A fuser kit on a printer is made up of two rollers that are used to fuse the printer's toner onto the papers being printed in the machine. Because the two rollers generate heat, the paper is warmed as it comes out of the laser machine.
According to the SuppliesGuys, an online retailer of office products in Midland Park, N.J., the toner particles that produce the images and text on a printed piece of paper pass an imaging drum. The paper is then directed to the fuser kit so the toner can adhere to or melt into the fibers of the paper. The application of heat and pressure produces the desired print.
Once the paper passes through the fuser kit assembly, it comes out onto a tray. The paper does not catch fire from the generated heat as it passes through the fuser kit rapidly. The Supplies Guys say that scratches can develop on the roller over time. If lines are seen streaking across printed paper, it's a strong sign that the fuser kit should be replaced.