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Turbocharger balancing
Why is it critical for turbos to be balanced ?
Imagine driving along with a brick attached to your wheel rim. The vibration at 70 mph would blur the mirrors and shake every nut and bolt loose.
Imagine this effect in a turbocharger. But instead of 70mph, the speed of the turbine blade tips are now travelling around 850 mph. The imbalance weight may be tiny, but the effect on the turbo components is just as severe.
The result is turbo failure.
This is why every Turbo Technics
turbocharger is balanced on our VSR machine, a machine also developed and manufactured by
Turbo Technics. In fact, the "Turbo Technics VSR Balancing Machine"
has, during the past 10 years, set the World industry standard, and it now used by most
reputable turbocharger specialists.
The VSR machine spins the turbine wheel, using compressed air, up to speeds reaching
210,000 revs/ min. Whilst spinning, the machine measures the tiny amount of imbalance
created by the rotating components and calculates the procedure for correcting this
imbalance. Our skilled machine operators will then make adjustments, until the vibration
results are below the prescribed limits.
A certificate records the vibration limits of every turbocharger. This information is
included when you receive a Turbo Technics turbo.
If this balancing process is not carried out using a Turbo Technics VSR machine, the result can be a turbo which will be noisy in operation and will suffer failure prematurely. Only the Turbo Technics VSR machine measures imbalance to the speeds necessary to be an effective test.
THE HIGH SPEED BALANCING PROCESS
KEY
_____ As the turbo is tested after assembly. Peak vibration 4.4
g-pk
_____ After balancing, peak vibration is
reduced to under 1.0 g-pk
(Results from a typical Garrett GT15 on Turbo Technics VSR Mk III balancing machine)
Why do turbochargers need to be balanced ?
All high speed machinery needs to be balanced to fine limits. In the case of the turbocharger this has traditionally been achieved by careful balancing of individual components which normally ensures an adequate level of balance for heavy duty applications, typically large diesels.
The advent of the passenger car turbocharger has brought with it a more demanding requirement because of the higher rotational speeds and the more exacting demands of the installations. The typical car engine is light in construction and hence susceptible to vibration sources, which cause noise, and the vehicle driver will not tolerate even modest noise levels.
For these reasons the car turbocharger requires balancing to much finer limits and this cannot be achieved by balancing of individual components alone. Assembly tolerance stack-up means that even carefully balanced components, when assembled in a group, can give a cumulative imbalance which is unacceptable, while geometric errors in shaft straightness, squareness of faces etc., can also considerably influence the total assembly. This problem is exaggerated when parts are re-used in reconditioned units, and modern high-speed turbochargers are particularly sensitive.
The solution to this problem is to achieve a more precise state of balance which can only be attained by balancing the complete assembly over a speed range close to the maximum operating speed of the unit.
Turbo Technics have developed the "Vibration Sorting" technique for service use and have been producing machines employing this principle since 1983. The method has been improved and refined over several years experience of balancing Turbo Technics’ own production units, and is the same method as used by major manufacturers, incorporating trim balance.
The very wide range of turbochargers in use today has created the need for a machine which has great versatility and short-cycle times. The Turbo Technics Mk III machine has been developed specifically to meet these requirements in the aftermarket.