Advanced Welding Processes: Technologies and Process Control

122
Advanced welding processes
Pulse amplitude (A)
500
400
300
200
this gives rise to the band of conditions and it is possible to select a range of
values which lie within the operating area.
Typical values for I p and t p for a range of consumables are given in Table
7.3. Ideally, the parameters are chosen to produce droplets of similar diameter
to that of the filler wire and similar in size to those found in the drop spray
transfer mode.
If it is assumed that a constant length of wire is burnt off at each pulse, a
simple relationship between pulse frequency and wire feed speed may be
defined where W is wire feed speed, F is pulse frequency and 1 d is the length
of wire detached per pulse:
W = Fl d
Lower boundary
Upper boundary
2 3 4 5 6 7 8
Pulse duration (ms)
7.24 Pulse current–pulse duration relationship for one drop per pulse
transfer (1.2 mm diameter carbon steel wire in argon/5% CO 2).
Table 7.3 Typical pulse parameters for controlled droplet detachment
Wire diameter Pulse amplitude l p (A) and duration t p (ms) for a range of
(mm) common materials
Plain carbon steel Austenitic Aluminium
stainless steel alloys
I P t p I P t p I P t p
0.8 300 1.5 300 1.5
1.0 300 2.0 350 2.0
1.2 350 4.0 350 3.0 250 2.5
1.6 400 4.0 200 5.0
(7.10)