Plastic welding

9 Frequently Asked Questions About Welding Plastics

Many people automatically think of metal when the topic of welding is introduced, but welding plastics is actually commonplace. This is the recommended solution for our clients in industries such as medical devices, life sciences and semiconductors.

Because plastics are generally lighter in weight than many metals, plastics welding can be a faster and simpler fabrication process than welding with metals. Plastics, by nature, are more chemically-resistant than most metals, so plastic welds for your components that will be used to transport caustic materials are recommended to maintain safety and reliability of the end product.

Here are some of the top questions asked about plastics welding, and we’ve included answers that can assist the decision-making process for your next project.

What is plastics welding?

Plastic welding is the operation of creating a molecular binding between two thermoplastics that are compatible in nature. Hot gas welding is the process we utilize most-frequently for welding plastics.

How do you join two pieces of plastic?

At Axenics, we use a hot gas welder for welding plastic. This process is also known as heat fusion or butt welding. We recommend a thermoplastic pipe welding process using heat to join two polymer-based products. The plastic goes through a process where heat is added to soften the plastic and then it is pushed or fused together to bond the two pieces. This results in a viable and stable bond.

Here are the main aspects involved in joining plastic by welding:

  • Surface Preparation: It’s important that your technician checks each plastic piece for potential defects. The plastic pieces are typically cleaned to make the process smooth.
  • Welding Applications: Plastic pipe welding can be performed with the use of heat or it can be performed through use of a chemical solvent, depending on the type of plastics being fused. With heat, a plastic is softened to make it pliable. Heat is applied in various ways, including, steam, hot gas, a welding rod, a hot plate or a laser. With the plastics softened, they are put in a vise, where pressure is added, causing the edges to bond together. Consistent pressure is essential to ensure the high quality of a weld.
  • Cooling: After welding, the new component needs to cool. However, you can still apply pressure during the cooling process, which can help the component keep its intended shape. Shrinking of the piece can occur if pressure is not applied during the cooling process.

Which plastics can be welded?

Plastic-welding solutions are generally performed using the following polymer-based materials:

  • Polytetrafluoroethylene, which is resilient, stable and features the ability to withstand exposure to harsh chemicals.
  • Polyvinyl chloride, which is lightweight and rigid as well as known for its strength and fire retardant properties.
  • Chlorinated polyvinyl chloride, which is known for its ability to withstand high temperatures.
  • Polypropylene, which is known for its elasticity and high chemical resistance.
  • High-density polyethylene, which is known for its broad strength-to-density ratio.
  • Polyvinylidene fluoride, which is a durable, strong plastic known for its ability to withstand harsh chemicals.

What will best bond plastic to plastic?

A bonding agent used to adhere plastic to plastic depends on the types of plastic being utilized. Some plastics react better to a chemical solvent bond, while other plastics have a better result with a heat bond being used.

Is it possible to weld together dissimilar plastics?

Again, this depends on the types of plastics being used and the process used to bond them. Generally, it is not recommended to weld two varying plastics, as they may not create as strong a bond as two similar plastics.

How strong are the welds?

Thermoplastics, while extremely versatile, can be used to create durable, long-lasting welds. Certain plastics will also have a slower deterioration time than metals, so depending on the project and the ultimate use of the components, we can recommend a solution to you that will ensure the welds have staying power.

What are common uses for welded plastics?

Welded plastics have virtually thousands of uses. For example, you can utilize welds in the medical field to transport gases and chemicals through small-to-large life-saving components.

Using plastic welds avoids the complications that come with corroding metal components from the materials being transported. This is why we see plastic welding most-often used in these industries:

Can you melt plastic together?

Yes, plastic can be melted together as long as the two pieces of plastic are the same type of material. “Melting” plastics together is not necessarily the same as welding plastics together, though.

Can you use a soldering iron to weld plastics together?

Using a soldering iron to weld two plastics together is not recommended, as the bond formed will likely be weak, and not useful for the transport of most liquids, gases or other chemicals. You’re not going to get a permanent bond by using a soldering iron, therefore it’s not a practice we can recommend.

Decades of plastic welding experience

If you’re looking for expertise in plastic fabrication, it’s been one of our specialities for more than 30 years. Our team of experts is cross-trained in plastic and metal welding, which means we can offer educated guidance on your next project.

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