Ultrasonic Welding Tooling Basics

A. Ultrasonic Mold Amplitude Parameters:

Amplitude is a crucial parameter for the materials being welded. It's similar to the temperature 

in fusionwelding; if the temperature isn't right, the fusion won't happen. Similarly, if the amplitude

is too low, welding might not occur, and if it's too high, it could cause material burning or structural

damage leading to reduced strength. Different companies use different ultrasonic transducers, resulting

 in varying output amplitudes. Adapting ultrasonic boosters and welding horns with different gain ratios

 can correct the working amplitude of ultrasonic mold heads to meet requirements. Generally, transducers

have an output amplitude of 10-20 μm, and the working amplitude is usually around 30 μm. The shape

of the booster and horn, along with factors like the front-to-back area ratio, plays a significant role in 

the gain ratio.

B. Ultrasonic Mold Frequency Parameters:

Each ultrasonic welding machine has a central frequency, such as 20 kHz, 40 kHz, etc. The working 

frequency of an ultrasonic welding machine is primarily determined by the mechanical resonant frequency

of the ultrasonic transducer, booster, and horn. The generator's frequency is adjusted based on the mechanical

resonant frequency to achieve consistency. The ultrasonic generator and mechanical resonance frequency

have a resonant working range, often set at ±0.5 kHz. This range ensures proper functioning of the ultrasonic

welding machine. When producing ultrasonic mold heads, adjustments are made to the resonant frequency, 

aiming for aresonance frequency deviation from the design frequency of less than 0.1 kHz, typically controlled

within19.90–20.10 kHz for a 20 kHz ultrasonic mold head.

C.Ultrasonic Mold Vibration Nodes:

Ultrasonic mold horns and boosters are designed as resonant bodies with half-wavelengths of the working

 frequency.In the operational state, the amplitudes at the two end faces are most sensitive to stress, while 

the amplitude at the nodposition (usually a fixed location) is zero,minimizing stress. Though node positions

are typically designed to be fixed,the design of fixed positions often involves a thicknessgreater than 3 mm 

or groove fixation. This means the fixed positions might not necessarily have zero amplitude,leading to a 

slight loss of energy and the possibility of sound generation. Sound can be mitigated by using rubber rings

to isolate components or by using soundproofing materials for shielding.

D. Ultrasonic Mold Precision:

Due to their operation at high-frequency vibrations, ultrasonic mold horns should be symmetrically designed 

to avoid imbalanced stress and lateral vibrations caused by asymmetrical sound wave transmission, which 

could lead to heating and fracture. Precision requirements vary for different welding applications. For instance, 

applications involving thincomponents like lithium-ion battery electrode sheets and tabs,or applications requiring 

the precise coating of gold foilsdemand high precision. Using CNC equipment (such as machining centers) ensures

 that the machined parts meet the required precision standards.

E. Ultrasonic Mold Lifespan:

The lifespan of an ultrasonic mold horn is determined by two key factors: material and process. Material-wise,

 ultrasonic welding requires materials with characteristics like good flexibility (to minimize mechanical losses 

during sound wave transmission). Aluminum alloys and titanium alloys are commonly used due to their desirable 

characteristics. The choiceof material significantly affects mold lifespan and welding quality. The ultrasonic

 mold manufacturing process is complex.Thus, material selection by ultrasonic mold engineers should be careful 

and consider the product requirements to avoid compromising both lifespan and quality.