Troubleshooting Edge Banders

Uneven glue application could have several causes (and fixes) March 17, 2005

I have an SCMI bander that applies glue on just half of the 3/4" edge of the panel once in a while, leaving the entire length loose. Since it's intermittent, it's hard to spot what's happening. Glue quantity is good and panels don't seem to be going into the machine at an angle. What else could be causing this?

Forum Responses
From contributor M:
Check your temperatures in the pot and on the roller. Make sure they are within range. You could have a heater going out. Also clean your glue pot. You could have old glue caked on, keeping the new glue from getting to the roller effectively.

From contributor W:
We have a Basic 2 that did the same thing. We cleaned the pot and to our amazement... it worked fine. Cost $0.00!

From contributor S:
We've been experiencing similar problems with our Brandt KD56 for two years. Several of the dealer's technicians and a Stiles technician have tried various fixes on the machine, such as adjusting the glue roller angle, adjusting the roller shoe (roller distance from edge of board), and we cleaned the glue pot. I thought the problem was solved, but much to my dismay, this week I found long pieces with one edge flapping.

When we turn the glue up, we end up with glue slung everywhere inside the machine and much glue clean-up on the panel. We are using good glue with a high solids ratio. The boards are cut on a vertical panel saw and the edges are square. Is it normal to have to apply so much glue to the edge that there is a lot of glue to clean up in the machine and on the panel? When you turn the glue rate down, do you get skips and one side of the edges without glue? Any help would be greatly appreciated.

From contributor W:
I also had a problem in that the blade on my panel saw was just a hair out of adjustment. The rip was not perfectly square and caused the same half glued tape.

From contributor M:
No, it is not normal to have glue squeeze out. When you adjust your glue, you need to tap it with a wrench - I mean the smallest adjustments. Start with not enough glue, tap it over, and tighten the nut. Keep doing this until you get it right. You might want to ask your banding supplier for some clear banding. It will allow you to run samples and see the glue bond.

You might want to check your temp as well. I think that the heaters are only made to last 3-4 years. The 56 should have 4 heaters - 3 in the base, and 1 in the tower. Get a cooking thermometer and test the temp on the roller.

Another thing that might be happening is your sheet stock could be bad. You could be cutting straight, but your stock bending. We have had melamine and plywood curve. It is much like cutting a piece of lumber that has been case-hardened. Watch the edge when you feed it. Does it stay against the fence?

You might not have enough clamping pressure. Try cranking down a little more on the pressure beam. Some of my pieces act like this when I do not have the height set correctly. It will start to glue, but the pressure roller pushes it out away from the glue because the clamping rollers will not hold it.

The next step may be a rebuilt glue pot. I know they are expensive, but there is only so much they can do in the field. The tolerances on those Brandt glue pots are in the .001's. That roller can be pushed out of alignment if it has not been well maintained.

From contributor D:
The four bolts under the glue pot came loose on my Brandt. You must tighten them up when the machine is hot so that the glue that has dripped into the holes will melt and allow the screws to turn. They are a pain to get to, but it straightened my glue roller up.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor R:
The first generation of uneven roller coater glue application on Edge Banders was a disaster. Some companies have proven the system out now and they are switching in Europe. To understand how the system works you could check out Robatech. They are expensive retrofits but they can reduce glue consumption by 40% alone. So if you produce enough, and with improved quality and reduced maintenance, the payback can be quick.