Vibration welding systems have revolutionized the process of joining thermoplastic parts, offering a reliable and efficient method for creating strong and air-tight welds. With the ability to weld large parts and complex shapes, vibration welding systems have become a popular choice in industries such as automotive, medical, and appliance manufacturing. In this article, we will explore the principles behind vibration welding, the advantages it offers, and the various models available in the market.

What is Vibration Welding?

Vibration welding, also known as linear or friction welding, involves the physical movement of one part horizontally under pressure, creating heat through surface friction that melts and welds the parts together. Unlike ultrasonic welding, which operates at higher frequencies, vibration welders work at lower frequencies, higher amplitudes, and greater clamping forces. This process is achieved through a swing frame assembly containing precision springs, electromagnets, and an electromagnetic drive assembly that controls the amplitude and frequency of the vibrating head.

Advantages of Vibration Welding Systems

Vibration welding systems offer several advantages over other conventional plastic welding processes. Firstly, the heat is generated at the interface, preventing oxidation and contamination of the weld during the process. This makes it a suitable choice for applications requiring clean welds with minimal particles or contaminants. Additionally, vibration welding systems do not require filler material, and when welding components of the same material, the joint can be expected to be just as strong as the bulk material. This ensures high strength and hermetic welds, making it ideal for applications that require air-tight seals.

Another advantage of vibration welding systems is their ability to join large parts and complex shapes. The process can accommodate out-of-plane curvature to some extent, allowing for the welding of components with irregular shapes. This makes it a versatile solution for industries such as automotive, where complex geometries often prevent single-component molding processes. Furthermore, vibration welding systems are cost-effective, with short cycle times and no consumables required.

The Vibration Welding Process

The vibration welding process consists of several stages, each contributing to the creation of a strong and durable weld.

Stage 1: Solid Friction

In the initial stage, the two parts to be welded are placed into precision holding fixtures, ensuring proper alignment and support throughout the process. The lower holding fixture rises to close against the upper fixture, compressing the parts together. The vibration process begins with alternate energizing of the electromagnets on the swing frame assembly, generating frictional heat at the joint surface. However, no melting occurs at this point.

Stage 2: Transient Flow

As the vibration continues, the surface of the polymer begins to melt, initiating the transient flow phase. The thickness of the melt layer quickly grows, causing a decrease in frictional forces. This decrease in friction reduces the heat input to the system, and a lateral flow of molten material starts to occur.

Stage 3: Steady State Flow

In the steady state flow phase, the melting rate of the material matches the flow of material extruded at the lateral surfaces. The material flow and the thickness of the melt layer become constant. This phase determines the quality of the weld and is maintained until the desired melt-down thickness is achieved. At this point, the vibration is stopped, and the weld is allowed to cool.

Stage 4: Solidification

During the solidification phase, the vibration is halted, but pressure is maintained on the workpieces until no more molten material remains. As the weld cools, it forms a strong molecular bond between the two parts. Once cooled to room temperature, the joint should have a strength comparable to that of the bulk material. The pressure is only relieved once the joint reaches an acceptable strength.

Vibration Welding Systems Available in the Market

There are several vibration welding systems available in the market, each offering unique features and capabilities to suit different application requirements. Let's take a closer look at some of these models:

Vibration Welding System 515e

The 515e series vibration welding system is designed for precise and high-quality welding. It utilizes a linear scale to control the lift table and the melt during the welding process, ensuring accuracy and consistency. With a short auto-tuning time of 4 seconds, a user-friendly touch panel, and real-time resonant frequency tracing, the 515e series offers efficient and reliable performance. This system is suitable for applications in the automotive and plastic appliance industries, thanks to its superior weld strength and quality.

Vibration Welding Machine 630e / 615e

The 630e / 615e series vibration welding machines offer precise and high-quality welding for a range of applications. These machines utilize a linear scale to control the lift table and the melt, ensuring accurate and consistent results. With a fast auto-tuning time of 4 seconds and user-friendly touch panel interface, these machines provide efficient and reliable performance. The 630e / 615e series is suitable for welding large rear lamps, intake manifolds, spoilers, and other plastic components.

Vibration Welding Systems 730e / 715e

The 730e / 715e series vibration welding systems are designed for welding larger plastic components. These systems utilize a linear sensor to monitor and control the lift table position and melt during the welding process. With a short auto-tuning time, user-friendly touch panel, and specialized software, these systems provide high-quality welds and superior strength. They are suitable for applications in the automotive parts industry, such as instrument panels.

Vibration Welding Systems 740e

The 740e vibration welder is specifically designed for welding wide plastic products. It offers a higher vibration capability than other models, making it suitable for welding large components such as engine compartments and technical plastic parts. The 740e vibration welder utilizes a linear scale to monitor and control the position of the worktable and the melt depth, ensuring precise and consistent welding. Additionally, the 740e is available as a hybrid vibration welding system with infrared preheating, making it ideal for applications requiring clean welds with minimal particles or contaminants.

Vibration Welding Systems 820s / 815e

The 820s / 815e series vibration welders are compact yet powerful systems suitable for welding relatively large parts. With a high-frequency vibration range and precise control over the lift table and melt, these systems offer reliable and efficient performance. The 820s / 815e series is designed for applications that require high weld strength and quality, making it suitable for industries such as automotive where instrument panels and other large components need to be welded.

Vibration Welding Systems 930e / 830e

The 930e / 830e series vibration welding systems are designed for welding larger plastic components compared to other models. These systems utilize a linear sensor to monitor and control the lift table position and melt during the welding process. With a short auto-tuning time, user-friendly touch panel, and specialized software, these systems offer superior weld strength and quality. The 930e / 830e series is suitable for applications in industries such as automotive, where instrument panels and other large components need to be welded.

Conclusion

Vibration welding systems have revolutionized the process of joining thermoplastic parts, offering a reliable and efficient method for creating strong and air-tight welds. With their ability to weld large parts and complex shapes, these systems have become indispensable in industries such as automotive, medical, and appliance manufacturing. With a variety of models available in the market, each offering unique features and capabilities, manufacturers can find the perfect vibration welding system to meet their application requirements.