Types Of Expanded Metal & Their Uses

04 Jun.,2025

 

Types Of Expanded Metal & Their Uses

Expanded metal would most likely be the right product choice for your next project due to its strength and durability. It outranks its competitors, like chicken wire, as it is cost-effective and comes in multiple sizes and weights.

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Examples of metals used to make expanded metal include aluminum, stainless and galvanized steel, copper, and titanium. There are several types of expanded metal. Each type is made in different ways that provide various functions. Let’s figure out which one suits your needs the best.

What Is Expanded Metal?

The process of creating expanded metal was first developed and copyrighted in the s in Hartlepool, UK. Despite advancements in technology, the modern process of expanding metal remains similar to the original technique.

Expanded metal is a metal produced from a solid metal sheet. Stainless steel, aluminum, steel, titanium, and copper sheets are used. The sheet goes through a process of cutting and stretching using industrial machinery. Stretching and cutting result in a mesh with diamond-shaped spaces. Many other patterns can also be created.

The ratio of open to closed mesh area specifies the amount of space for the passage of light, air, and water. The ratio can be changed according to the mesh usage. As the process starts with a small sheet of steel and results in the production of a large mesh, it is lightweight and cost-effective, making it the best pocket-friendly option to choose among others.

The versatility of expanded metal widens the opportunity for usage. It can be used for a variety of applications. While still allowing airflow and light in, expanded metal is very strong and durable.

The diamond shape does the best at absorbing energy and deforms the least after being installed. Other design variants consider the size and angles of the shapes and how well they can absorb energy.

How Is Expanded Metal Made?

The manufacturing of expanded metal begins with a metal sheet. The sheet is cut and stretched. This procedure expands the cuts uniformly into diamond-shaped openings. There is no metal wastage during the expanding procedure, making expanded metal a green product. As mentioned, expanded metal comes from a single sheet of any metal. An industrial cutting machine moves back and forth to cut the sheet in alternating cuts for a specific shape. Several different knife patterns can be used to cut the sheet into different shapes and sizes. The purpose of creating expanded metal is to stretch it. You only need a small piece of metal for this process.

Expanded metal machines have various functions. Sometimes the process requires multiple machines. The standard method is to expand the metal sheet in a press that creates the diamond-shaped voids. Then, a flattening machine is used to flatten out the metal, followed by a shearing and slitting machine which cuts and creates the holes. This process can vary based on the available resources.

Different Types of Expanded Metal

There are 4 main types of expanded metals: standard expanded metal, flattened expanded metal, expanded metal mesh, and expanded metal grating. They all start as a metal sheet but evolve into their respective types.

  • Standard Expanded Metal

Standard expanded metal is created by entering a metal sheet in a machine press that cuts and stretches metal. Through this process, overlapping strips of a diamond pattern are created. This pattern permits air circulation, but it does not let the metal lose its strength and durability. In contrast to other types, standard expanded metal turns into a finished product as soon as it is made in the press. Expanded metal can be produced in various sizes and weights and these can be used when making lockers, warehouse fencing and machinery safety doors.

  • Flattened Expanded Metal

Flattened expanded metal is about 5% lighter than the standard expanded metal. After the standard process is used to make standard expanded metal, another step is involved, which creates flattened expanded metal. After exiting the machine the cold rolling press is used to flatten it. This step of the process helps to make the metal mesh flatter, thinner, and longer. Flattened expanded metal is perfect for fences, ventilation, cages and flooring. The slip-resistant coating is perfect for constructing walkways or stairways, allowing pedestrians a durable surface with a great grip.

  • Expanded Metal Mesh

The expanded metal mesh comes in various shapes and sizes. It ranges from delicate mesh to stronger ones. It is made by using a single sheet of solid metal that is compressed and stretched. Ornamental and constructive products are made using expanded metal mesh such as dividing screens, fences, and aerated storage systems.

  • Expanded Metal Grating

Low carbon steel plates are created using this type. They are heavier than ordinary ones. These are used for areas where durability is necessary such as walkways, stairs or main pedestrian zones. Expanded metal grating products have a terrific strength-to-weight ratio. They are also naturally slip-proof and do not require a nonslip coating as the slitting and stretching of metal plates result in a non-slip surface. This type proves to be one of the most economical and strong materials.

Raised vs Flat Expanded Metal

There are 3,500 different types and grades of steel on the market today, but this article will focus on two types: raised metal, and flat expanded metal.

Both types of metal have their pros and cons, so it is important to learn about what each brings to the table so that you choose the right type for your project:

Raised Expanded Metal

Raised metal, also known as standard metal, is a steel product used for anything from fences to grates. It’s called standard metal because its final form is exactly how it is when it leaves the expanding press.

The strands on raised metal have horizontal angles. making a less smooth surface. The characteristics of each sheet are customizable depending on the pattern size and the amount of expansion applied. Despite the customizable size and thickness of the sheet, the holes and the strands around them are uniform in size and thickness.

