for 21-34 dBn = caution, red for 35 dBn and more = bad condition.
The maximum value dBm defines the bearing’s position on the condition scale. The difference between
dBm and dBc is used for a finer analysis of the causes for reduced or bad condition.
Unnormalized readings
For unnormalized readings, set the dBi value to “- -” (see chapter “Input data”). You will then measure in
dBsv (absolute shock values) and get no condition indication, as the condition scale is graded in normalized shock values, dBn. This method is used for comparative readings on different bearings and/or other
shock pulse sources.
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