Mold release agents are typically used in injection molding to prevent plastic parts from sticking to the mold during the manufacturing process. However, these agents can have an adverse effect on parts in ultrasonic welding.

When a mold release agent is used, it can leave a thin film or residue on the surface of the plastic part. This residue can act as a barrier and prevent proper bonding during ultrasonic welding. As a result, the presence of mold release can lead to weaker welds, increased flash, and even part failure.

To avoid these issues, it is important to thoroughly clean plastic parts prior to ultrasonic welding. This can be done by using a cleaning solution that is compatible with the material being welded, such as isopropyl alcohol or a specialized plastic cleaner. Additionally, the use of mold release agents should be minimized, and if necessary, the parts should be cleaned and dried thoroughly after the release agent is applied to remove any residue.