Some of the primary applications of raised metal are fences, walkways, and grates. The reason that raised metal is coveted for these purposes is because it is durable and strong. The small openings also allow for air, liquid, and light to pass through. It acts as a strainer by allowing those things to pass through while stopping large objects.

Some other standard uses for the raised expanded metal are for use in lockers as walls and doors to close off areas of warehouses.

Pros and Cons

Raised metal is structurally stronger than other types of expanded metal. The strands distribute a load of weight more evenly, allowing the expanded metal to support more weight than flat expanded metal can.

Additionally, because of the angled strands, raised expanded metal provides more grip and makes them skid-resistant for anyone walking on them. This makes them a great option for walkways. Because they come from steel, raised expanded metal is very durable and will last a long time. This means it will save you money because you won’t need to pay for repairs or a replacement for 40 or more years.

Some cons of raised expanded metal are that it is not as aesthetically pleasing as flat expanded metal. It is also heavier and denser, which can cost you more to have it delivered.

Flat Expanded Metal

Flat expanded metal is made the same way that raised expanded metal is, with one difference in the process. After exiting the press it is milled to make a smooth and flat surface. By removing the ridges of standard or raised expanded metal gives the expanded metal a much sleeker appearance.

Compared to raised expanded metal, flat expanded metal is thinner and flatter. It is most useful where abrasion isn’t as important and aesthetics are more valuable. Removing the ridges also makes flat expanded metal weigh less than raised expanded metal. It also has a finished surface to make it look even more aesthetically pleasing.

Some typical uses of flat expanded metal are fencing, use for enclosures and safety areas, and even walkways on billboards. It can also make great railings, gates, paths, and grates.

Pros and Cons

The big pro of flat expanded metal is that it weighs less. Because it weighs less, it costs less to transport and manufacture. It can save you money by opting to go with flat expanded metal.

Its distinctive finish also sets it apart from raised expanded metal. If the grip is less important than appearance for what you need the expanded metal for, flat expanded metal will be a better fit for you.

Similar to raised expanded metal, flat expanded metal is great for letting light, air, and water through it while still presenting a barrier to larger objects. It is also a very strong and durable material for whatever application you are using it for. Corrosion won’t be an issue either since it is made from stainless steel and coated to protect it from the elements.

Some cons of flat expanded metal are that you don’t have as good of a grip in wet conditions if it is used as a walkway. It also isn’t as strong as raised expanded metal due to being flattened out and stretched.

Ultimately, flat expanded metal looks much nicer and is less expensive but it isn’t as utilitarian as the raised expanded metal alternative.

Uses of Expanded Metal

Expanded metal is used in projects involving architecture, agriculture, horticulture, transportation, and art installation. The metal allows for flexible designs while also being very sturdy and durable. Due to great variations in size and dimension, its uses are endless.

Sizes of expanded metal depend on the company you purchase it from. Overall, it is generally used as a barrier for lighter objects.

Benefits of Expanded Metal

Expanded metals have hundreds of uses and there are many advantages of this type of metal. Some are described below:

  • An advantage of expanded metal is that it is environmentally friendly and is considered a green product. The process through which expanded metal is created, from raw product to end product, there is very little waste (scrap metal), making it a cost-effective solution.
  • The material is recyclable and less expensive than metal sheets.
  • Expanded metal permits air, fluid or light to flow through so you can protect an area without closing it off entirely.
  • Due to its diamond-shaped openings, air, water, fluid, and dirt can easily pass across to maintain a safe slip-resistant surface.
  • It is made using a wide variety of steel and other metals. It can be used as per your needs such as small battery cells and heavy-duty shelves.
  • Since expanded metal is made by using steel, its strength and flexibility are matchless. It has an extremely high strength-to-weight ratio, making it durable. It can endure a lot of weight.
  • There are many diverse options. You can get it cut to the shape and size according to your needs, especially when you buy it from Bushwick Metals.

Expanded Metal Products

Each type of extended metal can be used to make different products. Common products made by using expanded metals are:

  • Air or fluid filters
  • Radar antennas
  • Battery cells
  • Speaker covers
  • Ventilation systems
  • Satellite antennas
  • Benches
  • Outdoor grills
  • Securing walls
  • Fences
  • Ceilings
  • Protective appliance covers (an air conditioning unit is covered by expanded metals)
  • Reinforcing concrete
  • Basement window well covers
  • Stairs and walkways, especially in industrial settings
  • Benches
  • Heavy-duty shelves

Find the Best Expanded Metal Near You

Take time to consider the components of what you are constructing and how the benefits of expanded metal will work to your advantage. One of the good things about expanded metal is that it is used for projects ranging from small developments around the house to massive construction sites.

