A manufacturing facility in Ohio needed machine guarding that met OSHA requirements. While they wanted visibility and ventilation, they also required that it be a cost-effective solution. Welded wire mesh would cost 18,000 with a three-week delivery lead time. At 18,000 and with a 3−week delivery, expanded metal mesh is a 2nd option offering the same protection. Expanded metal mesh for 11,000 can also be obtained with immediate availability from stock. This scenario gave them a one-piece construction that eliminates possible weld points that might fail, while 70% open area provided for sufficient normal airflow while blocking access to dangerous rotating equipment.
Not only is this quite typical for just about any industrial facility worldwide, but potential buyers and engaged parties all require determining at a policy-making juncture whether that CHAPTER Expansion mesh surpasses welded wire mesh, woven mesh, or perforated metal. Decisively, the answer to that question starts with an understanding of the peculiar manufacturing process, structural clear merits, and apposite rotation aspects of expansion metals.
In this guide, everything you need to know about expanded metal mesh is discussed-ranging from how it is made, types of patterns and dimensions, options on materials, load capacity, and selection factors for structural, security, and architectural applications. How to select the best expanded metal for your projects? If you are engineering machine covers, security barriers, or ornamental facades-this information stands your best shot.
Explore our complete (specialty wire mesh guide) for application-specific guidance.
What Is Expanded Metal Mesh?
Definition and One-Piece Construction
Expanded metal mesh is made by slitting a metal sheet into strips and extending the strips diagonally, thereby creating a netted frame with substantially shaped opening- octagonal, square, or even round. As opposed to woven wire mesh that is comprised of individual wires interwoven or welded wire mesh where wires are conjoined at intersections, expanded metal is fabricated from a continuous single piece of material. No welding, joining, or weaving is performed during the manufacturing stage.
This one-piece construction delivers fundamental advantages. The material maintains consistent strength throughout because there are no weld points, connection joints, or weak spots. Every strand connects to every other strand through the original metal sheet’s grain structure. When force is applied, stress distributes across the entire mesh rather than concentrating at connection points.
The expansion process creates strands (the solid metal strips between openings) and bonds (the intersection points where strands meet). These bonds form natural load-bearing nodes that give expanded metal its structural integrity. The diamond pattern emerges from the geometry of the slitting and stretching process, with each opening bounded by four strands meeting at bond points.
How Expanded Metal Differs from Wire Mesh
Understanding the distinction between expanded metal and wire mesh helps buyers make informed material selections:
Manufacturing Method
- Expanded metal: Single sheet slit and stretched; one-piece construction
- Wire mesh: Individual wires woven or welded together; multi-piece construction
Structural Integrity
- Expanded metal: Continuous material with no connection points to fail
- Wire mesh: Potential failure points at welds or wire crossings
Cost Structure
- Expanded metal: 30-50% less material cost than equivalent welded mesh
- Wire mesh: Higher material and labor costs for equivalent coverage
Open Area Options
- Expanded metal: 30-80% open area depending on pattern
- Wire mesh: 20-90% open area depending on mesh count and wire diameter
Fabrication Flexibility
- Expanded metal: Can be cut, bent, and formed like sheet metal
- Wire mesh: Requires special handling to prevent unraveling (woven) or weld breakage (welded)
Need structural mesh specifications? View our (welded wire mesh applications guide)
Key Advantages and Limitations
Advantages
- Strength to weight ratio: Expanded metal pattern has more weight bearing capacity compared to flat sheet metal pound for pound due to the structural geometry of the diamond pattern
- Cost-efficiency: No material waste during manufacture (as opposed to perforation which removes material).
- Immediate Astm: Standard patterns and materials are often in stock.
- One-piece construction: No joints, welds, or connection points are present, which could give an example.
- Formability: Can easily be rolled, bent, stamped, and formed using standard sheet metal equipment.
- Slip resistance: Raised patterns provide natural walking surface traction for those walkways and standing platforms.
Limitations
- Fixed patterns: The limited scope of patterns, which are confined to the diamond and specialized geometries, as compared to the geometrical possibilities found in woven metal mesh
- Sheet size: Standard sheet sizes are available (4 x 8 ft or 5 x 10 ft) for their manufacturing.
- Poor filtration: Many openings are larger than the capability to filter below 100 microns
- Appearance: A very industrial mood may damage its acceptability in all architectural applications if left without treatment.
