[Miron.Costin]

Dear friends ,

I have recently boght a chinesse CO2 laser cutting and egraving machine at 150 watts power
reci tube . But I have some problems when cutting metals .
I mention that I m using Oxigen for helping the cut .
But in my opinion the focus lens that I use isn ;t the right one .

The focus lens that came with the machine is a Zn Se type with 20mm diameter and focal lengh of 64.5 mm

Surfing the youtube I found lots of guys who cut 1-2 mm metal wiht 150 watts co2 laser , but i saw that the nozzle is
around 5 mm from the top of the cutting sheet area and in my case has to be 21.5 mm .

Maybe you can provide me some informations regarding my problem .

Best wishes ,

Costin .

[keebler303]

Distance from the nozzle is not important. What matters is the distance from the lens. A shorter focal length will give you a more tightly focused beam and therefore higher power density which will cut metal better. I would recommend 20 or 25mm focal length. The shape and size of the nozzle is also very important. Ideally the nozzle is very small and close to the metal so the gas jet can blow the molten material out of the way. If your nozzle is 25mm away from the work, it will never work.

Additionally, I doubt your machine provides circular beam polarization or any means of blocking reflected power from traveling back into the tube. These are features that will also increase the performance and life of your machine.

A 150W laser on a high quality machine on youtube is NOT the same as the dirt cheap Chinese attempt you have. It would not be reasonable to expect your machine to cut the same as a Kern, for example.

Good Luck
Matt

[underthetire]

We use 50 and 100 MM lenses all the time. I believe the last thread is correct, you are measuring either from the nozzle, or the protective lens cover, not the lens itself. You should do a wedge run on some burn paper to find the smallest beam diameter at a particular distance. This is done by moving the cutting nozzle close to the paper, then moving in either X or Y and Z. we typicaly move 2" in X and up 1" in Z at the same time. This will give you the rough focal length. Then set your Z about where you think the beam is the smallest and do another run moving the Z in smaller amounts until you find the best focal length. The test pattern should look like an hour glass, starting out large, narrowing down, then getting larger again.

[Melody-gweike]

The machines you found in youtube are not common co2 lasers, and the laser heads are also special designed. In fact, the focus length of the tube for this style of machines is only 63.5.

[Miron.Costin]

Guys thanks for the tip , i attached here a link to show someone who pretends to have a laser just like mine and cutting 2mm metal .

Láser Reci Metal 150W - Routec CNC Chile - YouTube

What do you say ?

Thank you all

[chuck767]

Dear friends ,

I have recently boght a chinesse CO2 laser cutting and egraving machine at 150 watts power
reci tube . But I have some problems when cutting metals .
I mention that I m using Oxigen for helping the cut .
But in my opinion the focus lens that I use isn ;t the right one .

The focus lens that came with the machine is a Zn Se type with 20mm diameter and focal lengh of 64.5 mm

Surfing the youtube I found lots of guys who cut 1-2 mm metal wiht 150 watts co2 laser , but i saw that the nozzle is
around 5 mm from the top of the cutting sheet area and in my case has to be 21.5 mm .

Maybe you can provide me some informations regarding my problem .

Best wishes ,

Costin .

Costin
Did you ever get this resolved?
Chuck

[grawley]

When laser cutting metals, a number of factors are important in the setup. The people most familiar with this are the ones that have been cutting stainless and other metals for years. See the image below, from PRC laser that shows several factors (cut speed, assist gas pressure, focal length, nozzle diameter).

Next, see the invisible. In other words, see what the high pressure stream of gas looks like when laser cutting. Then ask yourself, does it matter what my nozzle standoff distance is?--of course it matters. And, as another reply here indicates, the low power laser guys do not typically sell that adjustment. We do, if you search Chinese laser beam delivery upgrade.