Graphite Guide Bushings for Mold Ejector Plates

An ejector plate moves along guide pins while carrying the ejector system. A locating-collar graphite bushing is a candidate where a recessed flange must seat inside the plate assembly. This page is for drawing-based ejector-guide enquiries, with MPIZ/OFR11 geometry as a starting point; it does not identify a complete ejector unit or a drop-in mould-brand replacement.

Graphite-plugged copper-alloy bushing with round flange and locating collar — 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.

Guide the ejector plate through its return stroke

Unequal ejection resistance can tilt the plate and load a guide near an edge. The guide arrangement must be reviewed with pin spacing, unsupported pin length and the plate travel. The bushing cannot compensate for a bent pin, a displaced housing pocket or a return mechanism that drives the plate out of square.

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
Guide layout	Pin diameter, spacing, support arrangement, bearing engagement at both travel limits.
Recessed interface	Collar diameter and height, pocket depth, flange thickness, fixing coordinates and sleeve projection.
Cycle and temperature	Ejection/return stroke, velocity profile, cycles, actual guide temperature and contamination.
Purchase specification	Drawing revision, quantity, units, exact material or composite specification, finish, inspection-document requirements and delivery destination.

Selection boundaries and installation

Check the locating pocket and corner relief before fitting. Align the assembled guide bores with the pins, then check free movement over the full return stroke without forcing the plate into line. Identify the sliding surfaces and graphite arrangement on the drawing. Confirm end stops separately so the guide is not treated as an impact stop.

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.

The application description is a design-review starting point. No stock availability, service-life guarantee, machine approval, universal load limit or test result is claimed. Contact pressure, motion, temperature, counterface condition and the assembled load path must be checked for the chosen specification.

Purchasing questions

Is this a guide for the ejector pin itself?

The application here is the ejector-plate guide pin. Small ejector-pin running fits are a different requirement.

Can I replace a ball-cage guide with this bushing?

Not by bore size alone. Sliding friction, engagement length, clearances and the return drive must be reassessed.

What should an RFQ show at the stroke limits?

Include a section in the fully returned and fully advanced positions, showing minimum guide engagement and nearby interference.

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.