End bearing assembly for annealing lehr and hot-conveyor rolls: bearing heat, axial float for roll growth, and grease or self-lubricating bushings
The bearing, housing and lubricant at the end of a lehr or hot-conveyor roll · grease that burns out at 500–900 °F, a fixed end and free ends that carry up to 15 mm of roll growth, and a 160 °C grease or a 535 °C self-lubricating bushing
A lehr roll is only as reliable as the two bearings that carry its journals. Those bearings sit just outside the hot chamber or along conveyors fed with glass at hundreds of degrees, so the questions are about heat reaching the bearing, room for the roll to grow, and a lubricant that survives, not about the roll body itself.
End bearing assemblies that carry the journals of glass annealing lehr rolls and of hot conveyors feeding a lehr: the rolling or plain bearing, its split or flanged housing and seals, the fixed and expansion (axially free) positions, and grease, central lubrication or self-lubricating bushings for hot positions. Lift-out and lehr roll bodies, their materials, coatings and roll marking are covered on the Float glass annealing lehr roller page; lehr drives are outside this page. A continuous-caster roll patent is cited only for its bearing arrangement and expansion figures.
CNFX editorial research · Sources checked October 13, 2026 · 4 sources
What the heat does to greased roller bearings at a lehr: 900 °F chambers, 500 °F conveyors and seizures within weeks
Graphite Metallizing Corporation's case study from a Pennsylvania glassware plant gives the conditions: ware moved on mesh-belt machine and cross conveyors into lehrs whose temperatures averaged 900 °F (about 480 °C), with the conveyors at about 500 °F (about 260 °C). Grease-lubricated conventional roller bearings on those conveyors lost their grease quickly; staff purged and re-greased continually, spilled grease became a cleanup and fire concern, and the bearings “typically seized up over a period of operation from three weeks to three months”. [1]
Each change stopped production for one to three hours, at a lost-production cost the plant put at about $700 per hour, and seized bearings sometimes had to be cut off the shaft with a torch, taking the shaft with them. The plant reported that high-temperature lubricants, blowing air on the bearings and daily lubrication had not solved it. [1] The same company's glass-industry flyer reports a custom glass maker whose lehr and cross-over conveyors ran at 400 °F to avoid checking of the ware, where heavy greasing to make up for lubricant burn-out had created a fire hazard. [2]
Give the bearing supplier the temperature at the bearing position, not only the lehr zone temperature, and say whether the bearing is inside the chamber, in the wall or outside it.
02
One fixed bearing, the others free to slide: carrying up to 15 mm of roll growth without opening the seal
Voestalpine's patent for wide slab-caster rolls states the requirement plainly: the bearing must accept the roll's thermal expansion without impairing the bearing seal, and for a 2 m roll with about 700 °C between roll and supporting structure the expansion may reach 15 mm. One bearing is made the fixed bearing, held axially by abutments on both sides of its housing; the others are expansion bearings whose housings rest on expansion bearing plates so they can move along the axis. [3]
The patent also shows why the seal design matters at the free end. With a bearing lid fixed to the housing, lateral play would have to allow for axial wear, and over long operation that play would widen from 4 mm to 8 mm, too much for a heat-proof seal to bridge; its answer is a floating lid with play on all sides. It notes that above 700 °C in a cooling failure, bearing grease cokes and the bearing blocks. [3]
Ask which end is fixed, how much axial movement the free end allows at the hottest roll temperature, and how the seal follows that movement.
03
Grease for the cooler positions, self-lubricating bushings for the hot ones: a 160 °C polyurea grease against a 535 °C graphite-metal bearing
Bechem lists Ceritol PSA 12 H, a mineral-oil grease with a special polyurea thickener, NLGI 1–2 and base-oil viscosity of 240 mm²/s at 40 °C, for thermally loaded rolling and plain bearings including the glass and ceramic industry. Its stated working range is −20 to 160 °C, and it is described as not clogging central lubrication lines when exposed to heat or thermal radiation. [4]
Graphite Metallizing rates its Graphalloy graphite-metal bearings for operating temperatures up to 1000 °F (535 °C) without grease or oil, and lists lehr bearings and float glass drive mechanisms among glass-industry uses. [2] In the glassware plant, the conveyors of five of nine lehrs had been converted to Graphalloy bushings at the time of writing, for an estimated saving of just under $250,000 a year on an investment of less than $10,000. [1] In the flyer's lehr case, greased bearings were replaced with type 845F4 four-bolt high-temperature flange units. [2]
Editorial note: by the figures above, a 160 °C grease limit sits below the 204–260 °C conveyor temperatures reported in these two cases, so a greased rolling bearing at such a position would depend on the housing being kept cooler than the conveyor.
State the measured bearing temperature, whether the plant has central lubrication, and whether a plain self-lubricating bushing is acceptable in place of a rolling bearing for that roll speed and load.
04
What to send for a lehr or hot-conveyor roll end bearing assembly
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Roll: [lift-out, lehr or conveyor roll; journal diameter; length; load; speed]
Position: [inside chamber, wall or outside; measured bearing temperature]
Arrangement: [fixed end; free end; axial movement needed at temperature]
Housing: [split plummer block or flange unit; seals; mounting]
Lubrication: [grease and temperature rating; central system; or self-lubricating bushing]
Service: [change time; access with the lehr hot]
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
Share this page
Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
Why do greased bearings fail on lehr conveyors?
In one glassware plant with lehrs averaging 900 °F and conveyors near 500 °F, the grease broke down quickly and the roller bearings “typically seized up” within three weeks to three months, despite re-greasing. [1]
How much axial room does a hot roll need?
A Voestalpine patent gives up to 15 mm for a 2 m caster roll about 700 °C hotter than its frame, with one fixed bearing and the others on expansion plates. [3]
What temperature can a high-temperature bearing grease take?
Bechem's Ceritol PSA 12 H, listed for the glass and ceramic industry, has a working range of −20 to 160 °C. [4]
Are there bearings that need no grease at lehr temperatures?
Graphalloy graphite-metal bearings are rated by their maker up to 1000 °F (535 °C) without grease or oil and are listed for lehr bearings. [2]
Sources and what still needs a direct check
Sources checked 2026-10-13. Lehr and conveyor temperatures, bearing failures and the self-lubricating alternative come from Graphite Metallizing Corporation's case study and glass-industry flyer; the fixed and expansion bearing arrangement and expansion figures from a Voestalpine patent; grease data from Bechem's product page.