Standard vs Flattened Expanded Metal
Standard (Raised) Expanded Metal
Standard expanded metal leaves the strands in their original raised position after stretching. The strands angle upward from the sheet plane, creating a three-dimensional profile with enhanced structural depth. Standard expanded metal provides:
- Greater rigidity and load-bearing capacity per unit weight
- Natural skid resistance for walking surfaces
- Better air and light diffusion due to angled strand geometry
- Deeper shadow lines for architectural applications
- Typically 10-15% lower cost than flattened equivalent
Flattened Expanded Metal
After expansion, the mesh passes through flattening rollers that crush the angled strands into a single plane. Flattened expanded metal offers:
- Smooth, level surface suitable for applications requiring flatness
- Reduced overall thickness (important for space-constrained installations)
- Smoother edges that reduce snagging and improve handling safety
- Better contact surface for framing and mounting
- More uniform appearance for architectural and decorative uses
The Manufacturing Process
Sheet Metal Preparation
The whole starts with the selected flat sheet of metals in accordance with the final product’s specifications. The main metal, whether carbon steel, stainless steel, aluminum, or other metals, is received in the form of coils or flat sheets, with the thickness varying typically from 24 gauge (0.025″) up to 1/4″ plate. 16 gauge (0.060″) gauge and 14 gauge (0.075″) gauge material are common for industrial applications.
Based on the material and, in addition to the intended requirements, the sheet receives certain surface treatments. This might include degreasing or surface cleaning or may the application of some lubricants to help the expansion process. Forth with material needing post-expansion treatment (extra galvanizing), a raw metal can be developed plus then only treated by overlay of the noted zinc coating to be done after the formation.
The Expansion Process (Die Cutting and Stretching)
The main phase of expanded metal production occurs at specialized expansion presses, which perform two actions simultaneously: cutting (slitting) a metal sheet and stretching it into the open pattern.
The Slitting Mechanism
The machine’s perforated expanded metal pressing cylinder has several steel-hardened knives that are coordinated with the metal sheet in a precise herringbone pattern. Knives, leaving desirable cross-cut cuts without cutting from top to bottom in complete formation, being corrective.
The Method Raises Sheet
The metal is gripped by the machine while being stretched across the slit Acts. These slits open up, when the metal, which is partially cut, can be pulled apart, to form the diamond-shaped open-area windows. The uncut space between the self-opening area forms these strands, and the uncut vacuum points will become the bonds.
The extension determines the overall finish of the expanded metal:
- Short axis of diamond (SWD) is the distance between the bond centers that are perpendicular to the short diamond length.
- Long axis of diamond (LWD) is the distance between bond centers dealing along the longer dimension of diamond.
- Girdle: Width of the metal strip on the sides of the diamond.
Standard resin ratios create diamonds with an LWD slightly less than twice the SWD, though some tooling mechanisms could create variations.
Raised vs Flattened Finishing
After expansion, manufacturers either leave the mesh in its raised (standard) condition or process it through flattening rollers.
Standard Finishing
Raised expanded metal exits the expansion press and undergoes edge trimming to standard sheet sizes. The raised strands remain angled, providing structural depth and skid resistance. Standard mesh is ready for immediate use in applications where the dimensional profile is acceptable.
Flattening Process
Flattening occurs in a separate operation where the raised mesh passes through a series of heavy-duty rollers. These rollers progressively crush the angled strands until they lie flat in a single plane. The flattening process:
- Reduces overall thickness by approximately 50% compared to raised mesh
- Work-hardens the material slightly, increasing tensile strength
- Creates smoother edges that improve handling safety
- Produces consistent flatness for applications requiring planar surfaces
Shearing and Edge Finishing
Final processing includes cutting the expanded mesh to required dimensions. Shearing can be performed parallel to the diamond pattern or at angles, though cuts parallel to the strand direction produce cleaner edges.
Edge finishing options include:
- Raw edge: As-cut edge with standard expansion characteristics
- Flattened edge: Edge strands crushed flat for reduced sharpness
- Framed edge: U-channel or angle iron framing welded to perimeter
- Safety edge: Edge grinding or rolling for high-contact applications
Expanded Metal Patterns and Sizes
Standard Diamond Pattern
The diamond pattern dominates expanded metal production, representing approximately 85% of all expanded metal manufactured. This pattern emerges naturally from the orthogonal slitting and stretching process.
