How to Choose the Right Expanded Metal Mesh Size for Your Baskets

Expanded metal baskets can be a great alternative to using sheet metal or custom wire baskets in many situations. Baskets made with expanded metal offer the better durability and tensile strength than steel wire while having better drainage and air flow than sheet metal baskets. This makes expanded metal baskets almost perfect for heavy-duty parts washing processes where thin custom wire baskets wouldn’t cut it, but sheet metal would interfere too much with parts finishing processes.

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However, not all expanded metal baskets are the same. When building an expanded metal basket, it’s important to carefully consider the size of the mesh—i.e. how much open space there is between solid surfaces (also known as strands) in the expanded metal sheet and the size/thickness of those surfaces.

If the expanded metal mesh size is too tight, it might interfere with wash processes or allow water (or other chemicals and process runoff) to collect in the basket. Too open, and parts may fall through or the basket might be too weak.

So, how can you pick the right expanded metal mesh sizes for your custom parts washing baskets? Here is a quick guide:

The Factors Behind Your Mesh Size Choices

When creating a sheet of expanded metal mesh, the manufacturer will need to consider the:

• Weight of Held Parts. Naturally, the weight the basket will be designed to hold plays a factor in how wide the space between strands can be, as well as how thick each strand needs to be. The heavier the expected load, the thicker the strands of the expanded metal mesh will need to be.
• Type of Metal Used for the Mesh. The type of metal used in the expanded metal mesh also plays a role in determining how thick or thin the strands can be and how much open space there can be between strands. For example, 304 stainless steel is sturdier than aluminum at the same sizes, so 304 SS can be made thinner and wider for the same weight tolerances. High-carbon steels are even stronger, so carbon steel expanded metal mesh can take even more weight than 304 SS mesh of the same size.
• Needs of the Wash Process. The wash process itself will heavily influence the design of a custom expanded metal mesh basket, right down to the spacing of the mesh. Many aqueous wash processes require a lot of open space to facilitate water/air flow and keep runoff from collecting in the basket (this is why custom wire baskets are usually the first option for these processes). So, for water- or chemical-based wash processes, thinner mesh with more open space is usually the go-to option. Additionally, the chemicals and temperatures used in the wash process may influence the material choice.

Some Examples of Different Mesh Size and Material Choices

Special thanks to Alro Steel for the following examples of metal mesh sizes for stainless steel, aluminum, and carbon steel:

Metal Type

Strand Width (inches)

Strand Thickness (inches)

% Open Area

Weight Capacity Per 100 Sq. Ft. (lbs.)

Carbon Steel

.072

.036

45

86

304 Stainless Steel

.080

.037

70

50

Aluminum

.094

.051

70

27

As you can see, the carbon steel example, though possessing the thinnest strands, had the highest weight capacity of all the expanded metals in the Alro Steel list. This may have been bolstered somewhat by the fact that it had the least open space, but the difference is still significant.

304 stainless steel serves as a great “all-round” option, with its ability to resist chemical attack/oxidation and moderately high tensile strength—being able to take nearly twice the weight of the aluminum expanded metal example. In most cases, the stainless steel would be the better option, unless the chemicals in the wash process were severe enough to corrode it but would not affect aluminum.

Some manufacturers may even choose to use a specialized polymer coating to protect their expanded metal baskets from corrosives so they can use stronger metals while prolonging the useful life of the basket.

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. 

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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.