Bushwick Metals takes pride in staying committed to providing quality services to its customers. Our company has 3 major goals:

  • To source only the first-rate structural steel and plate products from every part of the world. We aim to provide the most extensive range of steel products to our customers.
  • To create a warehouse with an extensive inventory of steel structural plates and ornamental products to make sure we deliver them to customers within a day. We aim to help customers avoid warehousing fees, allowing them more efficient management of their production schedules and material costs.
  • We strive to provide steel-processing services to help our customers meet strict deadlines and decrease their basic equipment investments.

We contribute to your workload by producing the optimal products and managing your costs. All you need to do is figure out what your project needs and put your plan into action. We will do the rest. Head over to our products section to see the selection of services we offer. Don’t let any project hold you back anymore. We have the expanded metal and it is ready for your use.

We are proud to have the power of Triple-S Steel and have been making structural steel products for more than 100 years. We have 5 locations, some of which include carbon service centers.

Expanded Metal: Types, Applications and Advantages - IQS Directory

Expanded Metal: Types, Applications and Advantages

Chapter 1: What is Expanded Metal?

Expanded metals are sheets of metal that have been stretched to create a pattern of openings or gaps with diamond, square, or hexagonal shapes. It is a form of sheet metal mesh produced by elongating a slitted sheet of ductile metal. The slits are placed perpendicular to the direction of stretching, creating a mesh composed of multiple holes from the slitted sections.


The concept behind expanded metal is grounded in the natural tendency of metals to expand and contract when exposed to varying conditions. This tendency is governed by the metal's atomic structure and inherent chemical properties, leading to the formation of expanded metal.

Chapter 2: Expanded Metal Material Types

Technically, all malleable metals can be expanded. However, many of them cannot be viably expanded at an industrial scale.

Copper Expanded Metal

Traditionally, copper is not the first-choice structural material, that is, if the considerations are purely structural. Also, copper is relatively more costly, especially when rated per unit volume. Volume is a particularly important parameter since it influences the eventual dimensions of the expanded metal sheet. Copper’s high specific weight counts as a demerit where weight is of concern, such as in rigging.


The usage of copper comes when there are more aspects of significant concern other than structural concerns. Such include:

  • Corrosion resistance – Copper is known for its excellent corrosion resistance. It forms a protective oxide layer on its surface that prevents further corrosion. This property makes copper expanded metal suitable for outdoor and marine applications where exposure to moisture and other corrosive elements is a concern.
  • Electrical conductivity – Copper is one of the best conductors of electricity among all metals. This high electrical conductivity makes copper expanded metal ideal for applications where electrical conductivity is required. It is commonly used in electrical and electronic components, as well as in RF shielding.
  • Appearance – Copper has a distinctive reddish-brown color that gives it a unique and attractive appearance. Copper expanded metal can be used for architectural purposes, decorative elements, and interior design, where aesthetics play a crucial role.
  • Malleability – Copper is a highly malleable metal, meaning it can be easily shaped and formed into various patterns, designs, and configurations. This property is advantageous when creating intricate or custom expanded metal designs, allowing for versatility in applications.

Expanded Aluminium

Aluminum has a wide range of structural applications due to its strength and lightweight nature. It is an effective conductor, which is why it's often used in overhead power lines.

The malleability of aluminum makes it easier to work than cold steel. Aluminum’s resistance to corrosion is one of the main reasons for its wide use. Its high melting point and thermal reflectivity makes it well-suited for high-temperature applications.


Expanded aluminum mesh is valued for industrial and architectural uses and has optimal balance, durability, and low weight. Aside from its high resistance to corrosion, aluminum has an excellent strength to weight ratio.

  • Lightweight and Structurally Strong – aluminum expanded metal creates lightweight yet rigid grating and mesh panels, making it ideal for walkways, partitions, fences, and security panels in commercial and industrial buildings.
  • Corrosion Resistance – the natural oxide layer on aluminum offers superb resistance to oxidation and rust, suitable for both outdoor and humid indoor environments.
  • Versatility – available in various mesh patterns, thicknesses, and finishes, aluminum expanded metal provides flexible design options for architectural screen panels, sunshades, enclosures, and ventilation grilles.
  • Sustainability – aluminum is fully recyclable, making it a preferred material for projects prioritizing green building standards and eco-friendly manufacturing.

Aluminum’s combination of strength-to-weight ratio, corrosion resistance, and adaptability makes aluminum mesh a top choice for construction, transportation, filtration, and electrical components industries.

Expanded Steel

Steel is the most widely used structural metal, known for its exceptional strength, compared to other metals, provided it remains free from corrosion. Expanded metal sheet is highly versatile, which makes it ideal for applications involving security, heavy-duty fencing, industrial flooring, machine guards, and architectural facades. There are many grades and types of steel, a factor that makes steel adaptable to a wide range of applications.

