Soldering iron erosion?

[Tractorfan]

Hi,
I recently replaced the mains flex on an old CCTV camera and used small bore heat shrink sleeving to cover the soldered connections to the switch, transformer, etc.
Like most of us, I imagine, I use the underside of the soldering iron bit to heat the sleeve.
However, I've noticed that the bit is being eaten away by this practice, and wonder if there's something in the material of the sleeve capable of removing the (iron?) plating and eating away the copper beneath? The 'business end' is still OK after many years use.
It's an Antex 15 watt iron bought from Maplin's many moons ago.
Cheers, Pete.

[The Philpott]

I read that at least 7 different plastics can be used in heatshrink sleeving, including PTFE, PVC and 'Viton'. I imagine some nasties could be given off if they are overheated.
I prefer a heatgun rather than shrinking it by iron.

I keep an old (JML? WMS?) iron for rare occasions when i need to hack a rough hole in something- usually ABS. I leave it switched on afterwards in the hope that as much of it is burned off as possible. The bit still looks reasonable considering this abuse.

Dave

[ColinTheAmpMan1]

Taking my info from Google, heat-shrink tubing can be made from a number of materials including polyolefins, PVC and polyfluorinated polymers. Other ingredients include whatever might be in the dye used to colour it and any adhesive that it is lined with. I can't see how polyolefin might cause any damage, but polymers containing chlorine or fluorine may well liberate the halogen or the acid derived from it (I would hope not, though). The halogens or their acids might well attack the iron plating or copper (but again I would hope not, as they are not nice chemicals to have around).

The best that I can suggest is to halt the practice of using your soldering-iron to shrink the tubing, as that will also result in somewhat uneven heating and shrinkage, as well as damaging the soldering-iron. Use a heat-gun to do the job better.

Sorry to sound dictatorial, but your soldering-iron and the joints you make will thank you for it.

Colin.

[Crossed with The Philpott, but at least we agree]

For the odd small home heatshrink job I use a lighter, very quick and no heat up time. You can get three from Poundland with an inbuilt torch, for a pound! Very handy.

[Bazz4CQJ]

Originally Posted by Tractorfan

Like most of us, I imagine, I use the underside of the soldering iron bit to heat the sleeve.

Nope, it is exceedingly rare that I use a soldering iron on heat shrink - too hot.

B

[elanman99]

I do occasionally use (the shank only) my soldering iron if I need to apply very local heat on sleeving so it can be shrunk in a controlled sequence but normally just use a temperature controlled heat gun. I avoid at all cost the tip making contact with plastic!

Metcal tips are not cheap and I found out the hard way when I dropped a thin polythene bag over the iron when it lay on the bench. It seems that even brief contact with some plastics destroys iron plated tips big time. I have recovered some but they never seem as good as they were.

Ian

[Philips210]

Originally Posted by The Philpott

I imagine some nasties could be given off if they are overheated.

Dave

Hi.

I remember overheating some heatshrink sleeving many years ago and the fumes given off were terrible.
Is it likely the corrosion on Pete's soldering iron bit may be due to hydroflouric acid being produced by overheating the tubing?

Regards,
Symon

EDIT: I agree it's best to use a heat gun for safety and consistent results.

[The Philpott]

For anyone not in the know, Hydroflouric acid can etch glass and eat flesh. This is (one) reason burnt out vehicles are treated as hazardous waste.

PTFE generates Hydrogen Cyanide if it's seriously overheated.

[Skywave]

Originally Posted by merlinmaxwell

For the odd small home heat-shrink job I use a {cigarette} lighter.

Ditto - for almost all applications. But when the flame might damage something nearby, out comes the hair dryer.

A.

[joebog1]

At most tobacconists you can buy a pipe lighter. It's very like a tiny blowtorch and is perfect for heatshrink. They cost about $3. They also have a torch !!! run by three tiny batteries. They are also refillable from a standard lighter gas cartridge. A cartridge costs about $3 also from the supermarket.

A soldering iron tip costs me about $8 from China.

If I buy "real" Hakko tips they cost about $25, so I can see you didn't study economics.

If you were my apprentice, you would still be standing in the corner with the dunce hat on!!! WHAT a horrible thing to do to a soldering iron.

Joe

[Bazz4CQJ]

Originally Posted by The Philpott

For anyone not in the know, Hydroflouric acid can etch glass and eat flesh. This is (one) reason burnt out vehicles are treated as hazardous waste.

PTFE generates Hydrogen Cyanide if it's seriously overheated.

Is that a typo; think you meant that PTFE generates hydrogen fluoride? Polyurethanes will decompose to give HCN.

Back in the 1980's I worked for a company with a really good H&S guy who told me about a case he had been involved in where a fitter had overheated some PTFE tape and ended up losing a finger. I never forgot that; we were just about to use some PTFE tape in an application where it would have been a bad idea .

B

[McMurdo]

for the smallest heatshrinking jobs I use the iron but only the 'hot air stream' above the tip, not contacting it. Anything else and the hot air blower attachment on the gas iron is always ready.

[Sideband]

Hot air blower every time for heatshrink. Mind you I bought an RS kit many years ago which came with an appropriate blower so no excuses!

[David Simpson]

Pete, I'm in agreement with all the other guys - use a heat gun.
For years I've seen "Ed China" on "Wheeler Dealers" use a soldering iron on H/S sleeving - sets a bad example. Mind you, he also fits replacement suspension units with the original rusty bolts & washers. Say no more !

Regards, David

[M0FYA Andy]

I always use a hot air gun. The right tool for the job.

Andy

[The Philpott]

Yes Bazz, my mistake. I was thinking of Polyurethane. Once upon a time i was forming PU edgings and had serious reservations about the method they were using to move drums of isocyanate down two steps into the PU room- immediately adjacent to a smashed floor level 13amp socket..

Dave

[Tractorfan]

Hi,
Thanks for your replies.
The only hot air gun I have is for stripping paint off woodwork, so maybe a bit over the top for a bit of HS sleeve 2mm diametre by 10mm long.
My wife has one of those little cook's blowlamps for incinerating stuff in the kitchen. I could have used that, but was afraid of accidentally torching the CCTV camera!
Luckily, I found a new bit that I'd forgotten about, so I can keep the old one for future shrink jobs.
Cheers, Pete.

[The Philpott]

A full size hot air gun is fine, it's what i use- just hold it further away and wiggle it! With some sleeving a hairdryer can be enough.
Dave

[Nickthedentist]

I use a full size hot air gun too. The biggest PITA is unwinding the flex and finding somewhere to plug it in.

[David Simpson]

I use a 2 heat/blow strength B & D air gun. Just the ticket. 'Trubble with using a soldering iron tip is that h/s/s is not designed for being subject to 360-ish degrees of direct metal heat. Also, cheapo pvc insulation on flex/wires could also be damaged, even if it's beneath h/s/s. Butane plumber's gas torches are also far too hot for h/s/s.
If folk are worried about hot air damaging delicate circuitry behind the locus of the wires being joined & sleeved - then get some small heatproof mats from a plumbing store. Plumbers use them when repairing pipework close to painted or veneered woodwork etc.
Can folk still buy lovely old pink Hellerman sleeving(& lovely scented Hellerene) ? I've still got a small amount which is ideal if h/s/s is inappropriate.

Regards, David