Saturday, January 15, 2011

Plasma CNC Drill Line Runs Rings Around Standard Equipment

The economy of structural steel fabrication is very dependent on the path the workpiece travels as it goes from raw steel inventory to eventual loading on a truck headed for the job site. Every time the workpiece is "touched" adds delay and cost to the final finished beam, channel or angle.

A beam with ten or so bolt holes and cut to length has really very few "touches" . But many fabricated sections are considerably more complicated than that.

For example, complete fabrication recently performed on an 96" W16x31 structural beam involved three dozen unique operations:

* Front Trim Miter Cut 1/4"
* 2 Copes on the front of the beam
* 3 Bolt Holes on that same end of the beam
* 6 bolt hole angled cluster on web
* 4 layout marks on web
* 2 bolt holes on top flange
* 2 bolt holes on bottom flange
* 3 slots on web at rear of beam
* Piece Mark - 2 Lines - 9 characters total
* Flange notch cut flush with web (each end of the beam)
* Cope on rear of beam
* Notch cut on flange

An analysis of fabricating this section by three different "paths" was very revealing in terms of the time requirements that result.

To begin, the "high touch" path is a traditional manual approach. The beam has to be measured and marked, then cut on the bandsaw. After that, there is plenty of "manual" drilling (admittedly using a heavy duty drill press) and significant thermal (torch) cutting to make the copes and flange cuts, in addition to stamping by hand to make the nine letter piece marks. The total time involved to perform these processes was estimated to be 120 minutes - 2 hours. But because of the transport involved and the time in queue at subsequent stations, the clock time would cover at least two shifts - normally two days at most shops.

Second, a more updated and automated approach was used to fabricate the section. This involved cutting the piece to length on the bandsaw, then shuttling it to a beam drill line to make the thirteen bolt holes and three slots. The newer CNC drill lines can probe the steel section to determine location and dimensions, then put the holes according to instructions determined by specialized software. The remaining features have to be measured and marked on the beam before cutting. Then cutting is done by hand coping torch, plate burning machine, and stamping in the piecemark letters. The total time for this approach is 82 minutes. Again, when including the time needed to shuttle the workpiece between stations and time waiting at those stations, the actual clock time totals to take most of a shift.

Then the piece was fabricated on a new and one-of-kind approach. All features were produced on a single machine - a robotic plasma cutting system. Using this approach, there is no use for any measuring or marking. The sensor tip probes the workpiece for position and geometery, then follows its own calculated cutting instructions it calculates from standard software files of the workpiece downloaded into the operator control from programs like TEKLA, SD/2,StruCAD and others.

PythonX starts cutting on the section and doesn't stop until it's done . . . 10 minutes and 13 seconds later. All thirty seven features are fabricated in this time and the beam is completed. There is no time lost in moving the piece or waiting , therefore the time from beginning to completion isn't a day, or a shift . . . it's the time needed for a standard coffee break.
(ArticlesBase SC #1420886)

Seismic Energy Dissipation Devices

Seismic Energy Dissipation Devices