Expanded Mild Steel

Mild steel is a robust and economical solution for a wide range of expanded metal applications. It is hot dipped in molten zinc to galvanize it, which increases its strength and resistance to corrosion. Although it is a durable metal without galvanization, it is susceptible to rust and corrosion. Galvanization makes expanded mild steel stronger, corrosion resistant, and a cost-effective solution for the manufacture of fencing, grating, catwalks, platforms, and non-slip walkways in warehouses and factories.


Grating Metal Sheet

Grating metal sheets are made from various materials, including mild steel, stainless steel, and aluminum. They are designed with a grating pattern for strength and load bearing. Grating metal sheets are commonly used in applications where strength and the passage of air, light, or liquids are required, such as platforms, catwalks, stair treads, and drainage covers.

Typically made from mild steel, grating metal sheets are made from higher gauge steels. They are used in heavy-duty settings, including industrial flooring, security panels, and machine platforms requiring high load-bearing capacity and slip resistance. Grating metal sheets are often chosen as an alternative to welded grating due to their enhanced strength and weight distribution.

Stainless Steel Expanded Metal

Stainless steel is resistant to corrosion and capable of enduring high-temperature environments. Stainless steel expanded metal is used in applications that require superior cleanliness and resilience, such as food processing, pharmaceutical plants, architectural cladding, and chemical filtration systems. Expanded stainless steel is widely used across several industrial sectors.

For more copper expanded metal meshinformation, please contact us. We will provide professional answers.

  • Excellent Durability – With high tensile strength and resistance to impact, stainless steel expanded metal is ideal for security applications, industrial partitions, and protective barriers.
  • Low Maintenance – Its inherent resistance to staining and corrosion means less upkeep, providing cost savings over the life of the installation.
  • Heat and Chemical Resistance – Suitable for extreme temperature ranges, caustic environments, and outdoor use without significant degradation.

Although stainless steel, carbon steel, aluminum, and copper are mostly used for producing expanded metal, under special circumstances that require more robust metals, titanium, nickel, and various alloys are used. Each of these metals has high strength, resistance to high temperatures, and resistance to corrosion.

The initial steps in the manufacture of expanded metal is in regard to the type of metal. Expanded metals enhance structures and provide features and performance that meet or exceed expectations. To achieve the proper results for a project using expanded metals, it is highly recommended to seek the assistance of an expanded metal manufacturer.

Choosing the proper material for expanded metal panels, mesh, or grids depends on the application for which it will be used. Load-bearing capacity and environmental conditions, visibility, use for security, and decorative accents are some of the factors to be considered when choosing the right expanded metal. To ensure the best value, consult with a manufacturer to evaluate each metal's properties in the context of their performance and budget constraints, since certain resilient metals can be very costly.

Chapter 3: Manufacturing Process of Expanded Metal

The machines that produce expanded metal turn solid metal sheets and coils into expanded metal. The knife on the expanding machine determines the pattern that will be placed on the expanded metal as the metal is fed into the machine. Depending on the application for which the metal will be used, different thicknesses of metals are used and different patterns are chosen. Long way diamond (LWD) and short way diamond (SWD) are used as indicators regarding the desired length, width, and shape of the expanded metal holes.


Sheet Metal Selection

The first step in the manufacturing of expanded metals is to select a material, which can be steel, aluminum, stainless steel, or other metals. The choice of material depends on the intended application, the desired characteristics of the expanded metal, the necessary tensile strength, and its environment.


Properties of Metals to Consider When Selecting Metals

  • Rigidity/Stiffness: The rigidity or stiffness of sheet metal is crucial for many applications, especially when it needs to support loads or maintain its shape under stress. Thicker and harder materials tend to be more rigid.
  • Corrosion Resistance: Depending on the environment and application, you may need sheet metal that is resistant to corrosion. Materials like stainless steel and aluminum are known for their corrosion resistance.
  • Strength: The strength of sheet metal determines its ability to withstand loads and forces without deformation or failure. Different alloys and thicknesses will have varying levels of strength.
  • Appearance/Aesthetic: In some applications, the appearance of the sheet metal is important, such as architectural or decorative uses. Factors like surface finish and color can be critical.
  • Specific Weight/Density: The specific weight or density of the material affects its overall weight and the ease with which it can be handled. Lightweight materials may be preferred in certain applications.
  • Toughness: Toughness refers to a material's ability to absorb energy and resist fracture or cracking. It's important in applications where the sheet metal may experience impacts or high levels of stress.
  • Flexibility: For applications that require bending or forming, the flexibility of the sheet metal is crucial. Some materials are more ductile and easier to shape than others.
  • Elasticity: Elasticity is the ability of a material to return to its original shape after deformation. Sheet metal that retains its shape after bending or stretching is preferred in certain applications.

