C86300 Graphite-Plugged Sleeve Bushings for Industrial-Oven Conveyor Rollers
A C86300 graphite-plugged sleeve bushing is a candidate for a slow-moving oven conveyor roller only after the complete bearing system is qualified at its actual operating temperature. Use journal, hub and housing temperatures plus loaded running and hot-restart conditions. The oven air setpoint and an alloy property table cannot establish a safe bearing limit.
Specify the bearing system, not just C86300
Concast describes C86300 manganese bronze for heavy-load, slow-speed bearing applications. Its material sheet provides alloy composition and physical properties; those data describe Concast’s material and do not rate a BONIU graphite-plugged bearing, a solid-lubricant formulation or an oven installation.[1]
A finished bushing adds plug material, plug distribution, machining, shaft compatibility, running clearance and retention to the base alloy. Specify each item and ask for written application limits for the proposed combination. Do not treat JDB or 500# as a complete C86300 material specification.
Engineering boundary: no universal oven temperature, dry-running life or PV capacity is asserted here. This is a qualification workflow for a proposed component, not evidence of an existing BONIU oven-conveyor product or customer installation.
Replace the oven setpoint with a temperature history
| Operating state | What to record | Why it changes the review |
|---|---|---|
| Cold loaded start | Load, starting torque, ambient condition and initial clearances | Checks assembly condition before thermal growth develops |
| Steady hot operation | Journal-adjacent, hub and housing temperatures with relative speed and load | Defines the actual contact environment and heat-removal path |
| Stopped hot soak | Temperature rise or redistribution after motion stops; dwell duration | Friction heat stops, but heat conducted from the oven can continue |
| Hot restart | Temperatures, accumulated dwell, breakaway torque and available drive torque | Restart may occur at a different condition from steady running |
| Cooldown and restart | Temperature differences, freedom of movement and retention condition | Checks whether the assembly recovers without binding or looseness |
Use a documented measurement plan with safe sensor locations, instrument suitability and clearly stated limitations. A sensor on the outside of a housing does not directly measure the sliding interface. Relate readings to the assembly’s heat paths and, where needed, validate the estimate with the responsible engineer.
Keep a material property range separate from an operating rating
For example, Concast lists a C86300 thermal-expansion coefficient of 20.7 × 10−6/K over 20–300°C. That interval describes the property measurement range. It does not approve a graphite-plugged bushing for continuous operation at 300°C.[1]
OILES’ design guidance identifies high-temperature concerns including changes in hardness, removal of frictional heat, clearance and stress relaxation affecting retention. Its selection guidance also treats pressure, velocity and PV limits as interdependent rather than maxima to combine simultaneously. These are manufacturer design principles, not numerical BONIU ratings.[2]
Application analysis: the hottest state may occur during a stationary soak, while the most demanding sliding event may be the following loaded restart. A single “maximum temperature” field loses that sequence. Submit the time history with the operating states so the supplier can evaluate temperature, contact loading, lubricant system and motion together.
Identify what rotates and where expansion can go
A roller hub rotating on a stationary pin places the sliding pair inside the hub. A roller shaft rotating in a fixed housing places it at the housing. Show the actual arrangement in section: it changes the temperature path, retained member, accessibility and contamination route. The words “conveyor roller bush” do not resolve these differences.
Draw the axial locating feature and the intended expansion freedom of the roller assembly. Do not assume that a radial sleeve can also carry the roller’s axial load. If a separate thrust face or washer is needed, specify and review it independently. Check the hot and cold geometry of both the shaft and the surrounding structure.
Retention must remain effective throughout the thermal cycle without distorting the running bore. Do not add an arbitrary set screw through a finished graphite-plugged bearing: its position and loading can damage the plug pattern or alter the bore. Any positive retention feature belongs on an approved drawing.
Installation, lubrication and contamination controls
- Measure housing and shaft geometry before pressing. Use the specified lead-in and tooling, support the correct face, and verify the installed bore and alignment after assembly.
- Review shaft material, surface condition, coating and finish with the selected solid-lubricant system. A smooth cold shaft alone does not prove hot-service compatibility.
- Identify whether the duty includes washdown, condensed moisture, cleaning chemicals, abrasive dust or product deposits. Guards and cleaning access may be as important as the nominal alloy.
- Apply auxiliary grease or oil only if the qualified system requires and permits it at the real temperature. Adding grease is not a substitute for confirming the graphite formulation and service limits.
- Establish inspection access for retention, plug condition, running surface and axial freedom. Define safe isolation and cooling procedures before maintenance.
Agree on commissioning evidence before ordering
Ask the responsible equipment engineer and bearing supplier to agree on a representative duty sequence, instrumentation, acceptance criteria and stop conditions. It should include loaded hot operation, the relevant stopped soak and a controlled restart. Compare measured torque and temperature trends with the agreed envelope; a short unloaded spin does not reproduce that duty.
Record the part revision, material documentation, installed measurements, sensor positions, load history and inspection findings. If a trial shows scoring, a rising torque trend, loss of retention or binding, investigate the complete arrangement. A larger clearance or a different graphite pattern is a design change requiring review, not an automatic field remedy.
Frequently asked questions
Does C86300’s physical-property table give the bearing temperature limit?
No. A material coefficient, test interval or melting point does not establish the operating limit of a finished graphite-plugged bearing system.
Can this replace an oven conveyor’s rolling bearing directly?
Not from this guide. The load path, friction, drive torque, alignment, thermal movement and maintenance arrangement need an equipment-level review.
Is intermittent rotation automatically an easy duty?
No. Long hot dwells and repeated breakaway events can govern selection even when average rotational speed is low.
Should the RFQ include the oven temperature?
Yes, but include measured or justified bearing-region temperatures, sensor locations, load and motion history as well. Identify estimates explicitly.
Technical sources
- Concast: C86300 alloy sheet. Base-alloy information and thermal-expansion data; no finished graphite-bearing operating rating.
- OILES: Bearing design and selection guidance. Manufacturer guidance on combined duty, heat, clearance and retention; branded ratings are not assigned to BONIU.
Request a drawing review
Provide a roller section showing the rotating member, shaft and housing dimensions, axial location and expansion freedom, load and speed history, hot-soak and restart sequence, bearing-region temperature records, contamination and cleaning conditions, quantity and acceptance requirements. Request review of the base alloy, plug system, installed fits and retention as one application.