Q: Common weld designs include butt joints, steps, grooves and shear joints. Which is the best? 

A: No single weld design is considered "best" for all applications. They have their own unique advantages and disadvantages and must be considered according to the material and dimensional characteristics, application requirements, and design constraints of each part.

Q: Welding strength is the first criterion to evaluate the quality of the weld. How do other factors, such as aesthetic or sealing requirements, affect the design of the joint? 

A: All these factors will certainly influence the joint design. For example, simple step joints are suitable for most applications where only strength and aesthetics are required. Shear or grooved joints are preferred if sealing is required. If you are welding medical components with internal fluid channels, it is best to use grooved joints to isolate internal spillage and prevent loose particles from entering the fluid channels. When discussing specific applications, we look at all requirements, overall part design, wall thickness, materials and constraints, and select the most appropriate joint design.

Q: What is the role of materials in ultrasonic welding joint design? Does a specific material require a specific joint design? 

A: In most cases, materials can be selected from either joint design. However, in some cases, there are some factors that affect the joint design. For example, in larger parts made of semi-crystalline materials such as PP, the thin walls become very soft and unstable. In this case, we do not recommend a butt or step joint design. Soft, thin walls can deform and bend, resulting in energy loss and misalignment of joints. Of course, if you add fiberglass to the plastic and increase the stiffness of the material, you can offset this problem to some extent.