I have just tested TherMark, (have not tried CerMark yet). It works on a CO2 laser and leaves a black lettering. It is a mat black not a deep shiny black. It is done in the raster mode so the lettering is just as it appears on the screen. It cannot be scratched with a fingernail, I have not 'David' tested it yet.

My laser is 25 watt and 40 IPS. The settings that work best, (and are the recommended ones), are a power of 100% and a speed of 30%.

On small pieces, 1x3, it takes very little time. I think it took about 1 1/2 minutes.

Philadelphia, PA (Really Bensalem)

Harvey's Sub Page When you finally understand it completely... it changes.

what metal have you been using? What's the difference between thermark and cermark?

Zona

I have tried it on stainless steel dog tags.

I have not tried Cermark, only TherMark. My memory says that people have said that CerMark is blacker. It is also about 1.5 times the price. I figured that for experimentation I would first try the cheaper spread. It seems to work well on stainless. There was a slight issue with super polished nickle plate on brass. The manufacturer would like a sample and it will be sent this week.

Philadelphia, PA (Really Bensalem)

Harvey's Sub Page When you finally understand it completely... it changes.

Zona,

A YAG laser WILL mark stainless steel and some other metals, a co2 laser will NOT mark metal. That is where the Thermark & Cerdec come in, they each do the same thing using a little bit different chemical compound. They allow you to put a black mark ON the metal. It really bonds the chemical to the surface of the metal using the heat generated by the laser. The mark is on the surface of the metal and will not be "engraved into" the metal. As Harvey said, it is a medium black mark, not a dark, rich black.

You may want to get a sample to show your customer before switching them over. It is much easier to cerdec/laser than it is to rotary & color fill. Another benefit is you would be able to put barcodes & logos on much easier if the need is there.

Cermark (and any of the other many metal marking pastes - some of which are much cheaper and better) will work on stainless and the mark will be permanent.
A YAG need not just engrave thin lines , it can do the same as a Co2 in terms of how it can engrave.
Your rotary will do just fine however , the expense of a Co2 and even more pricey YAG wont be worth it for that job unless you are doing vast volumes of 'em.
In terms of Stainless engraving , ideally you should use a high speed steel cutter , not a carbide one , you need a bit of ooomph in your motor , the cutter should be bottom supported with the least amount of protrusion possible (IE a very short cutter than cannot flex).
The most important thing is the speed and feed and removing heat from the material. Very high rotational speeds and slow feeds actually work harden the SS and result in poor engraving. Some sort of lubricant or coolant system is vital to be able to engrave SS at resonable rates.
What machine do you have , what is the power of your spindle motor, what type of bits are you using and exactly how do you engrave it?

I use cutters from Bruce - EH-8 (I think that is what they call them) for stainless steel, yes I use a cutting solution. I have a Vision Phoenix machine. Some of these 304 plates take 4-5 repeats to get deep enough to color fill, which is my second problem getting the cutting solution out so that paint will stick. They are very labor intense. Reading all the replys has convinced me that I will have to continue doing them this way as I don't believe the thermark/cermark will meet the specs for the building. Not all the orders are color filled and they are going into manufacturing businesses that have to meet all kinds of chemical restrictions. I've always wondered if there was a better (i.e. faster/cleaner) way to do them. Thanks everybody for the answers.

Zona
Zona's Engraved Creations

Hi Zonas
I use Cerdec on Stainless and it has been tested with alot of different chemicals & acids for resistance. According to the Test sheet, the sample SS was even heated to cherry red and plunged into water. While the metal showed discoloration, the mark apparently was unaffected.
On the VERY rare occasion that I do have to rotary engrave SS, I normally use a strip of 'Blue Tac' rolled into a snake, and used to form a dam around the edge of the plate surface. I then pour in a 50/50 mix of Methylated Spirits and water to a depth of about 2 - 3mm. Then engrave away. The Solution keeps the cutter tip cool, and lubricates at the same time. I use the same process when engraving Brass, Bronze & Aluminium Plates.The upside is, once finished, rinse off the plate, dry & colorfill. No oily residue to try and remove. The downside is that you will get a slightly shorter cutter life.
John

Antares makes a special spiral cutting bit for stainless steel. I have purchased one in .010, (I believe), and need to test it. It is supposed to be a great improvement.

Philadelphia, PA (Really Bensalem)

Harvey's Sub Page When you finally understand it completely... it changes.

John,

I use that same process when drilling mounting holes through glass, using only water as the coolant. I can't believe I didn't think of it for metal engraving applications. Thanks for opening my closed mind a little bit further.

Harvey,

FWI

Thermark and Cermark are now the same Ferro Corp. just finished the purchase of Thermark. In fact the two companies started as one (Cerdec) and then split and now are back together again.