Welding technology: introduction to spin welding for plastics

(what is it, how it works, and when it applies)

Spin welding is the ideal method for strong joints and perfect sealing between thermoplastic parts with symmetrical rotation; therefore circular objects (for example: spheres, cylinders, frustrum of cones, disks, rings, and so on) which can spin freely

The particular simplicity of this technology makes the choice between ultrasound or rotation welding a difficult one (see also: http://www.siriuselectric.it/index.php/en/blog-en/40-technologies/160-ultrasonic-friction-welding).
With modern spin welders however, the choice often falls on the latter also because of the following advantages:

  • The investment required to obtain the same output is lower with spin welding than with ultrasound welding. Construction of the machinery, which can be greatly customized, poses no particular difficulties;
  • The process is based on physical principles that can be universally and fully understood. When the tools and the welding conditions have been selected correctly, the results can only be optimized by adjusting a single factor: speed;
  • There is more freedom in the design of the weld joint and there is no need to worry about designing the edges, pins or fins that can break off. Modelled metal parts cannot come loose and damage pre-assembled mechanical elements. Moreover, it is not essential for the mass of parts to be symmetrical or uniform for distribution as it is for ultrasound welding;
  • The relative position between assembled parts is possible today thanks to modern angular control systems that ensure optimal tolerance.

 (Example of welded samples)

Applicable for:
What materials can be welded using spin welding?

Spin welding technology is used widely in the manufacture of hydraulic parts. It is indeed ideal for assembling circular parts, such as filters, funnels, floats, pipes and fittings. In general terms, all plastics can be spin welded. The only differentiating factor is the outline of the joint area, which must be circular.

The speed of rotary movement, the intensity of pressure and the welding time are the parameters to be set according to the thermoplastic material being processed, and the shape of the parts.

The following are suitable for spin welding is suitable for injection moulded, extruded, compression moulded, thermoformed, blow moulded, 2D/3D (2-component) suction moulded and rotomoulded pieces.

To know more on the SPIN welding, you might be interested also to "Ultrasound or spin welding? That is the question…" .For further information please contact Sirius Electric Srl (www.siriuselectric.it) , Italian company specialized in the manufacturing of plastic welding systems and in the manufacturing of sonotrodes.

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