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Technical data are subject to change without notice.
ISO 9001 certified. © Copyright SPM 2003-10. 71679.Z
SPM Instrument AB
• Box 4 • SE-645 21 Strängnäs • Sweden
Tel +46 152 22500 • Fax +46 152 15075 • [email protected] • www.spminstrument.com
Condition Based Maintenance
Condition Based Maintenance is by now a widely accepted concept in industry. The idea is simple and not
exactly new: keep plant machinery in good working condition by locating and repairing minor faults
before they grow large enough to cause expensive breakdowns and production stops.
The problem is to assess machine condition and detect a slow deterioration long before a piece of plant
grinds to a shuddering halt. In the past, a skilled operator could do this largely without the help of
instruments, by listening, touching, smelling. Modern machinery is often unattended, soundproofed, out
of easy reach. It rotates faster and is less massively constructed, which means that even a minor
deterioration of its working condition can have very serious consequences. Therefore personal skill and
subjective judgement have to be supported by monitoring systems and instrument readings.
Vibration Monitoring
Vibration monitoring is a very useful method for an overall assessment of machine condition. Changes in
the vibration level always imply changes in the operating condition. Excessive vibration has basically three
causes: something is loose, misaligned or out of balance. These three causes cover virtually all possible
mechanical faults.
Moreover, the assessment of machine vibration has been much simplified by international standards which
define the acceptable vibration level for a given type of machine and recommend monitoring methods
suitable for industrial purposes.
A Maintenance Tool
Effective Condition Based Maintenance requires economical and simple monitoring methods which can be
applied by maintenance personnel without special training. Their primary task is to locate trouble spots
early and direct the efforts of the maintenance crews to the right place at the right time. Fault analysis and
repairs are a secondary step which may require expert knowledge and a different type of instrumentation.
SPM vibration monitoring equipment is designed as a maintenance aid. In accordance with the interna-
tional standards, it measures vibration severity over a large frequency range. It allows a practical
classification of machine condition in relative terms: good, acceptable, just tolerable or bad. Regular
measurements will also show the development trend of the vibration level and thus the urgency of the
maintenance problem: stable condition, slow deterioration or fast deterioration.
Measurements can be carried out in various ways; either periodical readings with portable equipment
(Vibrameter VIB-11B), or continuous monitoring of preset limit values (Machine Guard MG4 or CMM
System). This manual gives an introduction to vibration monitoring and describes condition assessment
and basic fault analysis with SPM Vibrameter VIB-11B.
Measuring Units
ISO Recommendations use metric units (mm/s RMS) for measuring vibration severity. In this manual, all
metric units have been converted to inches /1 in = 2.54 mm / 1 mm = 0.03937 in). A metric version (VIB-10)
is available, together with an instruction manual (71678 B) and follow-up forms (VIC-11) with metric tables.
