Deep engraving text - steel and aluminium

[lukes (Sas Lucian)]

Hi,

since few time I have start a small laser business, I try to develop my engraving skills to be able to give best solutions to customers. I intend to engrave small batches on request and also to give tailored solutions for customers with his own lasers.
At this moment I have a request to engrave text on steel (carbon) and aluminium pieces, as quick as possible at good quality (clean and clear) at 0.2 mm depth, text height 1.5-4-6 mm. Doing some tests to do this I have the impression that the engraving time is limited strong by the material itself, in aluminium I have obtained more easy big depth compared to steel (even if aluminium is declared more difficult to engrave). After a limit, increasing power give only bad quality. I will add some pictures.

Machine fiber galvo JPT 100W MOPA (M6 … I suppose).

My best results obtained for steel with speed 4000mm/s power 75% interval 0,01mm freq 120kHz, qpulse 350ns, 80 pass bidirectional no-cross, increment 3, no wobble; but time is too long compared to expectations. For aluminium I have only decreased the pass to about 35.

results in aluminium

results in steel

I am sure that somebody with more experience in this field can give his advice. Which way should I take for better performance ?

Thank you,

[jkwilborn (Jack Wilborn)]

@lukes

quick as possible at good quality (clean and clear)

This is a universal want.

@lukes

engraving time is limited strong by the material itself, in aluminum I have obtained more easy big depth compared to steel

I’ve had a 60W JPT M7 MOPA for about 2 years… It’s quite a creation and does a bit of brain teasing also.

I think there are at least two items you need to account for and cause a variation in engraving.

1. heat conductivity of material.
   

   

2. hardness - melting point
   

   

You can see that Aluminum isn’t very hard compared to steel and the heat conduction of each is different. Note that you should check what the metric is used. Some are Imperial, some Metric… I’ve even seen a mixture of them, very confusing.

There are on-line calculators that are available for computing heat energy required … I’m still figuring out how to use this one and apply it’s pulses/mm to how much heat I’m adding to the material.

How much material, such as mass or volume, material type and temperature increase you need for your purpose.

Most of the time, so far, I’ve gotten there quicker using the materials test.

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You can speed up a job by two techniques… do less scanning or scan faster.

You did not mention the lens you use. I have four and the F420mm has a spot size of ~50 microns (0.050mm) and an F100mm has a spot size of ~15 microns (0.016mm). I use one of the many on-line calculators for spot size, depth of focus (dof).

Using your interval of 0.01mm –

If you’re using an F420mm you are going over the same area 5 times.
If you’re using an F100mm you are going over the same area ~60% of the time.

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It’s likely you can double the interval, this cuts the passes in half for the same area and reduces the job time by half also.

Using the spot size you can determine a good dpi.

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The steel looks a little over cooked. Have you tried to lower the frequency to get a deeper cut? Also lowering the q-pulse duration will allow the fiber to drain more thoroughly. My manual says the highest power is at a frequency of 40kHz.

I’d suggest a cleaning pass using a higher frequency and quicker (shorter) q-pulse to help with definition.

I assume these are filled vectors?

[lukes (Sas Lucian)]

Thank you Jack !

you’re right, a deeper knowledge of the basics help for sure. I have try to understand the basics but without a guru as a guide the road to heaven is much longer. Fortunately, you gave me a confirmation that only testing without a plan is not the right way.
My actual lens is 254 mm focal length but I will change soon the machine with a JPT 60W Mopa and I will have more lenses. The text used it’s filled true type font. I have try also with SHX fonts, the situation changed a little bit but for similar thickness of the character I waste similar time (logic !).
I can see now that my spot size and my setting don’t fit very well.
I will first study better the basic data, make a small plan an then some new tests.

Thank you again for your time and kindness to share your experience, it’s more and more unusual in actual world.

[jkwilborn (Jack Wilborn)]

Although a video on photo etching with a laser, the Laser Everything on photo engraving is great for explaining how to pick the right interval for your job. Might be worth a watch. I know you’re not doing photos, but picking a good interval is important.

The COMPLETE Photo Engraving Guide Part 1 | Fiber CO2 UV and Diode

We also do some things a bit different with a fiber when we’re heating metal for colors, you many want to cover the same area multiple times… this is pretty rare with a co2 or diode.

Have fun and Good luck.

[lukes (Sas Lucian)]

I want to learn to do all kind that a fiber laser can do . A CO2 laser is also on my list to have.
From time to time I do service for such machines, a job more easy than working with them. My feeling was that fiber laser could be more profitable with industrial clients, the time will tell me if I was wrong or not; only after few years I can decide.
Thank you again !