Try polishing tooling and/or recut with larger offsets.
The part does not match CAD data used to cut tooling.
Specify the parts to be “dry as molded” and dry the parts by heating prior to welding.
Consult with the molder and ensure correct molding conditions.
Consult with a resign supplier(s) or Dukane Application Engineering.
There is a material or resign grade incompatibility problem.
Ensure correct molding conditions and check the mold design.
There is a non-uniform distribution of filler/reinforcement in the plastic material.
Clean the mating surface and use paintable grade mold release.
There is mold release on the joint surface(s).
Check for sinks in the molded parts, check the fit of the part to the horn, and check for proper support in the fixture.
Ensure correct part dimensions and tolerances, ensure knockout pin marks are not in the joint area, and check for misalignment of the mating part halves.
There is a lack of intimate contact around the joint area.
Check for part shifting during welds, the alignment of mating parts, and for parallelism of the horn, the part, and the fixture.
Ensure correct part dimensions and molding conditions.
Redesign the fixture to improve the support in critical areas (underneath weld region), use a more rigid fixture, and add a rigid backup to unsupported sections in resilient regions.
There is insufficient support in the fixture.
(Make sure knockout pins are flush with the surface).
Redesign the part so the knockout pin is not in the joint area.
The knockout pin location is in the joint area.
Add ribs to the part and incorporate fixture component to prevent outward flexure.
Try level tooling to the part and ensure correct part dimensions.
There is lack of parallelism between the horn, the fixture, and the part.
Redesign the energy director to ensure uniform height and use an interrupted energy director.
Try checking part dimensions, ensure there are correct molding conditions, use a higher Trigger Force/Trigger Delay, use a higher Hold Pressure, and increase Melt-Detect™ percentage.