pressings, shiny patch problems on mild steel 1

[jammie]

im having problems with a prima m/c whilst cutting 3mm pressings.This is the thickest job we have on our m/c but quite often it makes a mess on some but not all of the jobs & the problem area is always where the job has been drawn by pressing . We are using a 1.5mm tip & running the job with the cutting head sensor on. I have allready checked that the cutting head is perpendiular at all points .I am using a second O2 pressure for piercing but sometimes there is some blow back causing slag to stick to the tip . I have thought that this is what might be causing our problems as this might be causing the head to sit further away from the job than it should but im not sure.
only other thing that i havnt really got into is the focus point of the laser. Is there something i can do to get rid of this problem or is it just a case of having to put up with the odd job being scrapped out .

 

[caren]

Hi Jammie,

What is the assist gas you are using for cuttin. You mention Oxy for piercing, are you using it for cutting as well?
You may be able to set a offset when piercing to lift the tip higher, I would recommend 2mm. If you still have problems you could try step piercing, I use this on thick Mild Steel. It is slower but cleaner with little or no blow back.
You might like to try putting your focus point at the bottom of the sheet. This will create a larger kerf on the cut and allow the cutting gas to get to the bottom of the cut.

Good luck