Dimensions of Metal Sheets

  • The total area covered by the metal sheet before expansion
  • The thickness of the metal sheet before expansion
  • The flatness and squaring
  • Size of each cut, hence the size of each hole
  • Mesh dimensions

  • Considerations for Diamond Patterns
    • Long way of diamond – the larger diagonal. The long way of diamond is the dimension along which rows are defined.
    • Short way of diamond – the shorter diagonal. The short way of diamond is the dimension along which the die moves when stretching a piece of metal.
    • The long way of diamond and the short way of diamond become equal when a square mesh is being produced.
    • Long way of opening – the larger diagonal of the opening
    • Short way of opening – the smaller diagonal of the opening
  • Extent of flattening and leveling
  • Area to be covered after expansion
  • Thickness after expansion
  • Distance between the cuts in regard to the thickness of the strands. This is controlled by controlling the speed of the feed during the cutting and stretching process during expansion.
  • Before expansion, the metal sheet is cut to size. The cutting is often done with an automatic guillotine. The desired pattern determines the size of the expanded metal sheet.

Cutting and Stretching Metal

The metal sheet or coil is fed into the expanding machine and performs precision cuts and stretches the metal in a single operation. It is then sheared and stretched to achieve the pattern with uniform openings. Metal sheets can be expanded up to ten times their original width, which makes the final product lighter and stronger than its original shape. In some instances, cutting and stretching is achieved using two separate processes.

A die is used that defines the pattern half a row for the entire width of the sheet. The metal sheet is placed flashing with the inner edge of the die, which also flashes with the platform upon which the sheet rests. The feed for the process is equal to the desired thickness of each strand. As the die punctures the sheet, cutting and stretching are complete all at once.


If the shapes on the expanded sheet metal are all the same size and shape, the same die is used for the entire expansion.

  • The die moves sideways the distance equal to the maximum dimension of each shape along that axis.
  • The sheet is fed again.
  • The die comes back down, cutting and stretching the second half of the first row, simultaneously cutting the first half of the second row.
  • The next cut and stretch complete the second row, simultaneously cutting the first half of the third row, and so on.

If the shapes are different, different, complementing dies are used, which alternate in descending order to create the shapes. The manner of the cutting and feeding gives expanded metal sheets a raised, ridged surface. Expanded metal with a raised surface is referred to as standard expanded metal.


Coolants and lubricants used by the presses during the expanding process remain on the surface of the expanded material. They may be left there, especially for expanded metal that is not intended to have any other finishing done post expansion and flattening. The remaining lubricants and coolants may protect the expanded metal from corrosion. In addition, they may be beneficial during finishing or when appearance is important. As with all metal working processes, coolants and lubricants can be removed using solvents, detergents, and various chemicals.

Expanded Metal Patterns

Diamond pattern – this is the most common shape for expanded metal sheets.

Hexagonal pattern – is a geometrical extension of the diamond achieved by elongating the bond along the plane that is perpendicular to the direction of the feed. Compared to the diamond shape, the hexagonal shape is more difficult to execute bond shearing on.

Square pattern – a variation of the diamond shape where the diagonals are equal.

Louvered – the metal is pressed to give a louvered finish. It is a type of opening that has the least expansion and increases the outer dimensions of the metal sheet.

Decorative – combine the strength and functionality with style and appearance. They are produced by precision application of stretching and cutting to create intricate and appealing patterns.

Custom – are patterns that are designed by expanded metal manufacturers to meet specific requirements or the designs of their clients to provide style and practicality, much like decorative patterns.


How Patterns are Chosen

There are specific factors to consider when choosing an expanded metal pattern. In most cases, expanded metal manufacturers provide alternatives with detailed information regarding the nature, use, appearance, and viability of a pattern.

  • Purpose – Expanded metals serve several purposes including structural support, decoration, security, or ventilation. The choice of purpose affects the type of material to be used since the durabilities of metals varies between supportive functions and decorative ones.
  • Material – The choice of pattern also varies in accordance with the type of metal. Copper, aluminum, or stainless steel can be decorative and supportive while carbon steel, mild steel, and hardened steel are stronger and supportive.
  • Open Area – The percentage of open space in a pattern affects airflow, light exposure, and the weight of expanded metal.
  • Strength Requirements – During the manufacture of expanded metal, the metal is flattened and leveled to remove raised surfaces. Some applications require a raised pattern for load bearing purposes. Flattened and level patterns are more suited for aesthetic and appearance purposes.

Strand Thickness

For any die pattern, the thickness of the strands influences the percentage of open spaces on expanded metal sheets. The strand thickness determines the eventual ratio of the area of the expanded metal sheet to that of the solid sheet from which it was formed.

Strand thickness is determined by the feed rate. Higher feed rates yield expanded metal sheets with a smaller percentage of open spaces. Sheets can have sections with varying strand thicknesses, which is achieved by adjusting the feed rate.

Flattening Process

Flattening expanded metals gives them a flat, even surface finish. During cutting and stretching, a ridged or rippled finish is created, known as a raised surface. The presence of raised surfaces is desirable in some cases but not all. In cases where a smooth finish is needed, flattening is applied.

