Galvo vs Plotter

[matthew knott]

I'm intensely curious what the control software is like (especially compared to the software used for the Chinese flatbeds). I'm working on quotes now for a fiber, and the question has been raised about galvo versus flatbed. I deally, I could print from Corel directly (i.e., native driver, not a translator written in Visual Basic that never works perfectly and insists on translating everything to Adobe illustrator format first)... but next best thing is import a file from Corel into their driver software.

I've taken a real shine to SPI Laser's redENERGY G4 cartridges... lots of options there. I'm guessing I would need to use SPI's control program and they have standard control drivers for most galvos... downside to that is I'm stuck with however SPI has decided my workflow should be. Maybe it's good, maybe not so much... wish I could play with one firsthand.

Honestly when you get used to using a proper program written to control the laser with all the features it brings Dan you will never want to go back to a print driver. I won't go into all the clever stuff you can do but, a print driver just cant cut it as you need a higher level of control to get the best from.
We have a redENERGY G4 on loan for a development project, its a 85 watt pulsed with over 4 joules per pulse, it kicks arse! only downside is the beam quality is m2=5 ish, so it suits a shorter lens. Did this today, its 1mm deep
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You don't have to use SPI controllers, they are quite basic and if someone contacts SPI about buying engraving machine they just recommend a company that uses their lasers. IPG also make pretty nice fiber lasers. Dan if you want to try some demo software I can send you a link, but nothing beats sitting down and trying a machine to see the software and hardware link up.

[Dan Hintz]

Matt,

Expect a PM when I get a longer chance to sit down and put my thoughts together. I sent SPI an email asking for a quote, but I haven't heard back from them... if you happen to speak to one of the reps at some point, see if you can get a list of manufacturers in the US who use their lasers. I'll gladly take that demo software link, too.

What kind of removal rates are you getting with that 85W? I'm looking at a 20-30W system (M2 would be in the low 1.x range), and from what I can tell, 20W puts me in the 4-5 mm^3/min range for stainless (also want to work with aluminum, brass, and titanium). I'm only looking at going 1mm deep (+/-), but I imagine that will involve multiple passes at that power level... it seems 0.1mm/pass is the typical range. At that rate, small items will take me 30 minutes while the larger items I have in mind could very well take all day (literally).

[Bruce Boone]

I came close to getting an SPI fiber, but found the IPG worked the titanium better. The SPI was continuous, and the IPG quasi continuous mode allows pulses 10 times higher power in 1/10 the time increments. It is able to still run air cooled that way, and you get massive peak power. I sent samples to both and although the SPI had a finer beam, it did best fot very thin stuff like stents. It couldn't handle the 7mm of titanium requirement.

[Rodne Gold]

2 years ago , I had a demo of a 20w fibre at shenui (their galvo platforms were pretty good as far as I could see with their Co2 and Yags ) and I asked them to cut thru a piece of 1mm or thinner aluminium , it took like 10 passes to get thru , but the passes were real quick... what concerned me more was the heat of the piece after .. when they did engraving , deepish , if you turned the piece around , you could see the impression on the back side.

[Dan Hintz]

I'm sending out a handful of samples to be deep engraved... I'm interested in engraving times, chosen parameters, as well as final quality (such as the rear impression you mentioned, Rodney).

[matthew knott]

I will work out the material removal rates for you, .1mm per pass is optimistic, but i guess it depends on the speed, we normally run a high speed with loads of repeats, it helps keep the HAZ damage down as the heat is more evenly distributed. Deep engraving into thin material is almost impossible. Stainless is awful and has to be clamped down, aluminium is better but you still get damage on the back. At the end of the day the laser is just heat, cold laser technology will be the future, but way too expensive right now.

[Dan Hintz]

So let's say 0.05mm/pass on aluminum with a 20W... what would your rough speed be (ipm)? I'm looking at a flatbed to keep my options open, particularly since most of my work will be deep engraving, not marking (where a galvo would be much faster), so speeds will be very slow.

[matthew knott]

So let's say 0.05mm/pass on aluminum with a 20W... what would your rough speed be (ipm)? I'm looking at a flatbed to keep my options open, particularly since most of my work will be deep engraving, not marking (where a galvo would be much faster), so speeds will be very slow.

OK, I engraved a box (as seen in the picture) 28 x 5 mm with the text inside, with a 30 watt fiber it to 7 minutes to go in .5mm, I think the speed was 600mm/sec and 60 repeats, 254mm lens. On the 85 watt laser it took 5mins to go in .95mm but with a 100mm lens

One thing that really helps with deep engraving is to change the hatching angle every pass, i use 45 degree increments, this is not possible on a flat bed as you only have one angle of attack.

[Dan Hintz]

OK, I engraved a box (as seen in the picture) 28 x 5 mm with the text inside, with a 30 watt fiber it to 7 minutes to go in .5mm

I estimated roughly 50 minutes to do 1mm deep on a 5mm x 50mm range with a 20W... scaling those numbers up sounds like my estimate wasn't too far off. I expect to use an 80mm lens, so power density should be quite a bit tighter than your 254mm lens... I'm hoping for a much faster removal rate because of that.

[matthew knott]

I would think the lens would help a lot, we have a 100mm lens so i will try it tomorrow, should be close to an 80mm, i will try a 5mm x 50mm box and measure the result, someone else was working out the 85watt, i will post their results to. You can't beat a traditional cutting bit for deep engraving, but you cant get the quality of a the laser, its as good as EDM. It really depends what your doing, and sometimes a laser is not the right tool, but sometimes its ace! What are you hoping to do?

[Dan Hintz]

I will be looking for extremely fine detail in tight areas... no bit could ever hope to touch what I plan on doing. I'm very keen to learn what you get with the 100mm lens... any chance you can remove the cross hatching and just have it do passes in the same direction each time, try and get it as close as possible? Thanks!

[matthew knott]

I will be looking for extremely fine detail in tight areas... no bit could ever hope to touch what I plan on doing. I'm very keen to learn what you get with the 100mm lens... any chance you can remove the cross hatching and just have it do passes in the same direction each time, try and get it as close as possible? Thanks!

Can do, it won't be quite as deep and the bottom won't be as smooth but it will still work, I only have 30 watt lasers running right now, but at 80% power they are pretty close to 20 watts. The SPI 85 watts is big bucks, its not out for sale yet but estimate is £19k (x1.5 for $). A 20 watt source can be had for less than $8k (not spi)

[Dan Hintz]

Hoping you find the time to try out those new settings, Matt... once I find a suitable brass road to join the stainless and aluminum rods I already have, I'll be sending them off for some test cuts.