Annealing aluminium rivets

I have a need to anneal some ally rivets in order to form the domed end....

How best would this be achieved?

Can't help with how to do it, but when I had a short spell in aircraft fuselage manufacture they had different coloured rivets which I was told was to suit the ambient air temperature, so it probably matters! Of course they could have been having me on as a young sporog

Rub them with a bar of soap and heat until the soap goes black the chuck them in a bucket of water.

Duncan is correct. Different alloys need different treatment.

Good stuff here: http://www.flight-mechanic.com/aircraft-hardware-rivets-part-two/

I was an army aircraft tech for a number of years and repairs using rivets were a logistic horror owing to the need for differing heat treatment requirements specified by W******d Helicopters.

When the fit hit the shan, however Mr Pop was king!

Edited By charadam on 15/09/2017 00:29:31

You need solution heat treatment. That puts the elements needed for age hardening into solid solution. The alloy will naturally age harden as those elements precipitate out. Please see this reference:

http://www.bodycote.com/en/services/heat-treatment/solution-and-age/aluminium-alloys.aspx

Did they not come soft? A the ali snap heads I have set were soft enough as supplied.

Pure aluminium rivets will be supplied, and will remain, soft. Pure aluminium is often used for cowlings and other non-structural parts as is it easy to work and ductile. But aircraft skins are usually stronger alumimium alloys. Consequently they need stronger rivets. If I recall correctly the rivets we used for aircraft metal repairs were coloured purple. The alloy used was age hardening. So the rivets had to be solution treated and quenched (resets the age hardening process) before use. After treatment you only had a few hours to use the rivets, as the age hardening process is logarithmic.

Andrew

Thank you all for your responses, I shall pass on the advice....( I was enquiring on behalf of someone else....)

Andrew,

The purple rivets are hiduminium, if memory serves,

All depends on what type of alloy you're using. If you dont have a part number (which will normally give you the material type) you can check the markings on the rivet head. Colours will not identify a rivet material, the colour is the protective coating, so generally a golden rivet is cadmium plated, silver ones are alclad, blue ones are anodized etc. The head marking denotes type of material, so, an unmarked rivet head is denoted as A, a single dimple on the head is AD, a single raised dot is D, two raised dashes is DD....and so on...

Below is a procedure form the structural repair manual for an A320, with information regarding material and heat treat temp and duration.

If you need further clarification I'm happy to help out

Charadam you are right purple used to denote hiduminium, but I am going back 50 years when I first joined the airforce and was repairing aircraft, it is more than likely that identification standards have changed with the passing of time.

Dave

Dave,

I have now realised how old I am.

My first use of hiduminium rivets was in 1967 - 50 years ago!

But they are still purple.

Charles

Charadam I think I still have a packet in my workshop from 50 years ago, how time flies.

Dave

OK talking about head markings and colours but what if they are just snap head rivits, you all seem to be assuming they are aero rivits. The fact John wants to form a round head rather than a flat one suggests snap heads for models.

Maybe John could confirm

If the rivets are unmarked I doubt they will be aluminium alloy rivets, and if they are not an alloy such as 2017, 2024 etc, no heat treatment will be required as they are soft.

Will need to see what rivet we're talking about....

Because if they were pure aluminium there wouldn't be a need to anneal in order to form a snap head. Plenty of snap head rivets are used on aircraft.

Andrew

John can confirm .....yes just plain ordinary snap head rivits (rivets? )

Their application is for a door on a Landrover....no aero application this time but thanks guys....

Edited By John Rudd on 16/09/2017 12:28:10