Comparing ink wastage on the Designjet T520 versus the Canon iPF750

25 February 2014

When looking at the Total Cost of Ownership or Cost per Print, most manufacturers who commission an independent review of their Large Format Printer expect to see many different aspects reviewed - some of which may not be on your radar. Although you may look at the ink cartridge size and cost/ml, printers can and do vary in terms of how much ink they use to print the same image. Printers also use ink to clean their printheads - so 'ink wastage' is another factor to take into consideration when considering which printer offers best value for money. For this blog I'd like to explore the HP 711 Printhead, designed for the HP Designjet T120 and T520 printers and compare the ink wastage with a competitors product - the Canon iPF750.

Background on the Designjet T520 printheads

HP announced that the latest HP 711 printhead offered higher print quality, higher print speeds and longer printhead life. Recent advances in the Scalable Printing Technology (SPT) covering printhead design, fabrication and materials has enabled HP engineers to develop this printhead so that it lasts the natural lifetime of the Printer. While this in itself is a cost-saving (an average Canon printhead costs £320 incl VAT) this doesn't present the whole story on why these printheads reduce the cost to the customer.

Functionalities of the HP 711 Printhead 

The HP 711 Printhead is part of a module that integrates 4 colour printheads with the ink delivery systems for the 4 inks. The ink cartridges have been mounted onto the printhead carriage and scan with it across the paper. The module has Low-on-Ink (LOI) and Out-of-Ink (OOI) sensors for each ink, pressure regulators and filters. Directly measuring ink levels produces dependable LOI signals advising the user to prepare for ink cartridge replacement. The OOI signal stops printing to prevent damage to the printhead from running out of ink. Both LOI and OOI are more accurately sensed in a system without the complexity of ink tubes, ink pumps, and remote ink supplies as were used in the earlier models such as the Designjet 510.

Counteracting Print quality issues

In order to eliminate print-quality issues such as streaks or smears in printouts where the printheads have become caked with ink or contaminated with paper dust and debris, printhead cleaning is carried out which involves the printers running ink through the nozzles of the printhead. Normally this will unclog and clean the printhead from the inside-out.

Ink Usage in Printhead Cleaning

The amount of ink used in cleaning differs according to the printer model and manufacturer. Generally cleaning of printheads should only be carried out as and when necessary because there is a cost attached to it. Specific comparison data relating to ink wastage on the Designjet T520 versus the Canon iPF750 show that the Canon wastes much more ink and stats provided indicate that HP wastes up to 94% less ink after the first year of use:

Ink Wastage: HP Designjet T520 - versus - Canon iPF750

Wasted ink - installation: HP 7.0ml / Canon 47.4ml
Wasted ink - normal cleaning: HP 0.4ml / Canon 7.8ml
Wasted ink - strong cleaning: HP 3.7ml / Canon 29.1ml