Originally Posted by
JOHNBOY
I work for a company that has 25 welding robots. We have converted 3 of the robots to plasma cutting. We are currently using Hypertherm air plasma on all the robots with excellent results. We currently own 2 Powermax 1250's and one of the new 65's We use them to cut scrap frames from press drawn parts. This has proven to be a very cost effective way to trim the parts. We do a lot of forming for Kubota. Plasma cutting has replaced many of their pinch trim dies which are costly to build and maintain. We cut hoods, floorpans, fenders, and mower decks this way. We normally cut steel gauges 18 thru 7 ga. Now we are going to cut a project on the other end of the scale. We are going to cut some 1 inch thick hot rolled bar with a 6 axis robot We will be buying a Powermax 1650 with a small mechanical torch for this job. My question has to do with starting and ending the cut. Since the bar has rounded edges from the rolling process would it be better for consumable life to start the cut angling away from the edge and roll into the bar or start square to the material? The reason I am concerned is that we made sample cuts with a 1250 using 80 amp consumables and saw erosion of the cutting nozzle after just a handful of cuts. The edge quality of the cuts was good with some dross that easily removed with a solid tap on the part. These samples were produced using the torch sq to the material at the start of the cut. I am concerned that with the rounded edges of the bar stock the pilot arc will be stretching a long way before it actually contacts the material edge. I am also wondering if the air quality becomes more critical as the cutting amperage goes up? Is anyone doing anything like this that can point me the right direction?