9 replies to this topic

[Steve]

Has anyone got any experiance using cylbebs (cylinders with diameter = length) and balls in milling? I've always used balls, with good results, but have run low on stock and my supplier is offering cylpebs. I've never used them before but I think I've heard people making them. Do anyone know how well they compare with regards to milling efficiency, lifetime and anything else that is relevient like ease of use etc.

[etrek]

I use brass rod where the diameter is approximately equal to the length, and I’ve had good results, but I have nothing to compare it to, I've never used spherical media. It takes a minute or so for the cylinders to 'align' themselves into an appropriate rolling position, instead of tumbling around, but other than that, they seem fine to me

Edited by etrek, 19 December 2006 - 10:44 PM.

[Frozentech]

Has anyone got any experiance using cylbebs (cylinders with diameter = length) and balls in milling? I've always used balls, with good results, but have run low on stock and my supplier is offering cylpebs. I've never used them before but I think I've heard people making them. Do anyone know how well they compare with regards to milling efficiency, lifetime and anything else that is relevient like ease of use etc.

My best milling media is hexagonal brass bar stock, .75" across x .75" long, so roughly that 'cylpeb' shape. it is more efficient than ball, the lifetime will depend on the material they are made of. A good brand of ceramic media ( Coorstek ) are that shape also.

[BrightStar]

I have always had good results with ceramic balls so would stick with them just to keep my milling times consistent. I haven't tried cylinders.

The suggestion from a few articles on Google seems to be that the greater contact area of the cylinders gives a narrower particle size distribution in the milled product, in particular fewer oversize particles remaining at the end. For the coarsest particles, cylpebs give a higher breakage rate than spheres. For the finest particles, the performance with each type of media is much the same, both giving an equally fine ultimate product.

This difference might be somewhat advantageous for making BP, allowing a slightly shorter milling time, but not so good for the partial milling of charcoal for screening or glitters / tigertails where a wide range of particle sizes is desirable. I suspect that we generally 'over mill' our BP in any case.

The size distribution is also said to be dependent on the media / charge volumes and mill speeds, so I am somewhat sceptical as to the validity of some of these claims. In the words of one author, 'The manufactures have made conflicting claims regarding the milling performance of Cylpebs in comparison with balls.'.

As to the questions of wear on the mill and media, intuitively it seems as if it should be less with the spheres - they should at least wear evenly. We could just look to Ziconia media for some really hot BP

A few refs of abstracts:

Comparison of grinding media: Cylpebs versus balls

Grinding media shape: cylpebs versus balls

Edited by BrightStar, 20 December 2006 - 03:13 AM.

[pyrotrev]

I would suspect that it would depend on what you're milling since the grinding mechanism would be a bit different, since the cylpeb has fairly sharp edges at the ends giving smaller, but higher pressure contact points.

[newtoolsmith]

Hi friends,

I use balls, lead balls, for BP and such mixtures only because they are sparkless.

For all other purposes, fuels, oxidizers and other pure chamicals, I use clypebs I took from spherical roller bearings. Their edges are very efficient nd they are very resistant.

MfG
newtoolsmith

[parabolic]

I tried a batch of 'lead ball' milled BP for my first time the other day, it was quite fast, I left it on for about 15 hours, I tried the same but with a big hand full 20mm brass bar cut to about 1" length, the result was alot slower burning BP it was run for the same time as the first batch.

perhaps cylinders need more time?,

[Steve]

I don't think you can compare Lead balls with Brass Cylpebs and draw conclusions based on shape entirely. I would probably consider the higher density of Lead to play a big part here.

[karlfoxman]

I have recieved my Cylpebs from Inoxia and they seem to make higher quality powder than my lead balls so im very pleased!

[portfire]

I have recieved my Cylpebs from Inoxia and they seem to make higher quality powder than my lead balls so im very pleased!

yes indeed,i'm also using cylpebs from Inoxia, i use them for oxidizers (kno3 at the moment) and after 5 hours milling is an extremely fine powder, so im very pleased aswel definitely recommend them

Edited by portfire, 28 January 2007 - 03:10 PM.