Troubleshooting Poor Edgeband Adhesion

      Temperature and priming could be the culprits when PVC edgebanding doesn't stick well. April 12, 2011

I've noticed that occasionally when I peel a piece of edgebanding off of a panel that I've run through my Brandt KD55, the adhesion is poor. The glue line looks fine and solid, but very little glue remains stuck to the banding when I pull it off. Other times (within the same batch), the bond is fine, and the tape pulls the glue and parts of the panel core (melamine) with it.

I'm using a good brand of glue, working within the recommended temp range. Machine is set for the correct thickness edgeband. I don't believe that it's bad edgeband, as it's happened with a few different rolls. Not sure what's causing this.

Forum Responses
(Cabinetmaking Forum)
From contributor D:
The glue is most likely too cold when the banding is applied to the board, thus poor adhesion. There are also a few other factors that could be in play. Is your banding material laminate? Also, what is the ambient temperature in the shop when you are having these problems? If the board material is cold when the glue is applied, you will get poor adhesion.

From contributor S:
How are your pieces cut? A shop I did some work for had an issue with poor edgeband adhesion on pieces cut by their CNC, on some of the coarser particle core material. The CNC was losing the core, so the edgeband was easily removable. They tried to get a denser core material and on the coarser material, they started blowing the loose material out with air pressure. I think this resolved most of their issues.

From contributor P:
You said tape, right? PVC? There are 4 things that come to mind to check.

1) If you are working with PVC, you could be having a problem with poor primer on the tape or skipped sections where there is no primer at all. Hot melt will not adhere very well to unprimed PVC.

2) The second thing is glue temperature. With PVC it's not as critical to have perfect glue temperature as with HPL, but there is still a need to be reaching at least 180c to 200c (with a machine the speed of a KD55). Check the element at the top of the glue roller housing to make sure it is working.

3) Do you have proper flotation with the glue station? If you do not see the glue system ease back when the leading edge of the panel contacts it, then you are not sure you are making good contact between the roller and panel edge. The proper kickback of the glue system should be around 1/16". Then when the panel leaves the roller, you should see the glue system return back to home position. Your pot should be spring loaded and thus swivel slightly.

4) Do you have proper flotation of the pressure station rollers? Once again you should see the rollers kick-back slightly when the panel edge comes in contact with each of them. You can have board, glue and tape, but if you have no pressure you will not achieve good bond. The rollers must be seen to return to home position once the panel exits the pressure station. Too much pressure on the rollers will push the panel material away from the correct sight line that the edge started at. You should be able to take your hand and pull each roller back without too much effort. It takes very little pressure to bond edging if all settings and material is correct.

Does your panel material have a dog leg cut when you lay them on a perfectly flat surface? This could cause the center of the panel to not get pressure if the rollers do not have enough movement.

From contributor J:
All good stuff so far. I'd throw in that on my Holz-Her, all else being equal with the banding, panel and straight edge quality, the biggest culprits seem to be temperature and glue brand. I used Jowat for years with satisfactory results, but I had to fiddle with the temperature pretty regularly, especially in the winter months to compensate for cold panel stock. I found that Dorus has better overall adhesion and is less fussy that I have the temperature exactly right. Good bit more expensive, but I don't worry about my banding coming off!

From the original questioner:
All good information - thanks very much. I think the issue is, in fact, temperature related. From what I can tell, the pieces of banding that are pulling off easily are those that are being run through the bander first, immediately after it has come up to temperature. The temp readout is saying that the machine is up to temp, but it seems this isn't the case.

I've let the machine marinate for a few minutes after it comes up to temp, with better luck. I've also turned the temp up from 190 to 210, which I'd rather not have to do, but at this point will do for the peace of mind.

Still not clear why the machine isn't always up to temp when it says it is. All the heaters in the glue pot and tower have been replaced recently, so I don't think the issue is there. The glue gate moves very freely, which leads me to believe that heater is working fine (it had failed at one point and the glue gate was very stiff).

From contributor C:
What is the air and board temperature when you have the problems? Sounds like a pre-cure issue, not a glue temp issue. If it's a pre-cure issue, then increasing the glue temp will not solve the problem. I also recommend Dorus over Jowat glues when it's cold.

From the original questioner:
Using Dorus glue, shop temp is 55 degrees. Most pieces bond very well, it's just some that occasionally don't, even in the same batch of pieces.

From contributor C:
Is it colder than that overnight? The parts could still be colder than 55. You should get a laser pyrometer to check the actual part temp. When it gets cold we direct a flow of kerosene heater hot air across the edges of the parts before they are banded. We also store the PVC in the office to keep it warm.

From contributor J:
55 is a bit chilly for banding. I have pointed that kerosene heater at the front end (gluing area) of my bander as well as the parts on occasion in the morning and heated up the whole thing. Set it far enough back so it won't get dangerously hot, and so you don't thermally shock the metal, but so that it will warm up reasonably quickly. Give it 20-30 minutes to warm up all the machine metal. Also, I have to let my machine simmer at temp for a few additional minutes on the first run after it is that cold, or run a few test pieces to get the glue flowing good. Might bump your glue temp up 5 degrees or so as well. Better yet, keep your shop above 60 degrees.

From contributor L:
Our bander has an optional hot air blower that blows on the glue line between the application roller and the first pressure roller. When no banding is present the flow is redirected up away from the machine. Works good. We use Dorus with a chain speed of 18meters/min. You can probably get the hot air blower as an optional kit from Stiles.

From contributor A:
Our bander has a heated shoe before the dosing wheel to warm the board. Check the Knowledge Base - I think there was a thread about adding this feature with parts from Grainger.

From contributor V:
What Dorus product is everyone using? We are using Jowat and are having issues with our 1/8" solid wood edging. Mainly white oak and maple. We sand the back side with 36 grit and have also tried using the primer, and still get edges falling off. I have tried Dorus in the past and it didn't seem much to help.

From contributor L:
Ask Dorus. The appropriate adhesive varies with your chain speed and material. While you're at it, get a jug of their primer - good for wood or HPL.

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