Linde BOC Smootharc Advance MIG 425R Operating Manual page 38

38 BOC Smootharc Advance III MIG 225C & 255C Operating manual
Tungsten tip preparation
DCSP (EN) or DCRP (EP)
= Diameter Flat
1/4–1/2x Dia
Taper length
2–3x Dia
Ball tip by arcing on clean metal at low current DCRP (EP) then slowly
increase current to form the desired ball diameter. Return setting to AC.
Tungsten grinding
Shape by grinding longitudinally (never
radially). Remove the sharp point to
leave a truncated point with a flat
spot. Diameter of flat spot determines
amperage capacity (See below). The
included angle determines weld bead
shape and size. Generally, as the
included angle increases, penetration
increases and bead width decreases.
Use a medium (60 grit or finer)
aluminium oxide wheel.
Tungsten extension
Standard Parts
General
purpose
3x Dia
ACHP General Purpose
Max. ball
1x Dia
Gas Lens Parts
General
purpose
3x Dia
Maximum
6x Dia
(in draft free areas)
Tungsten electrode tip shapes and current ranges
Thoriated, ceriated, and lanthanated tungsten electrodes do not ball
as readily as pure or zirconiated tungsten electrodes, and as such are
typically used for DCSP welding. These electrodes maintain a ground
tip shape much better than the pure tungsten electrodes. If used on
AC, thoriated and lanthanated electrodes often spit. Regardless of the
electrode tip geometry selected, it is important that a consistent tip
configuration be used once a welding procedure is established. Changes
in electrode geometry can have a significant influence not only on the
weld bead width, depth of penetration, and resultant quality, but also on
the electrical characteristics of the arc. Below is a guide for electrode tip
preparation for a range of sizes with recommended current ranges.
Electrode Diameter arc
diameter (mm) tip (mm)
1.0 0.125
1.0 0.250
1.6 0.500
1.6 0.800
2.3 0.800
2.3 1.100
3.2 1.100
3.2 1.500
Constant
included angle, Current range
(degrees) (A)
12 2 – 15
20 5 – 30
25 8 – 50
30 10 – 70
35 12 – 90
45 15 – 150
60 20 – 200
90 25 – 250