Corrosion Resistant Materials

A project log for CIJ Printer

An Open Source Continuous Inkjet Printer

dominik-meffertDominik Meffert 09/22/2023 at 01:372 Comments

While testing I realized that the ink that I used caused a lot of corrosion on steel, copper, aluminum, and brass parts:

Corrosion on the Printhead

Corrosion on the Piezo Ring and Contact Plates

Salt Crystals on the Aluminum Profile

Corrosion inside a Fitting

Corrosion on the Charge Electrode, Deflection Plate, and Gutter

I assume this is caused by the sodium propionate that I used for increasing the conductivity of the ink.

Since the ink has to be conductive for the CIJ printing process, it needs to contain something that makes it this way and since all salts that I know so far can cause corrosion on metals like steel, copper, aluminum, and brass, these materials have to be replaced by other corrosion resistant materials like stainless steel, rubber, and plastic to prevent corrosion of the printer and also contamination of the ink.

Fresh Ink on the left, Used Ink on the right

So, I searched for corrosion-resistant fittings to replace all the brass fittings and ultimately stumbled across the Reverse Osmosis plumbing system of white fittings of all sorts + white 1/4 inch and 3/8 inch PE tubing.

Old Setup at the bottom, New Setup at the top

Top Cap of the Vacuum Tank made out of Stainless Steel with Plastic Fittings
Vacuum Buffer/Overflow Tank, Valves for Draining the Tank, Ink Pressure Regulator in grey, Stainless Steel Vacuum Pump Exhaust Suppressor, Ink Filter
From left to right: Ink Pressure Tank, Ink Pump Tank, Ink Pressure Overflow Tank + New Plastic Check Valves and Solenoid Valves
Vacuum Tank
Valves for Ink and MakeUp at the bottom, Valves for Pump Pressure and Venting at the top, Ink Pressure Regulator on the left, and Pump Pressure Regulator on the right
Besides the Pressure Regulators/Gauges and Vacuum/Pressure Switches, all Parts were replaced by either Stainless Steel or Plastic on the Printer

I think with all brass parts replaced by plastic or stainless steel the printer should now no longer have problems with corrosion caused by a small amount of salt in the ink.

While the printer hydraulics should be fine now, the printhead is still made out of brass, copper, and aluminum and will also need an upgrade to withstand corrosion.


William wrote 09/23/2023 at 04:18 point

Maybe you should consider electroplating some of the things that cant be replaced by plastic with something more corrosion resistant, or add sacrificial anodes to them. Also, ensuring that there is only one metal (except for any sacrificial anodes) helps prevent galvanic corrosion. Up here in Canada, some people have electronic protection to help prevent rust on their vehicles from salt, but how well these work I'm not sure, additionally the charge pumping of these rust preventers might be a problem for this particular system.

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Dominik Meffert wrote 10/18/2023 at 12:54 point

Good idea, over the last days I could replace almost every metal part with stainless steel and switched to a less corrosive salt.

Maybe I can electroplate the remaining parts like the feedback antenna and piezo ring.

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