Continuous Inkjet Coder Product

Overview

A continuous inkjet coder prints date codes, lot numbers, and traceability data onto products moving past it at full line speed without ever touching them. It is the workhorse marking technology of bottling halls, dairies, cable extrusion lines, and pharmaceutical packaging: a wall- or stand-mounted cabinet, a slim Printhead clamped over the conveyor on a Printhead Bracket, and a flexible Umbilical joining the two.

Unlike drop-on-demand printers, a CIJ machine jets continuously. A pressurized stream of ink leaves the Nozzle at all times while the machine is running; only a fraction of the drops carry image data, and the rest are caught and recycled. This is what lets the printer mark a bottle every 80 ms on a 60,000 bottle-per-hour filler, and what lets it use fast-drying solvent inks that would clog an intermittent head.

How it works

The Ink Pump holds the feed line at roughly 3 bar, forcing ink through the Main Ink Filter and into the Drop Generator. There a Piezoelectric Crystal vibrating at about 64 kHz imposes a pressure ripple on the jet, so the stream breaks into a chain of identical drops about 1 mm after leaving the nozzle — roughly 64,000 drops per second, each around 70 µm in diameter.

Break-off happens inside the Charge Electrode. At the instant a drop separates, the controller applies a voltage between 0 and 300 V to the electrode, and the drop carries away a proportional electrostatic charge. The Phase Detector continuously verifies that charging is synchronized with break-off, retuning the modulation amplitude if ink properties drift.

Charged drops then pass between the Deflection Plates, which hold a constant field of about 6 kV from the EHT Supply. Each drop deflects in proportion to its charge, so a column of differently charged drops fans out vertically as it flies toward the substrate. The product's own motion past the head provides the horizontal axis, paced by an Encoder on the conveyor, and the dot-matrix character builds up column by column. Uncharged drops fly straight into the Gutter, where vacuum generated by the Venturi pulls them back to the Mixer Tank for reuse.

Printing is triggered per product: the Photocell detects the leading edge, the CPU Board counts encoder pulses to the programmed print position, and the message — already rasterized into per-drop charge values — streams to the head.

Ink management

Solvent ink loses carrier to evaporation every second the jet runs, mostly in the open flight path and gutter. Left uncorrected, viscosity climbs and jet velocity, break-off length, and drop placement all drift. The Viscometer times ink flow through a reference orifice; when the reading rises out of band, the Solenoid Valve Manifold meters solvent from the Make-up Cartridge into the mixer tank. A typical machine consumes 2.5–4 mL of make-up per hour against roughly 1 mL of actual ink laid on products.

Fluids load through the Cartridge System: the Ink Cartridge and make-up cartridge seat onto Septum Couplings that pierce only when fully engaged, and the Cartridge Reader checks an RFID chip so the wrong chemistry cannot be drawn into the circuit. Start-up and shutdown sequences flush the nozzle path with solvent automatically, which is what allows MEK inks with 1–2 s dry times to coexist with weekend stoppages.

Construction and environment

Everything except the head lives in the Cabinet, a stainless IP55 enclosure split into a fluid bay and an electronics bay. The Positive Air Fan keeps the electronics side at slight positive pressure so solvent vapour and washdown moisture stay out. The Umbilical bundles PTFE Ink Tubes with the piezo drive, EHT, and sensor Wire Bundle inside a solvent-resistant Umbilical Sheath; standard length is 3 m, which sets how far the cabinet can sit from the line.

The Gun Body itself contains no pumps — all hydraulic power comes down the umbilical — so the head stays under 1 kg and fits into tight spots such as between filler and capper. A Printhead Heater keeps jetting stable in cold rooms down to 5 °C.

Operators interact through a LCD Panel with Touch Digitizer on the cabinet front: message selection, date offset rules, and line setup are stored locally, and most failures the machine can detect — gutter fault, high viscosity, EHT trip, low cartridge — surface as coded alarms before they become misprints. Routine service is largely confined to annual filter and pump-related replacements and quarterly nozzle inspection; the Nozzle jewel itself typically outlives the printer.