Print bed Aluminium plate W28, EN AW 5083

Hello, I bought an aluminium plate and wanted to use it as print bed,heated.

It is AlMg4,5Mn0,7-O = EN AW 5083, W28

In the datasheet in the last line of
[www.cnc.at]

is a strange comment, it shall not be used above 70 °C ????? So if I heat the bed to 100 °C, this makes trouble?

I think it cannot be a typo for 700, because melting temp is 580-640.

Does anyone know what this means? Is this important for me?

Edited 1 time(s). Last edit at 08/02/2018 05:26PM by JoergS5.

5083 aluminum is formulated to be welded. It's for things like car bodies, etc., not for machining. Not sure what happens at 70C- maybe it becomes susceptible to corrosion or stress fracturing. It is rolled sheet which means it may not be especially flat.

If you want flat, get cast tooling plate (Ecocast in Europe, MIC6 or ALCA5 in the Americas) which is great for machining and comes milled flat.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thank you for your information.

I am more confused now after detecting
[reprap.org]
the information of Stud54:

Das eignet sich nicht. AlMgSi 0.5 oder 1 ist normales Alublech, gewalzt.
Ich benutze nur Gussplatten, plangefräst aus Al Mg 4,5 Mn.
( translated: That's not appropriate. AlMgSi 0.5 or 1 is normal rolled aluminium sheet.
I only use cast plates, face milled from Al Mg 4,5 Mn. )

This is the description of the seller also, where I bought: soft, good to route Aluminium, but as cast plate, finely milled.

Funny fact is, that the seller sells the wastes separately and in this description he sells it as rolled...

I'll ask the seller also.

Edited 2 time(s). Last edit at 08/03/2018 01:43AM by JoergS5.

I found an explanation for 70 °C now:

Unter bestimmten Belastungen und Temperaturen >70° C besteht jedoch die Gefahr von Spannungsrisskorrosion (SpRK).
(translated: However, under certain loads and temperatures >70° C there is a risk of stress corrosion cracking.).

I found at wikipedia that for corrosion cracking, you need 3 conditions: material, there must be tension stress, and there must be a means of attack.
Means off attack for aluminium alloys is chlorine for example, low ppm concentration is sufficient.

So I will avoid temparatures higher at 70 °C and bed stress. I will avoid it anyway with loose 3 point attachment.

I investigated AW 5083 further: the production can be rolled or cast. Cast can be fine grinded. I was lucky to buy casted.

If I buy a new aluminium bed, I will buy Ecocast/Mic6.

Edited 1 time(s). Last edit at 08/03/2018 05:54AM by JoergS5.