CuSn12 CC483K Thrust Washers for Worm-Gearbox Shaft End Float
A CuSn12-C / CC483K thrust washer may be reviewed for a worm gearbox that already uses a plain axial sliding face. Release it by the gearbox drawing, axial reaction, oil supply, counterface and end-float requirement. The alloy name does not establish allowable thrust or justify replacing a rolling thrust bearing.
This guide focuses on the annular washer between a shaft shoulder and a stationary support in an existing plain-thrust arrangement. It does not treat the washer as a gear tooth material or a radial shaft bush. The critical procurement question is whether the complete axial stack can control motion and reject frictional heat.
Specify CC483K with its product form and condition
WISCO’s W-12 producer sheet identifies CuSn12-C as CC483K under EN 1982 and distinguishes continuous and centrifugal casting references. Its comparison table includes C90700 and historical names, but a closest-grade list is not a certificate of identical limits.
[1]Write the exact contract standard and edition, casting route, condition and inspection requirements into the order. Confirm the complete chemistry rather than accepting “12% tin” as a batch specification. The cited sheet is a producer reference; use the agreed contract edition for acceptance.
A ring-shaped plain thrust washer is an established bearing form in ISO’s plain-bearing vocabulary.
[2]That geometric term does not identify its lubricant. Plain dense bronze, graphite-plugged bronze and oil-impregnated porous bronze are different constructions. BONIU’s washer category illustrates these distinctions; availability of this exact CuSn12 washer remains subject to drawing review.
Compare constructions without changing the gearbox architecture
| Existing construction | What must be preserved | Main review boundary |
|---|---|---|
| Oil-lubricated dense bronze washer | Oil feed, face geometry, axial stack and retention | A CuSn12 grade review does not establish oil-film thickness or allowable thrust. |
| Graphite-plugged washer | Approved base alloy, solid lubricant and plug layout | Adding plugs changes contact geometry; it is a design change requiring review. |
| Oil-impregnated sintered washer | Porosity, impregnating oil and replenishment concept | Dense CuSn12 is not an equivalent porous bearing. |
| Rolling thrust bearing | Its specified races, preload or clearance, stiffness and oil requirements | No conversion to a plain washer is established by a dimensional match. |
An annular-face calculation exposes a hidden heat question
The following is an original screening example with assumed dimensions and duty. It is not a BONIU test, a pressure rating or a service-life prediction. Assume a 12,000 N axial force on a washer with 80 mm outside diameter, 40 mm bore and no grooves or holes in its nominal contact annulus.
| Quantity | Method | Calculated result |
|---|---|---|
| Nominal annular area | A = π/4 × (80² − 40²) | 3,770 mm² |
| Mean nominal pressure | p = 12,000 / A | 3.18 N/mm² = 3.18 MPa |
| Mean rubbing radius; uniform pressure | r̄ = ⅔ × (40³ − 20³) / (40² − 20²) | 31.1 mm |
| Mean surface speed at assumed 60 rpm | v̄ = 2π × 0.0311 × 60/60 | 0.195 m/s |
| Friction torque; assumed μ = 0.08 | T = μ × F × r̄ | 29.9 N·m |
| Heat generation at that assumed duty | Q = T × 2π × 60/60 | About 188 W |
The coefficient 0.08 is an input chosen only to demonstrate sensitivity; it is not a source value or BONIU specification. Doubling it doubles the calculated torque and heat. A uniform-wear assumption gives a different mean-radius model. Real face pressure, mixed lubrication and start-up friction require their own assessment.
The outer track travels faster than the inner track. An acceptable-looking average pressure can therefore coexist with a local thermal or lubrication problem. Grooves, holes, incomplete shoulder contact and tilt further reduce or redistribute the working area. Review the face and heat path rather than treating p or pV alone as acceptance.
Control the axial stack and face alignment
Recover the approved cold end float or preload requirement from the gearbox drawing. Include the washer thickness, shaft shoulder position, housing seat, other thrust elements, shims and assembly tolerances in the stack. Evaluate the operating temperature and expansion of the full stack; a material expansion figure alone does not predict running clearance.
Specify thickness variation, flatness and the datum face. Check shoulder runout relative to the shaft journal and support-seat alignment. A new washer on a dished or scored counterface may contact only a narrow ring. A worn sample cannot establish the unworn design thickness.
Identify which side slides and which side is restrained. Show anti-rotation tabs, dowels, fixing recesses and groove orientation where the original design uses them. Keep any screw head below the permitted wear surface throughout its service interval. Do not add a retaining feature through a loaded area without approval.
Review oil access during starts and thrust reversals
Confirm the actual axial force and its direction for each duty case. Reversing rotation or torque can change the loaded thrust face; a washer at one end may not describe the complete support arrangement. Include starts, overloads, dwell and duty cycle rather than only motor power and nominal shaft speed.
Trace oil from the sump, splash or feed passage to the working face at start-up and steady operation. Specify the gearbox-approved lubricant and check any proposed grease or cleaning-agent compatibility. An added groove can improve access in one location while removing loaded area or venting oil elsewhere; copy only approved groove geometry.
For initial inspection, record end float, oil condition, counterface scoring, washer wear pattern and temperature evidence. Set replacement and run-in criteria with the equipment owner. CuSn12 chemistry and hardness do not establish a dry-running temperature or a guaranteed wear interval.
Frequently asked questions
Can CuSn12 replace a rolling thrust bearing in a worm gearbox?
This guide does not establish such a conversion. Retain the original bearing architecture unless the gearbox designer approves a complete redesign of thrust support, lubrication, stiffness and end float.
Does a bronze washer automatically provide hydrodynamic lubrication?
No. A flat washer does not by its material name establish a converging oil film. The face geometry, motion, oil feed and load history determine the lubrication regime.
Can thickness be copied from a worn washer?
A worn sample helps identify features but does not define the original thickness. Recover the approved axial stack and end-float requirement, then inspect the shaft shoulder and housing seat.
Is CC483K identical to C90700?
A supplier cross-reference is a comparison aid. Complete chemistry limits, casting route, condition, mechanical requirements and inspection terms must be compared before agreeing substitution.
Request a drawing review
Send the gearbox section and washer drawing, exact grade and contract standard, casting route, OD × ID × thickness, axial force in both directions, shaft speed, duty cycle, oil details, mating-face measurements, end-float stack, quantity and inspection requirements.
Send your drawing for review or email sales@boniubushing.com. BONIU reviews manufacturing feasibility, material availability, documentation and quotation scope for the particular enquiry. This guide does not confirm stock, a certified material batch or approval for a named machine.
Technical references
- WISCO: W-12 CuSn12-C / CC483K producer sheet, revision R08. Casting-route references and international comparison names; not a finished-washer duty rating.
- ISO 4378-1: plain-bearing terminology. Vocabulary reference for annular plain-thrust bearing forms, not application approval.
The cited manufacturers describe their own products and material references. Their ratings, tests and certifications are not BONIU specifications. The application analysis, calculations and enquiry workflow here are engineering guidance; final limits require review of the actual assembly.