Steel-Housed Copper-Alloy Guide Bearings for Mold Unscrewing Racks
Enquire about a cylindrical steel-housed guide bearing with a graphite-plugged copper-alloy inner sleeve for a mold unscrewing-rack carriage. The product supports sliding on guide shafts adjacent to the rack. It is not a rack tooth insert, pinion bearing or drop-in recirculating-ball bearing.
Resolve rack tooth force into guide reactions and overturning moment
Provide pinion pitch geometry, rack driving force, gear engagement plane and the distance to the guide shafts. Tooth force offset from the guide plane creates unequal reactions at the sleeves. Include guide spacing, bearing span and carriage overhang at both stroke ends. The rack drive should not pull an unaligned guide into position.
Specify the steel shell and copper-alloy liner as separate material items, followed by graphite pattern and shaft surface requirements. Neither material grade is confirmed by the construction name. The steel housing seat controls retention while the liner bore controls running clearance; they are different fits. Confirm the effects of housing interference on the assembled bore before accepting a replacement by outside dimensions only.
Application boundaries to confirm
Unscrewing synchronization, tooth backlash and molded-thread release are machine-system requirements, not guaranteed by the sleeve. Review heating from the mold, coolant exposure and contamination from grease or polymer debris. A guide change that alters friction or clearance needs validation against rack timing and actuator force.
Dimensions and drawing-based quotation checklist
| Review item | Information required |
|---|---|
| Outer housing | Steel specification, OD/length, shoulder or circlip retention, housing bore and interference. |
| Inner sliding pair | Copper-alloy grade, graphite layout, shaft diameter/finish and installed clearance. |
| Rack assembly | Guide span/spacing, tooth-force line, stroke, cycle, overhang and alignment datums. |
| Quotation | Drawing revision, quantity, required shell/liner inspection and operating-temperature information. |
Identify metric or inch units and distinguish worn sample measurements from intended new-part dimensions. Include the mating-part drawing and requested material or dimensional documents; their scope and availability are confirmed with the quotation.
Installation and selection checks
Check the housing seats and guide-shaft parallelism before pressing the units. Apply assembly force through the steel shell rather than the liner edge. Verify the installed bores and full unloaded carriage travel, then check rack mesh and machine timing by the approved procedure.
Frequently asked questions
Is bronze the material of the outer housing?
No. This construction has a steel outer shell and a copper-alloy sliding liner. Confirm their exact grades separately.
Can I replace a ball linear bearing with the same OD?
An equal envelope is insufficient. Friction, shaft compatibility, clearance and load distribution require review.
Should the rack carry the carriage side load?
Provide the complete guide and gear design. Bearing reactions and tooth engagement must be assigned intentionally, not inferred from the bushing size.
Request a drawing-based replacement quotation
Send the drawing and duty to BONIU, identifying Steel housing and graphite-plugged copper-alloy liner, quantity and revision. Material route, fit, manufacturing feasibility and inspection scope are reviewed before the quotation is confirmed.