What is the benefit of applying the glue in a "delicate grid" of "fine, intersecting lines" (as opposed to the bad "solid slab" of glue)?
Also, how are the "fine, intersecting lines" of glue extruded?
Also, how are the "fine, intersecting lines" of glue extruded?
Which is weird, actually. A lot of Chinese counterfeiting happens in the same factory. Say you're a famous clothing brand and you outsource making 10,000 of your ski jackets to a Chinese factory with Gore-tex. They make them and ship them back to you, then they keep the production line running with nylon, make 10,000 more and ship those to market vendors, eBay merchants, etc.
This saves cost, but is also better engineering. The glue has data sheets and tests and you know you're meeting the engineering requirements. Some glues 'dissolve' / 'melt' the surfaces to be bonded, and you only need a thin smear to get a good bond.
You need to control stuff like glue or conformal coating over a run of X thousand units, otherwise you find people can use crates of the stuff.
Having said all that: Maybe it's just what was drawn on the CAD drawings, and it's been followed faithfully by workers ever since, and there's no actual reason for it other than the CAD worker chose something that looked nice and not confusing.
Maybe a simpler approach would be to extrude through a mask that has a grid-like pattern of holes? Obviously you could only make isolated dots of glue, but not overlapping lines of glue (you can't have floating islands in your mask layer). So although it wasn't the technique used in this article, I guess it could work just as well, right?
Maybe someone with experience using cyanoacrylate in industrial settings can speak to this. All I know is that my hobby-store super glue nozzles (cheap plastic) get clogged almost instantly. :P
http://en.wikipedia.org/wiki/Cyanoacrylate
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But, my main concern with any kind of XY gantry (as in an inkjet printer like you describe), is that it would take frigging FOREVER. There's no way you want this glueing step to take 45 seconds per unit or more. That's the puzzle, I think, is how did they create this glue grid so quickly that it rivals the blob approach (1 - 2 seconds)?
[1] http://equipment.loctite.com/productLineDetail.cfm?pl=21
[2] http://www.youtube.com/watch?v=q4RR67d8CC8 (larger epoxy extruder, same idea)