Like a true flashaholic i’ve been interested in the different thermal properties of the metals used in lights these days. I understand most people have come to the conclusion copper is best followed by aluminium and brass then just about everything else. But I haven’t found an easy to read at a glance comparison between the commonly used metals. When comparing to copper even brass looks poor. But which grade of brass or copper. Some thermal characteristics can change quite a bit when alloyed with other metals.
Half the problem is I don’t actually know which grades of metal are used. I suspect 6061 aluminium, C101 copper, 6al-4v titanium, 316 stainless and brass …???…
So after some googling I put together this graph to capture at a glance the difference between the thermal properties of some common metals. If you see an error then you’ll know it’s because I just googled it. The only surprise to me is ti and ss are as bad as each other, for some reason I thought ti was marginally better than ss. Copper also looks to be a solid performer no matter the grade.
Aluminium
1000 – 230 W/m-K
5052 - 138 W/m*K
6061 - 151-201 W/m-K
6063 - 201-218 W/m*K
7075 - 130 W/m-K
Copper
C101 (99.9%) - 391 W/m-K
C106 (standard commercial grade) - 391 W/m-K
C110 (99.99%) - 390 W/m-K
Titanium
6al-4v (grade 5) – 7 W/m-K
all grades are poor – 7-22 W/m-K
Brass
C360 – 115 W/m-K
73/30 – 120 W/m-K
Stainless steel
316 – 16 W/m-K
304 - 16 W/m-K
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I remember reading a thread a few years ago of somebody testing the thermal aspects of al vs cu. From memory the al took slightly longer to (heat) soak, was only a couple degrees hotter but maintained that small difference until the temperature of the heat source was changed. I don’t actually remember reading it but I suspect the al cooled faster than the copper. My guess is it did because the lighter density of al does not ‘hold’ as much heat as copper. When a hand warmer becomes a hand burner I want it to cool as fast as possible when it’s turned off.
Of course, the thermal properties of a light is only one facet of the many aspects of a light. I’m not a big fan of copper host lights but I am a big fan of dtp copper mcpcb’s. A copper host is not the best choice when using a brass pill or regular mcpcb.
Anyway I hope someone else finds this interesting. Copper reigns king, aluminium is good, everything else…. meh. For reference here’s another related table I found it shows even more metals - Thermal Properties of Metals, Conductivity, Thermal Expansion, Specific Heat