Please click for content. - Orhan Holding

22
Spin welding is a friction welding technique used on
thermoplastic materials, in which the parts to be welded
are heated by friction.
The process of spin welding uses heat generated by
rotational friction at the joint line. The heat generated
during the rotational contact melts the plastic in the
heat⤓affected zone forming a weld upon cooling.
There are 4 phases observed during spinwelding process:
1. Solid Friction Phase: In this phase, heat is generated as
a result of the friction between the two surfaces. This
causes the polymer material to heat up until the melting
point is reached. The heat generated is dependent on the
applied tangential velocity and the pressure.
2. Melting Phase: In the second phase, a thin molten
polymer layer is formed which grows as a result of the
ongoing heat generation. At first only a thin molten layer
exists and consequently the shear-rate and viscous heating
contributions are large. As the thickness of the molten
layer increases the degree of viscous heating decreases.
3. Steady-State Phase: In this phase the melting rate
equals the outward flow rate (steady state). As soon as this
phase has been reached, the thickness of the molten layer
is constant. The steady-state is maintained until a certain
"melt down depth" has been reached at which point the
rotation is stopped.
4. Cooling Phase: At this point (phase 4) the polymer melt
cools and solidification starts. After all the material has
Distance
Spin welding
Phase1:
Solid
Friction
Time
Welding Time Hold Time
Phase2:
Melt
Formation
Phase3:
Steady-State
Melting
Phase4:
Setting/Cooling
Down
Figure 1 - Spinwelding Process Diagram
solidified, drainage stops and the joint is formed.
Process parameters
Spin welding is restricted to cylindrical parts with a
maximum diameter of about 250 mm (10 in). Large batch
sizes are possible. Typical process parameters for spin
Semih AVDAN
FL Project Engineer
welding are:
• Tangential velocity: 3-15 m/s
• Rotational speed: 1,000-18,000 rpm (depending on the
part diameter)
• Welding time: 0.25-1s
• Holding time: 0.5-1s
• Cycle time: 1-2 seconds
• Weld pressure: 2-5 MPa
Advantages of Spinwelding
The advantages of spinwelding with respect to quick
connectors which have been used for serial production can
be summarized as below:
• Less failure possibility
• High capability
• High possibility of failure detection
• More durable
• Less risky in terms of leak
Figure 2 - Quick Connector Figure 3 - Spinwelding Connector
Figure 4 - Quick Connector Assembly
Figure 5 - Spinwelding Assembly
Figure 6 - Spinwelding Machine Figure 7 - Spinwelding Machine -
Head & Jaws