Expanded Metal: The Strong Material With Thousands of Tiny Openings

Take a careful look at a security fence, a factory walkway, or the grill over an industrial fan, and you'll likely find expanded metal. It looks like a woven steel fabric, with diamond openings punched edge to edge, but nothing about it is woven or stitched. It's not a bunch of pieces of solid metal cut and welded into that shape; there are no joints, there's no welding, and there's not a lot of metal wasted in creating such a pattern. This combination of strength, airflow, visibility, and effective use of the raw material is what has made expanded metal one of the most popular industrial materials in the world today.

Expanded metal is a one-piece, rigid sheet metal that is slit and stretched, forming a continuous pattern of diamond or hexagonal openings, usually made from steel, aluminum, or stainless steel. Expanded metal begins and ends as a single piece of metal, unlike woven wire mesh, which is formed by braiding individual wire strands together, or perforated metal, which is formed by punching holes in a solid piece of metal and discarding the removed material. The manufacturing process does not add to or remove from the material, which is one of its most unique and useful features.

What you end up with is a piece of the sheet with the strength of the original metal in each strand of the diamond pattern, as every strand of the pattern is just a stretched and reshaped portion of the original sheet, instead of a separate piece attached to the other strands. There is no weak spot where the metal strands come together, as in woven wire products, allowing expanded metal to provide mesh materials with structural integrity they may not otherwise have.

The manufacturing process is mechanically simple but requires well-designed tooling to create one pattern in a sheet. A sheet of solid metal is pushed into a special machine that expands the sheet while cutting it with a special tool in a coordinated, repeating motion. The die pushes down and cuts a short series of slits into the metal; at the same time, the die pushes the slit sections outward and to the sides. This slitting and stretching is repeated in a staggered manner as the sheet is continuously fed in, row after row, until the entire surface changes to the familiar diamond mesh pattern.

Since the metal is stretched rather than punched, it does not lose any material during the process. Nothing that goes into the machine as a flat sheet is lost—the process is amazingly efficient compared to punching or drilling, which leave offcuts and scrap. The near-complete material usage of expanded metal is a significant advantage compared to other meshes available, which are more expensive in industrial use per unit of coverage.

Expanded metal can be supplied in an expanded condition, or it can be further flattened using heavy rollers to flatten the diamond pattern, creating a smoother, flatter surface suitable for the intended application. This flattened form is also known as flattened expanded metal and produces a more level surface that is easy to walk on or work with while retaining much of the strength inherent in expanded metal.

The mechanical manufacturing process of expanded metal is also responsible for its strong strength-to-weight ratio. Perforated metal is punched or drilled to create openings, and the material punched or cut away is lost; the remaining structure must support the same load with less material, with stress concentrations around the punched edges. In expanded metal, however, this is nearly eliminated because the metal is not cut away but reshaped, so the diagonal strands that make up each diamond opening in the sheet remain structurally connected to the rest of the metal.

Because of this continuity, a load placed on any one portion of an expanded metal sheet is spread along the diagonal strands throughout the sheet; therefore, expanded metal sheets can often carry surprisingly heavy loads relative to their overall weight. This is partly why expanded metal is a popular flooring choice in industry applications such as industrial platforms, catwalks, mezzanine floors and offshore platforms where strength and weight reduction are a concern.

The diamond-shaped openings that run across the expanded metal sheet continuously are also beneficial because of the airflow, light transmission and visibility that they provide that no solid sheet of metal can provide. It is useful virtually everywhere ventilation is important, and air should flow freely without losing the physical barrier provided by the metal, for example in machine guards, equipment enclosures, or HVAC components.

This open layout also provides some light transmission, which can be advantageous in applications such as walkways above work surfaces, where it would be dangerous or difficult to prevent light entering the space below the work surface. This openness is also great for security applications, as expanded metal fencing and expanded metal screens allow guards or security staff to see through the barrier clearly without losing the barrier's strength or making it easier to penetrate.

Expanded metal is available in a variety of different patterns and types. The diamond pattern is the best-known and most commonly made pattern of expanded metal, but many different types can be used for different purposes.

Standard expanded metal is typically referred to as raised expanded metal and retains its raw diamond pattern from the expanding process, with strands of raised metal at a slight angle to the original sheet plane. This provides a rough, grippy surface texture ideal for flooring and grating applications where slip resistance is important. Flattened expanded metal is flat-rolled expanded metal that retains the open pattern of expanded metal but has a smoother, more uniform surface, used in applications such as fencing, furniture, and architectural panels where a cleaner, more finished look is desired.

