Understanding Plastic Welding Methods and Ideal Applications

In the recent past, there were very limited options when it came to welding plastics. The most popular options were gluing or using vibration/ultrasonic welding. Both of these options have benefits and ideal applications. While this is true, they aren’t up to the task of handling the smaller and more sophisticated product designs that use plastics today.

Identifying Plastics

Before diving into plastic welding, it’s important to understand the different types of plastics available. Being able to identify plastics is imperative when it comes to choosing an effective welding method. It’s important to understand that it’s only possible to weld together “like” materials. For example, the material most car bumpers are made of is Polypropylene. It can only be welded using a Polypropylene welding rod.

This means it is imperative to identify the material being welded first before moving forward with the project. The good news is, the majority of plastics used for various projects today are stamped with identification codes. If there is no identification code, it’s necessary to perform a welding test to identify the material being welded. By identifying the material, it’s possible to determine the right type of welding method to use, as well.

Getting to Know Plastic Welding Methods

At first look, it’s often confusing to try to compare plastic welding methods to figure out which one is best for joining plastics in a specific product design application. Also, there is a wide array of tools and equipment, like the products from Hot Air Tools.

Due to this complexity, getting to know more about the options is necessary. Keep reading to learn more about plastic welding methods and ideal applications for each. After all, knowledge is power.

Laser Plastic Welding

This method provides flexibility for large, 3D part geometries, intricate, and complex projects. This method uses sophisticated online process monitoring features, which help ensure a higher level of quality control. Also, fewer bad parts that need reworking are created.

This is one of the reasons laser plastic welding is a smart option to weld plastics in the automotive industry for sensor housings, in manifolds, and taillights. It’s also a popular method used for plastics used in consumer electronics applications and for medical devices, such as catheters and microfluidics.

Ultrasonic Welding

This is considered the best method for projects that require very short cycle times of five or fewer seconds. Ultrasonic welding is also ideal for working with 3D contour joints that aren’t required to be completely flat. Keep in mind, though, the high resonance frequencies produced by ultrasonic welding will exist throughout the entire part.

It could damage components beyond the specific weld zone. This can result in excess melted plastic or flash protruding from the joined plastics. Dust-like particles may also be generated. This can result in part contamination. Most manufacturers use ultrasonic welding for the joining of plastics in intake manifolds, bumper reinforcements, and mobile phone housings.

Hot Plate Welding

Hot plate welding is considered one of the most affordable plastic welding methods. It is also less complex. With this method, handheld devices are used to bond plastics. Hot plate welding is ideal for welding joints that have simple contours, rather than more intricate designs.

Keep in mind, though, this method is susceptible to tack. This occurs when the molten plastic sticks to the hot plate and flash. Hot plate welding is used most often for larger profile applications, such as in fishing buoys, glove box lids, and auto consoles.

Friction Welding

This is also an inexpensive process that uses low-maintenance machinery that has minimal downtime, as well as low cycle time. However, with this method, manufacturers and designers are limited to just welding plastic parts that have two-dimensional contours

In this situation, too, a higher mechanical load can cause damage to the surrounding parts. Also, friction welding generates a significant amount of flash. This method of welding is a smart option for larger profile, two-dimensional applications, including pipes, bumper reinforcements, housings, and manifolds.

High-Frequency Welding

The advantages offered by high-frequency welding is that it is a touchless process and has a low thermal load. Due to these advantages, the surrounding parts aren’t damaged or marred, and minimal flash is produced. The equipment for high-frequency welding is expensive.

Also, the machines used for this are only able to join polar polymers, PA, and PVC. The users of this welding method are required to follow strict rules and regulations to help protect and prevent electromagnetic radiation that’s produced when this method is used. While this is true, many still consider high-frequency welding a viable option. This is especially true for continuous welding applications. Some examples of these include the housings for various electronics, along with other consumer products.

The Preferred Option: Laser Plastic Welding

While it’s good to have and know about the options for plastic welding, there is one method that stands out from the others. Laser plastic welding is leading the way, especially for more complex applications that other welding methods can’t accommodate. Thanks to the recent advances made in laser plastic welding, the medical device and fluidics industries specifically have been revolutionized. Today, both these industries are benefiting from the ability the laser has to join two clear components.

Getting Ready to Weld

Regardless of the type of plastic welding used, there’s a universal task to do before getting started. This is to prepare the surface being welded properly. Preparing the surface involves removing all soils, which include greases, oils, UV degradation, and paint. With larger parts, start by washing them thoroughly. Avoid using any industrial detergent, as this can introduce a film coating. In some cases, this can affect the welding results achieved.

Understanding Plastic Welding

There’s no question that plastic welding has a wide array of applications and uses today. However, choosing the right type of welding method and using it in the best way possible is essential to achieve the desired results. Review the options here to ensure the proper method is selected. Also, remember to prepare the surface of the plastic properly before welding. This can help ensure the desired results are achieved.  


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