How Does Expanded Metal Work?

How are expanded metal sheets made? And what makes them such a widely used material?

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Expanded metal sheet fabrication is a highly efficient process that includes stretching, slitting, and rolling sheet metal. A machine stretches and then cuts the metal with an upper and lower blade to produce diamond-shaped openings. These openings provide structural bonding value without need for additional strengthening processes and give expanded metal a unique mesh-like appearance. Once the expanded metal sheet has been die-cut it is flattened with a rolling mill.

This fabrication process produces zero metal waste and fashions a strong, highly versatile, metal product that can be sheared into custom-sized sheets or wound into coils for various uses across industries.

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What is Expanded Metal Sheet Used For?

Expanded metal sheet provides strength and versatility across industries. Since the die-cutting process is adjustable, expanded metal sheet is ripe with decorative possibilities, whether for sculptural artworks, architectural screening, or other commercial designs.

Here’s a non-exhaustive list of expanded metal sheet applications:

• Machine and window guards
• Catwalks, platforms, and stair treads
• Screens and flooring
• Railing mesh on stairways, balconies, and construction sites
• Conveyor belts
• Racks and shelving
• Fire pits and grills
• Sound proofing
• Stereos and microphones
• Outdoor equipment, park benches and other playground equipment
• Air and fluid filters/strainers
• Shielding
• Ventilation Systems
• Decorative dividers and partitions
• Security Walls, Ceilings, Floors, Doors
• Concrete Reinforcements
• Greenhouses

What are the Types of Expanded Metal?

There are three common types of expanded metal sheets:

Standard Expanded Metal

Standard expanded metal is considered the most flexible and high value type of expanded metal sheet. It is widely available in a range of gauges and sizes and is characterized by a raised, slip-resistant, base. All strands and bonds are set at the exact same angle, made from sheet metal that has been pressed and die-cut. Raised expanded metal is commonly seen in stair treads, trailer ramps, shelving, and other applications where slip-resistance is beneficial.

Flattened Expanded Metal

Flattened expanded metal grating requires passing standard expanded metal through a cold rolled reducing mill. This process flattens the signature raised bonds of standard expanded metal and reduces thickness and weight to create a smooth, flat surface. This is a suitable material for many applications in the agricultural, commercial, and automotive industries.

Expanded Metal Grating

Expanded metal grating is a low-maintenance product produced from a single metal sheet. Without joints or welds, this metal product is a heavy-duty, open-air solution ideal for fire protection, and to prevent dirt, snow, grease and other unwanted debris accumulation.

Where does Expanded Metal Mesh Fit In?

Expanded metal mesh is made of a single sheet of compressed and stretched material. It can be used to replace metal or wire mesh since doing so produces a material that is stronger than fine metal mesh. It also allows for improved airflow and drainage capabilities. It is often the go-to choice for wire baskets.

What is Expanded Metal Mesh Used For?

When expanded metal is used for mesh baskets it can go into several high-impact industrial applications. From shot peening parts to shot blasting parts, expanded metal mesh baskets will provide the impact resistance needed to endure constant exposure to high stress conditions.

Expanded metal mesh baskets are also selected for storage, stacking, packaging, and delivery processes. They also provide good surface quality which aids in overall durability and withstands exposure to outdoor settings. Expanded metal mesh also provides protection from fire and can be seen as a protective shield on fire pits, grills, heating devices, and other products requiring high heat tolerances and airflow.

What are the Key Advantages of Expanded Metal?

There are various benefits of using expanded metals:

• Metal-saving, efficient manufacturing process. When compared to similar metal products—like perforated metal, which requires metal to be punched rather than cut and stretched—expanded metal fabrication does not produce any metal waste.
• Light weight. Flattened and expanded metals are thin and light.
• Low maintenance. Metal grating maintenance is simple and straight forward, and often comes with a protective coating that will prevent rust.
• Indoor and outdoor applications. Expanded metal sheets are used across indoor and outdoor applications, adding to this metal product’s versatility.
• Reinforcement. Expanded metal mesh can mix with glass, concrete, and other materials to add strength.
• High tensile strength. Expanded metals handle more weight and tolerate stress better than woven metals or jointed welds.
• Free movement of air and light. Metal that has been expanded allows for free movement of air and light. Liquids, dirt, grease, and other materials are also able to pass freely.
• Acoustic improvement and sound deadening capabilities. Expanded metal mesh can be used in microphones and speakers as well as extra layering to sound proof rooms and walls.

What are Common Expanded Metal Terms?

Expanded metal sheets are unique and include specific terms that will aid in understanding expanded metal sizes and expanded steel products in general. The above image shows standard expanded metal, with the gray areas indicating the raised, skid-resistant edge quality.

Bond: This is the intersecting point where adjacent strands meet. The bond is always twice the width of the strand.

Strand: This is the single metal strip which forms the border of the opening.

Strand width: The amount of material advanced for expanding.

Strand thickness: The thickness of the metal from which the expanded metal is produced.

Opening / Aperture Size: Typically the open area formed by bonds and strands is diamond shaped. Different die-cutting settings can alter the final material output characteristic, however.

SWO or SWA: Short way of opening, or short way of aperture is the dimension measured across the sheet in a direction parallel to the smallest side of the diamond, accounting only for the size of the opening.

