Orbital welding
Orbital welding is Automatic Tunguston inert gas welding. It
eliminates chances of manual errors in welding. It produces
identical welds for hundred of times hence accuracy in welding.
Orbital welding was first used in the 1960's when the aerospace
industry recognized the need for a superior joining technique
for aerospace hydraulic lines. A mechanism was developed in
which the arc from a tungsten electrode was rotated around the
tubing weld joint. The arc welding current was regulated with a
control system thus automating the entire process. The result
was a more precision and reliable method than the manual welding
method it replaced. Orbital welding became practical for many
industries in the early 1980's when combination power supply /
control systems were developed that operated from 110 V AC and
were physically small enough to be carried from place to place
on a construction site for multiple in-place welds. Modern day
orbital welding systems offer computer control where welding
parameters for a variety of applications can be stored in memory
and called up when needed for a specific application. The skills
of a certified welder are thus built into the welding system,
producing enormous numbers of identical welds and leaving
significantly less room for error or defects.
Orbital Welding Equipment
In the orbital welding process, tubes / pipes are clamped in
place and an orbital weld head rotates an electrode and electric
arc around the weld joint to make the required weld. An orbital
welding system consists of a power supply and an orbital weld
head.
Power Supply: The power supply / control system supplies and
controls the welding parameters according to the specific weld
program created or recalled from memory. The power supply
provides the control parameters, the arc welding current, the
power to drive the motor in the weld head and switches the
shield gas (es) on / off as necessary.
Weld Head: Orbital weld heads are normally of the enclosed type
and provide an inert atmosphere chamber that surrounds the weld
joint. Standard enclosed orbital weld heads are practical in
welding tube sizes from 1/16 inch (1.6mm) to 6 inches (152mm)
with wall thickness' of up to 0.154 inches (3.9mm) Larger
diameters and wall thickness' can be accommodated with open
style weld heads.
The Physics of the GTAW Process
The orbital welding process uses the Gas Tungsten Arc Welding
process (GTAW) as the source of the electric arc that melts the
base material and forms the weld. In the GTAW process (also
referred to as the Tungsten Inert Gas process - TIG) an electric
arc is established between a Tungsten electrode and the part to
be welded. To start the arc, an RF or high voltage signal
(usually 3.5 to 7 KV) is used to break down (ionize) the
insulating properties of the shield gas and make it electrically
conductive in order to pass through a tiny amount of current. A
capacitor dumps current into this electrical path, which reduces
the arc voltage to a level where the power supply can then
supply current for the arc. The power supply responds to the
demand and provides weld current to keep the arc established.
The metal to be welded is melted by the intense heat of the arc
and fuses together.
Reasons for Using Orbital Welding Equipment
There are many reasons for using orbital welding equipment. The
ability to make high quality, consistent welds repeatedly at a
speed close to the maximum weld speed offer many benefits to the
user: