ultrasonic welding guide, ultrasonic welding help, ultrasonic welding, toolcraft plastics
Some ultrasonic welding help - plastics ultrasonic welding guide
The process of ultrasonic welding of plastics is achieved by applying a vibrating metal tool (horn) at 90° to the stationery plastic parts which then vibrate. When combined with pressure, friction produces heat & melts the parts at the horn contact point. Once cooled down a solid homogeneous weld between the 2 parts is created.

The ultrasonic welding guide below gives you a little ultrasonic welding help by listing the most common unfilled grades of plastic available & their suitability for each style of ultrasonic welding  As a rule, stiffer materials are easier to weld & those with higher melt temperatures need more energy. To weld different materials, they need similar molecular structures - crystalline ones are only weldable to themselves

MATERIAL TYPES, ABBREVIATIONS & STRUCTURES
CLOSE
WELDING
DISTANT
WELDING
INSERTING SPOT
WELDING
STAKING
Acetal Co/Homopolymer
POM
C Good Fair Good Fair Fair
Acrylic
PMMA
A Good Fair Good Good Fair
Acrylic-Impact Modified
PMMA
A Fair Poor Poor Fair Fair
Acrylonitrile Butadiene Styrene
ABS
A V.Good Good V.Good V.Good V.Good
Cellulose Acetate...
CA/B/P
A Poor NS V.Good Poor Good
Polyamide 6 & 66 (Nylon)
PA6 & 66
C Good Fair Good Fair Fair
Polycarbonate
PC
A Good Fair Good Good Fair
Polycarbonate/Abs
PC/ABS
A Good Fair Good Good Good
Polyester-Thermoplastic
PBT/PET
C Good Fair Good Fair Fair
Polyethylene-Low/High Density
LD/HDPE
C Poor Poor Good Good Fair
Polyphenylene Oxide
PPO
A V.Good Good V.Good V.Good V.Good
Polyphenylene Sulphide
PPS
C Good Fair Good Fair Poor
Polypropylene
PP
C Fair-Poor Poor Good V.Good V.Good
Polystyrene-General Purpose
GPPS
A V.Good V.Good Good Fair Fair
Polystyrene-High Impact
HIPS
A Good Poor Good Fair Fair
Polyvinyl Chloride-Flexible
PVC
A Poor NS NS Poor NS
Styrene Acrylonitrile...
SAN/ASA
A V.Good V.Good Good Fair Fair

A (Amorphous) = polymers with a random molecular chain structure. This & their wide softening temperature range enables them to soften gradually without solidifying quickly, thus making ultrasonic welding them easy.
C (Crystalline) = polymers with an orderly molecular chain structure. This & their sharp melting & solidification points makes them absorb vibrations when solid, thus making ultrasonic welding them more difficult.

Close Welding = ultrasonic welding where the horn is applied close to (<6.35mm) the assembly joint - good for welding materials whose low modulus of rigidity dampens vibrations a short distance away from the horn.
Distant Welding = ultrasonic welding where the horn is applied away from (>6.35mm) the assembly joint - good for welding materials whose high modulus of elasticity propagates vibrations without dampening them.
Inserting = ultrasonic embedding of metal components like inserts into preformed holes in the moulding - provides high strength & speed, no stress build up & reduced moulding cycles.
Spot Welding
= ultrasonic assembly of parts without premade holes or energy directors - good for large parts
Staking = melting and reforming a post on the moulding to mechanically lock dissimilar materials in place - provides short cycles, good appearance & tight assemblies.

For more help with plastics for your application (costs, properties etc), please view our material selection guide