Ultrasonic Weld Types & Weldability

Near Field Weld (Direct): Refers to a weld where the contact surface of the horn is 1/4" or less away from the joint surface.

It is important that the horn fits exactly the contour of the part to be welded.

Far Field Weld (Indirect): The distance between the contact surface of the horn and weld between the contact surface of the horn and weld joint is more the 1/4".

Ultrasonic energy is transmitted through the upper portion of the part to the joint surface.

Factors Influencing Weldability in Ultrasonics

Amorphous vs. Semi-crystalline resins
Mold release agents

Moisture content
Lubricants

Pigments
Plasticizers

Resin grade
Fillers

Ultrasonic Weldability of Plastics

EASE OF WELDING EASY MEDIUM COMPLEX DIFFICULT

Resin Polystyrene/PS
Acrylic
ABS
SAN
PMMA
PC-ABS Blends Polycarbonate/PC
PC-ABS Blends
PPS
Polysulfone/PSO
PVC
ASA
PPO
PC-PBT Blends
Polyester
Ryton
PET
Polyamide Co-polymer (Nylon 6-3-T)
Valox Polyamide/Nylon 6
Polyamide/Nylon 6/6
PBT
PP
PE
Polyacetal
Ultem

20kHz Peak to Peak Amplitude 35 to 45 microns 45 to 55 microns 55 to 80 microns 80 to 100 microns

Joint Design Energy Director
90 - 0.7 mm Energy Director (60 /0.8mm)
For low strength mechanical assembly only

Shear Joint
(0.5 - 0.6 mm) - (1 - 2 mm)
for higher strength or hermetic assembly Shear joint
0.4 mm wide -
(0.8 - 1.4 mm) Shear joint
0.4 mm wide -
(0.8 - 1.4 mm)