Bystronic 3015: Parameters for Cutting Aluminum 4

[AceLaser]

Hello,

I am in charge of the daily use of our Bystronic 3015 and seeking help with cutting aluminum. Our stock for the laser consists of .080" (2.5mm) , .125" (3mm), and .250" (6mm) 5052 alloy - 4'x10' and 5'x10'. Please refer to the lower part of this post for machine specs.

Currently, we are receiving a hard, "sawblade" burr on all cut edges of .125" and .250". The .080" leaves a smaller burr is the same density. Both burrs are hard enough to shred our strongest 80 grit that we use for debur. The plume is usually tilted slightly away from the the feed direction with white and yellow "sparks". We don't typically get a plasma burn on the top of the material, but it does still happen at points where an axis change will happen on top of a grate. In the past, .250" has always produced a worse result, but we have been succesful in reducing the burr to the same as what we get on .125". The .080" tends to cut clean, only leaving a finger-rocking burr if any.

We use Nitrogen for all of our aluminum work and Oxygen for steel. .250" aluminum requires Oxygen as an assist gas.

Tape shot reveals that we have an oval shaped or "cat's eye" beam path. Main operator claims that this causes a lot of our trouble. I have not found enough information to back up that claim.

Our ultimate goal is to minimize impact on our Spray Prep department with post-laser prep. I'm personally trying to set a tolerance of less than 1mm for acceptable burr.

Here are our parameters:

.080
Head: 5"
Focal Point: 1mm
Nozzle Diameter: 1.5mm
Nozzle Type: HK15
Power: 4K, 70% piercing, 40% Cutting
Feed: 7500 mm/min
Gas Pressure: 3 bar piercing, 8 bar cutting

.125"
Head: 7.5"
Focal Point: 3.5"
Nozzle Diameter: 1.75"
Nozzle Type: Hk17
Power: 4k, 80% piercing, 75% cutting
Feed: 3150 mm/min
Gas Pressure: 2 bar piercing, 9 bar cutting

.250"
Head: 7.5"
Focal Point: 6.9"
Nozzle Diameter: 2.5mm
Nozzle Type: HK25
Power: 4k, 80% piercing, 90% cutting

Machine Specs:
Resonator: BTL 4000 (DOB 2001) - 4200w - 20 mm beam
Chiller: Koolant Kooler - 13HP Compressor - 5HP Pump
Filter: Torit Filter System (Barrel)
Air Supply: Shop Air on isolated line set - 120 gal - 175 max pressure - 1100 rpm - 15 hp motor

Any suggestions are welcome and I will try to respond as quickly as possible. I can provide pictures of the cut quality, if interested.

Thanks for your time.

 

[drossfree]

when cutting aluminum you should always be cutting with %100 power due to the reflection possibility. i would also use nitrogen for the .250. your focus should be 60 to %80 through the material eg. for .250 your focus should be -0.16 to -0.22. an oval beam will cause you to get more burr but usually on one side more than the other. an oval beam can also be caused by being reflected off of the nozzle before exiting the orifice. use a larger nozzle when doing a beam alignment then when you are close to center use your smaller nozzle to fine tune. an oval beam in a larger nozzle would mean your mode shot is off and would need to be tuned. nitto paper on the underside of your thinner aluminum will improve your cut quality.

 

[LaserSpyder]

I use a 4.0 Double Nozzle to cut my .250 Aluminum and id go -0.120 to -0.180 you want to be half way to 3/4 into material and super check that oval beam it should be round lol

 

[AceLaser]

Thanks for your responses

@drossfree - I will see that our parameters are switch to 100% when cutting and compare the results. I had always thought that as well. I tried a tape shot with the larger nozzle and still received an oval shape. The last time we had bystronic come down this was brought up to him and a mode shot adjustment was suggested I believe.

@LaserSpyder - What benefit do you find in using a double nozzle?

 

[drossfree]

i also use double nozzles. i find you use less bulk gas and there is also less chance of harmful reflection getting back to the lense or mirrors

 

[AceLaser]

@drossfree - Could you provide me with an example nozzle? Part number and what not.

 

[drossfree]

3.0mm double mushroom nozzle from II-VI =p#L588x

 

[AceLaser]

Thank you. I will look into that. Turns out that Bystronic is having a "Mid-September Parts Sale" from the 15th thru the 30th. Might be able to try a couple of different nozzles

 

[drossfree]

oh yeah that part number is for amada so no good for you most likely

 

[krugtech]

have you ever been able to cut this material without problems? I'd check the optics, power stability and alignment. make sure the beam purge system is ok.

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[AceLaser]

Update from the Front!

After increasing our power to 100%, we are able to drop the focal point further into the material. This produced significantly less burr and even clean edges on certain parts. We ran several trials throughout the day and were able to replicate this cut quality with each trial. I believe we are on the right path.

I have found out that we achieved a clean edge at one point in time by utilizing 100%, but ran into an issue with a few capacitors (which have been replaced). The same concern is still there, but time will tell on that one.

@drossfree - I realized that after searching for an hour. Bystronic does sell double nozzles, but require you to buy bulk. Still, the suggestion is in consideration. I just need to find someone to let me borrow a couple to try.

@krugtech - Thanks for your input. At one point they did. But it was accomplished in a backward manner (100% Power with way too much gas pressure). Blew through a whole NO2 cradle in a matter of days. We are on point with keeping our optics clean as well as our external alignments. We are actually in the process of monitoring the power going in and out of the machine (part of the capacitor concern). However, I am not too sure how focused anyone has been about beam purge. I will look into that one.

 

[krugtech]

is it the yellow capacitors in the high voltage chassis? its easy to set those chassis up wrong, if the inner core of the ballast tubes on the hv chassis glow orange it shortens their life. if you get over currents during modulation the tubes have had it.

Chris Krug

http://krugtech.com/

Maximum Up-time, Minimum BS

 

[AceLaser]

@krugtech - I will seek the answer to that question and get back to you. Thanks for the tip!