Balance service of Ali Akbari centrifuge fan and rotating equipment of factories in Alborz province

Under the management of engineer Ali Akbari

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10 secrets of fan balance

The most useful and shortest Persian text related to Balance Fan presented by the professors of "Balance Fan Alborz".

1. The quality of the fan construction can be seen from the weight of the balance. If you are a fan maker, it is better to balance it in 2 steps.

At the first stage, to balance the fan, try to loosen the umbilical screws and tighten them in such a way that the fan is drawn to the opposite side of the unbalanced area, to compensate a little amount of weight. In that case, the amount of imbalance will not increase by inserting the spike.
If you are using laser cutting to make a fan, try to fit the spikes and holes connecting the blades to the hub and shroud. Of course, not to the extent that it is not assembled.
Do the shaft turning process in such a way that there is no need to remove the shaft from the three systems and reverse it. The turners know what we are talking about.

2. Be careful of fans that have couplings.

Most couplings are cast and unbalanced. This is a silent imbalance that affects the system. You balance the fan but it still vibrates. Because the coupling can be unbalanced.
Misalignment of couplings in fans is the second most frequent problem after imbalance. If you think that you can align the coupling with a cutter blade and filler alone, we must say that it does not work in many cases. Unless the employer does not want quality from you. In short, a lot of fan troubleshooting ends with this misalignment.
Misalignment can also happen in fan belts and pulleys.

3. If the navel is crooked with respect to the shaft, the vibration can be reduced to some extent with dynamic balance.

But you will have the lameness of the butterfly. If you are going to accept this issue, then you need to slightly increase the space between the hub and the back wall of the spiral and the shroud and the front wall of the spiral. This will reduce the efficiency of your fan.

The sign of this problem is that the propeller requires abnormal weight.
Remember this golden saying: if you see a limp fan with the naked eye, but this limp does not cause abnormal vibration or noise, and at the same time the fan provides adequate air output, no one can say that the fan is broken. Even if you see lameness with your eyes. If someone says it's broken, answer: Why? According to which criteria?

4. The lack of distance of the shaft can be fixed to some extent by static balance.

But the correction weight should not be too much compared to the total weight of the impeller. Define what we mean by "a lot".

5. The best balance of the fan is done when the assembly is final.

If you balance the impeller or the impeller on an industrial balance machine, then install it in its place, it will become unbalanced again due to assembly errors. So the best possible balance is after the final assembly.

In many heavy equipment, even lifting and transportation results in imbalance, for this reason, they are balanced once at the destination and place of operation.

6. Fans with large dimensions or high rotation speed should be balanced on an industrial balancing machine before final assembly.

No matter how carefully the production of these equipments is done, due to their large dimensions or high circumference (or both), they still suffer from imbalance. If you balance this equipment on the final location from the very beginning, not only the safety of the work will decrease, but there is a possibility of serious damage to the bearings and structure and the appearance of looseness and the fan base.

7. Plastic fans such as Fan 206, Pride, Peugeot, etc. are only balanced on a single plate.

If the umbilical or electromotor shaft (internal or external) of this equipment is not tilted, you will definitely get the result with a single-plane balance. If not, you will know that the work is lame from somewhere else. This issue is also true in relation to the types of backward and forward fans with low thickness.

8. Weld the large balance weight between the hub and the spiral wall.

Of course, in this case, you should consider the fan balance weight a little wide and place the center of the weight on the center of the place opposite the imbalance.
Putting a heavy weight on the edge of the blades or on the shroud will cause the fan to howl.
A bitter truth: the bigger the balance weight, the lower the quality of your construction.

9. Unbalance is the last manufacturing or maintenance operation on the fan.

After balancing, doing any kind of wrenching, grinding, welding, hitting, even painting can unbalance the fan again. Balance the fan before putting it in the carton. If you are welding the weights, only repaint over the weld black.

10. If you can balance the system statically (in a state where the vane rotates up to the nominal speed), it is much better than doing dynamic balancing.

Dynamic balance is suitable for equipment that has dynamic imbalance. If fan vibration is solved by static balance, its dynamic balance is unacceptable. In dynamic balance, we install at least 2 weights on the rotating part, which brings the following disadvantages:

More weight means creating more fluid noise. Maybe you have ever tried to spin a wire in the air. In such a situation, the sound of the rotation is clear in the direction of splitting the air. Now suppose an additional weight is going to be installed in a part of the propeller and rotates at a speed of 1500 rpm.
The risk of further separation in the future and the separation of the balance weight means creating imbalance. Also reducing the safety of the equipment operation.
If the equipment that needs static balance is balanced with a dynamic method, the balance system will probably offer you very heavy weights that are unreasonable to install on the rotating part.