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Summary Unit 11 Assignment B Distinction
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Unit 11 Assignment B-Distinction
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Unit 11 Assignment B:Apprentice Name: Nicole Senyurt
Apprentice Role: Trainee Maintenance Technician
Company: CNC Ltd.
Introduction:
CNC Ltd. Is an engineering organisation that manufactures a range of household
appliances including microwaves,freezers and washing machines . As a young
individual,I am a trainee maintenance technician whose role is to maintain a wide range
of pieces of machinery . At CNC Ltd, I focus on maintaining these two type of machinery-
manual and CNC machinery which are used for the manufacturing of these appliances.
Due to my enthusiasm for working on the maintenance activities, my supervisor has
requested me to investigate how condition monitoring is used in order to detect faults
and potential failures in engineering machinery. This is to ensure that I gain further
understanding about my role as a trainee maintenance technician. Therefore this report
will include these objectives below to ensure that I understand the purpose of condition
monitoring within maintenance.
Condition Monitoring techniques & equipment:
Vibration analysis:
What is vibration analysis?
Vibration analysis is a type of condition monitoring technique that involves monitoring
the levels and patterns of vibration signals within machinery in order to detect any
potential abnormalities within vibration events and to evaluate the complete condition of
the test object.
What is vibration analysis used for?
Vibration analysis is a type of condition monitoring technique that involves monitoring
the levels and patterns of vibration signals within machinery in order to detect any
potential abnormalities within vibration events and to evaluate the complete condition of
the test object. It is used to identify three major measurement parameters as each one of
these holds importance to various frequency ranges:
Acceleration- This is essential to high frequencies as it can observe bearing
condition of the shafts we use within our CNC machines. Therefore when the shaft
could potentially be faulty or is bent this causes vibration , hence with the aid of
acceleration this can see the bearing condition of the shaft in order to potentially
enhance its bearing condition and help to minimise further delays when
manufacturing our microwaves.
Velocity- This is essential to both high and low frequencies as it is related to the
destructive force of the vibration caused in the CNC machines for example. Thus
it is important to have velocity as it is the most important unit available.
, Displacement- This is essential to low frequencies as it is essential for during
dynamic balancing, orbits and Operating Deflection Shapes. For example, when
handling electric motors in the CNC Lathe machine, you will need to be able to
use displacement during dynamic balancing which occurs within the shaft of the
electric motor by rotating parts quickly and measuring the imbalance with the aid
of an electronic equipment so that the imbalance can be corrected by
adding/subtracting weight from the rotating shafts until the vibration is minimized
with dynamic balancing.
Furthermore, vibration analysis is typically used to detect:
Irregularities of bearings
Rotor imbalance
Misalignment and loose coupling
Thermal instabilities
Mechanical and electrical systems of generator irregularities
Thus vibration analysis is a common condition monitoring technique used typically
within rotating machinery due to how it monitors the condition of the critical components
like bearings,shafts and gears in the large rotating machinery.
How does vibration analysis work?
Vibration analysis is a type of condition monitoring technique that involves monitoring
the levels and patterns of vibration signals within machinery in order to detect any
potential abnormalities within vibration events and to evaluate the complete condition of
the test object. This is commonly directly conducted both on the time waveforms of the
vibration signal which is obtained by using a Fourier transform on the time waveform.
Once this is done, the time domain analysis that is based on chronologically recorded
vibration waveforms help to reveal when and how grave the abnormalities found within
the vibration events occur which is done by extracting and understanding the
parameters not excluded just to RMS, standard deviation, kurtosis, skewness and much
more. Time domain analysis is also useful for reviewing and evaluating the overall
condition of the monitored targets.
