Anyone have experience (good or bad) trying to seal plastic clamshell packaging on a budget, and have it look semi-professional?
Translation: My little garage experiment didn't work as well as I had hoped. (Don't ask.)
I'm planning to use this one:
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BTW: VERY nice stuff - will fit perfect, the cost is right, and the tooling cost is $0. :)
I have an email into them, since their website does not say what kind of plastic it's made of. I'm going to guess PET, but it might be Polystyrene.
The usual methods are: RF welding & ultrasonic. RF is too expensive for this project, and (handheld) ultrasonic takes too long (and is also expensive). Staples and/or tape are certainly cheap enough, but I'd really like to avoid them.
Yes, I've seen these online, but have not tried them. A video I watched shows these types of handheld sealers taking about 5 seco nds of heating time for a single weld. The weld is quite small. You need at least three welds to minimally secure the package (i.e., clamshell left, right and top), and probably more like five (2-left, 2-right, and 1 top). 3-3-1 would be ideal.
Even if you could instantly move and re-position the workpiece, we're still talking production of only about 2 per minute. (Maybe 100/hour)? Too slo w.
Another video showed a contraption that had 5 or 6 of these handheld units arranged in a jig.
It just seems like there should be a better way. (like a hot bar press?)
If I machined a piece of aluminum to fit the clamshell, and then (pre)heate d it (measured with thermocouple) to maybe 200 deg F. -- and then had anoth er heated plate with welding "nibs" in the right places, it seems that I wo uld (should?) be able to modulate the temp & time of the top plate and real ly ramp up production by doing all the welds simultaneously. (As many as n eeded.)
Wouldn't be the safest thing I ever built, but I'm wondering if the approac h would even work, or will the temp/time specification simply be too sloppy to control via feedback? How tolerant is this stuff anyway?
I'll stop now before I get into too much detail about my little garage expe riment. The only thing that little venture really told me was I'll have to pay more attention if I want it to look "nice". The "getting it welded" p art is actually pretty easy. (Though it's definitely possible to weld clea n through the material too!) I would have to have a jig, and a mechanical stop of some sort.
I would think a cheap temperature controller with strip heater and thermocouple, a die hacked out with a small milling machine and an arbor press would do the job. Maybe $100-200 in materials.
--sp
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Best regards,
Spehro Pefhany
Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8
What's wrong with welding through it? It might be faster and easier to use several pins that are hot enough to melt through the plastic making small holes that weld around their edges?
That's an interesting thought. But probably still requires a jig, and at that point, I might as well take the plunge.
Guys (and gals), I'm going to cobble-up a "hot bar press" of some sort this coming week and let you know how it turns out.
BTW: the reason for pre-heating the (lower) jig holder was to take some of the uncertainty out of the overall heat time. Might not be that helpful? Will know soon enough...
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