I cut 3/8" mild at around 500W CW with oxygen at 2 - 3 Bar with as fast a feed rate as possible, between 400 - 750mm per sec. Alternatively if the heat input into the plate is too high then using pulsed Wave with 1ms duration and 500Hz to 700Hz. This will give about 1kW average power but less heat into the work piece at a faster feed rate.

You can of course use inert gas such as Nitrogen at 15 Bar and use full power on you PRC then vary the feed rate for best results.

Of course, I expect that your beam alignment through the nozzle doesn't move around as the axis move!!! especially on a 5 axis system.

What the cut your getting like at the moment?

Thanks axiomatrix for the reply. At present all we are getting is a good cut at the top but on the bottom it is like molten metal. We were using 1500W and I'm not sur what oxy pressure because we were increasing and decreasing.I will try these settings you suggested and let you know.