Graphite Bronze Bushings for Steel-Mill Shear Pivots

Steel-mill shear pivot bushings guide the lever or linkage pins of a cutting mechanism. This enquiry covers a cylindrical graphite-plugged copper-alloy sleeve, using BONIU JDB/500# construction as the starting point. The pivot bearing is a separate component from the shear blade, drive gearbox and hydraulic cylinder.

Straight copper-alloy sleeve bushings with embedded graphite plugs — Existing BONIU product image reused as a construction example. It is not a photograph of this application or proof of an alloy grade. The approved drawing defines the supplied part.

Define the pivot reaction during the cutting cycle

The pin reaction changes as the mechanism accelerates, cuts and returns. A quotation needs the normal and peak bearing reactions, rather than only the shear capacity or blade force. Hot stock, scale and cooling spray can affect the pivot even when it is outside the direct cutting zone. Identify the actual heat path and any long dwell under load.

Start with the matching BONIU product construction. Send the assembly section as well as the individual bearing drawing so that the working contact, locating surfaces and installation access can be reviewed together.

Dimensions and operating data for quotation

Review item	Required information
Pivot dimensions	Pin and housing diameters, bearing length, support span, tolerances, chamfers and retention.
Cutting-cycle duty	Load direction and peak reaction versus position, oscillation angle, cycles and shock conditions.
Thermal and debris control	Temperature at the bushing, distance from hot stock, scale, spray, shields and lubrication access.
Purchase specification	Drawing revision, quantity, units, exact material or composite specification, finish, inspection-document requirements and delivery destination.

Selection boundaries and installation

Check the pin and housing for damage from the previous bearing failure. Align paired supports before inserting the shaft. Review clearance at the operating temperature and keep scale out of the contact. Do not transfer a rated temperature or impact load from another graphite-bearing formulation to this part.

Material and replacement approval

For copper-alloy parts, state the exact standard and grade required by the design. JDB/500# and geometry codes do not establish chemical composition. Do not treat different national alloy designations as interchangeable without checking their specifications. Product colour and a reused image cannot confirm material. Required documentation, dimensions and manufacturing scope are reviewed with the quotation.

Agree the material, counterface, operating clearance and acceptance criteria before approving a replacement. Include any required dimensional inspection, material documentation or sample review with the RFQ so it can be addressed in the quotation.

Purchasing questions

Can the machine cutting force be used as the bushing load?

Not directly. Supply the linkage reactions or the geometry and load case used by the machine designer.

Which high-strength copper alloy should the RFQ identify?

Use the exact specified standard and grade. If the drawing calls for CuZn25Al5Mn4Fe3, include it for availability and material-document review; do not infer it from colour.

Can I order from a worn sample alone?

A sample helps establish form, but wear may obscure the original bore and fit. Include shaft and housing measurements and the approved replacement drawing.

Can the original product image be used to approve this application?

No. It illustrates the bearing structure. Use the approved part and assembly drawings to confirm dimensions, material, clearance and duty.

Request an application-specific quotation

Send your drawing and the checklist above through the BONIU enquiry page. Identify any proposed substitution explicitly so it can be reviewed before order confirmation.