In general, inkjet printing machines or printers include at least one printhead that ejects drops or jets of liquid ink onto an image receiving member, which may be media, either in sheet or web form, or a rotating intermediate member from which the ink is later transferred to media. A phase-change inkjet printer employs phase change inks that are solid at ambient temperature, but transition to a liquid phase at an elevated temperature. The melted ink can then be ejected by a printhead directly onto an image receiving substrate, or onto an intermediate imaging member for transfer to an image receiving substrate. Once the ejected ink is on the image receiving substrate, the ink droplets are transfixed by pressure and/or heat to form a durable ink image on the substrate.
In some phase change ink imaging devices, the image receiving substrates are individual sheets of recording media. The sheets are typically stored in one or more supply trays and retrieved, one at a time, for image processing. This type of printer is very effective for customized image renderings and document production. In other phase change ink imaging devices, the image receiving substrate is a web of recording media that is continuously fed into the printer on a path that transports the media past the printheads to receive ejected ink and then the media is transported to an output area. In some web printers, the web is rewound onto a take-up roll, while in others the web is cut into sheets or otherwise processed.
Some web printers are configured to cut perforations in printed media to enable binding of the printed media through the perforations or subsequent separation of the perforated portion. The perforations are typically formed by a perforation wheel or roller, which has a plurality of blades around the circumference of the wheel that cut small lines or holes in the media web as the web is fed through a nip formed between the perforation wheel and a backer roller. Phase change ink can sometimes transfer from printed media or other printer components and adhere to the surfaces of the perforation wheel and in areas on and between the teeth of the perforation wheel. Phase change ink on the perforation wheel can be deposited on subsequently printed media, reducing the quality of images produced on the media. Thus, removal of phase change ink from perforation wheels is a desirable goal.