Quick question. Does glass-filled nylon have good bearing properties? I would have expected its bearing properties to be poor, because wear would essentially cause particles of sand to break off, but I have been told otherwise. The product in consideration is a ground nylon piston in a reamed brass cylinder. A little lubrication, but not a lot. Anyone know?
How long is a piece of string? A few more details about the application would help, dimensions / load / pressure / sliding speed / how many cycles or how far do you need it to slide? Do you want the cheapest solution, or is it an expensive bit of kit that you don't mind spending money on?
Transparent doesn't sound like glass filled nylon, more like acrylic, polycarbonate, perhaps epoxy?
Glass filled nylon is cheap, readily available, easy to machine. There are also nylons which contain some oil to make them more self-lubricating.
PTFE is pretty good, though not so strong. Fabric reinforced phenolic is strong, but less happy at combination of high load and sliding speed. Polyimide (e.g. Vespel) is the Rolls Royce material for many applications, but not cheap.
The only issue I can see with Nylon in that application is Nylon is Hygroscopic - it attracts and absorbs moisture to some degree - so make sure you provide ADEQUATE clearance for expansion. Glas filled should wear very well in that application - just make sure cooling is adequate as well as the clearance.
It is too clear to be filled with anything. It could be nylon, polycarbonate or even low density polyethylene. If you can do destructive testing, strong acids will eat nylon, and ketones (lacquer thinner) will eat polycarbonate. Polyethylene will be more resistant to both, but it is not compatible with mineral oil.
There are some easier tests for basic plastic types and more detail can probably be found on the net. 3 of the basic ones I remember are nylon when burned smells like burning hair, polypropylene and polyethylene smell like a burning candle but one floats in water though I can't remember which one, it'll be the less dense one anyway. There are a number of other simple tests like these to help narrow down the basic stuff.
I have actually been told that this proved to be a problem at times. I'm trying to trace the history of this product, and have been told various things about the plastic: that it was thermally moulded, that it was special nylon with a low coefficient of friction, that it was hygroscopic, and lastly that it was glass-filled nylon. I've been told these things by different people, and am trying to figure out the truth. The glass-filled nylon part I had doubts about.
Well, 'nylon' means polyamide plastic, glass-filled means it was probably thermally molded to a precise size (that's the benefit of the glass filler, that the size is stable).
I suppose you could burn a sliver to see if it has the ammonia-like smell of polyamide. It's more likely that a low-friction plastic (Delrin aka acetal) would be used, rather than polyamide, for a sliding part.