Application Note Zirconia Plungers in High Pressure Dosing Pumps

The Engineering Challenge

A metering plunger has to hold its diameter in a packed gland while the medium it doses is often abrasive, corrosive or both. Hardened steel and hard chrome surfaces score, and a scored plunger changes the dose before anyone notices the leak.

Pain Points This Addresses

• Dose accuracy drifting between calibration intervals
• Packing being replaced far more often than the maintenance plan allows
• Pitting and seizure on plungers running in chloride bearing fluids

The Specification We Propose

Zirconia at 6.0 g/cm3 with 800 MPa flexural strength is the body that survives this duty as a slender driven shaft. The plunger is ground and polished to a smooth running surface, supplied either as plain ceramic rod or bonded to a metal driving end so it mates with the existing crosshead.

How the Part Is Made

• Confirm the plunger diameter, the seal bore and the running clearance
• Confirm whether a metal driving end has to be bonded on
• Grind and polish the running surface to the drawing
• Verify diameter and straightness before packing

Quality Control

Diameter and straightness are checked against the drawing, an inspection report is issued to that drawing, and packing is photographed before shipment.

What You End Up With

The specification that comes out of this route is a non-magnetic, corrosion resistant plunger with a polished running surface, quoted against your own drawing rather than a catalogue size.

This note is written from our published product data. It does not describe a named customer project and no client results are claimed.