C90700 Tin-Bronze Worm-Wheel Rims for Rotary Positioning Tables
For a C90700 tin-bronze worm-wheel rim in a rotary positioning table, specify the complete mating worm geometry, rim-to-hub mounting and installed backlash before choosing the bronze supply route. The material name establishes neither positional accuracy nor permissible torque. Review tooth contact, supporting bearings, lubrication and reversal duty as one drive assembly.
This guide concerns a custom replacement or approved gear design study. It does not state that BONIU stocks, cuts or has tested C90700 worm wheels. Gear manufacturing and inspection capability must be confirmed for the enquiry before any quotation is treated as a commitment.
Release the alloy and the tooth system separately
Concast lists C90700 tin bronze for gears, speed reducers and worm wheels and provides continuous-cast information referenced to ASTM B505/B505M-23. National Bronze also identifies C90700 with the SAE 65 purchasing name and gear applications.
[1][2]Keep the standard, edition, product form, supply condition and required inspection attached to the material callout. C90700, CuSn12, C93200 and a general “gear bronze” description are not unconditional substitutes. Compare the exact requirements rather than choosing by colour or nominal tin content.
A material certificate cannot define the worm-wheel teeth. Send the mating worm drawing or a controlled set of its geometry, not merely the wheel tooth count and outside diameter. Identify module or pitch system, pressure angle and reference system, worm starts, hand, lead geometry, centre distance and required tooth form.
| Item | Why it matters | Required handover |
|---|---|---|
| Mating worm | Determines the intended conjugate tooth geometry | Drawing, revision and condition report |
| Wheel tooth definition | Controls mesh and ratio | Tooth count, system, hand and approved manufacturing data |
| Rim and hub interface | Controls retention and distortion | Seat, fasteners or other approved joint details |
| Reference datums | Connects teeth to rotation axis | Inspection datum and runout requirements |
| Assembly duty | Determines the application review | Torque, speed, reversals, inertia and temperature |
Translate backlash into an output positioning question
The following original example assumes a small circumferential clearance measured at an 80 mm wheel pitch radius. It uses rigid-body geometry only. Let the circumferential backlash be 0.08 mm. The corresponding wheel angular lost motion is approximately 0.08 / 80 = 0.001 rad, or 3.44 arcminutes.
| Quantity | Calculation | Result |
|---|---|---|
| Wheel angular lost motion | 0.08 mm / 80 mm | 0.001 rad |
| Angular conversion | 0.001 × 180 / π × 60 | 3.44 arcminutes |
| Motion at a 250 mm fixture radius | 250 mm × 0.001 rad | 0.25 mm |
The assumed backlash is not a BONIU tolerance or a recommended setting. The calculation excludes elastic deflection, worm bearing end play, shaft coupling movement, tooth errors and control behaviour. State where backlash is measured, how the worm is restrained and what reversal load is applied.
Positioning from one direction and reversing into the same target are different test conditions. Define the required unidirectional accuracy and bidirectional behaviour separately. If the table has a clamp, report positioning and holding performance under the specified clamp state.
Control the assembled contact pattern before reducing clearance
KHK’s worm-gear technical notes call for checks of installation geometry, tooth contact, backlash and lubrication. They also distinguish duplex arrangements with their own adjustment method. These are manufacturer assembly principles; KHK product tolerances and torque tables are not ratings for a C90700 custom wheel.
[3]Inspect the mating worm for wear and damage before installing a new rim. An unworn wheel is not evidence that a worn worm will produce the intended contact. Agree the contact-pattern method, checking position and acceptance criteria for the assembled pair. Include the wheel’s datum relationship and the worm’s axial location.
For a separate bronze rim, follow the designer’s approved connection to the hub. Retention forces and machining sequence can distort the tooth system. Specify whether final tooth finishing occurs before or after the rim is mounted, and define which assembly condition is used for inspection.
KHK advises avoiding zero backlash in its start-up checks. Do not force a conventional pair into a nominal zero-clearance setting to mask reversal error. A controlled low-backlash design requires its intended tooth geometry, thermal allowance, bearing location and adjustment method.
[3]Specify sliding duty and lubricant compatibility
Provide worm speed as well as the slow output speed. Low table rpm does not, by itself, mean low sliding speed at the teeth. Include starts, reversals, dwell, acceleration, inertia and external torque so that surface durability, tooth strength and heat rejection can be evaluated by the gear designer.
Use the drive maker’s lubricant type, viscosity and supply method. Confirm additive compatibility with copper alloys and the intended operating temperatures. Keep delivery, oil level and replenishment requirements explicit. This plain bronze wheel is not a graphite-plugged bushing, and a self-lubricating sleeve rating cannot be reused for its tooth mesh.
Review the supporting worm and wheel bearings, housing stiffness and thermal movement. Do not infer self-locking or safe load holding from the reduction ratio. Where a load needs a brake or positive restraint, retain the mechanism’s independently approved holding arrangement.
Make the inspection plan match the positioning requirement
Separate material acceptance, gear geometry and complete-table performance. A raw bronze test report addresses the supplied material; tooth inspection addresses the manufactured wheel; the final table test addresses the assembled system. One document cannot stand in for all three.
The enquiry should define the required material documentation, dimensional inspection, tooth accuracy standard and grade, contact check, backlash method and functional acceptance. If a drawing is incomplete, request a geometry review before manufacture rather than reconstructing the full tooth system from a worn sample alone.
Record the final installed backlash through the agreed positions and temperature condition. Verify the specified reversal response and running behaviour under the approved commissioning procedure. No torque capacity, accuracy class or service life is assigned by this article.
Frequently asked questions
Is C90700 automatically equivalent to CuSn12?
Use the exact material and product standards, condition and inspection requirements. A broad tin-bronze description is insufficient for a substitution.
Can the old wheel’s outside diameter and tooth count define a replacement?
They leave important geometry unspecified. The mating worm, tooth system, centre distance, datums and assembly requirements are also needed.
Will tighter backlash guarantee better table accuracy?
The assembly also includes contact geometry, bearing location, elastic movement and temperature effects. Define the required reversal performance and evaluate the intended design rather than simply closing the mesh.
Request a drawing review
Send the complete wheel and mating worm drawings, proposed C90700 product specification, rim/hub joint, accuracy and backlash requirements, torque and speed history, reversal duty, lubricant, installed datums, quantity and inspection plan. State whether the request covers a bronze blank, a machined rim or a finished inspected gear; BONIU must confirm feasibility and scope.
Send your drawing for review or email sales@boniubushing.com. BONIU reviews material availability, manufacturing feasibility and inspection scope for each enquiry. This article does not confirm stock, application approval, certification or BONIU testing.
Technical references
- Wieland Concast: C90700 material sheet. Tin-bronze identity, continuous-cast reference and gear/worm-wheel applications.
- National Bronze: C90700 SAE 65 gear bronze. Purchasing terminology and gear application context; no equivalence to European grades asserted.
- KHK: Worm gear technical information. Assembly, backlash and tooth-contact checks, including start-up cautions; manufacturer product values are not transferred.
Published manufacturer information belongs to its source and applies to the stated product or material. Original calculations and checklists here are engineering analysis using declared assumptions. They are not BONIU specifications or test results. Release the supplied component against the approved drawing.