Expanded material that is not flattened is referred to as standard expanded metal. Flattening is achieved by cold rolling the finished expanded metal. Compression from cold rolling thins and flattens expanded metals. As the cold rolled expanded metal sheet gets thinner, it gets longer along the direction of movement of the sheet through the rollers.


Lengthening of expanded sheet metal stretches its openings along the direction of lengthening. Openings become elongated, or widened, compared to the standard expanded equivalent sheets.

Metal Leveling

The purpose of flattening is to remove ridges on the surface of the expanded metal. Leveling is to ensure that the sheets are level when placed on flat and level surfaces. Flattening flattens the surface, while leveling flattens the entire sheet. Leveling is concerned with the three-dimensional geometry of expanded metals. It is a measure of how well corresponding points in different rows fit on the same plane. A level expanded metal sheet is free from waves and buckles. If eliminating waves and buckles is impractical to achieve consistently, tolerances are set to determine what is acceptable.

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Chapter 4: Surface Finishing for Expanded Metal

Finishing processes for expanded metal serve several purposes from enhancing the properties of the sheets to improving their appearance to comply with application requirements. Many of the finishing methods associated with expanded metals are the same as those associated with other metal working processes. They include cleaning, anodizing, painting, lacquering, and galvanizing. In some cases, finishing is designed to protect expanded metals from the conditions in which they will be used.

Finishing Through Painting

Painting is the most economical and cost-effective way to finish the expanded metal sheet. The paint is applied to improve appearance or for corrosion protection. For the latter, the paint is applied evenly to ensure complete coverage of the metal. Small gaps allow corrosion and rust to appear. Of the coatings listed, painting is the least expensive, is the least protective, and requires regular reapplication.


Powder Coating

Powder coating has similar results as those of painting. The process is more durable than painting. A spray gun is used to apply the powder evenly onto the metal sheets. To attract the powder to the surface of the expanded metal, it is electrically charged to create electrostatic powder. The use of electrostatic powder coatings ensure an even and complete coverage of the surface of the expanded metal. After the application of the powder, the expanded metal is heated, which melts the powder coating. During cooling, the coating forms a tight bond with the expanded metal sheet.

Galvanizing Process

Galvanizing involves submerging the expanded metal sheet into molten zinc. This gives it a coating of zinc. Such coating protects the mesh from corrosion. Given the temperatures at which this process is feasible, it gives a limit to the dimensions of expanded metal that can be galvanized. Very fine meshes cannot be galvanized for this reason.

Anodizing Process

This is an electroplating process. The name anodizing denotes the polarity of the expanded sheet metal (to be coated) during electrolysis. The sheet metal is coated at a much more granular level than with the rest of the coating techniques. Also, the bonding of the coating to the sheet metal is better than other methods. The process is fairly costly over and above the cost of the plating material. The apparent unpopularity of this method emanates from its cost implication.

Anodizing is usually common with iron-based metals (which are prone to corrosion). This process circumvents some of the dimension limits that arise from the galvanizing process since it can be carried out at much lower temperatures.

Shearing of Expanded Metal

Shearing cuts the expanded sheet to size. This is the process used to attain smaller expanded metal sheets from a larger sheet or reduce the size of a given sheet and/or alter its shape. The shearing is done with shears. Shears are a set of metal blades or some mechanism such that the blades come together, like scissors. The shears can be manual or mechanized. When the blades come together on an expanded metal sheet, they exert enough shear forces to tear the expanded metal apart.

Side Shearing

Side shearing is a common shearing process where the edges of the expanded metal sheet are trimmed or cut to achieve the desired width or length. This type of shearing helps to create straight and even sides on the expanded metal sheet.

Bond Shearing

Bond shearing involves cutting the connecting strands or bonds between the raised diamond-shaped or hexagonal openings in the expanded metal. This process can be used to create custom patterns or designs within the expanded metal sheet while maintaining its structural integrity.


Raised expanded metal should be bond sheared along the bonds between rows.

Random Shearing

Random shearing does not necessarily cut along shape edges. It, therefore, leaves open shapes and irregular patterns at the edges. This process leaves out spiked strands that can be sharp and piercing. It follows that random sheared expanded metal should have U-edging to facilitate better handling. Framing can also be done as an alternative to U-edging.

U-edging is the use of a U-shaped strip of metal to cover the edge of a sheet of expanded metal.

Centerline Shearing

Centerline shearing is a shearing process that cuts an expanded metal sheet along its centerline. This is used when you need two identical pieces from a single sheet, especially for symmetrical applications.

Balance Shearing

Balance shearing involves cutting the expanded metal sheet so that equal amounts are removed from each side or edge. This method is often used to maintain the balance of the expanded metal pattern and is essential in applications where symmetry is critical.