Pattern Nomenclature
Expanded metal is specified using a standardized numbering system that indicates strand width and thickness:
- #9 Expanded Metal: Strand width approximately 0.125″ (1/8″)
- #13 Expanded Metal: Strand width approximately 0.094″ (3/32″)
- #16 Expanded Metal: Strand width approximately 0.060″
- #18 Expanded Metal: Strand width approximately 0.048″
The numbering system originated from traditional gauge references and continues as an industry standard. Mesh with heavier strands (lower numbers like #3 or #6) provides greater strength; lighter strands (higher numbers like #20 or #22) offer higher open area and lower weight.
Common Diamond Sizes
| Mesh Designation | SWD (in) | LWD (in) | Strand Width (in) | Typical Open Area |
|---|---|---|---|---|
| 1/2″ #16 | 0.500 | 1.200 | 0.060 | 65% |
| 3/4″ #9 | 0.923 | 2.100 | 0.125 | 70% |
| 1″ #8 | 1.000 | 2.400 | 0.165 | 72% |
| 1-1/2″ #9 | 1.333 | 3.000 | 0.125 | 78% |
Flattened Expanded Metal
Flattened expanded metal uses the same diamond patterns as standard mesh but with strands crushed flat. The flattening process slightly elongates the diamonds, increasing both SWD and LWD by approximately 5-10% compared to the raised equivalent.
Applications for Flattened Mesh
- Architectural facades and sunscreens requiring smooth appearance
- Machine guards where personnel contact is likely
- Filtration supports needing flat contact surfaces
- Decorative applications where shadow lines should be minimized
- Applications requiring rolling or curving of the mesh
Flattened mesh provides approximately 10-15% less structural strength than equivalent raised mesh due to the work-hardening and geometry changes, but offers significant advantages in handling and appearance.
Hexagonal and Special Patterns
While diamond patterns dominate, specialized expansion tooling produces alternative geometries:
Hexagonal Expanded Metal
Created using specialized slit patterns, hexagonal expanded metal provides:
- More uniform stress distribution in all directions
- Higher open area for equivalent strength
- Distinctive appearance for architectural applications
- Better flow characteristics for some filtration applications
Square and Rectangular Patterns
These patterns emerge from modified expansion processes and offer:
- Uniform openings in two perpendicular directions
- Predictable light and air diffusion patterns
- Grid-like appearance for design applications
Micro Expanded Metal
Produced from very thin foils (down to 0.001″), micro expanded metal creates patterns with SWD as small as 0.020″. Applications include:
- Battery electrodes
- EMI/RFI shielding
- Medical devices
- Acoustic panels
Understanding SWD, LWD, and Strand Width
SWD (Short Way of Design)
The SWD measures the distance between bond centers across the short dimension of the diamond opening. This dimension determines:
- The largest particle that will pass through the opening
- Structural properties in the short direction
- Light and visibility characteristics
LWD (Long Way of Design)
The LWD measures the distance between bond centers along the long dimension of the diamond. The LWD is typically 2.0 to 2.5 times the SWD in standard patterns.
Strand Width
Strand width is the thickness of the metal strip forming the diamond edges. Strand width directly affects:
- Overall mesh strength and load capacity
- Weight per square foot
- Cost (heavier strands require more material)
- Open area percentage
Percent Open Area
The percentage of open space versus solid material determines airflow, visibility, and weight. Standard expanded metal ranges from 30% open area (heavy security mesh) to 80% open area (light screening applications).
