LEDgardener

Givin the drastic price difference, I’d like to discuss the factors that would cause one to preform better than the other.
There are a few key differences between the two, while at the same time being very similar to the average Joe.

Chinese Sinks:
Qty: 12
Price paid:$33($2.88 each) free ship
Weight: 142g / 5oz
Dimensions: 300mm x 25mm x 12mm
11.8” x .98” x .47”
Fins: 10
•Thinner base plate
•Thinner fins
•Fins are straight up and down

HeatsinkUSA: (ordered exactly 12”)
Qty: 6
Price paid: $33.68 ($5.61 each) w/ship
Weight: 116g / 4oz
Dimensions: 305mm x 25.4 x 11.8mm
12” x 1” x .46”
Fins: 6
•Base plate is thicker than China.
•Fins are thicker than China.
•Fins taper slightly to a point

Chinese Left / USA Right

I asked the seller if they could confirm which Aluminum alloy they’re made of. Their answer was “aluminum”.

•Does the weight difference suggest different alloys were used?

•Does more weight help or hinder heat dissipation?

Anyone with background in metallurgy?

No background in metallurgy, beyond an obsession with knife steels...

There is a difference in heat dissipation between different aluminiums, although they are usually not included in heat sink calculations. Anodization also improves dissipation.

I'm pretty sure the main factor is surface volume, so it would seem that the one with more fins will be more effective. This is why they grind solid pieces into fin shape to improve dissipation - there is no point where thickness is an advantage, unless is also translates into more surface volume. May I ask who the Chinese seller is?

unkle_psycho wrote: ↑

Wed Oct 31, 2018 10:29 am

No background in metallurgy, beyond an obsession with knife steels...

There is a difference in heat dissipation between different aluminiums, although they are usually not included in heat sink calculations. Anodization also improves dissipation.

I'm pretty sure the main factor is surface volume, so it would seem that the one with more fins will be more effective. This is why they grind solid pieces into fin shape to improve dissipation - there is no point where thickness is an advantage, unless is also translates into more surface volume. May I ask who the Chinese seller is?

I just ordered a two pack from aliexpress.

https://www.aliexpress.com/w/wholesale- ... m+heatsink

unkle_psycho wrote: ↑

Wed Oct 31, 2018 10:29 am

May I ask who the Chinese seller is?

Here’s the ebay listing. I got them in only 9 days which I thought was extremely fast. I don’t order much from China.
https://rover.ebay.com/rover/0/0/0?mpre ... 1934243617

I understand the surface area vs thickness. I did not know about the anodizing though.
One question I have is regarding the spacing between the fins. I wonder if the closer spacing of the Chinese sink would lower the dissipation somehow being that there is less of an air gap between them. At least in stagnant air I would think the USA sink would preform better. Again, this could be completely false but it seems plausible.
That being said most growers have at least some airflow in the area, if not directly on the light to aid in dissipation.
If I’m not mistaken, these heatsinks are not made by grinding the grooves. They are extruded I believe.

ubuntuuser wrote: ↑

Wed Oct 31, 2018 9:46 pm

unkle_psycho wrote: ↑

Wed Oct 31, 2018 10:29 am

No background in metallurgy, beyond an obsession with knife steels...

There is a difference in heat dissipation between different aluminiums, although they are usually not included in heat sink calculations. Anodization also improves dissipation.

I'm pretty sure the main factor is surface volume, so it would seem that the one with more fins will be more effective. This is why they grind solid pieces into fin shape to improve dissipation - there is no point where thickness is an advantage, unless is also translates into more surface volume. May I ask who the Chinese seller is?

I just ordered a two pack from aliexpress.

https://www.aliexpress.com/w/wholesale- ... m+heatsink

Your link is just a page of listings. No item in particular.

In some calculator it was interested in the direction the fins pointed, if they are pointing to the roof they dissipate more then if they are pointing towards a side.

Air movement is a huge variable. Just a 10w fan blowing over the canopy is enough to make a difference in the lights temperature, even though its not pointing directly at the light. Conversely in a space that has absolutely no air movement the leds heat up noticeably more.

unkle_psycho wrote: ↑

Thu Nov 01, 2018 7:33 am

In some calculator it was

Do you have a link to that calculator?

I well understand forced air convection.
My only thought is, since the fins are so close together, increased air flow would dissipate less because there is less free air volume between fins.

I did a search on that and didn't find the exact calculator I used. There are tons out there though.

This should be enough for you to gauge the basic performance of the two models you were looking at:

https://www.myheatsinks.com/calculate/t ... plate-fin/

And here they allow you to try their tool online for free, it seems to have a whole section on airflow:

https://heatsinkcalculator.com/version- ... lator.html

I bumped into one of the better articles I read back when I was reading about heatsinks:

https://www.designworldonline.com/How-t ... Heat-Sink/