Arc Machines 307 - Manual (Page 112)

Arc Machines, Inc. Model 307 Orbital Tube Welder Training
Document No. 740096 Chapter 9. Page 8.
Rev.A
Example: (Refer to chart at the bottom page 7). Based on 1
amp per 0.001” of tube wall thickness, Level 1 primary amps
for an 0.049” wall thickness would be 49 amps. Add the 10%
correction (5 amps) = 54 amps for level 1. The last level pri-
mary amps is typically 20% less than Level 1 primary amps.
(43 amps). Decrease Intermediate Level Primary amps
equally.
Note: Variations in materials will require minor amperage
adjustments.
Background Amps: Background amps are set at approximately
30% of Level 1 amps and generally remain the same throughout
the weld sequence. Example: Level 1 amps = 54. 30% of 54 =
16.2. If using whole numbers, round off to 16.
Example Amperage calculation for .500 in. O.D. tube with
0.049 in wall:
Primary Travel - Primary Travel speed is typically based on 5
inches per minute (IPM). Some customers prefer travel speeds
based on 4 IPM for larger sizes and/or heavier wall thicknesses.
Arc Machines recommends 8 RPM (6.28 IPM) for 0.250 in. O.D.,
0.035 in. wall tubing.
Calculation of RPM: Circumference = π x O.D. = 3.141 x .500 = 1.57 in.
RPM = IPM ÷ circumference = 5 IPM ÷ 1.57 = 3.18 RPM
Background Travel - Background travel is only active when
Travel Mode is Step. That is when the RPM has a different value
during the Primary and Background current pulse times. In STEP
mode, the Primary Travel (RPM) is typically set to zero (0.0) while
the Background RPM is calculated for 4 or 5 IPM (non-step).
Primary Pulse Time - Primary Pulse time is the time that the
amperage remains at the Primary Amps. Increasing the
Primary Pulse Time will increase the heat input into the weld.
Background Pulse Time - Background Pulse time is the time
that the amperage remains at the Background amperage. Pulse
times are typically “balanced” or kept equal. Short pulse dura-
tions result in weld beads that are close together while increasing
the pulse times results in weld beads spaced further apart.
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