Along with two business partners, I bought an engraving company last summer. They have a number of rotary engraving machines and two Universal 25 watt lasers.
We’re still learning the various machines’ capabilities.
Here’s my question: Can you engrave brass (mainly for plaques) with a higher wattage laser than the ones we now have?
Any feedback appreciated.
Bare metal can’t be engraved with a CO2 laser. It can only be ‘marked’. Spray a coating on the brass then engrave over it. It essentially is removing the coating, or baking on a marking solution like ceremark.
As to why you can’t do bare metal - my understanding is that the reflective properties of the metal deflects the heat, and there is the risk of the laser reflecting back onto itself and hurting the laser.
I really doubt that reflected laser light would hurt the laser. It is going to be diverging pretty fast. I guess if your lens nozzle is made of wood or plastic…
They engrave bare metals with q-switched yag lasers. The average power is actually lower than the smallest CO2 laser you can buy, but the peak power is in the 10s of kilowatts. It is this peak power that overcomes the reflectivity of the metal and blasts it away. Of course a 1000 watt CO2 laser will overcome the reflectivity of most materials too, but you might end up with a 1/2 inch deep engraving. :-)
Some CO2 lasers (the coherent diamonds?) can be pulsed to several times their rated CW output. Perhaps it would be possible to engrave bare metal with those?
I have all the parts to build a arc lamp pumped q-switched yag laser, but I doubt I will ever get around to it.
One of the tests I keep wanting to try is use the laser, some sort of resist and chemical etch on brass. Brass can be etched with ferric chloride which is available at radio shack to etch circuit boards. Ferric chloride is surprisingly safe stuff as compared to most acidetches. Many things work as a resist for ferric chloride (wax, paint, toner…). The trick is to find one that goes on and off quick and easy. Then my 30 watt laser could image the words then place the piece in the ferric chloride and let it etch.
You can engrave brass with a different type of laser I believe. I am pretty sure what you have now is a CO2 laser (I really don’t know the universal laser brand) - a CO2 laser will, with coated metal, anodized aluminum or use a cermarking compound, but it won’t “engrave”, it will rather just mark.
Now, there are different types of lasers, I know there is a person on this list that uses a Nd:YAG laser to engrave metal. I don’t know if a Nd:YAG would engrave brass, but I do know from his prior posts that he engraves aluminum and steel.
If you could find the company to make one and you wanted to spend the bucks to have a unit custom built, you can get a very high powered co2 laser that would probably engrave (when I say very high power, there’s a company in a neighboring town that uses 1000+watt CO2 lasers (at least that’s what they told me they used in terms of type) to cut metal. Of course I’m sure this is outside of most if not all of our price ranges =)