Trotec FineMarker getting Grain effect

[Derek Wagner]

I am new to the Forum been searching around and read on here a lot. I have a Trotec Finemarker 10watt YAG laser. I am mainly engraving on Black anodized aluminum parts. When I engrave the logos I am getting almost like a Grain effect, the logo will have lines in it like it is not filling all areas in from the previous pass. I have messed with heights of the table, realigned everything, check to make sure everything is clean, and checked the laser power. I am kind of out ideas and Trotec is starting to get to that point also.

Any ideas would be greatly appreciated.

[Joe Hillmann]

Are you sure the laser is causing the grain? Could the grain of the aluminum be showing through? What happens if you run the laser so it is filling in the Y direction rather than the X direction? Or at an angle?

[Mike Null]

Have you tried increasing the dpi? I don't have a yag so I'm guessing that you have a dpi setting.


by the way, welcome to SMC.

[Derek Wagner]

I am pretty sure it is the laser because I have run it in both the x and y direction and having the same results. I run many different parts with the grain going in different directions and some parts are machined faces. The parts I am currently running the grain of the material runs the opposite direction of the laser.

[Derek Wagner]

Mike

My standard setting is 500 dpi when I increase I get the same results. I took the speed from 50 to 10 and that helps but still not great. But I have never had to run below 50 before.

[Joe Hillmann]

Can you put up a picture of what it is doing?

I don't know your machine but have you checked to make sure everything in the laser is clean and tight? Such as belts, wheels, rails bearings?

[Derek Wagner]

272525
I have clean everything and checked everything multiple times.

[Dan Hintz]

Are you at 100% power? I'm wondering if you're starting to burn into the metal itself. I would start at 10P/100S and work my way up in power until the anodizing is coming off clean.

[Derek Wagner]

Dan
I have been from 10% to 100% power the best setting seems to be 50% power and 50 velocity.

[Joe Hillmann]

Are you sure that isn't the grain of the aluminum that you are exposing. Have you tried engraving on a piece of polished aluminum to see if the grain is still there?

[Kev Williams]

I have no idea if your machine is galvo or gantry or both, seems gantry from the size of the part in the picture-- From my experience, EVERY time I've run into goofy engraving, it's ALWAYS been a mechanical issue- either the lens is loose, lens housing loose, loose mirror, junk on the belt teeth, loose belt, goofy stepper motor, loose gantry bolt... Just my http://www.engraver1.com/gifs/2cents.gif

[Mike Null]

If you hadn't said it was anodized aluminum I would have sworn it was powder coated aluminum (based on your photo) and that a second pass would be required. Your result resembles the result I get on a first pass on powder coat with my CO2 machine.

[matthew knott]

Thats does look particularly grainy, i would recommend recommend dropping the frequency (my guess is that equates to dropping the dpi) and also slowing down the machine, also we ALWAYS run a second pass at 90 degrees at a high speed/frequency and different line settings to get a really nice smooth mark. Im guessing trotec use a print driver so im not sure what control you have, but it looks like the filling lines are 2 spread out also you have a very jagged edge which also points to this. Turning an outline would help to hide this and help the overall look. Some anodise can be a right , if we come across some we always check against a known good bit, hard anodise is awful stuff, always patchy, check if it is hard anodise if you can. Bottom line, anodise should engrave beautifully, this is what we get, its so white and smooth it looks like print.


272546

[Derek Wagner]

Thank you everyone for the input.

Matthew
This is a soft anodize that we receive from two different places and getting the same effect. This issue is something new we have had this machine for a couple years and use to get a nice white solid finish like you are showing. With the same settings for years with only needing one pass. I have had to put a new laser source in and was good for a while until I got this problem. I have checked the laser power and was told by Trotec that is was in spec.

Kev
I have been through everything mechanical. The latest thing I found was a loose lens but tighten that all up and got the same result still.

Thank you

[Rodne Gold]

How clean is the mains power to the laser? Dirty or fluctuating power to lasers can cause all sorts of issues.. Try loan a power conditioner or an Ac-Dc-Ac ups to see if it helps.

[matthew knott]

It will probably be something in the laser source, probably a datalogic laser (laserval) checking the power is not always a true indication of performance as this is a yag pulsed laser, Q switch's have a big effect as do the pump diodes and many other parts. Also at 10 watts you dont have much power to play with. Its going to be a headache for trotec as its not 'really' broken and is within spec, i spent 2 week in Korea with 3 lasers, one of which would not mark as white as the others, swapped everyting between all the machines and never got to the bottom of what it was. You could try Rodne's idea but its unlikely to help as the power supplies are all low voltage DC and have good power filtering on the input, most are happy to run from 250-100 volts ac with no problems at all.
I would sugest you get trotec to take some power measurments at different frequecnys of operation and compare to a good machine.
In reality you only really have 2 options
1; live with it
2; Get trotec to fix it (until reach option 1)
Also remeber this is a buy in OEM laser, so you might see if trotec will get (who ever made it) involved,
Sorry i cant be more helpfull :( hope you get it sorted soon

[Dan Hintz]

Send a sample piece (that's know to have that pattern) to Trotec's apps lab. If they can repeat the pattern with your settings but can also come up with settings where the pattern doesn't happen, well, there's your answer.

[Dan Hintz]

What did the Trotec apps lab say?

[Derek Wagner]

I have sent them the file and settings to trotec. Everything seemed to be good as far as I was told. I have been waiting for the service tech to get back from vacation that I have been dealing with, tomorrow going to get back after him about this issue. I need to try to figure out who can come look at this machine.

Matthew
I am dealing with it for the time being but don't want to struggle with it everyday. The thought you have is the same thought I have had about it loosing strength as it is in process vs just sending a test pulse.