plasma beam cutter experience

[pulleye223]

I'm supposed to evaluate purchase of a new plasma cutting system fro my company. It will replace drilling line. I don't have much experience with plasma - certainly nothing like this.

Does anyone have experience with one of these pythonx machines ?

[lost_cause]

I can't say that I've ever seen it, but I do have one thing to add. I worked in the structural steel field for 18+ years as a draftsman. My thought would be: Will all of your clients (engineer of record on each project) accept this? I haven't worked in a detailing office in a year and a half, but in all of that time, I don't think I have ever seen a case of where an engineer would accept a "burned" hole for a structural bolt.

I fully know that the capabilities of plasma cutting have become light years ahead of what a torch can do, but hole quality isn't the issue here. The issue is whether the engineer will allow this type of hole, and that's totally up to their discretion and your company's ability to sway said engineer's opinion. From my experience, many engineers are set in their ways about these details. I've seen a case where an engineer would not allow the use of tension control bolts, but instead insisted on hex head bolts with load indicator washers, even though we had been using TC bolts for several years without issue from any other engineer. It's all about what THEY are willing to accept, and not what will work.

Again, I'm a little out of date (but not too far), but I'd also see what the AISC says about this. In my experience burned edges are handled differently that sheared or saw-cut edges. It's something to do with the amount of material distressed by the cutting process. certain cutting operations cut down your theoretical design edge distance, and this may make a big impact on your design of connections - especially eccentrically loaded bolted connections. It's one thing to end cut your beams this way, but if cutting holes instead of drilling/punching them changes the theoretical hole properties for design, it may wreak havoc with your shop's standard practices for connections.

[jimcolt]

The PythonX machine uses Hypertherms latest technology HPR400xd plasma. This machine uses oxygen as the plasma gas and air as the shield gas, and has the ability to produce very high quality holes with superior metalurgy. I will be speaking about new hole cutting technology at the NASCC / AISC conference in Orlando next week....will be talking about tests that show plasma cut holes using Hypertherms new True Hole technology have outperformed drilled holes in stress fracture tests, which can be atributed to the oxygen cutting process, the smooth remelted plasma cut edges, and the minimal taper produced with this new process.

AISC does allow hole cutting on secondary components on bridge construction using oxygen based plasma, but has not officially approved plasma cut holes on primary members. We will be working to prove this new technology can be acceptable, possibly superior, although it will take more testing and proof.

An advantage of plasma may be the ability to cut accurate slotted holes which can solve bolt hole aliignment / fitup problems in construction.

Pics of todays plasma cut holes using Hypertherms True Hole technology:

Jim Colt Hypertherm