Latest Software Success From Balancing Expert Cemb Hofmann UK

The latest development at Cemb Hofmann UK is the intutive software which has been released for balancing flexible rotors.

This software will help users to achieve optimum results and the best possible balancing - through the use of pre-set balancing planes (2 or 3 planes) within only one measuring cycle.

During the same measurement, multiple readers are performed automatically in sequence and at varying speeds.

By comparing these measurements with the coefficients obtained during calibration stage, users can utilise reliable data and balance the rotor with only one measuring cycle.

This proceedure will stop automatically for the safety of both machine and operator if the rotor has excessively high unbalance. If this situation arises, the software will save the correction values which were measured at lower speed before stopping. Because of this functionality, the operator will be able to conduct a pre-balancing cycle, enabling the reduction of initial unbalance and making final measurement possible at maximum speed.

Using a pre-balanced shaft, calibration is obtained and the rotor is able to run at the maximum defined speed. Should this software not be enabled, the balancing machine will work as a standard hard bearing machine with manual speed adjustment.

Catch up on more of the latest balancing news from Cemb Hofmann UK today or call our experienced sales team on 0161 872 3123 for more information.

Portable Vibration Measurement | The new N600 instrument

CEMB’s range of portable equipment for vibration measurement and analysis, balancing and predictive maintenance has been enhanced with the new N600 instrument.

 

Equipped with an ample, backlit, high resolution LCD colour screen, N600 can be used in all types of lighting conditions.

Ease of use, calculation power and intuitive methods for the setting/presentation of measurements and graphs are the main features of this instrument.

The analysis functions provide the information needed for machine diagnosis and diagnosis of the condition of the bearings so the most appropriate maintenance work can be identified.

The balancing function can be used to balance any type of rotating body on one or more plane irrespective of size and weight.

The vibration trend over time, spectral analysis and Bode plot, which are essential tools for defining the corrective action needed with extreme precision, are all visible directly on the screen.

All of the readings taken can be saved in a database using sophisticated software for effective and rational organisation of predictive maintenance.

The equipment is supplied with standard accessories (2 accelerometers with a heavy-duty spiral cable, Hi-Speed 250,000 cpm photocell, USB stick, angle rule) sufficient for performing all of the main functions. Various optional accessories are also available (other types of sensors, extensions, Bluetooth printer) for when the equipment needs to be used in special conditions.

The software package, which can be installed on a PC, can perform data acquisition route creation (Route Manager) functions and provides diagnostics tools (Advanced Diagnostic Software).Three different levels are available to meet all requirements: storage, detailed analysis, diagnostics, measurement comparisons, trends, spectrums, orbits.

LEVEL 1 Basic

• Multilingual interface
• Trend data
• Route management
• Data export option
• Zoom

LEVEL 2 Standard

All Level 1 functions plus:
• FFT analysis
• Harmonic cursor
• List of peak values
• Waveform

LEVEL 3 Expert

All Level 1 and 2 functions plus:
• Waterfall analysis
• Orbit analysis
• Bode plot
• Nyquist plot
• Statistical analysis

N600 VERSATILE AND COMPLETE

Standard accessories:

• No. 2 accelerometer transducers 100mV/g
• No. 2 transducer connection cables L 2.5 m
• No. 1 heavy duty spiral cable L 2 m
• No. 2 magnetic bases Ø 25 mm
• No. 2 probes
• No. 1 250,000 Cpm Hi-speed, laser photocell complete with upright and magnetic base
• No. 1 roll of reflecting tape
• No. 1 USB stick for data transfer
• Angle rule
• Battery charger
• Universal plug
• Case complete with carry strap
• Manual

Optional accessories:

• Bluetooth printer
• Protective cover
• Velocity transducer complete with lead and magnetic base
• Proximity sensor complete with upright, lead and magnetic base
• Connection cable for transducers L 5 m
• 10 m-long extension cable for transducers
• 10 m-long extension cable for photocell
• CEMB ADS software for data storage and management

TECHNICAL DATA

Functions:

• Measurement of the overall vibration value (acceleration, velocity, displacement)
• Vibration phase measurement
• Analysis of vibration in the frequency range
• Monitoring overall vibration in relation to time or velocity (Bode plot)
• Balancing of rotating bodies in operating conditions on 1 or 2 planes
• Waveform

Measurement types

• Effective value (RMS)
• Peak value (Pk)
• Peak-to-peak value (PP)

