Thermal Bonding

Thermal Bonding refers to a welding process that uses high temperatures to soften and merge catheter materials (e.g., tube to tube, braid to non-braid welds, balloon-to-tube bonds, etc.) to each other at the contact surfaces and to firmly bond the two components together by applying appropriate pressure.

  • Thermal fusion: Using a heated copper tip or hot air blowing system to directly heat the joining surfaces and then apply pressure.
  • Ultrasonic welding: Using high-frequency vibration to generate heat to achieve localized soft fusion.
  • Laser welding: using laser energy to locally heat and melt the joint surface.

Thermal bonding includes three common types:

Butt joint

Butt joint, where two sides of a tube are joined together to form a joint.

Butt joints are used when the diameter of the material increases over the maximum outside diameter of the shaft. The materials used must be similarly compatible polymers, and the process usually requires thick-walled tubes to produce a successful weld and axial compression to facilitate material flow.

Lap joint

Lap joint, where two materials are overlapped to form a joint.

Lap joints are used to achieve high tensile/bond strength requirements. Lap joints can be made with a variety of materials, and while an increase in outside diameter is not a critical requirement for this process, lap joints do require sufficient overlap tube length and radial compression during processing.

Balloon bonds

Balloon bonds, where a catheter balloon is attached to the catheter shaft.

The third common application of fusion processing is balloon bonds, where the balloon is fused to the catheter, a process that requires heat shielding, joint transition and radial compression.

Thermal Bonding Advantages

  • High welding strength: the weld formed by melting and penetration of the material has high mechanical strength and can withstand various stresses in the use of the catheter.
  • Good sealing: the weld can be reliably closed inside the catheter to avoid leakage or infection.
  • Beautiful appearance: heat fusion welding can achieve a relatively flat, beautiful weld.
  • Simple operation: no complicated auxiliary tools, can realize fast, automatic welding.
  • Strong material compatibility: A variety of plastic materials can be bonded by hot melt welding.

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