LWO or LWA: Long way of opening, or long way of aperture is the dimension measured across the sheet, parallel to the largest side of the diamond, accounting only within the opening’s size and not the material edges.

Mesh: Expressed in inches, this is the nominal distance from the mid-point of one bond to the mid-point of the next bond measured across the SWA.

Percent of Open Area: Designers and engineers calculate the degree to which light, air, or other objects can pass through a piece of expanded metal.

Pitch: This is the measurement from a point on one diamond to the same point on an adjacent diamond. In certain decorative designs this number may not be consistent throughout the expanded metal sheet.

Style: Expanded metal style is expressed as the gauge number for the thickness of the original metal prior to expansion. For metal grating, style is expressed in pounds per square foot.

Why is Expanded Metal 4 x 8 the Most Common Size?

4 x 8 is a standard size for expanded metal sheet. It provides weight and metal savings while conveniently fitting a wide range of common and specialty applications. Check out the 4 x 8 sizing chart below as a reference.

4×8 Flattened Expanded Metal Size Chart

Contact Our Qualified Team

Looking for expanded metal sheets in a different size? Kloeckner Metals supplies expanded metal sheet to customer specifications and will work with you to meet your unique needs.

Download our mesh measuring guide.

Understanding the precise measurements required for different types of expanded metal is essential for selecting the right mesh pattern. In this article, we provide a comprehensive guide on how to accurately measure and specify expanded metal. 

Additional resources:
7 Types of Perforated Metal Mesh Buying Guide
7 Benefits of a Security Screen Mesh
Stainless steel square mesh - Dashang Wire Mesh

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Raised or flattened mesh, what is the difference?

When measuring expanded metal mesh, the first thing to consider is whether the mesh is raised or flattened. Each type has its own set of terminologies for measurement.

Expanded metal starts in a raised form due to the unique ‘slit and stretch’ manufacturing process, which creates angular strands inclined from the plane of the sheet.

Raised mesh is notable for its angular appearance, which not only enhances its aesthetic appeal but also provides practical benefits: it offers grip underfoot, directs air, liquid, and light, and serves as a key when used as a substrate.

Common applications for raised mesh include walkway ramps, security fencing, interior and exterior decorative building cladding, and laths for render and plaster.

A secondary process often flattens the raised mesh using heavy rolls, resulting in a completely two-dimensional sheet where all strands lie in the same plane. Flattened mesh is preferred when a smooth finish is desired.

Common applications for flattened mesh include security partition meshes, conical air filters, and machine guards.

How to Measure a Raised Mesh?

Key terminology for raised mesh is Longway Pitch (LWP), Shortway Pitch (SWP), Strand Width (SWDT) and Strand Thickness (STK).

LWP: Measured horizontally from either knuckle to knuckle or centre to centre, is derived from the size of tooling used within the production process.

SWP: Measured vertically from either knuckle to knuckle or centre to centre, is manifested through the overall expansion applied during manufacture.

SWDT: A measurement of the width of the resulting angular strand created during manufacture.

STK: A measurement of starting raw material thickness. Contrary to belief, the expanding process does not directly alter material thickness. Strand Thickness should not be confused with the overall height or depth of expanded metal. Typically, mesh height can be as much as 1-2 times the measurement of SWDT.

How to Measure a Flattened Mesh

Key terminology for flattened mesh is Longway Aperture (LWA), Shortway Aperture (SWA), Strand Width (SWDT) and Strand Thickness (STK).

LWA: Measured horizontally from one internal aperture point to the next.

SWA: Measured vertically from one internal aperture point to the next.

SWDT: The width of the angular strand created during manufacturing.

STK: The thickness of the raw material before processing.

The expanding process does not alter the material thickness, but the flattening process does. You can expect a 10-20% reduction in material thickness after flattening.

After flattening, the mesh becomes completely two-dimensional. Therefore, the overall height measurement of the mesh will be similar to the starting material thickness, with an additional 10-20% reduction.

How do I specify sheet size and orientation?

Expanded metal mesh exhibits different mechanical and aesthetic properties depending on the sheet's orientation.

When specifying sheet dimensions, it is important to consider the orientation of the diamonds in relation to the sheet size. The terms used to describe this orientation are Longway Mesh (LWM) and Shortway Mesh (SWM).

For example, when raised mesh is used as a walkway ramp platform, the surface grip is strongest when the diamonds run left-to-right underfoot. Conversely, in the security fencing industry, expanded metal fencing panels are commonly mounted with the diamonds pointing upwards. This creates narrower openings and makes it more difficult to climb and scale the fence.

The illustration below shows how a mm (LWM) x mm (SWM) differs from a mm (LWM) x mm (SWM), despite having the same overall dimensions.

In conclusion, this article has provided a comprehensive guide on measuring and specifying expanded metal, covering both raised and flattened mesh types. It delves into the unique characteristics and applications of each, highlighting key measurements.

These measurements are essential for selecting the right mesh pattern for various purposes, from walkway ramps and security fencing to decorative cladding and industrial applications.

By understanding these metrics and considering the orientation of the mesh, readers can confidently choose expanded metal that best suits their specific needs. For visual clarity, refer to the accompanying illustration to understand the differences in mesh orientation.

View an example of our F flattened steel mesh at a horizontal orientation here and view the same mesh at a vertical orientation here.  You can also view our raised steel mesh at a horizontal orientation here and at a vertical orientation here.