Ultrasonic welding is widely used in the automotive industry. Applications range from interior components (side door trim, center console) to engine compartment components (cylinder head cover, engine covers), to lighting, filters and acoustic foams. Welders can be operated immediately without heat-up time. Cycle times are short, and energy consumption is low.

For the process to be effective, the weld tool, called a horn or sonotrode, must be designed to fit the shape of the part while vibrating effectively. This is particularly true in the automotive industry, where material mixes and asymmetrical shapes can make it tricky to weld plastic parts.

All joining technologies reach their limits when different or difficult materials have to be bonded, especially if the parts have asymmetrical shapes. With hot plate welding, for example, this challenge could result in uneven temperature distribution. Some areas might become too hot and produce threads; other areas might remain cold and will not bond homogeneously. With vibration welding, additional plastic is needed in the joint area. As a result, a large amount of molten material is produced during welding. This material could get pushed out of the joint, creating an unsightly bond line.

Ultrasonic welding is also subject to such physical limitations when joining complex 3D-shaped parts. However, if the sonotrode is correctly dimensioned through the use of finite element analysis (FEA), ultrasonic welding offers numerous advantages:

Uneven asymmetrical geometries can be welded.

Delicate component surfaces stay mark-free.

Short weld cycles between 100 and 300 milliseconds.

Targeted energy input protects sensitive electronic elements.

Different types of material can be welded or bonded by embedding.

Smaller machine footprint compared to other joining processes