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 Post subject: Hammond die cast al case, heat sink?
PostPosted: Sat Jan 13, 2018 4:54 pm 

Joined: Fri May 10, 2013 12:55 pm
Posts: 31
I have various Hammond cases.

It says die cast aluminum. But it feels like low grade aluminum. Looks like compressed wood. Well see for yourself and some of you already have ones.

Would it be a good heat sink?

https://www.hammfg.com/electronics/smal ... t/1590.pdf


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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Sat Jan 13, 2018 6:44 pm 

Joined: Fri Aug 22, 2003 12:01 am
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Location: (somewhere), Afghanistan; from Rochester, NY
How much heat that can be "sunk" depends on outside surface area of the case. (not counting the area where it sits on the shelf or table)

Without fins the number Watts disappated will seem small for the size of the box.



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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Sat Jan 13, 2018 8:12 pm 

Joined: Fri May 10, 2013 12:55 pm
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So, it sounds like you're saying the quality of aluminum is ok compared to the type of aluminum in a typical heat sink.


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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Sun Jan 14, 2018 5:50 am 
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Location: NY
Better than no heat sink!


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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Sun Jan 14, 2018 8:43 am 

Joined: Fri Aug 22, 2003 12:01 am
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Location: (somewhere), Afghanistan; from Rochester, NY
solar3000 wrote:
So, it sounds like you're saying the quality of aluminum is ok compared to the type of aluminum in a typical heat sink.

I have no way to test the thermal conductivity of the aluminum, so ditto jwax. But I doubt Hammond purposely concocted thermo-insulating aluminum to make their boxes. I do believe the limiting factor is the amount of air exposed surface area.

((Out of curiousity - how many Watts, box size, and max ambient temperature to operate in?))



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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Sun Jan 14, 2018 4:20 pm 

Joined: Fri May 10, 2013 12:55 pm
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dyarker wrote:
solar3000 wrote:
So, it sounds like you're saying the quality of aluminum is ok compared to the type of aluminum in a typical heat sink.

I have no way to test the thermal conductivity of the aluminum, so ditto jwax. But I doubt Hammond purposely concocted thermo-insulating aluminum to make their boxes. I do believe the limiting factor is the amount of air exposed surface area.

((Out of curiousity - how many Watts, box size, and max ambient temperature to operate in?))



the pdf in the original post is what I have.


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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Mon Jan 15, 2018 4:52 am 

Joined: Fri Aug 22, 2003 12:01 am
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Location: (somewhere), Afghanistan; from Rochester, NY
The pdf linked to in the original post is the spec sheet for all the cases in the model series. (as in many sizes)

There is no way to tell if a box (unknown) will be a good enough heatsink for a particular project without more info.



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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Mon Jan 15, 2018 11:53 am 
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The difference in surface appearance is probably from the casting process which takes up imperfections and texture of the mold surface. if you are comparing to extruded aluminum or machined aluminum then that surface will be smoother and brighter and have less dark oxides from cooling. Sand with 220, 400, 800, 1600 and you'll be able to brighten it up. Scratch it and you'd find bright Al underneath. Its thermal conductivity should match that of any Al with minor variation for alloys. Thermal resistance depends on a lot of other construction factors but I'm sure you can dump at least 5W into a box like that and maintain low device case temp.

Casting is the best way to make a 5 sided box. with extruding you can have 4 sides max requiring removable 2 to 4 sides made of flat panels. Both methods usually require small machining touch up to remove flash or thread holes or cut extrusions


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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Thu Jan 18, 2018 7:43 pm 

Joined: Fri May 10, 2013 12:55 pm
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thanks. I dremeled it shiny. Definitely not as silvery as Al in heatsinks. But plenty of surface area for a single transistor.

looks like compressed particle aluminum. Like compressed wood.


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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Fri Jan 19, 2018 8:20 pm 
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if the polished surface still looks like round beads with voids between, I will believe it but the "Die cast" process formally uses molten metal and the molds are often very rough, maybe even sand molds or bead blasted surface. its not very different from plastic molding for a low melt temperature metal like aluminum


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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Sun Jan 21, 2018 11:42 am 
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Without definate specs and a headache full of calculations, it boils down to....
Clean the paint off the mounting surface, mount whatever makes the heat with thermal transfer paste, and try it. :razz:
Or if your insist...go to http://celsiainc.com/heat-sink-size-calculator/



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 Post subject: Re: Hammond die cast al case, heat sink?
PostPosted: Sun Jan 21, 2018 12:37 pm 

Joined: Fri Aug 22, 2003 12:01 am
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Location: (somewhere), Afghanistan; from Rochester, NY
Can you calculate with Ohm's law? The thermal calculations are about the same. Temperature (degrees C) instead of voltage. Thermal resistance (degrees C per W) instead of Ohms. Power (Watts) instead of current (Amps).

But as you say, it is IMPOSSIBLE without the specs.

Cheers,



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