Knowing the HP fuser film sleeve evolution explains why
Aluminum, polyimide, silicone, nickel and stainless steel. What do these have in common? They are all part of the evolution of the fuser. Printers have come a long way since the days of the SX (the old HP II and III). Same goes for the technology used to get toner fused to the paper.
HP fuser film sleeve
Understanding the way HP fusers and fusing technology have developed gives a clear picture why not all sleeves are interchangeable in HP printers, as believed by some.
Originally, the fuser started very simple. A silicone pressure roller mated with a coated hollow aluminum roller.
The heat source was a quartz lamp inside the aluminum roller. It produced two things:
heat and light. The inside of the roller is coated in a black paint to help absorb the light. The light bulb also creates heat, which is absorbed by the aluminum.
The lamp turns on, warms up the aluminum roller to the correct temperature, then shuts off. This process would repeat numerous times during printing and at idle to keep the fuser warmed. Unfortunately, this process is not very efficient for most users.
It does have a few advantages, however. It allows printing at very fast speeds because it enables much better heat retention, plus it causes less imaging defects. Due to its simplicity, this fuser is also the most reliable.
Its major downfalls are it takes the printer fuser a long time to get to temperature, and is not very energy efficient. For a user who either prints a lot or prints on thicker media like labels and card stock, this method is still the preferred choice.
HP Fuser's Instant on technology
HP Fuser's Instant on technology
A new fusing method appeared in the mid-late 1990’s thanks to government regulations on energy compliant devices and to decrease users waiting times. It involved a ceramic element or heater. The ceramic can be up to operating temperature in seconds. It is referred to as “instant on technology”. The major advantage is it can be ready to print within in as little as a few seconds. It’s also more energy efficient since it doesn’t require the machine to heat up an aluminum roller and keep it warmed.
There is a third technology used for heating the sleeve. In a few printers, inductive heaters are used. This is where they use the electromagnetic induction as a heat source on a metal based sleeve. Not many printers use this technology.
Instant on technology and inductive heating elements can be mated with a few types of sleeves:
stainless steel belts
A majority of the slower, older printers and personal use laser printers have polyimide sleeves. Polyimide sleeves are easier to manufacture and are more forgiving than the metal counter parts, resembling thin plastic tubes.
Nickel and stainless steel belts are much better at transferring heat than polyimide sleeves. They are more susceptible to coating failure and damage than polyimide sleeves.
Many of the faster output printers like the HP 4250 and 4015 contain metal-based sleeves. There are also printers that contain silicone coated metal sleeves. This silicone coating does a few things. First, it provides a better surface for fusing,because you can get more uniform pressure.
It lessens the impact on the metal base material, allowing for longer life. And since silicone coated rollers usually have a sleeve instead of spray coating for the outer most layer, the sleeves coating will also last longer.
There are also silicone coated aluminum rollers. These are found on high speed business HP laser printers. Silicone coated rollers are used here primarily to lessen the chance of image defects. They are also for better fusing performance.
All sleeves and rollers have a coating of some sort to prevent toner from sticking to them. Without this layer, a fuser would not work very well as toner would stick to the
roller or sleeve. Usually this coating is either a PFTE spray coating, or a silicone sleeve. This sleeve can be seen on some OEM rollers, such as the HP LaserJet 8100 UFR.
Each sleeve/roller is made for a specific application. This means that although sleeves are the same size or can be modified to fit in other HP fusers, doesn’t mean you should. Other considerations need to be taken into affect. Some sleeves are conductive on the inside, others are not. Some sleeves are thicker, while others have varying curvatures. All these factors can play into the overall success of a HP fuser’s performance.
Toner melts at a specified temperature; if it’s too cold, it will not fuse to the page properly. If it’s too hot, it will stick to the sleeve and cause ghosting. Add in the other things that the fuser is required to fuse, and this makes it even more complex. Labels, envelopes, thicker media, and transparencies add yet another list of complexity to
the proper fusing of media.
Some HP fusers have envelope tabs while others automatically separate the LPR and UFR to prevent wrinkles with envelopes. Labels, envelopes, and thicker media require more heat to fuse the image properly. This is due to the thicker media absorbing more heat than standard media.