From the looks of your torch, i think you need a bigger compressor as insufficient air allows the torch to overheat.
Also fit a low air cutout switch if you do not wish to replace the torch regularly.
I have the same model cutter and I am able to cut to 25mm clean, and more but ragged.
150 liters min is the minimum at 60 psi min 100 psi is better this was found to stop damaged torches. The manual tells fibs.
A low pressure cutout consists of a pressure switch similar to the pressure switch on the compressor, this is fitted on the back of the cutter on a tee connector with the air supply
Many of switches have a normally open as well as normally closed contacts, the normally open contact is wired in series with the on switch on the torch so if there is low pressure it cuts the current immediately.
They are available from many sources try Google.