There are several material factors that can affect the ultrasonic welding process. These factors include:

1. Material type: Different materials have different properties, such as melting point, thermal conductivity, and elasticity, which can affect the ultrasonic welding process.
2. Material thickness: Thicker materials require more energy to be welded, and may require different welding parameters than thinner materials.
3. Material composition: The chemical composition of a material can affect its ability to be welded, as well as the strength and quality of the resulting weld.
4. Hygroscopicity: As discussed earlier, the presence of moisture in a plastic material can lead to issues during the welding process and can affect the strength and quality of the resulting weld.
5. Surface finish: The surface finish of the material can affect the ability of the ultrasonic vibration to penetrate the material and create a strong weld.
6. Part geometry: The size and shape of the parts being welded can affect the ability of the ultrasonic vibration to create a strong weld, and may require adjustments to the welding parameters.
7. Part stiffness: The stiffness of the parts being welded can affect the amount of energy required to create a strong weld, and may require adjustments to the welding parameters.

By carefully considering these material factors and adjusting the welding parameters as needed, it is possible to achieve consistent and reliable welds in a variety of different materials and applications.

The factors that affect weldability of plastics are:

1) Lubricants

Lubricants such as mold release agents can inhibit the weldability of plastic parts. If mold release agents are used, parts should be cleaned prior to welding.

2) Impact Modifiers

Impact modifiers such as glass fibers can affect weldability of plastics. Because glass fibers melt differently than plastics, weld settings may need to be modified.

3) Foaming Agents

Foaming agents add air to plastic parts to reduce their density. These air pockets can affect weldability.

4) Colorants

The pigments in plastic colorants may have an affect on plastic welding requirements. While these can be minor, it is an important consideration if you are welding parts of the same geometry but different colors.

5) Resin Grade

There are many grades of resin for making plastic parts. Resins are designed to flow differently for injection molding, extrusion, blow molding, rotomolding, etc. The differences in flow rate can affect the part’s ability to weld.

6) Resin Age

Some resins change or breakdown over time. Attempting to weld parts of the same resin but different ages can have an effect on weldability.

7) Engineered Resins

In some cases, highly engineered resins may not lend themselves well to welding.