Expanded metal mesh is a coil of thin metal that has been precisely slit and stretched to form a uniform, mesh-like material with a regular pattern of openings (often diamond-shaped). Unlike woven wire mesh, expanded metal is made from a single piece of metal that is never completely cut—this creates a one-piece mesh with no welded joints, resulting in excellent conductivity and structural integrity.
CThru Metals specializes in micro expanded metal products, sometimes called expanded metal foil, which are made from very thin gauges of metal to create extremely fine meshes. The expanded metal process produces a material that offers precision, valuable in applications like lightning strike protection, current collection, filtration and EMI shielding— with significant weight savings compared to solid sheet metal (since much of the sheet becomes open area).
Expanded metal’s combination of strength and low weight makes it ideal for aerospace, energy storage, and other high-performance industries. Specifications are critical when discussing expanded metal because they determine the mesh’s performance characteristics—everything from filtration efficiency and airflow to structural rigidity and weight per area depends on getting the specs right.
In this post, we’ll explore the key expanded metal mesh specifications—such as SWD, LWD, strand width, gauge, open area, and more—and explain how to choose the right spec for your application.
When reviewing expanded metal mesh specifications, you’ll encounter a variety of technical terms and acronyms. Understanding these definitions is important for engineers to correctly specify the mesh and ensure it meets the application’s requirements. If you’ve ever wondered about SWD’s meaning or LWD’s meaning on a spec sheet, here we clarify those and other key expanded metal terms:
These terms refer to the clear opening size of the mesh. SWO is the short way of opening, meaning the distance between the inner edges of the strands along the short diagonal. LWO is the long way of opening, the distance between inner strand edges along the long diagonal.
In other words, SWO/LWO measure only the open gap, whereas SWD/LWD measure from center-to-center of nodes (including the material). For any given mesh, SWO is slightly smaller than SWD (by roughly one strand width), and LWO is smaller than LWD. These opening dimensions are very relevant for filtration and open area.
For example, if you’re designing a filter and need to block particles above a certain size, you would look at the SWO/LWO to know the actual free space a particle could pass through. Similarly, for applications like architectural screens or EMI shielding, SWO/LWO tell you how much light or electromagnetic waves can pass. Designers will specify SWO/LWO when the exact aperture size is critical to the function (whereas SWD/LWD are used for the overall mesh pitch including the strands).
The thickness of expanded metal is essentially the thickness of the original sheet or coil before expansion, often expressed as a gauge or in millimeters or inches. This is sometimes called strand thickness. For standard (raised) expanded metal, the final thickness is approximately twice the strand width. In flattened expanded metal, the coil is run through flattening rolls after expansion to make it flat; this process compresses the strands a bit, so the finished thickness of a flattened mesh is usually close to the original metal thickness.
When specifying expanded metal, one should clarify if the thickness refers to original material thickness or final mesh thickness (especially for flattened mesh). CThru Metals specializes in ultra-thin expanded metal foil, which can be made from extremely thin gauges. Standard expanded metal products might use thicker gauges (e.g. 16 gauge, 0.062″ steel, or even heavier for grating). In contrast, micro expanded metal foil is made from foils just a few thousandths of an inch thick. Our advanced expanding technology can produce metal foils as thin as around 25–50 microns (0.025–0.05 mm) into mesh.
Thinner gauge expanded mesh yields a very lightweight product which is excellent for weight-sensitive applications like aerospace, but handling and supporting such thin mesh requires precision (it’s flexible and delicate compared to thicker meshes). Always note whether a thickness spec is “pre-expansion” (the raw material gauge) or “post-expansion” (for flattened mesh or final product) to avoid confusion.
Open area is the percentage of the total sheet area that is open space (the holes) after the metal is expanded. It is calculated based on the strand width, strand thickness, and SWD/LWD of the pattern. For example, a pattern might be specified as having 70% open area, meaning 70% of the mesh is empty space and 30% is metal strands.
Open Area is a critical spec for many functional reasons: if you need maximum airflow or fluid flow through the mesh (like in ventilation panels or filters), a high open area percentage is desirable. High open area also correlates with better visibility through the mesh (important for applications like security screens or window guards where you want to see through the mesh). However, increasing open area (by using thinner/narrower strands or larger openings) will reduce the mesh’s strength. Engineers must strike the right balance—just enough open area to meet airflow or filtration targets, while still retaining sufficient metal for strength.
Expanded metal can be made with open areas from just a few percent (very heavy, secure meshes) up to over 90% (extremely fine, thin meshes used for things like EMI shielding or battery current collectors). Knowing the required open area helps in selecting the SWD, LWD, and strand dimensions that achieve that target.
Expanded metal is often specified with a nominal weight per unit area, such as pounds per square foot (lbs/ft²) or grams per square meter (g/m²). Because expanded metal removes a lot of material to form openings, it provides a huge weight advantage. For standard expanded metal used in construction, weight might be given in lbs per 100 square feet, for instance.
For expanded metal foil (micro-mesh), it’s common to use grams per square meter since the material is so light. For example, an ultra-thin expanded aluminum mesh might weigh only ~30 g/m² (versus a solid aluminum sheet of the same thickness which would be many times heavier). Weight per area is a handy spec for engineers concerned with overall system weight or comparing materials. In aerospace and automotive design, specifying a lighter mesh (lower g/m²) can contribute to fuel efficiency and performance. Keep in mind that material type affects weight too (steel is heavier than aluminum for the same geometry; copper is heavier than aluminum but offers other benefits like conductivity).
When comparing expanded metal options, consider both the open area and the base material density to get the weight-per-area. CThru’s expanded metal foils are designed for lightweight design optimization — for instance, our thin expanded titanium or aluminum foils provide the necessary strength or conductivity at a fraction of the weight of a traditional expanded sheet.
