Page 29 - MetalForming July 2019

Fabrication: Plasma Cutting
intricate parts on thicker material,” he says, “they become a pain to separate... they get stuck.”
Stainless steel and aluminum rep- resent other areas where plasma cut- ting provides an effective alternative to its laser counterpart on thicker sheet and plate.
“Plasma provides almost identical cut quality to laser for aluminum and stain- less steel if intricate cutting details aren’t required, “ Ott says, “and at a lower cost due to high gas consumption required for lasers to cut these materials.”
Another important issue in the plas- ma-versus-laser discussion: maintenance. “Laser cutting machines undergo higher acceleration than plasma cut- ting...to as high as 4 g,” says Ott. “That translates to greater machine-mainte- nance requirements. Motors must be
changed more often, for example.” Also, laser components tend to be more delicate, translating to damage from wear and tear or from material
hits or drops.
Sole-Source Systems May Be Best Option
A plasma cutting system typically consists of a table, power supply, gas boxes, the torch, height control and the CNC package. Dating back a decade or more, Ott notes, many times these separate components were mixed and matched to produce the system. While
integration from separate sources still occurs, Ott believes that an integrated system from a sole source provides the most effective solution, offering improved cut quality.
“In the past,” he says, “an equipment OEM bought a power supply from com- pany A, a height control from B and the CNC package from C, with the OEM tasked with combining these compo- nents. An OEM really needed to under- stand each of these components in order to produce a well-performing system. For example, the heart of the system, the CNC package, controls the power supply, the plasma system and the height control. The height-control system normally comes with little or no performance information, as all of that must come from the plasma-sys- tem manufacturer. Often, the plasma- system provider supplied limited infor- mation on that to its fabricator customers. This held true across the other components as well—not enough information transfer between the com-
Elements of this integrated plasma system include the power source, torch, torch height control, automatic gas control and CNC with operator
interface.
ponent manufacturers and the OEMs. So system per- formance suffered.”
Hole sizes and locations, important cutting parame- ters, provide an example of the benefits of a single- source integrated system.
“Hole optimization requires a very close interconnection of the CNC, the height control and the plasma system,” Ott explains. “Without that, a user couldn’t repeatedly produce the same holes.”
Consider a Cutting Family Affair
Given enough volume in thin and thick material, adding plasma cutting systems to on-hand laser cutting capa- bility, and vice versa, may prove ben- eficial. Material would route to each type of machine based on criteria such as that suggested above.
“A fabricator may need to cut 6- mm-thick stainless steel or aluminum, for example, requiring small, intricate shapes but not needing an intricate outer contour,” says Ott, providing an example of where the two technologies can work together. “With high labor and operating costs, fabricators don’t want to waste valuable time making a long cut with a laser. Do that on the plasma machine, then switch to the laser.”
Here, Ott points out machines employing both plasma and laser cut- ting technology, as well as machines combining plasma and waterjet cut- ting, thus enabling the advantages of each technology in a single unit. Fab- ricators perhaps with limited floor space may consider such a system, with a lower cost than that of two sep- arate machines. MF
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MetalForming/July 2019 27
Plasma Cutting Sweet Spots
• Sheet thicknesses from 2 to 6 mm • Thicker plates
• Simple internal contours and cut
details