Re: Melting point?
Posted by: nophead ()
Date: December 19, 2009 01:53AM
ABS softens at 90C, melts at 105C, can be extruded at ~180C but needs to be ~240C to bond strongly to itself.
HDPE melts at 130C, extrudes at similar temps to ABS.
PLA softens ~50C, melts at ~ 160C, extrudes and bonds well at 180C-190C.
[www.hydraraptor.blogspot.com]
I would be very surprised if a glue gun gets anywhere near the
240 degrees Celsius needed to properly extrude ABS.
I found the following in
Wikipedia under "Hot melt adhesive".
Glue gun specifications and usage
Glue guns come in a low-temperature and a high-temperature (hot-melt) version.
Low-temperature glue guns heat up to about 250 °F (121 °C) and are well suited when high temperatures are undesirable, such as gluing lace and cloth.
High-temperature guns heat up to around 380 °F (193 °C) and produce a stronger bond. Dual guns have a switch for both low- and high-temperature use.
In addition to bonding surfaces together, hot-melt glue can be used to fill gaps, but the properties that allow gap-filling (high viscosity, high toughness, and so on) keep it from forming an adhesive film as thin and smooth as is possible with other adhesives. (For example, a wood joint properly made with hide glue may be invisible, marked only by a difference in grain at the seam line.) Bonds must be made quickly before the glue has time to cool and harden. Usually it must be applied accurately with the glue gun, as it can not easily be spread, but it is always possible at any time to melt and spread the glue with a heat gun or a household clothes iron, which helps when bonding larger areas.
Surprisingly, hot-melt glue can be used to assemble and repair foam models as an alternative to foam-safe Cyano or UHU POR adhesive. Due to the insulating properties of the foam the hot-melt glue stays sticky for much longer than when used on wood, metal or plastics.
In addition, the temperature must be variable. This is not possible with a glue gun. If you want to extrude PLA you need a much lower temperature. In addition you should look at some of nophead's blog entries as regards extrude temperature during building e.g.
Thoughts on Rafts.
Edited 3 time(s). Last edit at 12/31/2009 12:22PM by rhmorrison.
Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
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