Integration of smart technology in production has helped improve the quality of products, reduced wastes from manufacturing processes and hasten production cycles.

Additive technology is one of the game changers in the field of manufacturing. Often, the term may appear so broad, but the basics of additive technology all point to growth of 3D printing.

One of the common techniques used for additive technology having prospective research potential for the 21st century engineer is ultrasonic welding. One, because of its dominant use with thermoplastics and two as a measure in combating pollution by plastic waste.

This technique uses high frequency sound waves to generate the heat required for bonding thermoplastic surfaces upon each other. The high frequency sound waves create friction on the surfaces of two different parts to be bonded, the frictional interaction gives rise to surface heating, plasticizing the surface and creating bonds.

This technique is particularly important for its rapid bonding time. The key challenge is in the design of welding fixtures that can be custom adjusted to meet a variety of manufacturing industry needs.

There is also the need to improve the ultrasonic generators to enable welding of thicker laminates, with a possibility to join multiple layers of material at one go.

Share your thoughts and experiences with any of the additive technologies you have had firsthand experience with.

 

Hi, I had a few questions about ultrasonic welding.

Can we do butt joints with ultrasonic welding? I can understand being able to use it for lap joints but I was wondering if butt joints made wıth ultasonic welding would be weaker than other methods of butt joins.

Also what about the technical dificulty level of using a machine like that? Do they have advantages and disadvantages depending on the shape of the joint substances?

Can they be used to also join composites like glass or carbon fibre? What is the scope of ultrasonic welding in the area of aircraft parts manufacturing? Do you have any experience or examples in that?

 

1. Butt welds are very common with ultrasonic welding. Butt welds are usually characterized by triangular like ridge shapes between two surface that are to mate. The dominant weld angle is between 60o and 90o (Usually dictated by the ultrasonic welding energy director/horn)

2. Just like any other welding methods, Ultrasonic Welding has several advantages and disadvantages as well. The following are some of the advantages:

· Ultrasonic welding is faster compared to other techniques, basically since it does not rely on external heat source or foreign material to create a weld. The rate at which the weld is formed also depends on the cooling rate of the joining surfaces.

· Safety: Ultrasonic welding relies purely on frictional heat, and as a result, there is very minimal chances that hot molten material can be spawn off the mating surface. The waves that trigger the frictional heat are also directly focused on the specific welding surface, reducing any unprecedented errors that may result from poor weld surface estimation.

· Reliability: Most of the ultrasonic welding equipment are equipped with automated tooling and event sequencing. The integration of controls in most welding equipment makes it easier to carry out precise welding operations.

· Ultrasonic welding is crucial in performing welding of dissimilar metals.

Some of the disadvantages are:

· High initial cost of equipment and tooling

· Limited for thin material layers, and can’t therefore be used with thick metal surfaces.

3. As for difficulty level, that is relative. It is dependent on the chosen tooling combination and level of automation. Generally, most ultrasonic welding equipment are customized to allow simplicity in use. It can therefore be used by semi-skilled persons, provided they are well trained and conversant with basic material properties and welding operations.

4. Usage of ultrasonic welding with aircraft parts is not very much developed. They are currently used to fuse together light alloys for applications like welding of electric coper connections. There is less advancement in welding of high strength aluminum alloys, though research in this field is ongoing.

5. Ultrasonic welding has gained a lot of popularity with fibers and composites. They can be utilized in creating bonds between different composites.

 

Thank you for the information. So if I had to create 8 layer carbon fiber sheet with lamination I could possible use ultrasonic welding right! This question sounds very vague but I am not the production guy, I am just trying to learn more about production, kinda advancing my knowledge.

What about any kind of residual thermal stresses because the welding would be done over the whole surface of the sheets ?

 

Multiple layer welding is very possible using ultrasonic welding. There are few features though that you will have to keep in mind:

• The design of the welding fixture
• Desired weld thickness
• type of weld director to be used.

Thermal stresses will exist, and that is unavoidable since the whole idea of ultrasonic welding lies on utilization of frictional force generated from high frequency waves. This however has minute effects on material quality, given that the entire process is not exposed to foreign material. Also important to note is that on cooling, the existent thermal stresses tend to drastically diminish.