May 12, 2008

Heat sealing bags

In the comments, Mike asks:

I am trying to seal 4 x 6 3 mil poly bags and currently having some problems. The sealer that we have is a AIE 310FDA impulse sealer that can handle up to 20 mil. The problem we have seen is either the seal is too weak or melts when the sealing time is turned up. It is hard to regulate and get consistent seals. I just think this too much sealer for these bags. I like the looks of the Bocsh Dough Boy. Do you have any thoughts or advice to help?

Sorry, about the delay, but I don't always see the comments from old posts. I looked up your sealer here, and I don't know if is "too much" sealer for your bags, but I suspect, with never having used or seen this particular sealer that you need a fairly major upgrade in sealer if you want more consistent results. I've had much better results with sealers that use air pressure to seal (although its not clear to me how yours works). You might be able to use that sealer for some applications, but for medical devices I'm doubtful, ours cost $11,000 new, it is a base model, and I'm still not completely happy with it.

If you want to make sure that your sealer is the problem, the first thing I would do is call the bag manufacturer and get their settings and the test data for the lot you have, make sure you are getting a decent bag. The other thing to check is there is probably (again I'm not completely sure about your sealer) Teflon tape that goes over the heated metal of the sealer, make sure that is in good condition and replace it if not- that tape drives me crazy. Once the possibility of the those being problems is ruled out, make a grid of time/temp/pressure and see if you can find a suitable setting, one degree or 0.1 seconds can make a difference, use one inch peel tests to the ASTM standard to test the strength.

1 comment:

J said...

We use Doboy's (I am guessing you are talking about continuous band sealers) and they are nice to a certain extent. You get a nice wide seal (the machine comes with the option of 3/8" or 1/2" wide seal bands). There also is the advantage of volume. You can pump out a fair amount of volume because you can continously load bags.

Drawbacks to the machine include FM and inconsistency. Over time with these machines you will see the brown teflon coated sealing belts flake off, the flakes get trapped in your seals and then rework is needed. Inconsistency is another problem with the doboy machines especially the B500-M. The doboy machine seals by first heating up your material by running it through a set of heater bars then through a rubber compression roller followed by a set of cooling bars. The problem with that we have found is there is inconsistency as sealing bands and other parts wear. Also trying to seal a tyvek/poly pouch consistenly is a nightmare.

As far as price goes you can expect to spend over 20k

If I were you I would try a different sealer possibly with a wider sealband. Sealing a poly to poly bag should be a slam dunk because you are creating a "weld". I have never had a failure at the seal on a poly to poly seal 99.9% of the time the material stretches beyond the limits of our peel test stand.

Hopefully this helps and hope I haven't rambled on too much.

Good Luck

J