Effect Of Focus Point When Cutting With Inert Gas - Mazak STX SC L PLUS CONTROL Training Manual

EFFECT OF FOCUS POINT WHEN CUTTING WITH INERT GAS

When cutting various materials with inert assist gasses such as nitrogen and argon, the focus set-up
differs greatly from that of oxygen cutting. To reduce or eliminate dross the focus point must be moved
deeper into the material. This can be accomplished by re-focusing the machine or by adjusting the nozzle
or lens mount, depending on which style torch is used. For torches with the adjustable lens mount, the
mount is turned down the appropriate amount to achieve the proper focus. For the standard torch, the
nozzle is screwed upwards to lower the relationship between the nozzle to focus (NF). One complete
revolution of the nozzle will move it 0.040". Therefore, once the machine is set up for the standard
focus, this set-up can be changed without performing the complete "blue flame" procedure. The
following diagram illustrates the effect of various focus points when cutting with inert gas. The lowest
focus will reduce dross, the higher focus will produce the fastest feedrate with the best edge quality.
Therefore, the focus is typically adjusted 1/2 to 2/3 into the given material. This compromise allows a
relatively fast feedrate with good edge quality and reduces or eliminates the amount of dross which
occurs.
CROSS SECTION
OF MATERIAL
FOCUS AT THE BOTTOM
OF MATERIAL:
- ROUGHER EDGE QUALITY
- SLOWER FEEDRATE
- LEAST DROSS
FOCUS ON SURFACE: - BEST EDGE QUALITY
- FASTEST FEEDRATE
- DROSS OCCURS
OPTIMUM FOCUS POINT
1/2 TO 2/3 INTO MATERIAL
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