Part marking can cause issues in ultrasonic welding for several reasons. Firstly, it can indicate that the welding process is not optimized, as excessive pressure or energy can cause the plastic to deform or even break. This can lead to inconsistent or weak welds, which can compromise the integrity of the product.

Additionally, part marking can create aesthetic issues, particularly if the markings are visible on the finished product. This can be a problem in industries where the appearance of the product is important, such as in consumer electronics or automotive applications.

Finally, part marking can also impact the functionality of the product if the markings interfere with critical components or affect the performance of the product. For example, if the markings obstruct a sensor or impede the movement of a mechanism, the product may not function properly.