There is a quick answer, cost. They are much more expensive. You also have to be careful as nylon and HDPE have very different thermal properties to metal and there are many cases of assemblies failing as a result of poor design. If you want to purchase them, take the time to get details of the way they have been assembled and preferably get a sample and have a look. They do have there application and they do work well

Cheers

Col Benjamin

Gulf Conveyor Systems Pty Ltd

www.conveyorsystemstechnology.com ■

Indeed John, plastic rolls are quite common, and are popular for the following reasons:

- quiet and therefore good when close to people (especially at night)

- light, so easier to change out

- good for next to the sea

- good for sticky materials

- some are machined round, and are good near weightometers, and eliminate belt flap

Make sure you get good quality ones though. The ones with the blue sleeve tend to fail when the sleeve tears and slides off.

You do score a bit on power consumption, but it is a small amount, and nowhere near 30%!

(See also previous thread on same topic)

LSL Tekpro ■

Polymer rollers life is much, much higher than those of conventional steel rollers.

Regards, ■

Nylon Idler rolls can work in some applications but do not appear to work well in hot climatic conditions. Rolls splitting, bearings flogging out the roll heads, disassembling the shell from the head ends, flat spotting, bending @ >0.25" = 1/2" (12.7mm) TIR, melting of the poly at temperatures of 60 degrees Celsius in the sun and just downright UV degeneration. I have attached one of my The Innovator Speaks commentary[The Innovator Speaks20100811.pdf] to illustrate my views. I have addressed what I believe is a very comprehensive insight into issues that I have seen arise from their use. Personally to date, I have yet to find a reasonably good roll in any sort of nylon or poly construction but that may be just my luck of the draw. Believe me, I would advocate nylon or poly rolls if I came across a good roll.

Attachments

the innovator speaks_20100811 (PDF)

■

Hello John,

At EMO, bulkterminal in Roterdam, we tried a few brands of non steel idlers. They melted down, broke in pieces, stood stil instead of rotating (and had flat surfaces)

Compaired to our steel idlers their performance is poor. our steel rolers have a lifetime of 10 to 12 years.

We are situated right at the seaside, so the conditions are not optimal. But I think this is a fair lifetime. we have some belts covered and here is the lifetime even longer. We donot use a cheap rollers but we have verry little breakdown. (and we run about 40 km of steelcord belt at 4.5 m/sec)

You can find information about them om: http://www.stokmanbv.com ■

Guys, I would be interested to hear if the historical problems with the cheap plastic rollers have been eliminated. I designed some a number of years ago that were very successful ( although not cheap ) I would be interested in working with anyone who is looking for as high quality solution at a competitive price.

One feature we integrated into our roller was a dual colour sleeve where the outside was blue and the inside was yellow, this meant that remote visual inspection could show up wear problems. This was something that I as a "non industry" guy though might have been useful

Look forward to some input

Stuart Dalrymple ■