Recycling has become essential today as we realize the environmental impact of disposing of waste materials. In the industrial world specifically, larger manufacturing operations can generate millions of pounds of waste each month – including metal and other materials. There are thousands of different alloys used, resulting in scrap metal that needs new life or risks ending up in a landfill.

According to the Institute of Scrap Recycling Industries (ISRI) in 2019, every year the U.S. scrap industry recycles:

  • 85 million tons of iron and steel
  • 5.5 million tons of aluminum
  • 1.8 million tons of copper
  • 2 million tons of stainless steel
  • 1.2 million tons of lead and
  • 420,000 tons of zinc

Challenges in Reducing Environmental Impact

The production cycle used for most mechanical components includes machining operations. This implies that a significant amount of metallic material is wasted as scrap during the performance of traditional cutting processes, according to this study in Science Direct.

Conventional recycling involves melting the material, which leads to an increased carbon footprint – and the metal fabrication industry is notorious for its heavy environmental impact. However, many companies are now taking steps to minimize their environmental impact by adopting more sustainable practices.

Researchers continue seeking innovative and efficient ways of recycling metal chips produced in manufacturing operations.  As noted in the study, machining chip is one of the most difficult kinds of scrap to be recycled as it is “characterized by elevated surface/volume ratio and it is usually oxidized and covered by different types of contaminants (i.e. lubricants used for the machining process).”

Due to these features, conventional recycling technologies may lead to different drawbacks and environmental issues – such as fumes and gas formation, and defectiveness in the final product. Recently, studies examining the recycling process of melting of aluminum and magnesium alloys reveal that the recovery rate of the entire process usually barely reaches 50 percent.

Solid State Recycling – A New Approach to Material Recycling

A new solid-state recycling process known as Friction Extrusion (FE) is changing the recycling and upcycling industry – and producing stronger recycled metal products. Solid-state recycling refers to a group of processes allowing direct recycling of metals scraps into semi-finished products.

A thermo-mechanical process, FE has emerged as a revolutionary method in the recycling of metal waste and the production of wire metals. This technique is gaining attention due to its environmental and economic benefits, particularly its energy efficiency and the quality of the products it generates.

What is Friction Extrusion?

Friction Extrusion was invented by researchers at The Welding Institute (Cambridge, UK), the same team that invented Friction Stir Welding.

Friction extrusion uses relative motion and high contact forces between a non-consumable tool set and a metallic workpiece to generate frictional heating and severe plastic deformation. The result is a metal with fine grain size, low dislocation density, and high quality. By processing custom-blended powders, new composite materials can be produced with unique properties, such as high thermal and electrical conductivity, high ductility, improved high-temperature performance, etc.

Environmental Advantages of Friction Extrusion

The novelty of FE is that it utilizes the frictional heating and extensive plastic deformation intrinsic in the process to stir, mechanically alloy, consolidate, and convert powders, chips, and other recyclable feedstock metals into a usable product form of highly engineered materials. It represents a potentially transformational sustainable manufacturing technology.

One of the main environmental advantages of friction extrusion lies in its ability to avoid the molten state of the material. Traditional remelting-based recycling methods can negatively impact the environment due to the high energy requirements and associated emissions. In contrast, friction extrusion, being a solid-state process, eliminates these energy-intensive melting and solidification steps. Therefore, FE is a highly energy-efficient, practically zero-emission, and economically competitive process.

Economic and Quality Benefits

The economic benefits of friction extrusion are closely tied to its environmental advantages. By eliminating the need for melting and solidification, the process becomes less energy-intensive, leading to significant cost savings.

In terms of product quality, friction extrusion offers a direct method to recycle metal chips or scraps, resulting in fully consolidated wire, rods, tubes, or other non-circular metal shapes. The temperature reached by friction softens the material, allowing for high plastic deformation, which is useful for the extrusion process.

The friction extrusion process can also be utilized for “upcycling” where low-grade feedstocks are utilized with certain alloying elements to create high-value alloys in a single step.

Stronger Metal Wires

Friction Extrusion has been widely studied, and it has been found that the process produces wires with exceptional mechanical properties. The mechanical properties are due to the formation of a refined microstructure within the extruded material, achieved by combining processing parameters appropriately. The process combines the principles of friction and plastic deformation along with the advantages of solid-state recycling. These fundamental advantages improve the physical and mechanical properties of the extruded material such as formability and resistance to corrosion.

Creation of materials with improved electrical and thermal conductivity is also feasible.

FE reduces waste and maximizes resources

Friction Extrusion is a game-changer for several industries such as aerospace, automotive, and electronics to name a few. The process offers a new avenue for reducing waste materials, ensuring sustainable production, and maximizing the reuse of resources. Aerospace industry scrap parts were recycled via Friction Extrusion, resulting in the development of high-performance wires of similar target composition and including the achievement of remarkable mechanical features.

Bond Technologies has the first FE system to market

Although the FE technique was intriguing and suggested numerous applications, there was a need for a purpose-built machine to begin to explore and tap into the potential of this process. Bond Technologies developed the first FE system, and more recent machines have been designed with enhanced features. This is an area of active, cutting-edge research worldwide. Bond anticipates that this research will produce new materials with special characteristics as the technology continues to advance.

Let Bond Technologies help you find the best Friction Extrusion solution for your application

Bond’s FE100 is our current standard offering. Bond is currently developing customized configurations in response to customer demands. Contact us to learn more about FE and how it can work for you.