Laser PPI setting

[geartech]

LaserCad laser PPI setting in layer settings

Thought I read somewhere this helps with cutting by reducing charring on the edge of the cut.
Can anyone give me an Idea as to when to use it and why.
Also what a safe limit would be?

Frederick

[Axeman]

PPI stands for Pulse Per Inch.

Basically the laser will 'chatter' on and off that number of times in an inch. What this does, it take advantage of having the sharp 'flare up' effect of the flash voltage and giving a spike of juice through the material rather than the vaporizing effect of having a solid beam push through the material.

This reduces charring. So basically if you want to do some experimenting...at 100 PPI, you'll have probably have a hard time getting a 'clean' cut. But start increasing in increments of 50 or 100 and re-cut until you land the sweet spot. It really all depends on the material.

There is no "danger zone" since if you had something like 2000 PPI, you're getting pretty close to just having a solid beam on.

[Techgraphix]

I did a test from 200 to 1500 PPI on a piece of 6mm multiplex scrapwood: any setting between 400 and 1500 gave approximately the same result but around 700 the cut was the deepest.
in compare to NO-PPI you need to use more power to get through the material. Where I cut through the material with 70% 10mm/sec NO-PPI, I needed 90% 8mm/sec to get through it when I used PPI.

Kees

[H.J.G.]

Hi,
I have read that PPI is actually causing the power to momentary go above max power of tube, and can lead to cathode damage and contamination of gasses in tube thereby shortening tube life.
But then isn't this what essentially happens when you get a very detailed engraving?

[Techgraphix]

But then isn't this what essentially happens when you get a very detailed engraving?

I seldom use a powersetting higher than 50% when I engrave something. Once I tried to deep-engrave (~1mm deep!) in glass with 80% power but I had to pause every minute to let the glass cool down to prevent cracking... Marble survived even 90% @ 100mm/sec!
But normally my power-settings are much lower when engraving..

Kees

[geartech]

Thanks guys, Thats what I thought it was supposed to do. Just looking for a little insite to it's use and what people have experienced while using it for cutting.