Heatsinks and Runtime

Hello All,

I am upgrading one of the 3D printers we run at my printshop with a laser engraver. We have a bunch of diodes we're testing (A140, M140, NDB7875) and would like to know what heatsinks will give us extended runtimes in the order of 30mins - 1 hour.

We're hoping to run the A140's at around 1A/1W and the NDB7875 at around 1.8A.2.5W. The lasers are in the copper aixiz modules currently and we already have a few of these:

12mm Holder Clamp Mount Heatsink Cooling Laser Module Pointer Lens Mirror | eBay

Or something very similar.

Seeing as the laser will be used for cutting and engraving it will be run duty-cycled, whereby it will be on for cutting moves and off for movements.

Any advice would be appreciated, I have no experience with diode lasers in order to guess at how hot they get, and what heatsinking is necessary.

Thanks!

Well aluminum cools down quicker but it absorbs heat less quickly than copper where as copper takes longer to cool down.
Best bet is to integrate a cooling system such as a TEC. Thermoelectric cooling - Wikipedia, the free encyclopedia

Both of those can get pretty hot,
especially the 9mm. Put the module in one
of those heatsinks and then mount that to
another larger heatsink with the flat sides
together. Use some thermal grease even if
you want. Then cool the big heatsink with
a fan. That should give you unlimited
runtime. Don't forget to put the driver on
its own heatsink. It will also get hot.
Don't forget to wear your 445nm laser
safety glasses!

I've been retrofitting a lot of 1watt and higher diodes into laser projectors and have more experience dealing with the thermal issues from the LED side.

The *best* heatsinks by a significant design margin I've found are these guys from Zbolt.

The biggest reason I like the Zbolt sinks is by design they grab the entire radius of the diode module jacket and allow it to radiate heat. The sinks listed by the OP on Ebay *do not* grab the entire diode module jacket and typically use a screw to press the module into place. Think of a cylinder sitting inside a smaller cylinder - only a small portion makes actually contact with an air gap around the rest.

If you have a tightly machined sink you can get away with this, and perhaps DTR knows some sources, but I've otherwise learned to avoid the solid / screw in place sinks for anything beyond .5 watts.

Even with the Zbolt sinks I advise some air flow...if just a little bit over the sink, especially with 1.5watts and higher. A spare 60mm CPU fan run off the same fixed supply that runs the drives (usually 6-12volts) works fine for this.