The key part of the laser printer: the fuser unit

Fuser unit (Canon)

Being a fuser unit is meaningful

The fuser unit, or a fuser assembly, is a counterpart of the printhead but is incorporated in the laser printer. It does the same job as the printhead–it prints images or texts by melting down toner onto the paper. Though being similar to the printhead regarding its task, the fuser assembly is vastly different technology-wise. Firstly, it uses toner instead of liquid ink. Secondly, its construction consists of other elements. The main of which are hollow tubes with the heating element inside. There are other important components, such as the photoreceptor drum and toner roller. But the fuser roller will actually finish the printing procedure and define how the end result will look like.

The fuser unit construction

The paper is moved by a drum directly in-between the rollers. The top roller is usually a bright tube of a green, blue, or orange color. This part melts down the toner. The bottom roller is a tube finished in rubber. This component is used to create pressure and to ensure the paper will easily pass through the rollers. The rubberized tube gets hot, too. Proficient manufacturers of laser printers cover the rollers with a certain type of protection (Teflon or ceramics, for instance). Certainly, we don’t want the tubes to get very dirty after the very first printing. The coating keeps clean the tubes.

You may ask, “But what makes the tubes hot?” So we answer this question: The tubes have one or two ultra-violet light sources. They consist of vaporized mercury and an arc tube. The temperature of the tubes can be very high–up to 200 degrees Celsius (or 392 degrees Fahrenheit). Do not confuse the operating temperature of a fuser assembly with its actual heating temperature. For example, an HP CB506-67902 fuser unit will heat the paper up to 150°C, while its operating temps are 15 to 25°C. There is no reason to worry about the paper warming up to high values in the laser printer. The paper becomes hot for an instant, so it doesn’t have time to ignite. The temperature of the paper should be even higher than 150°C so to allow faster printing. So, the best fuser units heat up to 180-200°C.

Why change a fuser unit?

This is an obvious question. If you read our previous article on the printheads, then you should know that the apertures for ink are getting clogged with paper and dried up ink. Something similar happens with the fuser unit, in particular, with its tubes. The toner with paper particles leave scratches on the brightly-colored rollers. When scratches appear, your printer will not do a great job any longer: You will have printings with redundant lines. You can continue using the printer if you do not need perfect quality. You need to displace the damaged apparatus, otherwise. Additionally, toner powder pollutes printers from the inside. To ensure longer operation period, regular cleaning is a must. In theory, anyone can do that manually. But before you start cleaning your printer, cover your hands with rubber gloves. The printer toner is very difficult to wash out.

We would suggest that you ask a repairman to address this problem. On the other hand, if you have deft fingers, you can try doing that manually. We should only warn you: Before you even try to remove the back or top cover, switch off the printer completely. This includes pulling a plug from the wall socket. Then your printer (and its inners including the fuser assembly) should rest in piece for at least half hour. The reason for these actions is simple. Firstly, you should prevent occasional actuation of the printer. Secondly, the printer should cool down to the room temperature. No one wants to get hurt during repair.

How to choose a fuser unit?

This doesn’t require much of an effort. Your aspiration to replace a broken fuser unit should be driven by choice of the correct manufacturer. If you have an Hewlett-Packard printer, then you need to select a fuser unit from HP. If you bought a Xerox laser printer, then again, the choice is obvious–find a fuser unit produced by Xerox for your exact laser printer model. You may need to consult the manual. If you have lost it, you are welcome to use the manufacturer website. Whenever the necessity to rectify the laser printer comes, look for a fuser unit by the printer’s part number. This is the fastest way to resolve the problem. Fuser units may cost a pretty huge amount of money–up to $1000 and even more. But this price is set for the entire fuser assembly. Since generally the unit becomes bad because of the scratched rollers, this is obvious you may not need to change the whole fuser unit bar the roller. That is why you need to think firstly if the fuser roller is replaceable. It costs a small sum of money. And you will economize eventually.

And the last advice: We suggest you find an official retailer of your fuser unit. The issue is that if you buy a fuser unit from some non-official store, you may not be satisfied with the replacement.

In total

The fuser unit is an indispensable part of any laser printer. Thanks to it, you can print out images and texts really fast. They are not ideal, though. So, as soon as the printer signals that the fuser unit is in bad shape, buy a new fuser unit.


One Comment

  1. Good article! Thanks
    I have one more tip how to continue life of your fuser unit. It helped me a lot. I also have HP printer and this kind of unit http://hardware.nl/fuser-unit/hp and after it stopped working I put it off and shaked it little then put it again on its place! Till now it works very good! Maybe it can help you too!

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