5. Friction Welding
DEFINATION;
Friction welding (FW) is a class of solid-
state welding processes that generates heat through
mechanical friction between a moving work piece and
a stationary component, with the addition of a lateral
force called "upset" to plastically displace and fuse
the materials. Technically, because no melt occurs,
friction welding is not actually a welding process in
the traditional sense, but a forging technique.
9. One of the work
pieces is attached to
a rotating motor drive,
the other is fixed in
an axial motion
system.
One work piece is
rotated at constant
speed by the motor.
An axial or radial force
is applied.
10. The work pieces
are brought
together under
pressure for a
predator-mined
time, or until a
preset upset is
reached.
Then the drive is
disengaged and a
break is applied to
the rotating work
piece.
11. One of the work pieces
is connected to a
flywheel; the other is
clamped in a non-
rotating axial drive
The flywheel is
accelerated to the
welding angular
velocity.
The drive is disengaged
and the work pieces are
brought together.
Frictional heat is
produced at the
interface. An axial force
is applied to complete
welding.
12.
13.
14. Friction welding has become industry standard in
a number of applications. Some of the
advantages of the process are detailed below
• Weld monitoring can insure 100% weld quality
• Friction welding produces a 100% cross
sectional weld area
• Far superior weld integrity compared to MIG
welding
• Limited operator training require – full
automation also possible
15. • The weld cycle is fully controlled by the machine
• Repeatable results
• Friction welding is a solid state process and does
not suffer from inclusions and
gas porosity.
• Friction welding required no consumables therefore
becomes more cost effective
over time
• Friction welding typically will complete a full cross
sectional weld in 15% of the
time it take MIG welding to produce an 85% cross
sectional weld.
• Friction welding requires no special weld interface
preparation welding)
• No post machining is needed for friction welded
components in many cases
• Dissimilar materials can be joined with no alloying
of the material
16. Due to the advantages of friction welding, it has
now become industry standard in a
number of applications:
• Trailer axles – welding spindle to the case.
Thompson Friction Welding are the
only company to make a double ended machine
which can weld two spindles to
the same housing simultaneously. Advantages of
this include
o fast production time
o extremely accurate weld
.
17. o required machinery footprint reduction
• Piston rods – welding the eye or yoke to the
shaft. Thompson Friction Welding
has supplied many machines that can weld pre
chromed bars without any damage
to the delicate chrome surface.
• API drill pipes and drill rods – welding of
connectors to pipes and rods.
Thompson Friction Welding are at the forefront
of technology advances in this
area with new developments including internal
flash removal over undulating
surfaces
Editor's Notes
In continuous “direct drive” friction welding, one work piece is attached to a rotating motor drive unit as shown above. The other work piece is clamped in a non-rotating axial drive unit. The two work pieces are gradually brought together with one rotating and the other still. When they make contact, heat is generated at the interface due to friction. Additional axial force is applied. The axial force is raised to a final constant value and held for a predetermined time, or until a preset amount of upset takes place. The rotational driving force is disconnected, and the rotating workpiece is stopped by the application of a braking force. The axial force (forging force) is maintained or increased for a predetermined time after rotation ceases.
In inertia friction welding, one of the workpieces is connected to a flywheel, and the other is connected to a non-rotating axial drive system. The flywheel is accelerated to a predetermined rotational speed, storing the required rotational kinetic energy. The drive motor is disengaged and the workpieces are brought together. This causes the faying surfaces to rub together under pressure. The kinetic energy stored in the rotating flywheel is dissipated as heat through friction at the weld interface as the flywheel speed decreases. An increase in friction welding force (forging force) may be applied before rotation stops. The forge force is maintained for a predetermined time after rotation ceases to complete the weld.
