abrasion resistant "rubber" 2

[Tmoose]

We have some 1/4 thick rubber flaps acting as valves in return piping transporting pulverized coal. They are Not in main stream flow, but subjected to continuous gravity return flow of coarse particles. several Angle iron strips are bolted to the rubber to enforce bending in one direction only.
Many of The originals reportedly have worn thru after about a year's service. I have asked for the worn parts to be sent here for evaluation.
They came from China and are of an unknown material.
We need to make or buy some replacements quickly.

My first choice (guess) would be some kind urethane material.

What material generically would offer the best abrasion resistance with good flexibility?

thanks,

Dan T

 

[tom1953]

Polyurethanes are generally the best for abrasion resistance. Flexibility would be determined by the hardness of the urethane material, which can range in hardness from <30 Shore A (~rubber band hardness) to >99 Shore A (!bowling ball hardness).

Without further info, I'd guess an intermediate hardness, ~60-70 Shore A, would give a combination of excellent abrasion resistance and flexibility. In this hardness range you could get/make parts from castable (liquid) urethane, TPU (thermoplastic urethane) or millable (rubber) urethane.

tom

 

[Tmoose]

should have mentioned operating temperature may reach 300 F

 

[tom1953]

Yes, temperature is definitely an important factor. That being the case, my vote would be for HNBR.

 

[GrahamBennett]

I agree with Tom. HNBR has the required temperature resistance. However, if 300°F is only intermittently seen, then EPDM is a good alternative. Both can be compounded to give high levels of abrasion resistance.

 

[tom1953]

I think HNBR would give significantly better abrasion resistance compared to EPDM, although the polymer cost for HNBR is probably 5X (or more) than EPDM.

I just completed a study where an HNBR had 124 mm³ loss in a DIN abrasion test, while two different EPDMs had 192 and 217 mm³ loss (lower is better). None of the compounds were compounded specifically for abrasion resistance, so I'm sure the gap could be narrowed, but if you're looking for the best abrasion resistance with moderately high temp resistance, my vote's still with HNBR.

tom

 

[Tmoose]

thanks !

The true operating temperature of this device seems to be creeping upward.
350 F continuous is the new (for now) requirement.
Fiberglass reinforced silicon has been promoted as perhaps our only choice.

Dan T

 

[GrahamBennett]

Dan, for your information "silicon" is the element, "silicone" is the polymer.

 

[Dtuck]

You may do well to check with fabric reinforced truck mud flap manufacturers. Multiple layers of woven fabric can do wonders for longevity. It may take higher temp materials but these companies have the equipment to make the types of stuff you are looking for.

D Tuck(Ironically another Dan T)