BEST MATERIAL SPEC FOR ROLLERS 2

[rgajewski]

I have an application where we are using 3-1/2" DOM steel tube to create rollers for a web handling machine. THe issue is we are "attempting" to have the roller dynamically balanced and are having issues. The RPMs are up to 3100 RPM, and in our clculations we go through 2 critical speeds. The roller is 60 " long/wide. Is DOM steel tube the best material to callout for this application?
Thanks
Ray

Every once in a while the voices in my head have good ideas.

 

[eromlignod]

Are you sure the tube is the issue, or could it also be due to the hubs?

Don
Kansas City

 

[rgajewski]

The "hubs" / journal ends are seperate from the main body of the pulley and the "initial" balancing of the pulley. The assembly will be balanced as a unit after the body is balanced, as the body consists of ~95% of the mass. The journals are a bolt on part, with the (4) bolt holes being equally spaced a equal on both ends.
Thanks
Ray

Every once in a while the voices in my head have good ideas.

 

[mfgenggear]

Ray

Depending on how close of tolerance you need on the dynamic balancing.
scale of 1 thru 10 , 10 is hardest,

.070 oz in. = 5
.005-.020 oz in. = 10

what is your requirement?

the tubing even tho Drawn may not be close enough.
it may require centerless grinding on the O.D.?
how round are the parts, wall thickness maintained?

Try this

if you do a sample inspect, on a surface plate. place the cut DOM Tube over two precision v blocks locating on the outside diameter & Indicate the ends of the ID's, indicate over the entire od with dial indicators.
this will tell you how true it is.

we have small tubes machined from solid bar, ground & we hold .001 in oz.

post back

HTH

 

[dvd]

...nothing like re-inventing the roller...

http://www.webexinc.com/index.html

 

[eromlignod]

I can't think of any straight-from-the-mill tubing that I would trust at such high rpm. You'll probably have to have some additional machining done to whatever you use.

You can centerless grind the outside, but since the process is "centerless", this doesn't really ensure that the ID is concentric with the OD. So you'll probably have to have the inside bored as well.

Don
Kansas City

 

[mfgenggear]

Link provided by DVD is your clue

STANDARD SPECIFICATIONS:
2" dia. x 0.25" wall 6061-T6 aluminum tubing machined for minimum stock removal
32 Ra finish on roll face
Dynamically balanced at 1000 FPM
O.D. and bore run out within 0.002"

Straightness over face width within the greater of 0.002" or 0.0005"/ft. of length
Low-friction bearings installed for a 0.75" dia. shaft*
*See "Shafts & Mounts" for more information.

 

[rgajewski]

Thanks to all for the help. Our vendor was able to balance the pulley. I believe the "dificulty" was in the DOM tubing to begin with, as I tried a method of checking how true the material was, as posted by MFGENGGEAR, and I was pleased/unpleased to find out that it was out about .010" And at the RPMs of 3100, it makes a diffeence. We will gun drill/bore the tubing next time, prior to balalncing.
Thanks
Ray

Every once in a while the voices in my head have good ideas.

 

[mfgenggear]

Good to hear all is well. :/
Thanks for posting back & letting us know.

Take Care