Laser Welding Design Guidelines

Download these guidelines.

Common Joint Designs

Laser welding uses a precise IR laser beam that is directed through a transmissive material and penetrated into an absorptive material. As with all plastic joining technologies, a properly designed weld joint is critical to achieving the desired weld strength and appearance.

General Guidelines

  • The transmissive part must be transparent/translucent to IR, but does not have to look transparent to the human eye.
  • The transmissive part should be approximately 3 mm thick or less for semi-crystalline materials and can be much thicker for amorphous materials as long as they are transparent.
  • If the transmissive part has glass filler, as the percentage increases, the maximum thickness decreases due to scattering of the laser energy.
  • Typically weld ribs are 2 mm wide, but narrower or wider is feasible and depends on customer requirements.
  • Typically plan for 0.2 – 1.0 mm interference (displacement) in the weld joint unless it is a simple lap joint or an inline lap joint that doesn’t allow for displacement.
  • Make gaps twice as tall as displacement depth to account for flash.

Lap Joint Designs

Simple Lap Joint

Sacrificial Rib Lap Joint

Inline Lap Joint

T Joint Designs

Simple T Joint

Sacrificial Rib T Joint

Lower Skirt T Joint

Upper Skirt T Joint

Upper Skirt Sacrificial Rib T Joint

Radial Welding Joint Design

Radial Welding Joint

  • Interference is required between the two components.
  • Typically plan for 0.1 – 0.4% of part diameter interference.
  • The angle of interference depends on overall part geometry, aesthetics, and strength. The angle should be between 45 and 85 degrees.

Material Compatibility Chart

This compatibility chart shows which materials are known to be compatible with each other. 

Please note: Weld compatibility depends on the absorption and transmissivity of the materials.


Click image for full size or Download as a PDF.

Have a question?

Please contact us with any questions.

Contact us.