Technical Information

Vibration welding is a velocity process; in
order to melt plastic, the parts must be
made to move relative to one another.
Motion is produced and controlled by
alternating energy to opposed
electromechanical coils for linear motion or
the sequencing of energy through three
coils for orbital motion. The high frequency
vibrational motion required for welding is
applied through a spring mass system. The
vibrating mass (springs, laminations, and
tool) is tuned to run at its resonant
frequency. A digital power supply is used to set and maintain the resonant frequency using a controlled feedback loop.
Branson offers two types of vibration welding: linear
vibration and orbital vibration. Linear vibration welding -
in production for over 25 years - uses transverse,
reciprocating motion; the vibration occurs in only one
axis. Two frequencies are available with linear welding:
100 Hz and 240 Hz. The frequency used is based on the
application: high frequency has more flexibility in part
design, especially parts with internal components; the
lower frequency is better with dissimilar materials.
Orbital vibration welding uses constant velocity motion,
a non-rotating circular motion in all directions at 240 Hz.
The vibration motion occurs equally in both the x and y
axes and all axes in between.
The vibration welding process eliminates the need for
solvents, adhesives, mechanical fasteners, and other
consumables.
Additional advantages and benefits of the vibration welding
process include:
• Fast, clean, energy efficient
• Suitable for large parts (up to 70” x 36” and larger!) and
irregularly-shaped parts
• No need for elaborate ventilation systems to remove
fumes or heat
• High productivity with lower cost than many alternate
assembly methods
• Ease of interface with automated assembly line production
• Can weld multiple smaller parts at one time.
Vibration Welding
How It
Works
Vibration welding uses the frictional heat generated at the joint interface
of two parts to be welded to melt the plastic. Branson offers both linear
and orbital vibration welders. Linear welding moves one section in a recip-
rocating motion against the mating piece. In orbital welding, the upper
section is vibrated using constant velocity orbital motion – circular motion
in all directions.
Vibration Welding
Applied
Technologies
Group
41 Eagle Road
Danbury, CT
06813-1961
[phone]
Fax [phone]
Vibration welding is a velocity process; in
order to melt plastic, the parts must be made
to move relative to one another. Motion is
produced and controlled by alternating ener-
gy to opposed electromechanical coils for lin-
ear motion or the sequencing of energy
through three coils for orbital motion. The
high frequency vibrational motion required
for welding is applied through a spring mass
system. The vibrating mass (springs, lamina-
tions, and tool) is tuned to run at its resonant
frequency. A digital power supply is used to
set and maintain the resonant frequency
using a controlled feedback loop.
Once the machine is set to run at the res-
onant frequency for the mass of the vibrating
tool, an amplitude must be set and main-
tained. Effective amplitudes run from 0.040"
- 0.070" (1.02 - 1.78 mm) (linear) or 0.030"
- 0.060" (0.762 - 1.52 mm) (orbital), peak to
peak, depending upon the thermoplastic
being joined and the post welding require-
ments. Amplitude is maintained through a
closed-loop system that ensures constant
amplitude during the entire weld cycle.
Linear & Orbital Vibration Welding
Branson offers two types of vibration
welding: linear vibration and orbital vibra-
tion. Linear vibration welding—in produc-
tion for over 20 years—uses transverse, recip-
rocating motion; the vibration occurs in only
one axis. Two frequencies are available with
linear welding: 120 Hz and 240 Hz. The fre-
quency used is based on the application: high
frequency has more flexibility in part design,
especially parts with internal components; the
lower frequency is better with dissimilar
materials. The newest process, orbital vibra-
tion welding uses constant velocity motion, a
non-rotating circular motion in all directions
at 240 Hz. The vibration motion occurs
equally in both the x and y axes and all axes
in between.
Process Advantages
The vibration welding process eliminates
the need for solvents, adhesives, mechanical
fasteners, and other consumables.
Additional advantages and benefits of the
vibration welding process include:
•
Fast, clean, energy efficient
•
Suitable for large parts (up to 20" x 60")
and irregularly-shaped parts
•
No need for elaborate ventilation systems
to remove fumes or heat
•
High productivity with lower cost than
many alternate assembly methods
•
Ease of interface with automated assembly
line production
•
Can weld multiple smaller parts at one
time.
+
Lower Upper Tooling
SpringsElectromagnetic
Coil
I-Section
Frame
Lifting Table
Principle of Operation
Lower Tooling
Upper Tooling
Vibration Welding: How It Works
Linear & Orbital Vibration
Welding
Vibration Welding Process
Advantages
One of Branson’s Clean Joining Technologies is Clean
Vibration (CVT). This is a vibration weld process with
non-contact heating and plasticization of the joint planes
by means of broad-band metal-foil emitters (see picture).
A subsequent vibration welding process of the molten layers
of plastic follows (no solid friction, no local melt zones,
uniform material flow).
The result is a “clean” vibration joint (compact weld bead,
no ‘angel hair’ by-product) with excellent mechanical
properties. (Contact Branson for information on this and
other Clean Joining Technologies such as Laser Welding
and IR Welding).
Clean Vibration Welding
with IR Preheat Option
Designing for Vibration Welding
Three basic requirements must be met when designing parts for
assembly using vibration welding:
• There must be enough relative motion (0.080”/2.032 mm)between
the mating parts to ensure that the proper amplitude can be utilized.
• The parts must be capable of being held rigidly in their respective
fixtures. Walls must be designed to minimize or eliminate flexing.
• A uniform clamp force must be able to be applied to the joint.
The amount of relative motion and the design features required to
prevent wall flexure during the process vary depending upon the polymer
being welded and the type of weld required. Several typical joint and
part design details are listed below:
There are infinite variations to these three basic joint designs. Refer to
Branson’s joint design specification sheet for typical dimensions and
other joint and part design information.
BUTT JOINT
The simplest joint design, the butt joint can be
used on short walls or walls that are parallel to the
vibration motion. No flash containment is included
in this design.
TONGUE AND GROOVE WITH GRIP TABS
This joint provides pre-welding part alignment and
also incorporates a design which will contain and
hide the weld flash. This joint design will produces
the “cleanest” finished appearance.
BUTT JOINT WITH GRIP TAB DETAIL
This design also uses a flange with a grip tab or
reverse flange detail to eliminate wall flexure and
part warpage. It allows the clamp force to be
applied directly over the weld area on parts that
have tall walls.
It is a common misconception that vibration welding joints
must be in a flat plane. Many parts are welded with all types
of joint shapes. As long as there remains one axis of motion,
the parts are candidates for linear vibration welding. As an
example, refer to the automotive air intake manifold (shown
in Figure 4), where the vibration motion is left to right.
Small angles in the direction of vibration (shown in Figure 5)
can also be welded.
Figure 4
Figure 5
Part Configuration
Vibration welding uses the frictional heat generated at the joint interface of two parts to be welded to
melt the plastic. Branson offers both linear and orbital vibration welders. Linear welding moves one
section in a back-and-forth, single axis motion against the mating piece. In orbital welding, the upper
section is vibrated using constant velocity orbital motion – circular motion in all directions. Clean
Vibration Technology is an option for linear vibration welding that applies IR preheat to the plastic parts
and attains virtually particulate free “clean” joints.
Vibration Welding