I am using an electric hot air gun on standard heat shrink tubing. The
gun has an LCD temperature adjust. What is the optimal temp in degrees
C I should set for this purpose? The tubing is 20mm size.
Norm King
Heat shrink can handle even the full 800°F that ours puts out.
The problem is usually the media the shrink is
surrounding/shrinking-up-to. That material is usually far more
susceptible to high temps than any shrink, and the 'guns' put out
very hot air streams.
But basically if it the thin, cheap, bought in bulk at the home
improvement store, you should stay low in temp. If it is the full
thickness industrial stuff, hotter is OK. You have to protect the
surrounded, underlying media though.
I slide a piece of higher temp plastic under that trailing edge of the
heat shrink to keep the heat from being applied directly to the medium it
is around. The medium under the shrink can handle the temp there. The
worry is protecting the exposed materials from direct blasts of the heat
gun air, which is why I use the guard. Once I shrink everything down, I
remove the protection, and shrink up the last little bit again to pull it
in tight.
Some plastics melt as low as a couple hundred degrees, so the worry,
again, is the underlying product far more than the shrink itself.
I would start with about 350·F and work up in 25 degree steps until the
shrink rate and safe performance level desired is obtained, then note the
setting.
Things that hate/soften/burn when shrinking are often exactly what you
are shrinking up to. Imagine that. You always find something lost in the
last place you look. Unless you are dumb enough to keep looking after
you find it!
Anyway, the braided cable sheathing that makes cables handle rougher
service melts easily if one does not pay attention. The spiral wrap
melts even easier.
If you have no sheath, the TFE wire handles the full heat, but PVC
insulated wire should have shrink operations performed carefully.
The sheath on expensive coax would likely be TFE, but cheaper coax
would be mere vinyl.
Anything from 350 to 600 should work, but be careful with the upper,
and it would be better to start low, and step up toward a comfortable
setting. Higher than that requires that you be very deft with shrink and
materials, so without constant, current daily experience, it would be far
more likely that you could damage underlying media.
The shrink should handle it all fine. It will rip open on some types
with the slightest scratch or tear while you are shrinking, so cut the
length(s) carefully, and take care not to damage them when placing them
for the shrink operation.
I train assembly personnel in manufacturing operations, so I am pretty
versed in this. There are also shrinks available with sealant linings in
them that fill gaps and seal connector closures, etc.
