Welding Plastics: Methods, Materials, and Limitations
We work with plastics daily and know that welding is an important step in many manufacturing processes. But which methods work best, and which materials are suitable for welding? In this article, we will go through the most common methods for welding plastics, and discuss material properties and common errors that can occur.
Methods for Welding Plastics
There are several methods for welding plastics, but the most common are hot gas welding, extruder welding, and butt welding. Hot gas welding is a method that uses a burner to heat the plastic to its melting point, after which it is shaped and welded together. Extruder welding uses an extruder to melt and shape the plastic, while butt welding uses pressure and heat to melt and weld the plastic together.
We have experience working with these methods, and can conclude that hot gas welding is one of the most flexible methods. But which materials can be welded with this method? That is a good question, which we will answer in the next section.
Materials Suitable for Welding
Some of the materials that are best suited for welding are PE-HD, PE-UHMW, PP and PVC. These materials have a relatively low melting point and are therefore easy to weld. PVDF is another material that can be welded, but it requires a high temperature and careful control of the process.
But what happens if we try to weld materials like POM-C or PTFE? Yes, that is a good question. Unfortunately, these materials are very difficult to weld, due to their high melting point and low ability to bind to each other. In fact, PTFE cannot be welded at all, due to its extremely low friction coefficient and high melting point.
We sometimes wonder why some materials are so difficult to weld. Is there anything that can be done to improve weldability? Yes, there are some things that can be done, such as using a different welding method or adding a weld-enhancing component to the material.
Preparation of Joints
An important part of the welding process is the preparation of the joints. It is important that the joints are clean and dry, and that they have the right shape and size to be able to be welded together. We often use a joint cutter to cut the joints, and then clean them with a brush and a cleaning fluid.
But what happens if the joints are not properly prepared? Yes, that can lead to the welding not being good, and the joints not holding over time. It can also lead to the material being damaged, or the welding not being strong enough.
Testing of Welds
When the welding is complete, it is important to test it to see if it is good. We often use a combination of visual and mechanical tests to check the quality of the weld. We look at the appearance of the weld, and check if it is straight and even. We also test the strength of the weld, by subjecting it to stress and seeing if it holds.
But what happens if the weld is not good? Yes, that is a good question. If the weld is not good, it may need to be redone, or it may need to be repaired. In some cases, it may also be necessary to replace the entire material.
Common Errors that Can Occur
There are several common errors that can occur during the welding process. A common error is that the weld becomes too hot, which can lead to the material being damaged or the weld not being strong enough. Another common error is that the weld becomes too cold, which can lead to the weld not being strong enough.
We have also seen that the weld can become porous, which can lead to it not being strong enough. This can be due to the material not having the right properties, or the welding process not being handled correctly.
When Welding Beats Bonding
Sometimes we wonder when welding is preferable to bonding. Yes, that is a good question. Welding is often preferable when the material is thick, or when the weld needs to be very strong. Bonding can be better when the material is thin, or when the adhesive is stronger than the weld.
But what happens if we cannot decide whether to weld or bond? Yes, that is a good question. In such cases, it may be a good idea to try both methods, and see which one works best.
Finally, we can conclude that welding plastics is a complex process that requires precision and experience. But with the right material, the right method, and the right preparation, the weld can be very good. If you have questions or concerns about welding plastics, do not hesitate to contact us. We are always ready to help and provide advice.
Why not contact us to discuss your needs for welded plastic components?
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