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Table of Contents
                            Section 1
	Shaft Alignment
		What is shaft alignment?
	A Definition
	Machinery catenary
	Operation above critical speed?
		Expressing alignment
	Alignment parameters
	Angularity, gap and offset
	Short Flexible couplings
	Spacer Shafts
		How precise should alignment be?
	Alignment tolerances for flexible couplings
	Coupling strain and shaft deflection
		Trouble shooting
			Causes of machine breakdown
	Couplings can take misalignment?
	Anti-friction Bearings
	Mechanical Seals
	Machine vibration
	The accumulated benefits of precision shaft alignment
	Symptoms of misalignment
		Alignment methods and practice
	Machine installation guidelines
	Measurement and correction of soft foot.
	Soft foot measurement
		Alignment methods – Eyesight
	The straightedge
	The feeler gauge
		Alignment methods – Dial indicators
	Rim and Face Method – By trial and error.
	Rim and Face Method – By calculation
	Reverse indicator method – By calculation
	Reverse indicator method – By Graph
	Indicator Bracket Sag Measurement
		Laser shaft alignment
	Laser systems basic operating principles.
		Laser shaft alignment – Case study
	Laser Shaft Alignment Cuts Energy Costs.
	Laser shaft alignment – Case study
	Laser shaft alignment improves pump reliability.
	Laser shaft alignment improves bearing and seal life.
	Laser shaft alignment reduces vibration alarms.
		Thermal expansion of machines
	Thermal growth calculations
		OPTALIGN smart laser alignment system
			Alignment of Pulleys and Sheaves
	Belt Tension
	Types of pulley misalignment
	Pulley Run Out
	Drive Belt fitting
	Checking Soft Foot
	Pulley Alignment
Section 2
	Vibration Analysis
		Conditon Monitoring
	The “Nuts and Bolts” of a CM system
	Implementing a CM programme.
	Returns on CM investment.
		Why Vibration Analysis?
	What is Vibration?
		Vibration analysis – Basic parameters
			Vibration analysis – Transducers
		Vibration analysis – Fault Detection
	Fault Mode analysis.
	Bearing Problems
	Aerodynamic and Hydraulic Problems
	Gearbox Problems
		Vibration analysis, Bearings – Enveloping
			Vibration analysis, Bearings – Shock Pulse
		Vibration analysis – a common sense approach
		VIBXPERT Data collector and analyser
Section 3
	Dynamic Balancing
		Balancing Standards
		Balancing Correction methods
	Single-plane three-point balancing
	Single-plane stroboscope method
	Correction by graphical method
	Correction by Calculation
	Two-plane stroboscope method (devised by A Wahrheit)
		Trial Weight calculation
		Balancing Safety
			VIBSCANNER Balancing system
Section 4
	Wear Debris Analysis
	Review of WDA methods.
	Assessing the Results from WDA analysis.
	Milestones in PRÜFTECHNIK Product development history
		Glossary of PRÜFTECHNIK products
	Laser Alignment systems
	Condition Monitoring hand portable systems
	Condition Monitoring hard wired systems
	Bearing Fitting system
		Alignment and Condition Monitoring Service
		Further Reading
Document Text Contents
Page 1


An Engineer’s Guide

Making Maintenance Matter
Optimising plant availability using
laser shaft alignment, vibration analysis
and dynamic balancing techniques

Page 2


Ask for the professionals

Plant Lane Business Park
Staffordshire WS7 3JQ
Phone: 01543-417722
Fax: 01543-417723
eMail: [email protected]

Take advantage of
our indispensable

Measurement Systems
or benefit from the
extensive experience

of our global
Machinery Service!

Machine park online + offline
condition monitoring

Roller alignment Mobile measurement,
Diagnostic + troubleshooting service

Geometric alignment
(surface profile, bearing shells, bores)

Laser shaft alignment
(horizontal, vertical, machine trains)

Turbine alignment

Page 96


3. Frictional vibration

The amplitude of vibration depends on the magnitude of the excitation
force, the mass and stiffness of the system and its damping. Vibration
occurs because we are not able either to build a perfect piece of machin-
ery or to install it perfectly. If we could build a perfect piece of machinery,
the centre of mass of the rotating element would be located exactly at its
centre of gravity. When the centre of mass and centre of gravity do not
coincide the rotor has a heavy spot and some degree of unbalance. This
unbalance produces a vibration proportional to the amount of weight of
the heavy spot. Additional sources of vibration are machine tolerances,
machine structure, bearing design, loading and lubrication, machine
mounting and rolling and rubbing between moving parts.

The analysis of vibration requires an understanding of the terminology
used to describe the components of vibration.


The cyclic movement in a given unit of time. The units of frequency are:

RPM = revolutions or cycles per minute.

Hertz (Hz) = revolutions or cycle per second.

These are related by the formula:

F = frequency in hertz = RPM/60.

Vibration analysis – Basic parameters

Page 97


Vibration analysis – Basic parameters


The magnitude of dynamic motion of vibration. Amplitude is typically
expressed in terms of either

Peak to Peak: 0 to Peak: RMS (Root Mean Square).

The sketch below illustrates the relationship of these three units of meas-
urement associated with amplitude.

Amplitude, whether expressed in displacement, velocity or acceleration
is generally an indicator of severity. Since industrial standards of vibra-
tion severity will be expressed in one of these terms, it is necessary to
have a clear understanding of their relationship. Care must be exercised
to note the “type” of amplitude measurement when comparing machin-
ery vibration to industry standards.

Fundamental Frequency

Fundamental frequency is the primary rotating speed of the machine or
shaft being monitored and usually referred to as the running speed of
the machine.

Page 192

Productive maintenance technology PRUFTECHNIK LTD.
Plant Lane Business Park
Staffordshire WS7 3JQ
Phone: 01543-417722
Fax: 01543-417723
eMail: [email protected] £ 9.99

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