Spin Welder User’s Manual
Section 5 – Theory of Operation
Page 33
Page 32
Dukane Manual Part Number 403-547-03
Dukane Manual Part Number 403-547-03
The generalization of RPM being a noncritical
parameter applies only to motor drives. An inertial
drive utilizes a flywheel’s kinetic energy which is
a function of the square of its rotational velocity.
Inertial drive units adjust the energy delivered by
adjusting the flywheel’s speed and are therefore
more sensitive to a change in rotational velocity.
Weld Time
Weld times are very application dependent but typi-
cally less than a second. Filler content may reduce
the coefficient of friction. Softer plastics (except
fluropolymers) generally have higher coefficients of
friction. This influences the weld initiation time. If
you require a short weld time, it may be necessary
to allocate part of the weld time to the deceleration
time in order to achieve the desired weld penetration.
Once the polymers reach Phase III, an increase in
welding time does not significantly yield an increase
in weld strength. Excessively long weld times may
draw out reinforcing filler and realign the interchain
bonds in the weld plane resulting in a weak axial
weld joint. It may also lead to part distortion in
extreme cases.
Hold Time
The hold time typically ranges from 1.0 to 3.0 sec-
onds. Amorphous plastics will normally take longer
to solidify than semicrystalline plastics. It is during
the hold time that the axial pressure forces the parts
together until the plastic solidifies. For large parts,
it may be upwards of 5 seconds.
Part Size
For larger diameter weld joints, the 5 HP model is
recommended. This model will accommodate tool-
ing up to 12 inches in diameter and has sufficient
torque to handle large pieces. For smaller size parts,
the 3 HP model is preferred due to its higher RPM
capability. The 3 HP model has a maximum speed
