Tweco 15XC Merlin - Manual (Page 53)

Manual 0-2251 4-19 OPERATION
Cutting with a
Machine Torch
(continued)
4.7 MACHINE TORCH OPERATION (continued)
5. Cut with a standoff of 1/8 - 3/8 in (3 - 10 mm) from the
work. The torch should be held perpendicular to the
workpiece while cutting. Start cutting slowly and
adjust cutting speed for optimum cutting performance.
Section 3.11, Cutting Speeds, contains typical cutting
speeds for various materials and material thicknesses.
A standard shield cup is recommended for most machine
cutting applications. The touch cup (short shield cup) is
designed for light gage cutting where arc voltage measure-
ment is needed for a standoff control. Do not allow an
exposed torch tip to contact the workpiece.
The arc characteristics vary with gases used, cutting speed,
material, and thickness. Air plasma normally produces a
straight arc (on stainless or aluminum), while nitrogen
plasma generally creates a 5° trailing arc (see Figure 4-J).
Figure 4-J Machine Torch Operation