In summary, these specifications (SWD, LWD, SWO, LWO, strand width, thickness, open area, and weight) define an expanded metal mesh’s geometry and performance. An engineer will use these parameters to ensure the mesh meets the precision requirements of the project. For example, specifying the correct SWO/LWO ensures your filter will catch particles of the right size; choosing the right strand width and gauge will make sure the mesh supports structural loads; and targeting the appropriate open area and weight will meet goals for airflow and weight savings.
Understanding this terminology will also help you communicate with suppliers and compare products accurately.
With an understanding of the key specs, the next step is selecting the right expanded metal mesh specification for your specific application. Micro expanded metal (ultra-fine foil mesh) offers a lot of tunability to meet different design goals. Here is a simple guide for engineers on how to choose specs based on various project objectives:
Expanded metal mesh is a versatile material widely used across various industries, from construction to security. Its unique structure and properties make it ideal for applications ranging from decorative elements to functional barriers. In this blog, we will explore the different types of expanded metal mesh, their characteristics, and their applications. Let’sdive in!
Expanded metal mesh is created by taking a sheet of metal and cutting it in a way that allows it to be stretched into a mesh-like pattern. This process, known as expansion, increases the material's surface area and creates a mesh with a series of interconnected diamond-shaped openings. The result is a lightweight, strong, and durable material suitable for many uses.
1. Standard Expanded Mesh
Characteristics:
Pattern: Traditional diamond-shaped openings
Thickness: Varies; typically from 0.4mm to 6mm
Material: Commonly steel, aluminum, or stainless steel
Applications:
Construction: Used in walkways, staircases, and security barriers.
Industrial: Ideal for filtering, ventilation, and safety grilles.
Decorative: Often used in architectural elements and furniture.
2. Flattened Expanded Metal
Characteristics:
Pattern: Similar to standard expanded metal but with flattened openings
Thickness: Thicker than standard expanded metal, typically from 0.6mm to 10mm
Material: Steel, aluminum, stainless steel
Applications:
Building Facades: Provides a sleek, modern look for building exteriors.
Shelving: Used in industrial shelving for its flat surface.
Signage: Ideal for creating durable, weather-resistant signs.
3. Small Hole Expanded Metal
Characteristics:
Pattern: Smaller diamond openings, with finer mesh
Thickness: Thin; generally under 0.5mm
Material: Typically aluminum or stainless steel
Applications:
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Security Screens: Provides fine protection without obstructing visibility.
Filters: Used in air and fluid filtration systems.
Architectural Details: Ideal for decorative and detailed work in buildings.
4. Expanded Metal Grating
Characteristics:
Pattern: Larger, more robust diamond openings
Thickness: Heavier gauges, often above 6mm
Material: Steel or other high-strength metals
Applications:
Industrial Safety: Used for guards, barriers, and protective coverings.
Construction: Ideal for reinforcing concrete and other structural elements.
Mining: Commonly used in harsh environments due to its strength.
5. Decorative Expanded Metal
Characteristics:
Pattern: Customizable shapes and sizes, including intricate designs
Thickness: Varies based on design requirements
Material: Aluminum, stainless steel, or other metals
Applications:
Architectural Features: Enhances the aesthetic appeal of buildings.
Interior Design: Used in screens, partitions, and decorative elements.
Landscaping: Provides visually appealing fencing and trellises.
Based on Material
Steel Expanded Metal: Strong and durable, available in carbon steel, galvanised steel, and stainless steel for different levels of corrosion resistance.
Aluminum Expanded Metal: Lightweight, corrosion-resistant, and easy to handle. Ideal for outdoor applications and where weight is a concern.
Stainless Steel Expanded Metal: Offers superior corrosion resistance and durability, making it suitable for harsh environments and hygienic applications.
Copper Expanded Metal: Known for its aesthetic appeal and antimicrobial properties. Often used in architectural and decorative projects.
Titanium Expanded Metal: Extremely strong and lightweight, with excellent corrosion resistance. Used in high-performance applications.
Heavy-Duty Expanded Metal: Made from thicker metal for applications requiring exceptional strength and durability, such as security fencing and machinery guards.
Micro Expanded Metal: Features smaller openings and thinner strands, suitable for precise filtration and screening applications.
Decorative Expanded Metal: Offers various patterns and finishes for architectural and aesthetic purposes, including facades, ceilings, and partitions.
Selecting the appropriate type of expanded metal mesh depends on several factors:
Application: What is the primary function of the mesh?
Material: What level of strength, durability, and corrosion resistance is required?
Openings: What size and shape of openings are needed?
Thickness: How thick should the metal be?
Finish: Do you require any specific surface treatment or coating?
By carefully considering these factors, you can choose the ideal expanded metal mesh for your project.
Would you like to learn more about specific applications or have questions about a particular type of expanded metal mesh?
Factors to Consider When Choosing Expanded Metal Mesh
Material: Consider the environment and application to choose between steel, aluminum, or stainless steel.
Thickness: Determines the strength and durability of the mesh.
Opening Size: Affects the mesh's functionality, from filtering to decorative purposes.
Coating: Some applications may require additional coatings for corrosion resistance or aesthetic reasons.
Expanded metal mesh is a versatile and functional material with various types tailored to specific needs. Whether you need strength and durability, aesthetic appeal, or precision filtering, there’s an expanded metal mesh type that fits your requirements. Understanding the different types and their applications can help you make an informed decision for your next project.
Feel free to reach out with any questions or for personalized advice on choosing the right expanded metal mesh for your needs. Happy designing and building!
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