Units of measurement

• Acceleration: [g]
• Velocity: [mm/s] or [inch/s]
• Displacement: [μm] or [mils]
• Frequency: [Hz] or [Cpm]

Input

• 2 independent and simultaneous measuring channels (accelerometer, velocimeter, non-contact, any signal max. 5V-PP)
• 1 photocell channel (velocity and angle reference)
• 2 USB ports for data transfer

Vibrometer function

• Measurement of the overall vibration value in predefined frequency bands
(10-1000Hz; 3-300Hz; 10-10000Hz) or bands defined by the user (within the range of 3-20000Hz)
• Measurement of 1x fundamental vibration value and phase
• Measurement of rotating body velocity
FFT Function (Analysis in frequency)
• FFT analysis (manual/trigger)
• Maximum settable frequency (25; 100; 500; 1000Hz; 2.5; 5; 10; 15kHz)
• Resolution (100; 200; 400; 800; 1600; 3200 lines)
• Number of averages: from 1 to 16
• List of main peak values

Monitor – Data Logger functions

• Recording and display of overall vibration trend over time
• Storage and display of vibration trend and phase when rotation velocity changes.

Balancing function

• Number of correction planes: from 1 to 2
• Graphic indicator of measurement stability
• Balancing procedure, guided step by step, with option for editing and intermediate changes
• Vectorial breakdown of the unbalance
• Correction by adding or removing material

General characteristics

• Display: 7” colour LED-backlit TFT LCD
• A/D converter: 24 bit resolution
• Dimensions: approx. 225 x 200 x 50 mm
• Weight: 1.4 kg

Operating conditions

• Temperature: from -10° to +50° C
• Air humidity: from 0 to 95% without condensate

Power supply

• Rechargeable 6Ah Lithium battery
• Charging time: < 5 hours (when battery is fully discharged)
• Power supply-battery charger for 100-240 V, 50/60 Hz (24 V, 1.5 A)
• Battery life: > 8 hours based on typical use

 

Find Us At MACH 2014 Stand 5025 Hall 5

MACH 2014 is almost upon us and as the UK's largest manufacturing technology event, we are delighted to be exhibiting again this year on Stand 5025 in Hall 5.

Running from 7th to 14th April, this is a truly unmissable week for anyone with an interest in innovative technology especially as it has just been revealed that the exhibition will be opened by none other than the world land speed record holder Richard Noble - Project Director for the +BLOODHOUND SSC - 1,000 mph car

With companies such as +Bruderer UK Ltd celebrating a "world first" at the show and prestigious exhibitors such as +Airbus+ and +Rolls-Royce Motor Cars it comes as no surprise that registration figures are already up by 25%!

Our Balancing Machines

We will be exhibiting a number of our balancing machines at MACH 2014 including the ZB5 dynamic balancing machine and the VTB15/M vertical tool balancing machine.

ZB5 Dynamic Balancing Machine

Purposely designed for rotors weighing 0.2 to 10 Kg, the ZB5 dynamic balancing machine can be table mounted or supplied with a rigid base. Rotors are loaded on anti-friction pedestals or roller bearings, adjustable according to the size and type of rotor to be balanced.

In order to reduce operating time the Z5 is supplied complete with automatic indexing, dual rotation and a unique belt drive system that can be either over or under-slung.

B11 Measuring Instrumentation

The B11 is an unbalance-measuring instrument for hard or soft bearing balancing machines, either with vertical or horizontal axis and designed to solve the most demanding problems related to measurement and correction of unbalance.

The unit can be used with complex automated solutions, PLC and computer networks. The software offers user friendly correction programs for adding and removing material including:

Radial & axial drilling
Radial & axial milling
Adding weights
Vector partitioning

VTB15/M Vertical Tool Balancing Machine

The VTB 15/M dynamic balancing machine is designed to measure the unbalance in tools and tool holders for high-speed machine applications. The machine will accept all ISO, BT, HSK and ABS attachments and incorporates a program for eliminating mechanical eccentricity of the mounting tool.

Portable and Condition Monitoring Equipment

The N500 is a user friendly multi-functional analyser, designed for measurement of vibrations, FFT vibration analysis, monitoring total vibration against time or variation in machine speed, as well as balancing rotating equipment under service conditions on 1 or 2 planes.

Come and visit Cemb Hofmann UK at Stand 5025 at MACH 2014.

To reach our expert balancing team, call Cemb Hofmann UK today on 0161 872 3123 or visit our Website.

