Minimum rotation speed for a brush

[IndustrialPSI]

Hi all.

I'm trying to develop a transversal brush, and first I have to know the minimum rotation speed to keep the fibers straight. In this way, I've tried to calculate it through the tipical formula of a U.C.M system, but it doesn't works because the result obtained is higher than the empiric one (189rpm / 100-120 rpm).

Fc = P; --> where P = m · g;
Fc = m · (V)2 / r; --> where V = w · r;

Obviously, I know the mass of the fiber and its lenght.

Probably the problem is in the fact that the fiber is not a rigid solid, but flexible.

Please, can someone help me to find the best way to obtain the right result??.

Thank you in advance.

 

[mac]

I think you left something out of your equation. There are other factors involved. For instance the brush length on an Istobal is around 14”, while on some machines it can be almost 3’. Stiffness of the material plays a big part as a stiff brush doesn’t need a high rotation speed. The material itself matters a lot. I have seen some NS machines using what they call Lammscloth. These are basically real fuzzy pieces of carpet. Spin those greater than 40 revolutions per minute and inside the car it will sound like you’re in a demolition derby. Tire brushes are real stiff and spin slowly. Good luck.

 

[IndustrialPSI]

Hi.

First at all, thanks for your response.

Of course the material is basic to solve the question. Sorry, I forget to mention that I use to work with Favagrossa Filok brushes (the best in my opinion), formed by LDPE fibers that need higher spins than other ones to raise. Maybe I can try with the Young module based on the fact that is the minimum force to deform the fiber, ...I'm really a little bit confuse...

Thanks!!!

 

[mac]

Can you describe the fiber or show a picture of it? There are more factors involved here. The early machines used what looks like heavy fishing line. They were referred to as weed walkers, for good reason. Making a material that works on paper is different than real world operators using cheap spap or none at all. If it looks like heavy line many customers will not go through it. I am at my wash with an Istobal machine Most days for a few hours. I have to convince them my material will not scratch, dull, or mar a finish. I usually do this by showing them a picture of an Istobal washing $600,000 Lamborghinis coming off the assembly line.

 

[IndustrialPSI]

Can you describe the fiber or show a picture of it? There are more factors involved here. The early machines used what looks like heavy fishing line. They were referred to as weed walkers, for good reason. Making a material that works on paper is different than real world operators using cheap spap or none at all. If it looks like heavy line many customers will not go through it. I am at my wash with an Istobal machine Most days for a few hours. I have to convince them my material will not scratch, dull, or mar a finish. I usually do this by showing them a picture of an Istobal washing $600,000 Lamborghinis coming off the assembly line.

Yes, it is always the same old song. In my case, the brushes clean trams and trains of several million dollars, and the customers ask for the softest fibers to take care of their vehicles and bodies. I attach a picture with brushes turning around 100rpm. As you can see, they need more speed, and that's one of the reasons because I'm dessigning the machine from 0 again.

 

[soapy]

A top brush will need more speed than a side brush I think. As I recall side brushes rotate between 50 to 100 rpms but not sure of top brush on the units I have had.

 

[IndustrialPSI]

A top brush will need more speed than a side brush I think. As I recall side brushes rotate between 50 to 100 rpms but not sure of top brush on the units I have had.

Yes. I've talked with Favagrossa and they advice to set the speed of the top brushes at 120rpm's. The problem is that I would like to obtain the same theorical result.

Thanks!.

 

[mac]

Ah the age old conundrum of getting the theorical result. A method I sometimes use when faced with a complicated issue is simply to make a guess. For instance I have long forgotten the formula to calculate the cube root of a number. So I just guess and then cube the number. If the answer is too high, I just lower it a bit. After 3 or 4 times you will be real close. Just keep doing that till you reach the number of decimal places that count. Same here. Set up a brush and surface similar to the train you want to clean. Vary the speed and pressure and soap till tbe customer is happy with the results. If you want to really impress the customer, show them pages of calculations. They won’t understand it anyway.