Inkjet Printing Explained: Piezo, Thermal and Continuous
What is inkjet printing?
Inkjet places tiny droplets of fluid precisely on a substrate without contact. Two families dominate: drop-on-demand (DOD), which fires only when a pixel calls for it, and continuous inkjet (CIJ), which streams droplets and deflects the ones not needed. DOD is the workhorse of graphics, labels, textiles and decor; CIJ owns high-speed coding and marking on packaging lines.
Within DOD, the actuation method decides almost everything else: how hot the ink gets, which ink chemistries are safe, how fine the detail can be, and how long the head lasts.
Thermal drop-on-demand (TIJ)
A thermal head fires by superheating a resistor so a vapour bubble ejects a droplet through the nozzle. Because the head is built into a disposable cartridge, every cartridge swap renews the nozzles, which is why TIJ is maintenance-light and cheap to integrate.
The trade-off is heat: TIJ favours water-based inks and porous or lightly coated media, and nozzle density and native print width are modest, so wide marks are tiled from several heads. It excels at date codes, batch numbers, addresses and short-run colour on cartons and labels.
- Strengths: low cost, compact, zero routine maintenance
- Constraints: mostly water-based inks, limited native width
- Typical use: coding, marking, office and short-run packaging
Piezoelectric drop-on-demand
A piezo head squeezes the ink chamber with a crystal that flexes when voltage is applied — no boiling, no heat. That single fact unlocks the broadest ink compatibility in printing: UV-curable, solvent, aqueous, oil and even functional inks carrying nanoparticles or biological material.
Piezo also supports variable drop size (grayscale) for smoother tones and finer detail, and industrial heads are rated for billions of firings, so they are field-serviceable rather than thrown away. That is why piezo is the default for wide-format graphics, digital textile, ceramics, printed electronics and most high-definition industrial decoration.
- Strengths: widest ink range, grayscale, long head life
- Constraints: higher upfront cost than thermal
- Typical use: signage, textile, labels, ceramics, functional printing
Continuous inkjet (CIJ)
CIJ generates a continuous stream, charges individual droplets and steers them electrostatically, recycling the rest. It is unmatched for non-stop, high-speed coding on the fly — bottles, cans, cables, extruded profiles — where a few dropped characters mean a traceability gap.
Matching the technology to the job
Choose by substrate first, then ink, then speed. If the surface is plastic, glass or metal and the ink must be UV or solvent, piezo is the only serious option. If you are date-coding porous cartons at volume, thermal is simpler and cheaper. If the line never stops and the mark is small, CIJ wins.
- Non-porous + technical ink -> piezoelectric
- Porous + water-based + high volume -> thermal
- Non-stop high-speed coding -> continuous inkjet
- Resolution spans roughly 300 to 1200 dpi; firing frequencies reach tens of kHz on industrial heads
Where digital inkjet sits in prepress and packaging
In a modern prepress and packaging operation, inkjet is both a finishing and a decoration tool: variable data, serialization, direct-to-object printing and short-run customisation that plate-based methods cannot justify. McLantis digital inkjet lines share the same precision-motion and optical discipline as its imaging equipment, so the same engineering rigour scales from plate and screen exposure to printed output.