1. What thermoplastic materials can the ultrasonic plastic welder bond? Can I weld different thermoplastics?
Thermoplastic resins that can be welded can be classified as either amorphous or crystalline.
Solderable AMORPHOUS resins include: polycarbonate, polyphenylene ether, polystyrene, ABS, polyetherimide, acrylic and polysulfone. Weldable CRYSTALLINE materials include: thermoplastic polyester, nylon, acetal, polyethylene, polyphenylene sulfide and polypropylene.
Yes, a limited number of different amorphous thermoplastics (such as ABS and polycarbonate) can be welded together. The melt temperature difference of dissimilar materials cannot be greater than 50°F.
2. If my plastic material is flame-retardant, will it still be ultrasonically bonded?
Flame retardants can affect welding by reducing bond strength. In this case, "over welding" can sometimes be solved. This involves using a higher amplitude machine or a slightly longer welding time to produce a sufficiently strong bond.
3. What is the acceptable glass content for plastic ultrasonic welding?
20% is preferred. However, sometimes up to 30% of glass filler can be used for proper welding.
4. What are the common joint designs for plastic welding?
The so-called "energy director" method is used in many joints. This requires the use of triangular protrusions on one of the places that are connected and placed where melting begins. For sealed joints and certain semi-crystalline parts, shear joints are recommended. Shearing joints requires some interference between the parts to be welded. As the parts are heated and compressed ultrasonically, one part "shears" the softened plastic from another part.