Pattern Selection Guidelines
Selecting the appropriate expanded metal pattern requires balancing multiple factors:
For Security Applications
- Small SWD (1/2″ or less) to prevent passage of tools or limbs
- Heavy strand width (#9 or heavier) for cut resistance
- High carbon steel or alloy materials for strength
For Filtration and Screening
- SWD sized to target particle retention
- Moderate strand width for structural integrity
- Flattened mesh for surface filtration applications
For Walkways and Platforms
- Raised (standard) pattern for skid resistance
- Heavy strand width for load capacity
- SWD small enough to prevent heel penetration (typically 1/2″ or less)
For Architectural Applications
- Flattened mesh for smooth appearance
- Strand width and SWD selected for desired visibility and shadow patterns
- Material selected for weathering characteristics
Materials for Expanded Metal
Carbon Steel (Plain and Hot-Dip Galvanized)
Plain Carbon Steel
Plain Steel expanded metal would be the cheapest among other choices for trades in industries. It can practically be made employing many grades starting from mild steels of extremely low carbon to much high carbon alloys which shall provide:
- Excellent strength-cost kinds of ratios
- Ease to be welded together, thus, easy for fabrication
- Freely available in several standard patterns
- Allowable under paint or powder-coated finishes
The downsides are: constant attention in respect of corrosion unless preventive or protective coatings are employed or when applied in dry environments. Plain steel could normally be chosen for indoor use, temporary applications, or planned subsequent coatings.
Hot-dip galvanizing
The post-expansion application of hot-dip galvanizing provides optimal protection for all exterior and severe conditions. Regardless of the sector, hot-dip galvanizing applies a zinc coating of about 3 to 5 mil thick. All parts of the metal sheet-even on the internal surfaces including “tear edges”-will be coated with the zinc.
Here is the performance that galvanized expanded metal will give:
- When in assailment by harsh ambient conditions, the lifespan of the expanded metal will extend about 15 to 20 years.
- Corrosion protection of anodic origin of sacrificial corrosion (because the zinc would safeguard even within the scratched places)
- Its maintenance is lower compared to painted steel.
- It is good for industrial, agricultural, and marine uses.
ASTM F1267 establishes the coating weights for galvanized expanded metals, with G90 (0.90 oz/ft² total both sides) as a normal specification for industrial applications.
Stainless Steel Grades (304 and 316)
304 Stainless Steel
The most common stainless grade for expanded metal, 304 offers excellent corrosion resistance for general industrial and architectural applications. Composition includes 18% chromium and 8% nickel.
304 stainless expanded metal is ideal for:
- Food processing equipment
- Architectural applications in non-marine environments
- Chemical processing with mild corrosives
- Applications requiring hygiene and cleanability
- Temperatures up to 800°F continuous operation
316 Stainless Steel
316 stainless contains 2-3% molybdenum addition that provides superior resistance to chlorides and acids. This makes 316 expanded metal the choice for:
- Marine and coastal environments
- Chemical processing with aggressive media
- Pharmaceutical and biotechnology applications
- Wastewater treatment facilities
- Salt and brine exposure
316 expanded metal typically costs 25-30% more than 304 but delivers significantly longer service life in corrosive environments.
Aluminum Expanded Metal
Aluminum expanded metal offers unique advantages for weight-sensitive and architectural applications:
Advantages
- One-third the weight of steel for equivalent open area
- Excellent corrosion resistance without additional coating
- High strength-to-weight ratio
- Formability for curved or shaped installations
- Anodizable for decorative color finishes
Common Alloys
- 5052-H32: General purpose, good strength and formability
- 6061-T6: Structural applications requiring higher strength
Applications
- Green Sunsets, on the Sunset
- Vector Saaz and Vans
- Walking paths needing little weight
- Interior decoration panels and signage
- EMI/RFI shielding (with proper grounding)
Material Selection Decision Matrix
| Application Environment | Recommended Material | Expected Service Life |
|---|---|---|
| Indoor dry industrial | Plain carbon steel | 10-15 years |
| Outdoor general purpose | Hot-dip galvanized steel | 15-20 years |
| Food processing | 304 stainless steel | 20+ years |
| Marine/coastal | 316 stainless steel | 25+ years |
| Architectural/decorative | Aluminum (anodized) | 30+ years |
| High-temperature | 304/316 stainless | Varies with temperature |
| Chemical exposure | 316 stainless or specialty alloy | Application-dependent |
Structural Properties and Load Capacity
Tensile Strength and Yield Point
The mechanical characteristics are sustained in expanded metal structure and depend on material grade and configuration of filaments for its strength characteristics. The expansion process has marginally work-strengthened the material, particularly at points of bond where a certain degree of metal deformation takes place.
