How Does Flattened Expanded Metal Sheet 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.

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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

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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.

Expanded metal baskets are useful for heavyweight custom parts washing applications because they combine some of the best traits of wire baskets and sheet metal baskets. Expanded metal, unlike wire mesh, is made of a single solid sheet of material that has been compressed and stretched. Because expanded is a single piece of material, it tends to be stronger than wire mesh of the same thickness and requires less welding.

Compared to sheet metal, expanded metal offers more open space and is less costly per square inch of basket. In fact, expanded metal is even more resource-efficient than perforated sheet metal, since only very minuscule amounts of the metal are lost during the expanding process compared to the perforation process.

Moreover, there is more than one type of expanded metal that can be used for baskets. Expanded metal comes in two distinct varieties: Standard and flattened. What’s the difference between standard and flattened expanded metal? And, which one is best for your expanded metal baskets?

A Brief Explanation of Standard vs. Flattened Expanded Metal

The term “standard expanded metal” refers to the metal as it comes out of the expanding machine. While the specific dimensions of the expanded metal will vary depending on the expander and the thickness of the sheet metal that was expanded, the thickness of the metal strands and the open space between them will be consistent and regular. The surface of this expanded metal may have a slightly rounded appearance (depending on the expanding equipment), which helps reduce the risk of wash process runoff collecting in the expanded metal basket.

Flattened expanded metal is what results when standard expanded metal is put through a cold rolling steel mill to flatten the expanded metal mesh out. This makes the expanded metal mesh thinner, flatter, and wider/longer. Because it is sometimes difficult to predict how much expansion will occur in the mesh during the flattening process, flattened expanded metal dimensions may vary slightly from original estimates.

Additionally, flattened expanded metal dimensions will change depending on whether it is passed through the roller along the short way of design (SWD, the narrow direction of the diamond pattern) or the long way of design (LWD, the wider, longer direction of the diamond pattern).

Which Type of Expanded Metal is Better for Your Baskets?

The choice of using standard or flattened expanded metal baskets will depend on your application. The slightly rounded surface of standard expanded metal may be better for parts-washing applications where residue from process runoff may be a negative factor.

Meanwhile, flattened expanded metal baskets may be more desirable for some materials-handling applications where a flat surface may better distribute weight or prevent held parts from sticking to the basket’s metal strands. Also, because flattened expanded metal is slightly thinner and wider, it is marginally lighter per square foot than the standard equivalent—which may be important in expanded metal baskets where weight is an issue.

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