Single-pass inkjet printing

An interesting summary by Mike Raymond of inkjet printers at the 2015 ITMA textile print show in Milan led to a good discussion , in which I contributed the following:

“I’m more inclined to believe Aki’s point (customers will want a single source for reasons of accountability) rather than Aaron’s (customers will want 3rd party inks). Mike, you eloquently describe the high cost of wastage and downtime with these fast single-pass printers; in my view this makes the risk of reliability problems without clear accountability too high. Textile printing is probably the most demanding environment for single-pass inkjet. Not only for the reasons cited, but also the fact that existing widely-used single-pass printers either use UV-curable inks or ceramic inks, neither of which dry in the nozzle like water-based textile inks. You might argue that the ceramics market is an example of successful penetration by 3rd party ink suppliers (and consequent price erosion!), but the quality demands of printing on tiles are much lower than the printing of fashion textiles.

As for whether these machinery suppliers will ‘backwards integrate’ by buying a printhead manufacturer, I don’t see a compelling reason for them to do so – unless they are forced into it because the supplier is in trouble, or becomes available at a bargain price.”

To expand on the first point (about inks and reliability): piezo printheads, as I once said, do not die of old age – they get murdered. That is, by far the largest causes of failure (both temporary and permanent) are operations-related: head-strikes or ink clogs or debris in the nozzles. These are within the control of the operator, and printhead manufacturers typically will reject warranty claims for these causes. Thermal inkjet printheads have an inherently shorter life (Google “kogation”…) and, as anyone who has a desktop inkjet printer will know, use water-based inks that can dry in the nozzles. Printer manufacturers use a variety of strategies – capping, vacuuming, ‘spitting’, etc – to prevent this, and the more expensive single-pass printers use redundant heads or nozzles, and clever sensing techniques to detect and compensate for ‘jet-outs’.

Most of the printers Mike mentions in his article use piezo heads to jet textile inks, which are mainly water-based and hence prone to evaporation in the nozzles. This is a problem, and the printer manufacturers’ success at solving it will determine the adoption rate of their systems. They will want to control what inks are jetted, if only to manage costs during the warranty period; and I believe that their customers will not want to risk downtime by using 3rd party inks unless those ink suppliers come up with some compelling guarantees.