Learn when and how to perform an umbilical purge to clear blockages, stabilise ink flow, and maintain consistent print quality on CIJ printers.
What is an Umbilical Purge—and why it matters
Your CM750’s umbilical is the lifeline between the printer’s main unit and the printhead. It carries ink, solvent, and electrical signals. If ink thickens or residue builds up inside it, you’ll see drop instability, charge faults, and reduced print clarity.
The Umbilical Purge routine clears those lines using solvent—keeping the flow smooth and your marks sharp.
When to run the Umbilical Purge
Run this maintenance task if:
-
The printer has been unused for 5+ days
-
You recently switched inks or ran the Clean Ink System
-
You notice drop instability or stream deflection faults
-
Print quality is inconsistent even after head cleaning
What the Umbilical Purge does
The purge sequence:
-
Pumps solvent through the ink and return lines
-
Activates Valves 6, 11, and 12 to flush fluid paths
-
Avoids running the full Clean Ink System (saves time/solvent)
-
Clears minor clogs without removing the printhead
How to run an Umbilical Purge on the CM750
-
Check solvent level
Make sure there's enough solvent in the tank—about 150–250 mL is typically consumed. -
Navigate to the purge routine
From the Main Menu:System>Maintenance>Umbilical Purge -
Press Start
The system will activate relevant valves and circulate solvent through the umbilical for a few minutes. -
Complete & check print stream
Once the purge finishes, restart your ink flow. Check the print stream for a steady, centred drop formation.
Quick troubleshooting if purge doesn't help
-
Still seeing poor drop breakoff?
➤ Run a head clean or inspect the nozzle filter. -
Stream starts OK then drifts?
➤ Check for bubbles in the ink return line—this may point to a partially blocked restrictor. -
Charge faults persist?
➤ Inspect the charge electrode or consider running the full Clean Ink System.
Avoiding future build-up
-
Always flush the system before long shutdowns using Fill Mixer and Drain routines.
-
Use only Needham-approved fluids to prevent residue and gelling.
-
Avoid power-cycling mid-print; this can disrupt pressure balance and allow drying in lines.
Need help diagnosing your flow issues?
Contact our technical support team or check the CIJ Maintenance & Troubleshooting hub for related articles.