Lee Plastics offers a variety of value-adding processes. These processes allow us to provide intricately designed plastic pieces that are pre-assembled, feature product logos and more. One of the value-adding processes we offer is fusing pieces together with heat staking and ultrasonic welding. Both of these methods allow us to fuse multiple pieces together before we ship them. However, they provide different advantages and disadvantages.

How Heat Staking & Ultrasonic Welding Work

Both heat staking and ultrasonic welding use stakes to weld two parts together. One part has a hold carved into it while another part has stakes added in the form of threaded inserts, similar to an iron screw. The threaded insert is pressed into the hole of the piece and then through either heating or ultrasonic welding is kept in place. These processes create strong joints in plastic and metal pieces that can allow dissimilar pieces to be held together long term.

Ultrasonic Welding

Throughout the history of plastic manufacturing, manufacturers have always relied on whatever method is going to create reliable and repeatable results. Ultrasonic welding provided repeatable results long term. Ultrasonic welding uses high-frequency acoustic vibrations applied locally to force to solid pieces of matter to fuse together and become welded. It can be used to join two different materials together and best rated for plastic pieces and metal components. Ultrasonic welding became one of the most popular welding options for plastic manufacturers since it first was introduced. However, heat staking has been known to make more precise welds.

Heat Staking

Heat staking is a newer form of welding two dissimilar materials together. Heat staking works by expanding a stake from one piece into a hole of another piece. The insert fills in knurls and undercuts so that the two plastic pieces become bonded together. Heat staking resists rotational torque better than ultrasonic welding does. However, heat staking can cause damage to the areas that are under pressure and are heated during the staking process. To avoid this, plastic manufacturers have to control a variety of variables to ensure that the plastic piece is not damaged during the heat staking process.

Contact Lee Plastics

Lee Plastics provides a variety of services when designing, manufacturing, and delivering plastic pieces. Our team has over 100 years of experience in the industry and would love to offer a quote on your next project.

Since the 1950s, ultrasonic metal welding has been a useful resource in many industries that employ the use of joining applications or methods that utilize thermally conductive materials. Ultrasonic welding is popular in the plastic-processing industry, in particular, due to its high process speeds and repeatable weld results. Still, it is preferred in major industries, including packaging, hygiene, automotive, electrical and medical. Despite some disadvantages, like thickness limitations, ultrasonic welding appears to have a promising future in the automotive and aerospace industries as the popularity of lightweight materials continues to grow.

What is Ultrasonic Welding?

Ultrasonic welding is a technology that uses high-frequency vibrations or sound waves, which typically exceed the limit of human hearing, to heat and bond two parts that are touching under pressure. The vibrations create heat at the joint interface of the components being welded, causing the thermoplastic materials to melt and weld formation results after cooling. This process is a major advancement from using fasteners such as nails, glues, screws or thread, and is the fastest known welding technique. There are two common ultrasonic methods for welding plastic components, namely longitudinal and torsional.

The General Process

In simple terms, the process involves:

1. The materials to be welded are positioned between a nest, or anvil, or fixture.
2. The sonotrode, or horn, connected to a transducer, comes in contact with the material to be welded, producing low amplitude acoustic vibrations that produce friction.

3. The friction produces heat that creates a melt between the materials, bonding them together as it cools.

The ultrasonic welding process is controlled by a computer microprocessor fixed within the welding apparatus.

Torsional Ultrasonic Welding

The torsional ultrasonic welding method involves a high-frequency friction welding process, in which the vibrations are transferred tangentially. The horn activates the upper connecting piece of material and moves it horizontally in relation to the lower connecting piece. This method uses a high vibration frequency of 20 kHz, which creates friction and produces a melt between the materials, joining them together. It is ideal for delicate applications because it does not strain the materials in the process.  

Longitudinal Ultrasonic Welding

In the longitudinal ultrasonic welding process, the welding system is arranged horizontally, and the vibrations are tangentially transferred. Like the torsional process, in the longitudinal process, the horn activates the upper piece of material and moves it horizontally in relation to the lower connecting piece of material. The frequency is the same, 20 kHz, and results in friction that connects the two parts. The appropriate pressure is created with the utilization of a press.

Contact Lee Plastics

If you are interested in premier industrial ultrasonic technology, Lee Plastics offers a wide range of ultrasonic products and services that can meet your industrial welding needs. Contact us today to learn more!