[haascnc5]

Hi-
I should probably put this in a different forum, but I'm a newbie here and haven't looked around enough yet. If this should be asked elsewhere, please advise.

So my question is this-We're cutting parts on the plasma using a Nest generated on a computer program. My question is this, can the start point(lead in) of the plasma be anywhere on the part(we're using 38mm sheets of steel 8x12. The guy that does the nesting says he can only put the lead in on one side of the part because of how the part's are arranged to save on steel by getting the most parts out of the sheet. My plasma operator says where the lead in is placed shouldn't matter. Who's right? Thanks

[jimcolt]

The answer to this is entirely dependent on the Nesting (CAM, Post Processing, etc) software that you are using. The more sophisticated nesting packages will have background settings that will place lead ins in differnt places depending on your needs. Start points can be chosen for the quickest paths from part to part, they can be chosen to dissipate heat, they can be chosen for collision avoidance (avoiding traversing over a previously cut part that may have tipped), they can be chosen for best cut quality (entering on a sharp corner for least distortion), and they can be manually picked or modified after any of the previous are done.

Jim Colt Hypertherm

Hi-
I should probably put this in a different forum, but I'm a newbie here and haven't looked around enough yet. If this should be asked elsewhere, please advise.

So my question is this-We're cutting parts on the plasma using a Nest generated on a computer program. My question is this, can the start point(lead in) of the plasma be anywhere on the part(we're using 38mm sheets of steel 8x12. The guy that does the nesting says he can only put the lead in on one side of the part because of how the part's are arranged to save on steel by getting the most parts out of the sheet. My plasma operator says where the lead in is placed shouldn't matter. Who's right? Thanks

[plasmamatt]

The lead in can be placed anywhere it will fit. It doesn't matter to the plasma cutter. Your guy doing the programming might be referring to the software though. Depending on the software, he might not be able to easily move the lead in to a different location.

[haascnc5]

Thanks Jim, very descriptive answer. The reason I'm asking, is the machining a welding process that happens afterward. We are cutting segments as we call them. The segments are 38mm thick, about 4-5 ft long and anywhere from 1 ft wide to 2ft, and are shaped like a square-ended crescent moon. We assemble 7-8 segments(depending on specifications from customer) in a circle, for a base to the windmills going up around the country. The machining process the follows the plasma cutter is as follows- CNC milling machine drills 20 holes in a pattern through the segment with an inserted drill(usually 1.5 in), then switches to an inserted chamfer tool to make 45 degree bevels at the ends of the part for the welding/assembly process. They are then moved to weld area for assembly where the segments are placed into a circular weld fixture and assembled.

Now the problem is this, the lead in is usually on the end of the part, which damages the chamfer tool inserts, causing excessive breakage. If we change program on CNC mill to account for this, part will not be in tolerance. Lead in also effects welders, who must grind off lead in sometimes to make parts butt together properly for welding. I suppose we could simply just grind off lead in before machining to solve this problem, but this add's a step, and cost. The optimum placement for the lead in, is the outside radius slightly off the corner. This would be perfect for both machining and welding process that follow.

I will get the name of the nesting program at work on Monday Jim, to see if we can find a solution to this problem. Thanks again for your help.

[haascnc5]

The lead in can be placed anywhere it will fit. It doesn't matter to the plasma cutter. Your guy doing the programming might be referring to the software though. Depending on the software, he might not be able to easily move the lead in to a different location.

Thanks Matt, same thing my plasma guy told me. Both you and Jim agree, it come's down to the nesting software.

[haascnc5]

The name of the nesting program is Sigma.

[kkn]

the problem with plasma is that it makes a darn hard shell where it cuts.
leadins is places on a corner so it is easyer to finish.
its not that easy on a circle that it is on a square plate.

[Caramon6561]

What type of plasma cutter are you useing... i operate a ESAB Advenger II.. nesting is really easy on my machine..