I recently acquired a lightly used Holz Her 1432 HF edgebander and last week did about 200 lf of horizontal grade HPL strip banding. After some tweaking of the various stations I was very happy with the results. Seemed like a great job. Then, after I'd finished, I discovered that if you picked off the end of the strip on a panel, you could rip the whole strip of HPL off pretty easily in one piece. The glue left behind on the edge of the panel (MDF with HPL both sides) is stuck to the panel really well and does not come off without a huge fight, but the bond to the HPL is poor. There is very little glue residue on the back of the HPL strip when pulled off.
So now I'm very worried about a major failure after installation. These are all kitchen cabinet box parts, not doors, so failure after installation would be even more disastrous.
The temperature in the shop and the temperature of the parts being banded was about 50 degrees. The glue is Dorus HKP 25 and the temp on the bander is set to about 205 deg. I assume the cold panel pulled too much heat out of the glue, leaving it too cold by the time the HPL was pressed on, resulting in poor bond.
Reading around on WOODWEB, it seems I also should have primed the HPL and now will likely have to rip all the banding off, prime and redo it all. If I rip off all the banding, do you think I should also take 1/32" off the panel to remove the old glue, or is it fine to leave this on and have it be reactivated by the next pass through the bander?
Should I buy the Dorus primer, or is ordinary aerosol spray adhesive (like the 3M product sold at Home Depot, etc. or some other brand?) just as good or better? How about techniques for priming uniformly and quickly without a mess? Does the primer tend to get all over the feed station before it gets applied? Should I raise my temperature? How much?
From contributor S:
We are in Phoenix and occasionally in winter our shop gets that cold. We've had the same problem and solved it by raising the glue temp to 212. I've heard of priming but we didn't need to once we raised the temp.
I would like to avoid having to cut off the glue since it's a lot of double-sided parts and the scoring motor on my saw is currently out of commission.
Try priming with whatever contact cement you have laying around. Just a thin coat to give the back that wet look. Run a few pieces after it is good and hot and see how that works. If it is not good enough, ask your supplier about a primer. Poly is the last resort, but that stuff is super strong. I've used it on aluminum, plastics, laminates and PVC.
For all the potential problems of banding failure, I think I'd turn up the shop heat well ahead of time so everything was warmer.
- Heated infeed fence
- Using heated blankets at night to keep machine and materials warm
- Heat guns
- Disabling the glue pots idle heating function
As said by others, raising the pot temp is a bad solution. Not quite so bad is to raise the nozzle heater (Holz Her) or roller temp.