Ultrasonic staking of thermoplastic parts is an excellent method of joining large parts or assemblies comprised of dissimilar materials, including sandwiched non plastic components. Ultrasonic staking is one method of ultrasonic plastic welding.
Ultrasonic staking is the process of reforming a protruding plastic stud or hollow boss in order to lock, or sandwich, another component of the assembly in place. Please view the video above for a brief demonstration of ultrasonic staking (staking of chrome plated boss at 30 kHz shown).
The advantages of ultrasonic staking include:
Short cycle time compared to thermal or hot air staking.
Dramatically less air consumption than hot-air staking.
Replaces the need for consumables such as screws.
Consistent results and tight assemblies.
Able to stake painted or chromed studs or bosses in most circumstances.
Ultrasonic plastic staking equipment operates at 20 kHz, 30 kHz, and 40 kHz. Each frequency has pros and cons depending on the specific application. Below is a brief summary:
20 kHz -
Pro - Advantageous for large stud or boss sizes.
Con - Higher amplitude may damage the stud or boss base during weld and may read through marking to class A surface. Audible noise.
30 kHz -
Pro - Virtually silent. Capable of staking even large stud or boss designs. Ultrasonic energy remains near field with minimal risk of class A surface marking.
Con - Exceptionally small studs or bosses may be damaged by moderate amplitude and be better suited for 40 kHz.
40 kHz -
Pro - Virtually silent. Well suited for exceptionally small studs or bosses.
Con - May lack sufficient amplitude to complete weld in reasonable cycle time, thereby causing stud or boss base damage or class A surface read through. Difficult to weld moderate to large studs or bosses.
Click the "A" Application button to view an example of an ultrasonic staking application.