Micro expanded metal is a type of expanded metal with smaller openings than normal patterns, used in filtration, fine security screening, and other situations where the smallest possible opening size is desired, but the expanded metal manufacturing process has superior strength characteristics compared with similar woven metal products. Grating-style expanded metal is a thicker-gauge metal product designed for heavy-gauge applications such as industrial flooring, stair treads, and other load-bearing uses, with larger, thicker metal diamond openings for heavy foot traffic and equipment loads.

Strength, flow, sight, and material efficiency have made expanded metal an "everywhere" material used in a broad spectrum of industries. It is widely utilized in the industrial and commercial sectors for walkways, catwalks, stair treads, and mezzanine flooring because of its strength-to-weight ratio and slip-resistant surface, making it an ideal material for elevated work platforms — much like the recovered structural steel that turns up on Melbourne green building projects. Expanded metal fencing, window guards, and enclosure panels are commonly used around secure equipment enclosures, industrial yards, and utility substations, as they offer a physical barrier that is hard to cut through or climb on without sacrificing visibility or airflow. It is found in agricultural applications such as equipment guards, animal enclosures, and ventilation panels, where both durability and airflow are crucial for the well-being and safety of animals and workers.

Flattened expanded metal has gained popularity in architecture and design for its industrial aesthetic and practical features, such as sun shading and airflow control on building facades, making it a desirable choice for creating a unique, visually appealing look. Expanded metal is used in vehicle grilles, filtration units, and equipment guards in the automotive and transportation industry, using its open design to promote airflow to the engine components while offering protection.

Although there are many similarities between these two materials, as both involve a pattern of openings in a metal sheet, the manufacturing process and properties are vastly different. Perforated metal is made by punching or stamping holes through a solid piece of metal, which results in material being removed and discarded during the manufacturing process, while expanded metal is stretched, but not cut, and no material is removed at all.

This distinction affects practice. Perforated metal usually features smaller, more uniform hole shapes and sizes and a smoother surface finish, making it ideal for applications that prioritize aesthetics or filter performance. Expanded metal, on the other hand, generally has superior strength/weight ratio and lower material costs per unit of cover because of no scrap, and the constant diagonal strands have better load distribution than a sheet perforated with punched-out holes.

Unlike expanded metal, woven wire mesh is made by interlacing individual wire strands. Woven mesh is not cut from a single sheet of metal, meaning that the intersections of the woven strands are a potential weak point for wires to shift, loosen, or break under intense or frequent pressure, which is not possible with expanded metal, where the strands are continuous with the rest of the mesh.

However, woven wire mesh may offer greater flexibility in terms of the opening size and shape that can be achieved. It may be more appropriate for very fine filtration applications where there is a minimum practical opening size that may be a limitation with expanded metal. This depends on what they are used for, and whether it is more important for them to be strong and inflexible or for the fine mesh control.

Several factors matter when choosing the right expanded metal product to meet application requirements. The choice of base metal matters because, for general industrial applications, carbon steel is a good choice for its strength and cost-effectiveness. In contrast, stainless steel is a better option for corrosive or hygienic applications like food processing or marine environments, and aluminum is suitable for its lighter weight and acceptable corrosion resistance, which is also why offcuts of it are worth taking to aluminium recycling once a project wraps up.

Opening size and pattern must also match the application's needs for airflow, visibility, security, or filtration, and a pattern that works for a decorative architectural screen might be the wrong choice for a load-bearing industrial floor grating. Lastly, when deciding between standard or flattened expanded metal, consider whether surface texture and grip matter more than a smooth finish; this depends on the material's use and whether it will be walked on, viewed from a distance, or handled directly.

Offcuts, damaged panels, and old expanded metal grating, screens or fencing removed during a renovation, fit-out or demolition are recyclable steel or aluminium scrap. Divine Metal Recycling offers commercial and industrial scrap metal pickup across Melbourne for expanded metal, sheet offcuts and other structural steel.

Not sure whether your scrap is ferrous or non-ferrous? Read our guide on what metals can be recycled to identify your materials before booking a collection.

Expanded metal earns its place across industry because it does one thing very well: it turns a single sheet of steel, aluminium or stainless steel into a strong, lightweight, open lattice without cutting away or wasting any of the original material. Whether it ends up as flooring, fencing, filtration or architectural cladding, the same stretched-not-cut structure is what gives it strength most other mesh products can't match.

If your business has expanded metal offcuts, old grating, damaged panels or fencing to clear out, Divine Metal Recycling can assess the material and arrange collection across Melbourne.