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Plastic Welding

by Aug 5, 2021Welding

Estimated Reading Time: 4 minutes

Some engineers automatically think of metal when it comes to welding, but plastic welding grows in popularity every year. Manufacturers in all tiers regularly make the switch from metal to plastic welding.

Plastic welding creates a molecular bond between two compatible plastics. Plastic welding provides first-rate strength, and finished welds are long-lasting, meaning any necessary replacements and/or repairs will occur in the distant future. One way plastic welding proves superior to steel weldments is that chemicals can corrode and contaminate metal, severely decreasing its usefulness in certain applications.

Plastic welding produces durable, reliable and complex transportation, monitoring and purification systems. Plastic welders can perform pipe-to-pipe weldments that meet your exact requirements. Plastic welding is a complex process that requires the right set of skills and a strong passion for improving those skills. Plastic welders require significant dexterity and mobility. There is no formal education for plastic welding, you learn best on the job and gain expertise with years of training and working with the various types of plastics used in welding.

Plastic Welding: The Process

Producing plastic welding involves three main steps:

Surface preparation

First, a technician will examine each plastic component for defects. The plastic components are cleaned, and/or abraded. This can be a time-consuming task, though it is required to achieve top-quality results. Performing surface preparation thoroughly reduces oxidation of the plastic and helps eliminate potential contaminants like dirt. Any contaminants may have a negative effect on the final quality of the welded plastic.

Heat welding

There are several ways to weld plastic. Heat is a commonly used option. Chemical solvents are another option for plastic welding, depending on the type of plastics being melded together.

Heat increases the malleability of plastic. Steam, hot gas, a welding rod, a laser or a hot plate heats the plastic. Hot gas welding a.k.a heat fusion or butt welding is a common practice that works effectively.

While the plastic components are pliable, they go into a vise, where pressure applies to the pieces, causing a bonding on the edges of the plastic. Applying consistent pressure ensures the quality and integrity of a weld.

A highly effective thermoplastic welding process uses nitrogen and heat when joining two polymer-based products, resulting in a stable, strong plastic weld.

Plastic weld cooling

After the heating stage, the plastic weld cools. Cooling is a necessary step for solidifying the bond between two plastics. The strength of a finished weld depends on how the plastic cools. Pressure applied during the cooling step assists in shape retention. Without pressure during cooling, the material may shrink and alter the shape of the product, negatively affecting the results.

Plastic Welding: Uses in Manufacturing

Many industries currently require the use of volatile chemicals, including alternative energy, chemical manufacturing, life science, semiconductor and medical device manufacturers. One of the biggest challenges they face is creating complex components with miniature segments through which liquids and gases can easily pass. Plastic welding is a top solution for manufacturing those components for safety purposes and to ensure a longer lifespan of the product. Plastic welding is used to construct patient-monitoring devices, diagnostic instruments and machinery used in life-saving operations.

Plastic piping kits provide gas or liquids transportation from one area of a system to another in one clean, clear shot. This allows simple transport around components and other obstacles in the system with a smooth inner bore. Tubing assemblies reduce potential leak areas along the way or remove areas where liquids could hang up and cause contamination.

Plastic Welding: Benefits

Plastic welding is often a faster and simpler fabrication process versus welding with metals because plastics are generally lighter in weight than many metals. Plastics are also a wise choice for maintaining the safety and reliability of your end product as they are more chemically resistant than most metals.

  • Plastic welds have a strong resistance to acids, alkalis, greases and solvents, hydrogen peroxide, demineralized water and hot steam.
  • Plastic welds offer a minimal release of gas under vacuum, which helps maintain a sterile environment.
  • Plastic welds have a strong plasma resistance reducing the possibility of corrosion.
  • Plastic welds resist thermal degradation and maintain a high operating strength and rigidity in high temperatures.
  • Plastic welds offer the benefits of good creep and chemical resistance, minimal thermal expansion and good wear resistance.

Plastic welding provides a simplified system that delivers a consistent, highly-repeatable performance. There is also the flexibility of easily adding thermoplastic sub-systems that provide multiple flow rates and pressures.

Plastic Welding: Frequently Asked Questions

What best bonds plastic to plastic?

A bonding agent for adhering plastic to plastic depends on the types of plastic being used. 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 dissimilar plastics?

This also depends on the types of plastic and the process used in bonding. Generally, welding two varying plastics isn’t recommended, as they may not create as strong a bond as two similar plastics.

How strong are plastic welds?

Thermoplastics, while extremely versatile, create durable, long-lasting welds. Certain plastics also deteriorate slower than metals. 

What are common uses for welded plastics?

Welded plastics have virtually thousands of uses. The medical device or biochemical fields utilize welds 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.

Can you melt plastic together?

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

Can you use a soldering iron for plastic welding?

Using a soldering iron to weld two plastics together is not recommended, as it generally forms a weak bond. This isn’t good for transporting most liquids, gases or other chemicals. You’re not getting a permanent bond using a soldering iron.

Axenics’ in-house plastic experts have decades of experience innovating thermoplastic welding and bending techniques. There’s virtually no limit on the length of thermoplastic pipe we can weld and bend for your production, and no limit on the complexity or number of welds.

Our plastic welding experts will answer any additional questions you have.

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