End Shearing

End shearing refers to cutting the expanded metal sheet from one end to the other, essentially shortening it. This is commonly used to achieve specific lengths or to prepare expanded metal sheets for further processing, such as rolling or bending.

Random Shearing

This is cutting across strands at points other than the bonds.

Chapter 5: Quality Factors for Expanded Metal

The wide use of expanded metals is related to their quality, which involves several factors. Although the form of expanded metals has been altered, they are still metals that have the same constraints as all other metals. In addition, the expanded metal process is similar to stamping. The outcome of metal expanding and stamping produces imperfections that have to be removed to improve the quality of the final product. Common factors such as burrs, broken strands, laminations, welded strands, and slivers have to be removed as part of the finishing process.

Tolerances in Expanded Metal

A characteristic of all metal products is their tolerances. During finishing, tolerances are adjusted to meet the parameters of the original design. With expanded metal, tolerances are adjusted using various methods

Tolerance Check

  • Bow - The center section can bow up to 0.5 mm measured from a straight line between the ends of the panel.
  • Straightness - Surfaces or edges can deviate up to 0.5 mm from a mm straightedge placed parallel to the long axis of the panel.
  • Flatness - As with bow, surfaces can deviate up to 0.5 mm from a straightedge placed against it in any direction.
  • Twist - Twisting must be less than 0.5° from any section on either end of the metal sheet.
  • Finished - Metal surfaces shall be flat and free from undulations and irregularities.
  • Warping - Tolerances should be ±1.5 mm to avoid any warping of the metal.

Camper Curve

Camper curve is the bow or curve in the expanded metal sheet, which may be inconsequential if the sheets are to be rolled for packaging. It is undesirable for applications that require more planar material. This is especially the case if higher rigidity is required, which would leave residual stresses on a structure.

Producing expanded sheet metal with no camper is rare. If the camper falls outside the required tolerance, corrective measures are necessary. If not, the material can be used as is.


Camper curves form along the edge in the direction of the feed during the cutting and stretching phase of the expanding process. Flattening, which involves rolling, removes or reduces camper curves, along with waves and buckles, resulting in an even flat surface.

Squareness Property

The squareness property refers to having a rectangular or square shape, characterized by 90° angles and straight edges with equal diagonals. It is a planar characteristic, applicable to a single plane viewed from above when the expanded metal is laid flat. Expanded sheets can be square without meeting all other spatial and geometric requirements, such as being level. Conversely, issues like camper and buckles can affect the squareness of an expanded metal sheet.

Deviations from squareness stems from the initial metal sheet, which is rarely perfectly square despite tight production tolerances or from defects in the die used. Re-squaring is achieved by random shearing along specific lines. Border shearing does not correct squareness since stretching the shorter diagonal results in non-straight edges.

Parallel Sides

Parallel sides are required, especially if the metal sheets used to expand have parallel opposite sides. Sheets that are perfectly square will always have parallel sides, but sheets with parallel sides are not always square. Metal sheets without parallel sides are never square, which may be caused by campers.

In some applications, expanded metal is produced with non-parallel sides. A die with varying "tooth" sizes across the sheet's width will create this effect from a square solid sheet.

Taper Sides

Taper sides are a deviation away from the edges of an expanded metal sheet being parallel and is a descriptor for the degree to which sheets vary from being straight or parallel. Flattening can cause taper sides. A rule of them, after a expanded metal is flattened, it should deviate from parallel by less than an eighth of an inch per foot.

Expanded Metal Customization

Often, expanded metal sheets require additional processing after they come out of the expanding machine. This can include cutting, bending, welding, bracing, and other modifications. Such customization work is not usually part of the standard production process due to the unique requirements of each project. Some applications may require different gauges of expanded metal that complement each other.

Customization involves expanded metal sheet modifications performed based on customer requirements and specifications.

  • Shearing to fit specific dimensions
  • Shearing to frame shapes
  • Shearing to produce a tear or cut without removing any material or isolating any pieces of the original expanded sheet metal
  • Bending the sheets
  • Joining sheets together
  • Rolling to specific curvatures, including affecting various curvatures on the same sheet

Chapter 6: Applications and Advantages of Expanded Metal

Since the introduction of expanded metal during the first industrial revolution, it has become an essential part of construction, architecture, and industrial applications. The uses for expanded metals are ever growing due to their ability to be both visually appealing and structurally sound. In addition to these two primary functions, expanded metals have become part of environmental concerns in regard to their ability to protect buildings from direct sunlight.