This is typically useful for especially the rotating machinery within our company as we
have machines like the CNC machines which is a type of electrical machine. It works by
having the AC motor converting the AC into mechanical energy and this machine
consists of two parts- an external stationary stator which has coils supplied with the AC
in order to produce a rotating magnetic field and an inside rotor attached to the output
shaft which is given a torque caused by the rotating field. Hence as our CNC machines
have some form of rotating machinery like the shaft used within the manufacturing of our
freezers, it is essential to involve both frequency spectrum analysis and time domain
analysis. As the CNC machine has a rotating component like the shaft ,this can typically
cause many vibrations. Hence it would be harder to only use time waveforms in order to
examine the condition of the most critical components within the CNC machine like the
,shaft and bearings within the large rotating equipment inside the CNC machine. And with
frequency spectrum analysis, it helps to decompose the time waveforms and describes
the repetitiveness of vibration patterns so that the frequency components correspond to
each of the components that are to be investigated within our CNC machines as it uses
rotating machinery. Additionally, with using the Fast Fourier Transform aka FTT
technique, this helps the manufacturers within our company to facilitate a quick and
efficient frequency analysis and also designing a range of digital noise filters in order to
block out the vibrations and at the same time ensure that the welfare of the
manufacturers is positive.
Why is it used?
After discussing how this technique works as well as its applications, this technique has
several advantages:
Preventing machine failure-As machines that have faults can lead to a
catastrophic failure,secondary damage or even downtime this will cause the
critical components to vibrate like the rotor within the AC generator as this is the
rotating part and produces a magnetic field in the generator which is based at the
plant ,hence by using vibration analysis this’ll enable us to understand the nature
of the problem and the seriousness of the fault. By having obtained this
information, we can use this in order to plan maintenance activities and minimize
machine downtime and reduce the plant costs at the company.
Cost Reduction-With the aid of vibration analysis, we can reduce the parts and
labour expenses quite vastly as vibration analysis is able to detect a problem with
a small less deer part which is replaced in time so that catastrophic failure is
prevented and also getting rid of the need of time and cost for replacing the entire
machine like our CNC machines for example in the latter.
Scheduling Maintenance in order to reduce critical callouts- By having scheduled
maintenance put in place ,this helps to replace the individual components of the
machines like the generators and pump at the plant in order to minimize the need
of downtime and the need of emergency overtime for unplanned repairs or the
need of having to replace equipment at the plant. As unplanned emergency
repairs can cost you up to thousands of pounds,which could jeopardise the
company’s profitability and the possibility of saving money for advanced
machines in the future, thus by having vibration analysis performed within
, proactive maintenance planning ,this helps to eliminate the need for critical
callouts which benefits the company a lot.
Optimising production and welfare of the plant- By having small and simple
repairs ,this helps to relieve the vibration issues that occur such as the bearings
within the CNC machines at the company as these are performed at planned times
which do not occur within the busy production process. Thus by having this done,
this results in a smooth operating equipment which enables the plant to be a safe
working environment and the employees within the area can feel safe and secure
when dealing with the rotating machinery.
Proactive Maintenance Efficiency- As vibration analysis helps to identify the
failure of the machine components, maintenance teams are then able to realise
which parts,tools and plant support is needed in order to do effective repairs so
that the plant can run and have a minimal downtime. Thus by troubleshooting the
problem without the need of having a diagnostic guesswork, this allows the plant
to have corrective maintenance action put in place and done correctly the first
time in a fast manner.
Why would someone not use it?
Extremely High frequency- As common sensors have a maximum frequency range
of 10 –15 kHz, then this would be a problem as when you do not invest in special
sensors ,higher frequencies will be not be able to be detected in the rotating
machinery with vibration analysis.
Lubricant condition- As this is one of the hugest limitations to this technique,
since lubricant condition cannot be evaluated with vibration analysis. This
technique is poor to perform an evaluation of this and hence the personnel can
only suspect the lack of lubricant through diagnostic guesswork which is not
really appropriate within a manufacturing plant as they need to be able to identify
the problems immediately of our shafts and get the CNC machines running again
in order to produce mass production of the household supplies at the company.
Ultra-low frequency- As vibration analysis is able to detect high,medium and low
frequencies, it is typically hard to detect extremely high frequencies and ultra-low
frequencies. As ultra-low frequencies are often ignored ,since they have the need
of having long samples which are not achieved in a normal route and has to go
through several phases, this can limit the effectiveness of vibration analysis and
how it tackles all ranges of frequencies at the plant.
Temperature analysis:
What is temperature analysis?
Temperature analysis aka thermal analysis is a condition monitoring technique that is
used to study the properties of materials as they change with temperature and detecting
changes in temperature within a critical component like a bearing, fuse or a relay.
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