Scratching Stainless Steel

Does anyone know why my laser appears to be "scratching" stainless steel mugs? On the attached example, it "scratched" the surface until just before the word "FIRE", but not past that. I have tried different settings, and it appears to act differently on different mugs. I have been able to do the Polar Camel mugs without, as well as some stainless steel mugs from JPPlus, but when it comes to Yeti's, I can't seem to get it quite right.

I use a Rabbit QX-80-1290. My settings on this mug were 400 lines per inch, 250mm/s, and 32% power.

Attachment 424213Attachment 424214

Looks like all the powder coat wasn't removed. Were you using a rotor or just placed in the laser? Or it could be the cups steel itself.Pretty sure the laser is not scratching the S Steel.

It's not scratching anything, the scratches are in the metal before it's powdercoated. They use reject stainless cups to powdercoat because it hides everything. They don't care that people are laser engraving that off.

It's in the cup, not your laser. Seen it a lot over the years.

Take a magic eraser to it...water, dna, sometimes acetone (beware it may eat more than you want) can speed up the cleaning process. If the "scratching" is removed by this process, you'll know it's residual powdercoat. If it remains, you'll know it's a defect in the cup itself.

I use simple green straight with magic eraser. Gets off 95% of the PC residue. I have found if you really want to shine base SS, get some BarKeeper's Friend.
Use a bit wet with the magic eraser. It will cut thru and shine really well with very little trouble.

I am not sure how to reply to multiple people in one reply, so this might be a bit jumbled.

Bert: I was using my rotary for this.

Scott: I am not sure how it could be in the cup before engraving. How is it that there are lines that correspond perfectly with the path that the laser took?

Chris: Magic eraser is also my go to method. These "scratches" do not come off for anything. In an effort to remove them, I have started removing powdercoat before using a magic eraser. At that point I stopped trying.

Again, I am not sure how this could be in the cup before powdercoat. I am not saying that it is not, I just don't understand. How is it that the lines perfectly correspond with my laser path? I also don't understand how the lines could show up, and then stop from one pass to the next. The lines stop in this example directly before the word FIRE. That is what I don't understand. Below is another example with the "scratches", only they are showing up on the top and bottom of each engraving.
Attachment 424347

Is it possible you're using too much power and ever so slightly annealing the metal within the beam path? What would happen if you lower the cup/ defocus the beam to increase your spot size?

A C02 laser, until your into the several-hundred watt range, simply cannot mark stainless aside from heat discoloration. I can darken SS with my 80w Triumph, and warp the daylights out of it, but it will not ablate/engrave/etch/scratch the metals surface, at all. Any of the metal's scratches- which, in the pic of just the "e", appear to me to be indicative of basic cross-hatch sanding prep for the powdercoating- were already there. The lines appearing to line up with what you're engraving in some way, is likely nothing more than how light is reflecting/refracting off the powdercoat residue along the laser's X path...

Thanks for your input guys. I appreciate your time. After thinking about it for a bit, it also doesn't make sense that it would be the laser as no parameters changed during the duration of the job. It doesn't make sense that it would stop doing it and start again in different areas on the cup. Thanks again!

So the most expensive cup has the garbage metal. Go figure, I have actually noticed that as well lately, many yetis have rough stainless, and very inconsistent powder coating. That really shows the power of the brand.

Jon

I do a lot of Yeti's and have never encountered poor quality. They are definitely the best quality of all the insulated cups I've done.

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Originally Posted by jon stevenson

So the most expensive cup has the garbage metal. Go figure, I have actually noticed that as well lately, many yetis have rough stainless, and very inconsistent powder coating. That really shows the power of the brand.

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I have actually done very little YETI's compared to the Polar Camel mugs. I have also had a better experience with the latter. I wouldn't say that they always have consistent powder coating either, but better than the YETI's I have done. I have also found the coating on the Polar Camels to be more durable. I have to be careful when cleaning a YETI to make sure I don't rub spots on the coating, but I have never had to worry about a Polar Camel before.