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Expanded Metal Applications

  • Security Fencing: Expanded metal is often used for security fencing in commercial and industrial settings. Its design allows for visibility while providing a strong barrier, making it suitable for prisons, airports, and other secure facilities.
  • Walkways and Catwalks: Expanded metal is used to create non-slip walkways, platforms, and catwalks. Its open design ensures that dirt, debris, and water can pass through, reducing the risk of slipping.
  • Gratings and Flooring: Expanded metal is used as grating for flooring in industrial and commercial buildings, providing support and ventilation. It is commonly seen in mezzanines, stair treads, and industrial work areas.
  • Filters and Screens: The material is used as screens and filters in various industries, including HVAC systems, agriculture, and automotive. The open structure allows for airflow while providing a barrier to particles.
  • Decorative Mesh: Expanded metal can be employed for decorative purposes in architectural applications. It is used in interior and exterior design elements, such as wall cladding, balustrades, and facades.
  • Vehicular Grilles: In automotive and construction equipment, expanded metal is used in grilles for ventilation and protection. It can be found in radiator grilles, engine covers, and HVAC systems.
  • Acoustic Panels: Expanded metal can be used in the construction of acoustic panels and sound barriers. Its perforated surface helps absorb and diffuse sound waves.
  • Battery Grids: In the manufacturing of batteries, particularly lead-acid batteries, expanded metal is used to create the grid structures that hold the active materials and facilitate the flow of electricity.
  • Shelving and Racks: In storage systems and warehouses, expanded metal is used for shelving, racks, and storage units due to its strength and durability.
  • Safety and Machine Guards: Expanded metal is used to create safety guards for machines and equipment in industrial settings, ensuring worker safety by providing visibility and protection.
  • Ventilation Grilles: It's employed as ventilation grilles in HVAC systems, enabling airflow while preventing the entry of debris or pests.
  • Sunshades and Awnings: In architecture, expanded metal can be used for sunshades and awnings. Its pattern allows light to pass through while providing shade.
  • Cages and Enclosures: Expanded metal is used in the construction of animal cages, safety enclosures, and storage lockers due to its durability and visibility.
  • Exterior Cladding: In some cases, expanded metal is used as an exterior cladding material for buildings, offering a unique and modern aesthetic.
  • Speaker Grilles: Expanded metal is used as speaker grilles in audio equipment and sound systems due to its durability and acoustic properties.

Advantages of Expanded Metal

  • Lightweight: Expanded metal is typically lightweight, making it easy to handle and transport. This characteristic is especially useful in applications where weight is a concern.
  • Strength and Rigidity: Despite its lightweight nature, expanded metal is strong and rigid. It offers structural integrity and can withstand various loads, making it suitable for applications where durability is important.
  • Versatility: Expanded metal can be easily customized to meet specific requirements. It is available in various materials, opening sizes, and thicknesses, allowing it to adapt to a wide range of applications.
  • Cost-Effective: Expanded metal is cost-effective when compared to other materials like perforated metal or solid sheets. Its efficient use of material and manufacturing process makes it an economical choice.
  • Ventilation and Visibility: The unique design of expanded metal provides excellent ventilation and visibility. This is valuable in applications where airflow and the ability to see through the material are essential, such as in security screens or grilles.
  • Anti-Slip Properties: The raised, diamond-shaped or hexagonal patterns on the surface of expanded metal can provide anti-slip properties, making it a safe choice for walkways, stair treads, and flooring in various environments.
  • Sound and Noise Reduction: Expanded metal can help dampen sound and reduce noise levels. It is often used in acoustic panels, barriers, and enclosures.
  • Security and Safety: In security applications, expanded metal provides a strong barrier without obstructing visibility. It is commonly used in fences, gates, and security screens.
  • Filtration and Separation: Expanded metal is used in filtration systems to separate particles or substances from a fluid or gas stream due to its customizable opening sizes.
  • Aesthetics: Expanded metal can be used in architectural and decorative applications. It can create visually appealing patterns and textures, and it can be finished in various colors and coatings to enhance its appearance.
  • Low Maintenance: Expanded metal is relatively low maintenance, as it is resistant to corrosion and can withstand harsh environmental conditions. This makes it suitable for outdoor applications.
  • Eco-Friendly: Expanded metal is a sustainable material as it efficiently uses raw materials, reducing waste. It is also recyclable, contributing to environmental sustainability.
  • Customization: Expanded metal can be tailored to meet specific design and functional requirements, including the shape and size of openings, the thickness of the material, and the type of finish.

Conclusion

  • Expanded metal provides strength, durability, and flexibility, making it a popular choice for industries ranging from architectural design to industrial filtering.
  • The open air design of expanded metal allows for excellent airflow and light penetration while providing security and structural integrity.
  • Expanded metal is made from a wide range of materials in several gauges and opening sizes, which ensures that it can meet the specific requirements of diverse applications.
  • Expanded metal makes it possible to create larger area surfaces from a solid sheet of material, requiring less metal to achieve the end result.
  • The structure of expanded metal has made it a valuable part of electricity conductivity, heat, and magnetic flux.
  • The single solid structure of expanded metal without moving parts makes care of the metal sheets easy and inexpensive.