Vibration Vs. Spin Speed

[pulsator]

A friend of mine asked me why their new Duet Sport seems to vibrate an awful lot on the slower speeds, but then seems to stabelize once it reaches the higher. That sparked a question from me to everyone here. I get that the machine vibrates more on slower speeds, and when it begins to reach higher speeds, it starts vibrating so hard that the vibrations cancel each other out and the machine is stable. But, at what speed do most front loaders seem to stabelize?

 

[toggleswitch]

The Euro crowd has said this as well. It will be interesting to hear the responses.

 

[jasonl]

Resonant frequency

I've seen my Frigemore do this. Apparently, the suspension system seems to have a natural frequency when the tub is spinning at the right rpm, the it will cause the whole thing to vibrate and as the tub goes beyond that certain frequency, it begins to settle down.

 

[bingwsguy]

Jamie,

Several years ago I had an ASKO set in my kitchen. Even though the cabinet of the machine was absolutely free from vibration at all speeds (thanks to it's great suspension and tub design) I could feel the vibration in the wood floor... especially around 1000 rpm, but it seened to get less noticable around 1200rpm and by the time it hit 1400-1600rpm it was gone completely.

My Bosch Axxis set was a different, yet similar story. The cabinet on that machine vibrated quite a bit at 1000rpm, but it also seemed to become less noticeable around 1200rpm which was it's top speed.

My Siemens set,which is much larger, does the same as the Bosch...cabinet vibration around 1000rpm then smooths out at 1200rpm which is it's top speed as well.

So... my real life test results say most stabilize around 1200rpm, but I don't know why. Anyone know the technical reason/answer?

 

[pulsator]

Hmmm... ok, thanks for your input guys! No wonder dad's Duet shakes ridiculously, it only has a top speed of 900 RPM!!

 

[dascot]

It's not just to do with vibrations, but resonance frequency as well. I think a lot of flooring materials seem to have a resonance frequency that corresponds with the frequencies produced by the washers at around 900-1000rpm, at least in my experience.

 

[sudsman]

I am not sure this is any help

One of o my maint. men here has told me that there is such a thing as "harmonic balance" and that it can cause such to happen. In his explaination to me it seems that it has to do with the size of the load and the weight and the speed it is turning at. He says that as more water is extracted from the load that it becomes lighter and it settles the balance .

 

[irishwashguy]

You can feel it

When mine spins at anything above 600, you can feel it. I also do not thing that mine is perfectly level either, it seems to be ok usually, but when you hear the 1300, one of my friends thought that it was an small Earthquake, nope, just the Miele.

 

[kirri]

Many years ago, i had a Hoover logic 1200.It was as smooth as anything at 500rpm, but when it jumped to 800rpm, it used to go crazy- vibrating like mad and REALLY noisey.When it then jumped up to 1200rpm, it was as smooth as anything with no vibration at all. I had hoover out over this but they couldn't explain it and said i would basically have to live with it!

 

[brisnat81]

My Miele is on a Wooden Floor

And at spin speeds around the 900-1200 mark, the vibration is quite noticable, both in the machine and through the floor. By the time it ramps up to 1800RPM for the final 2 minutes, it usually gets quiet and settles down usually with no vibration in the machine or the floor.

The machine I have now, is a TOL model, and surprisingly it has more vibration issues than the MOL model it replaced, regardless of the spin speed. I'm not overly happy with this one, and my biggest reccomendation to anyone looking to buy Miele is to not bother with the High end products, buy the one that has the features you require and dont bother with the gimmicks above that.

 

[rolls_rapide]

Wooden floors...

...can act like trampolines, amplifying any vibration.

A friend had a European Whirlpool frontloader, that span at 1000rpm. This machine danced everywhere, even though it was eventually moved into a corner, and the floor concreted!

She and her husband were about to go on holiday, when the machine packed up, so she bought another Whirlpool, and this spins at 1200rpm. This machine is very stable in comparison to the old one.

I believe that some machines have a poorly designed spin profile, and others have a much better designed spin programme.

For example, my Zanussi achieves a small spin burst to extract the majority of the water, before it redistributes back and forth, prior to ramping into the lower speeds. It then increases the speed in stages, up to 1600rpm. Seems to be a very stable spinner; just a bit of oscillation at 900rpm.

My Mum's Bosch seems to only distribute in one direction, before ramping up the speed. This creates a fair amount of vibration. Halfway through the spin cycle, it will decrease back to distribute, then ramp back up to the full speed, vibrating as it goes and making a hell of a noise. The other evening it was trying to rebalance a load of towels a couple of times, but couldn't as the towels had become stuck to the drum wall. I manually freed the load, rotating the drum by hand, then set it to spin again: this time it was perfectly balanced.

 

[launderess]

IMHO vibrations during spin cycles are more the result of unbalanced loads than anything else. When loads are in perfect harmony in my Miele, there is no sounds during the final spin other than the soothing "jet engine at full throttle" sounds. However if a load is unbalanced there will be some shaking/vibrations. How much will depend upon how unbalanced. My vintage Miele is not as picky as many of today's newer machines about unbalanced loads and spinning. While have yet to cause any harm, or cause the machine to bounce around the room, it sill will rise to the occasion and get the job done.

Simple laws of physics dicate if there is more weight on one side, the tub is going to pull towards that direction. That beind said, have stood near 50lb laundromat Speed Queen washers, and on a full load say of heavy featherbeds, you can feel the vibrations coming through the concrete floor from the machine. This even standing several feet away from the washer.

L.

 

[jaums]

That sudden increase in vibration . . .

I was curious about the sudden increase in vibration during spin-up and spin-down. Apparently it is an aspect of the nature of vibration called "resonance". As with an opera singer's sound being able to break a wine glass as the frequency of the vibrations of the voice reach the vibration rate of the natural frequency of the wine glass, the resonance speed of the drum of a washing machine is the speed at which the vibrations increase dramatically. That particular speed is not a good speed for the machine to maintain as it gradually speeds up or down, so engineers program the machines to pass through that speed quickly as a part of the algorithms that are designed to minimize vibration and noise.