TIJ Coding in Pharmaceutical Manufacturing

Thermal inkjet (TIJ) is one of the most common coding technologies on pharmaceutical secondary packaging lines. It offers high resolution, a compact print head, and relatively low maintenance compared with alternatives — provided the ink, cartridge, and line conditions are matched to the application.

This article explains how TIJ coding works, why pharmaceutical manufacturers frequently choose it, and the practical considerations for selecting cartridges and consumables. Axion Group supplies HP-compatible TIJ cartridges and supports customers through the trial and evaluation process.

How TIJ works

A TIJ printhead is built into a cartridge that contains both the ink reservoir and an array of tiny resistive elements. When electrical current is applied to a resistor, it rapidly heats a thin film of ink, creating a vapour bubble that ejects a droplet through a nozzle. The bubble collapses, drawing more ink from the reservoir, ready for the next drop.

The key characteristics of this arrangement:

• High resolution — 600 dpi or higher is standard, allowing crisp text, small character heights, and 2D codes.
• Low maintenance — the printhead is replaced with each cartridge, so there is no separate printhead servicing.
• Compact form factor — TIJ printheads are small and can be mounted in tight positions on a packaging line.
• Fast changeover — cartridge swaps are quick, reducing downtime on line-side ink changes.

TIJ is well suited to text, batch codes, 2D data-matrix codes, and small graphic elements on flat or gently curved substrates.

Why pharma manufacturers choose TIJ

Pharmaceutical manufacturers typically choose TIJ for coding on:

• Cartons (coated and uncoated)
• Labels (paper and film)
• Certain film wrappers
• Some blister foils, subject to compatibility trials

TIJ suits pharmaceutical operations for several practical reasons. First, code legibility for both human and camera-based verification is generally high. Second, the compact printhead can be integrated into existing packaging lines without significant re-engineering. Third, cartridge-based supply reduces the volume of open ink handled by line operators, which supports cleanliness on the production floor.

TIJ is not universal. Highly absorbent substrates, deeply textured surfaces, and specific non-porous substrates may benefit from continuous inkjet (CIJ) or other technologies instead. The right technology is a function of the substrate and the code requirement.

Cartridge selection

Two broad families of TIJ cartridge are used in pharmaceutical coding:

• Water-based (aqueous) — for uncoated paperboard, uncoated labels, and similarly porous substrates. Lower operator handling considerations; drying relies on substrate absorbency.
• Solvent-based — for non-porous substrates such as coated cartons, films, foils, and plastics. Faster drying on non-porous surfaces; requires appropriate ventilation and handling.

Within each family, individual cartridge references are tuned for specific substrate types and coding requirements. A cartridge selection should always be validated against the customer's actual line — a bench print is not a substitute for a short line trial.

Common line-side issues

Common TIJ issues we investigate with customers include:

• Missing dots or lines — often a cartridge purge issue or a partially dried nozzle plate; resolvable through routine wipes and correct cartridge storage.
• Poor adhesion — usually a substrate / ink mismatch rather than a cartridge problem; requires a re-evaluation of ink chemistry against the substrate.
• Inconsistent code density — check cartridge age, print speed, and firing frequency; some cartridges have a documented in-service life once opened.
• Bleeding on absorbent substrates — typically a water-based ink on an over-porous substrate; consider a slower line speed, a different cartridge, or a coated substrate.

Each of these has a systematic route to resolution. We can help work through them with the customer's line data.

Maintenance considerations

TIJ maintenance is generally simple: cap the cartridge when idle, wipe the nozzle plate periodically with the recommended cloth, and rotate stock so cartridges are used within their in-service window. Operators benefit from a short standard procedure covering these steps, and a documented in-service life for each cartridge family.

If you are evaluating TIJ for a new packaging line, changing cartridge references, or troubleshooting a print quality issue, Axion Group can support the evaluation. We will ask about the substrate, the coder platform, and the line environment before proposing a cartridge reference for trial.