CC493K (RG7) Bronze Journal Bushes for Machine-Tool Feed Shafts
For a CC493K (RG7) bronze journal bush supporting a machine-tool feed shaft, keep the European material callout and the finished bearing requirements on the order. Do not approve C93200 as an unconditional replacement from a cross-reference name. Check the exact product standard, casting route, batch documentation, lubrication and installed shaft position before releasing a repair.
The component considered here is a radial plain bearing for a feed shaft. A leadscrew nut, spindle bearing and axial thrust support perform different functions. This guide provides a material-acceptance workflow for an existing drawing or an approved redesign, rather than a universal machine-tool bearing recommendation.
Identify what RG7 means on the controlled drawing
Alumeco identifies CC493K as CuSn7Zn4Pb7-C, also known as RG7, in its bars-and-rods sheet. That sheet references EN 1982:2024 and lists both continuous and centrifugal casting information. Its C93200 cross-reference is useful for finding comparable purchasing terminology; it does not, by itself, certify any supplied batch to a second specification.
[1]Ask which document the legacy drawing actually invokes. A historical DIN name, an EN alloy designation and a supplier’s stock description can carry different levels of detail. Record the agreed standard edition, casting process, material condition and required inspection document. Do not silently replace that information with “bronze” in the purchase order.
Use selected chemistry checks to challenge automatic substitution
The table below compares selected producer-sheet limits, not complete standards. Alumeco’s CC493K sheet and Concast’s continuous-cast C93200 sheet publish different ranges. Concast attaches its data to ASTM B505/B505M-23. Use the full agreed specification for acceptance; these two checks cannot establish complete conformity.
[1][2]| Check, mass % | Alumeco CC493K sheet | Concast C93200 sheet | Assumed sample |
|---|---|---|---|
| Lead | 5.0–8.0 | 6.0–8.0 | 5.5: within the first range; below the second |
| Nickel | Maximum 2.0 | Maximum 1.0; source includes cobalt | 1.4 nickel: exceeds the second limit even before cobalt |
The assumed values are an original counterexample, not an actual heat analysis. They demonstrate why a material can pass these selected CC493K checks yet fail the selected C93200 checks. They do not prove that the hypothetical material meets CC493K in every respect. Other elements, process requirements, test definitions and documentation remain to be evaluated.
For an approved substitution, obtain the actual batch analysis and compare every required element and acceptance condition. If dual conformity is required, state both specifications explicitly and agree the supporting evidence before manufacture. A comparable-alloy list cannot replace that review.
Define the feed shaft’s bearing function separately from the alloy
Identify the radial support, axial locating arrangement and lubrication path on the assembly section. A journal bush should not acquire an unreviewed thrust duty because its end happens to touch a shoulder. Check the shaft’s motion during feeding, rapid movement, reversal and dwell, together with the load transmitted by the actual drive arrangement.
For a repaired machine, preserve the relationship between the bearing seat and the shaft’s functional axis. A dimensionally acceptable sleeve can still place the shaft incorrectly if the housing is worn or the repair seat was bored from the wrong datum. Material identity does not correct an alignment error.
| Review | Required evidence | What it does not prove |
|---|---|---|
| Material | Exact grade, product form and agreed batch documents | Installed clearance or machine accuracy |
| Finished bush | ID, OD, length, grooves, finish and drawing revision | Correct location in a worn housing |
| Installed assembly | Mounted bore, shaft condition, datum relationship and lubrication delivery | Service life without representative verification |
Inspect the housing and preserve the lubrication route
Measure the existing housing and shaft before selecting a replacement size. Record ovality, wear steps, fretting and damaged entry features. Specify outside retention and the running clearance independently. Determine whether the repair requires an approved oversize outside seat, an altered shaft or restoration of the housing.
Use the supplier’s approved insertion procedure and supported tooling. Check the installed bore rather than relying on the free-state ID. If finish machining after installation is planned for a solid-metal bush, define the stock allowance, datum setup, groove protection and final inspection in advance.
Keep the intended oil or grease supply accessible. Map housing feeds, bush holes, shaft drilling and the actual loaded zone. Confirm lubricant compatibility, contamination protection and commissioning instructions with the machine owner. RG7 is not, by name alone, a graphite-plugged or dry-running bearing system.
Define the acceptance temperature and method for measuring the shaft and mounted bush. Universal H7/m6 language is not a substitute for the repair’s fit assessment. A tighter fit can change the installed bore and may not restore the intended shaft position.
Make the first-article evidence useful to the purchaser
Agree the required dimensional report, material traceability and assembly checks before ordering. State the measuring datums and document revision so that the supplier and maintenance team assess the same features. Keep material approval, dimensional acceptance and machine commissioning as separate decisions.
During the approved commissioning sequence, check lubrication delivery, temperature trend, noise and the feed mechanism’s required movement. Record the conditions and the acceptance limits chosen by the machine owner. This article assigns no permissible load, speed, accuracy class or service life to a BONIU bush.
Frequently asked questions
Is RG7 always identical to C93200?
No unconditional equivalence is established. Compare the exact standards, product form, batch requirements and application before approving a substitution.
Can a composition report alone release the repair?
It addresses the reported material checks. The finished bush and installed shaft geometry still require their own acceptance.
Does a plain RG7 bush run without lubricant?
Do not infer dry-running suitability from the alloy name. Use the lubrication arrangement approved for the complete bearing system.
Request a drawing review
Send the bush and feed-shaft assembly drawings, legacy material callout, proposed current standard and casting route, shaft and housing measurements, running clearance, lubricant supply, required documents, quantity and inspection datums.
Send your drawing for review or email sales@boniubushing.com. BONIU confirms material availability, manufacturing feasibility and inspection scope for each enquiry. This guide does not establish stock, certification, application approval or BONIU test results.
Technical references
- Alumeco: CC493K bars and rods. Material terminology and selected published composition limits; supplier sheet references EN 1982:2024.
- Wieland Concast: C93200. Selected continuous-cast composition limits and ASTM B505/B505M-23 reference; not a finished-bearing rating.
Published data apply to the manufacturer, product form and conditions identified by the source. Original examples and application checklists here are engineering analysis, not BONIU product ratings. Final supply and acceptance follow the agreed drawing and material specification.