Laser Frequency setting

[David Fairfield]

What should I know about Frequency settings? Speed and Power settings are pretty easy concepts to grasp, but I still can't really figure out optimizing the frequency. I know its the speed at which the laser fires, but what does changing frequency do in terms of actually cutting material?

I use my laser at 500 frequency for just about everything. But it seems like I'm missing out on something important :confused: Information or rules of thumb or examples appreciated!

Thanks!:)
Dave

[Frank Corker]

David the frequency settings are the pulsing of the laser. More pulses on acrylic will get a smooth finish, same amount of pulsing on cardboard will create burning. 5000 frequency on an Epilog will make the laser pulse almost continuous but useless when used on card, but 500 frequency on card will make a very neat cut, not charring.

[Joe Pelonio]

What Franks says. Softer plastics like Rowmark engravables and polystryrene
need a lower frequency to eliminate rolled edges from melt.

Also, you can perforate card stock by going really low on the frequency.

[David Fairfield]

Does frequency effect cutting power? For example if I'm trying to cut 1/2" plywood on my laser (which is about the edge of the envelope on my 35w) will maxing out the frequency allow me to cut faster or deeper?

Dave

[Rob Bosworth]

Ok, I hope this doesn't get too long.

Let's say you have a 50 watt CO2 laser. That means it will only output 50 watts over a period of time. So if you turn the laser on, with a high frequency (5000 rate, 1000 ppi) that turns the laser on CW (Continuous Wave), then you will get pulses that turn on and give you 50 watts. Very steady, even power over time.

Now, say you turn your laser on at a low frequency( 750 rate or 250 ppi), the beginning of the pulse might start out at say 150 watts in a spike of power, then the power drops off very quickly towards the end of that pulse. You might get a spike of 150 watts of power on the front end of the pulse, but you will still only average 50 watts over the time period of the total pulse.

If you are cutting a material that is heat sensitive, like some engravable plastics, you will see a roll back of material on the edges of the cut. If you lower your frequency (PPI, Rate) you could see a lot less roll back of the edge. This is because you are in effect allowing the material to "cool" a little bit at the end of each pulse. If you lower the frequency enough, you will not have any overlap of pulses, and will see more of a stitching pattern on your material.