Harsh Environment Pulley ( 1 )
Air Wipes
Bow Guides
Eyelet Guides
Nozzle Guides
Pulleys
Ring Guides
Rods
Roller Guides
Snail Guides
Tube Guides
U- Guides
Welding Butts
Surface Finish
Glossary
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Where does it apply?
We innovated in year 2008 harsh environment pulley, also known as high temperature pulley, for wire processing under:
1. Elevated temperature
2. Corrosive baths at elevated temperature
3. Molten metallic baths.
For example: In zinc galvanizing baths at 440o - 450 o C or under hydrochloric acid pickling bath preceding the galvanizing bath, where the installation of ceramic pulley mounted on metallic ball bearing is out of the question.
What are they made of?
Our Harsh Environment Pulley consists of:
A solid ceramic pulley
A full-ball ceramic bearing
A ceramic-to-ceramic bonding between the pulley and the bearing
An optional factory-fit, thermally matched ceramic shaft
A non-sticking, diamond polished working surface.
The superior high temperature resistance of the solid alumina pulleys is well documented. The need for a heat-resistant ceramic ball bearing, particularly a full-ball ceramic bearing without a cage, is not obvious.The ceramic-to-ceramic bonding addresses the issue of bond failure as a result of mismatched thermal expansion. An optional shaft with a thermal expansion coefficient matching that of the ceramic bearing further eliminates the catastrophic damage inflicted by the unequal thermal expansion between the metallic shaft and the ceramic bearing race.
The service temperature
The service temperature of the solid alumina pulley, the alumina shaft and the ceramic-to-ceramic bonding all exceeds 1,000o C. The governing factor is the ceramic bearing material, of which TZP and Silicon Nitride are the most prominent:
TZP (Tetragonal Zirconia Polycrystal) 450o C
Silicon Nitride (Si3 N4 ) 1,000o C
The above figures apply to full-ball ceramic bearings. Ceramic ball bearings with ball cages made of Teflon are subject to premature failure as the temperature rises beyond
180o C. Cages made of TZP which offer higher speeds and axial load capacity are available upon request. All components in our harsh environment pulleys are immune to corrosive baths found in wire processing. Additional questions answered in next page.