Balancing Tolerances and Balancing Planes

Let us consider a rotor having a pure couple unbalance of 15 gr mm placed on two different planes with 100 mm distance:

Taking as reference the previous figure, it is clear that, depending on the position (distance ) of the two selected balancing planes, the measured unbalance which is to be corrected varies (30, 15, 10 gr mm).

If the acceptable balancing value per plane is 15 gr mm, then the rotor is considered within tolerance only if the two balancing planes are placed on the supporting position or at a distance of 100 mm; for shorter distances balancing planes the rotor is no more within tolerance.

Now, a rotor should be considered properly balanced (within tolerance ) indifferently of the two selected balancing planes.

As a consequence a correct unbalance tolerance can be specified in two ways by defining:

Defining a limit value (balancing tolerance) for the unbalance referred to the bearing journal directly gives a limitation to the rotating forces which exert on it.

This is particularly useful, because an acceptable residual unbalance calculated with the above mentioned rule, is valid whichever are the two selected balancing planes.

API 612 e 613 standards use this rule and calculate the residual acceptable unbalance with the following formula.

To avoid any confusion between the actual balancing planes (where we act ) and the two planes where the unbalance tolerance is specified.

To specify always, in a clear way, the two planes where the acceptable residual unbalance is valid.

With the use of a modern microprocessor measuring unit, it is possible to specify the tolerance on the two balancing planes or on the two rotor supports.

To specify the unbalance tolerance on the two rotor supports, it is sufficient to set the parameters A = C = 0 and the parameter B = Supports distance

Read more about balancing at the Cemb Hofmann UK site or call our expert balancing team today on 0161 872 3123.

Static / Couple Unbalance with Narrow Balancing Planes

When balancing on narrow planes, it is necessary to distinguish between static and couple unbalance, because the two types of unbalances have a different effects on the supports.

Example 1: Pure static unbalance

The following figure shows the effects ,on the rotor supports ,generated by a static unbalance applied on a over hang pump impeller.

Support loads are calculated according to the laws of static M = 0 ; R = 0 (The conditions for equilibrium are that the momentum and the resultant of all forces are zero).

Example 2: Couple unbalance

The next figure shows the effect generated by a couple unbalance on the supports of an over hang impeller.

 



The effect of couple unbalance is reduced by the ratio of the arms.

For the above mentioned reason, different values for static and couple unbalances are specified.

For instance:
Static unbalance tolerance = 1 gr mm
Dynamic unbalance tolerance (couple) = 4 gr mm per plane

For instance:
For axial fun impeller (width 30÷40 mm and an external diameter of 300÷400 mm) the normal required tolerance on the static unbalance is  30÷50 gr mm while a couple unbalance of 100÷200 gr mm is accepted.

 

 

 



Allocation of Permissible Residual Unbalance To Each Correction Plane According to ISO 1940/1

ISO 1940/1 standards calculate the total acceptable unbalance of a rotor (static unbalance) referred to the plane (rotor section) containing the centre of mass.

The acceptable residual unbalance on the two balancing planes (dynamic unbalance) is calculated taking care of the position of the centre of mass with regard to the position of the correction planes.



 

_Note:

 

_{If the calculated value for U1 , U2 is lower than 0.3 Ut  the value 0.3 Ut  is used ; if the calculated value is bigger than 0.7 Ut  the value  to be used is 0.7 Ut,}

 

 

A frequent application of the above mentioned rules happens with pump and fun impellers (over hang mounted.)

For more information about balancing visit Cemb Hofmann UK today or call our expert team on 0161 872 3123.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



Balancing tolerances calculated according to the maximum admitted load on the bearings

The goal of balancing is to reduce loads /vibrations on the supporting frames, in order to achieve an acceptable life.

The unbalance introduces internal couples and rotating forces on the bearings.  As a consequence, the residual acceptable unbalance can be calculated by stating a maximum acceptable value for the rotating (centrifugal forces) generated by the unbalance in service conditions.

A possible rule is to state that the rotating force is kept below 10 percent of the static load.(USA navy standards)

It is worth pointing out that according to API and to ISO standards, the accepted residual eccentricity (unbalance) varies with the relationship is linear while with the last rule (USA navy standards ) it varies with the inverse of the square of the speed (as the speed increases the accepted residual unbalance decreases rapidly.)

If you would like to speak with a balancing expert then call Cemb Hofmann UK today on 0161 872 3123 to discuss any area of unbalance that you may be experiencing with your rotating parts.