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PRINTER First-Aid Solutions for the Delaminating Problem of HP LaserJet 4200

1 Nov, 2006 By: Steve Geishirt imageSource

PRINTER First-Aid Solutions for the Delaminating Problem of HP LaserJet 4200

An issue that has been plaguing service providers on the HP LaserJet 4200
printer is the delaminating or tearing of film in the fuser. I think most people
would agree that the word “plague” is the correct choice of words. The film -
sleeve or belt as some call it - rotates around a ceramic heating element and is
used to transfer heat to the paper in the fusing process. It is essentially the
soft version of the upper fuser roller and lamp. The problem? The film is
tearing on the gear side of the fuser, causing image defects. Replacing the
fuser has been a temporary fix as the film will again tear in 15,000 to 35,000
prints. That’s unsatisfactory for a fuser that’s rated for 200,000 prints. It
hasn’t mattered if the fuser was an OEM or rebuild; and it is the service tech
who  first  gets yelled at by the customer. I wonder just how many customers
have switched service companies thinking that the company was the problem, only
to find later that they were still in the same problematic boat? Many, I’m

The HP LaserJet 4200 was introduced in November of 2002. Yet the problem
wasn’t well known until nearly a year after the introduction. It appeared that
the original fusers worked pretty well; the problem was with the replacement
fusers. It was June of 2004 when we started getting serious with this issue. Our
quality team became embedded in this project noting that not only did our
rebuilds fail, but also the OEM fusers. We were using the OEM replacement films
to rebuild our LJ 4200 fusers because a high quality aftermarket film was not
available at the time. We listened to field techs and experienced personnel in
the field on possible solutions. Theories were plentiful. One was that there was
too much tension between the fuser rollers. This was stressing the film and
causing the tearing. Another was that paper feeding into the fuser at too high
an angle essentially caused the paper to slowly chip away at the film as it
entered the fuser. Yet another theory was that a design flaw was causing the
film to slide over to the gear side which caused it to jam up against the
bushings and tear.

These and other theories were explored along with possible solutions. This
included using the LJ 4300 film on the LJ 4200 heating element which has an
inner metal sleeve making the LJ 4300 film tougher. However, the LJ 4200 & LJ
4300 films are different sizes making this solution unusable. Redesigning the
film was also discussed to make it thicker, or putting a metal sleeve inside the
4200 version. However, a thicker film would change the thermal transfer rate of
the heat from the ceramic heater, through the film to the paper. This way risked
image defects such as smudging or smearing of print from too little heat being
applied to the paper. This would occur as the thermistor in the fuser attempted
to regulate the temperature from inside the heating element but not be able to
check the actual fusing temperature of the paper, thus the temperature
differences. I find it interesting that HP added temperature sensors to the
replacement model LJ 4250 fuser delivery sensors essentially addressing this

Later that year, HP introduced a service note with a fix for the delaminating
fuser problem. They stated there was an issue with a flange that guided the film
around the heating element. The angle of the old flange was too sharp and as the
film rotated, it stressed the film and caused it to eventually breakdown. HP
stood behind their product by replacing the failing fusers under an extended
warranty (this expired in Nov 2005). This was an expensive solution to HP, but
it would have cost them more if they had not backed up their product – the
results of which would have been a loss in market share as customers decide to
try other vendors. HP is very strong on protecting their reputation of producing
a high quality product; they clearly succeeded here.

Companies that have been rebuilding the LJ 4200 fusers as an aftermarket
product have continued to struggle with this problem. Some companies who were
rebuilding the LJ 4200 fusers at the peak of the problem actually stopped
producing them due to the high failure rate. Others continued to chug along. Our
quality team has followed HP’s lead in replacing the flanges and reworking the
fuser to perform to the OEM specifications. We can say with confidence this
solution is working well. Since we introduced our new rebuilds in April of 2006,
the warranties relating to this problem have dropped 60 percent. While we’re not
yet at zero defects (which is what we are striving for), after five months of
data it looks like we’re well on the way.

With a 60 percent success rate, what is going on with the other 40 percent?
Some of the reasons we are still seeing problems appears to be related to the
“initially suspected reasons” for the failure of the fuser. These focus more on
paper movement into and through the fuser rather than a distinct failure of the
unit itself. For instance, there are end users whose printers still have this
tearing film problem. They will have two LJ 4200 printers sitting side by side;
one has the tearing film failure and the other does not. If the fuser that has
been running for 75,000 plus pages in the good machine is put into the problem
machine, the fuser film eventually tears too. Something clearly is going on with
the machine independent of the fuser. Our tech support staff has worked with
multiple customers to isolate the cause of the problem. The solutions boil down
to a couple potential causes - I say potential because it appears there are
multiple things that are causing this problem, complicating the issue.

One solution is replacing the registration assembly. The theory goes back to
some of the initial suspicions on how the paper enters the fuser, or how it
feeds through it. Incorrect feed of the paper into the fuser could cause a
breakdown on the one side of the film. There are two thoughts to this. First,
that there is a push-pull relationship between the registration and fuser units.
The two rollers sit approximately eight inches from one another with the
transfer section in between them. If the fuser starts grabbing the paper at a
faster speed than the registration and then begins to pull slightly against the
other, the stress could be enough to wear away at the film causing the
delaminating. One counter argument to this is why does the film always
delaminate from the gear side and not other places across the film? That
question can’t be answered with this theory.

The second thought stems off the first but focuses more on alignment of the
registration assembly to the fuser. Even if there is no tug-o-war going on, the
slightly different angles of paper entering the fuser cause the film to slide to
one side, which forces it up against the bushings and causes the breakdown of
the film. This theory has some merit. We have customers who, at the peak of the
delaminating fuser problem, have successfully solved the issue by replacing the
registration assembly.

Other customers told us that they solved the tearing film problem by
replacing parts such as the swing plate assembly. This assembly drives the fuser
but really doesn’t have much to do with the alignment of the fuser – thus our
quality team has ruled this one out. Following up on this further, we’ve had
others adjust the alignment of the power supply in the printer which the fuser
sits on top of. Some power supplies have come from the factory sitting a
millimeter, or two, too low which caused other problems such as wear of the
fuser drive gear and swing plate assembly. Still, a slightly lower fuser
shouldn’t affect the film; however, if one side is higher than the other
(factory misinstalled or technician misinstalled), this could create a slightly
skewed angle of the paper to the fuser, which could cause the film to slide to
one side and tear. These two items, the registration assembly and realignment of
the power supply, appear to remedy the rest of the plagued machines.

While this problem took a while for everyone to get their hands around, one
point becomes clear - the importance of the pursuit of quality and satisfaction
for the customer.

It’s expensive to have a quality team to identify root problems, and work
with technicians and customers alike to solve them, but it’s well worth it. This
delaminating film is a perfect example. Techs in the field don’t have time to
trouble-shoot and experiment with this complex issue. The solution isn’t just a
revision of a part to improve the fuser; it’s a multi-faceted situation. A
highly experienced, quality team will look at the issue differently and be able
to see the multiple issues going on. With good work done in this area,I think we
can say goodbye to the delaminating fuser film plague.

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