Steel Expanded Metal
- Yield strength: 30,000-50,000 psi (depending on base material)
- Tensile strength: 50,000-80,000 psi
- Elastic modulus: 29 x 10⁶ psi
Stainless Steel Expanded Metal
- 304 yield strength: 30,000 psi minimum (annealed), higher when work-hardened
- 316 yield strength: 30,000 psi minimum
- Tensile strength: 75,000-100,000 psi depending on condition
Aluminum Expanded Metal
- 5052-H32 yield strength: 23,000 psi
- 5052-H32 tensile strength: 33,000 psi
- Elastic modulus: 10 x 10⁶ psi
The diamond pattern creates anisotropic strength characteristics—expanded metal is stronger in the direction parallel to the LWD than across the SWD due to the geometry of load distribution through the strands.
Load Capacity by Pattern and Material
Load capacity depends on multiple variables: material strength, strand width, sheet thickness, support spacing, and load orientation. The following provides general guidance for uniformly distributed loads:
Walkway and Platform Capacity (per sq ft)
| Pattern | Material | Max Span 4′ | Max Span 6′ | Max Span 8′ |
|---|---|---|---|---|
| 3/4″ #9 | Steel | 150 lbs | 75 lbs | 40 lbs |
| 1/2″ #13 | Steel | 200 lbs | 100 lbs | 55 lbs |
| 3/4″ #9 | 304 SS | 135 lbs | 65 lbs | 35 lbs |
| 1/2″ #16 | Aluminum | 75 lbs | 35 lbs | 18 lbs |
These values include safety factors and assume proper perimeter support. Concentrated loads require additional analysis and may necessitate reduced spans or heavier patterns.
Security Barrier Impact Resistance
Heavy expanded metal patterns (#6 and heavier) provide significant forced entry resistance. Testing indicates:
- #6 carbon steel expanded metal: 15+ minute delay against hand tools
- #3 carbon steel expanded metal: 30+ minute delay against power tools
- Multi-layer configurations: Exponential increase in penetration time
Walkway and Platform Ratings
Expanded metal grating serves as economical walkways and platforms in industrial facilities. Design considerations include:
Deflection Limits
Industry standard limits deflection to 1/4″ under design load or L/200 (span divided by 200), whichever is smaller. Excessive deflection creates discomfort for personnel and potential safety hazards.
Skid Resistance
Raised expanded metal provides inherent skid resistance through the serrated edges of angled strands. Coefficient of friction testing shows raised expanded metal provides 30-40% better slip resistance than flattened mesh or smooth plate.
Heel-Proof Requirements
For areas with pedestrian traffic, SWD should not exceed 1/2″ to prevent high-heel shoes from catching in openings. This requirement is specified in many building codes for public access walkways.
Impact Resistance
The one-piece construction of expanded metal provides excellent impact resistance compared to wire mesh alternatives. Impact energy distributes across the mesh pattern rather than concentrating at connection points.
Ballistics and Forced Entry
Heavy expanded metal (3/16″ and thicker material) has been tested for security applications:
- UL 752 Level 1 handgun protection achievable with proper material thickness
- Delay ratings for forced entry correlate with material thickness and strand weight
- Multi-layer expanded metal creates effective blast and fragment protection
Primary Applications
Machine and Equipment Guarding
Expanded metal is the material of choice for OSHA-compliant machine guarding in manufacturing facilities, offering durability, unobstructed vision and airflow, and sheer in numerous applications for the protection of personnel from rotating machinery, nip points or projectiles.
In March 2005, a newly installed line in a manufacturing facility in Ohio needed machine guarding. The facility manager opted for inexpensive expanded metal as board protection. Perhaps Ryan has never heard of expanded metal material. The structure and Xsel safety ratings of 3/4″ #9 flattened creative designs which solved their problem while costing only around 11,000. It was available immediately and could be left in its unfinished beauty and still pass for dream guarding. It was so purchased and installed that it is not near as ugly as it otherwise would have been. Flexibility vanished overnight as the plant started using its guards on a daydream of erection! Simple and open fun with so many whims and giggles! Many customers even popped in to check more closer than we do. By conserving its use of material, the guards took on a life of their own and accelerated the installation of electrical cables too. This was done in two days, which is quite remarkable. The money saved and the advantage brought about during the full production was, therefore, about 7,000. The production line almost carried an additional 45,000 in terms of early production revenue since the transition was pretty fast.
Design Guidelines for Machine Guards
- Minimum #16 strand width for industrial applications
- SWD 1/2″ or smaller to prevent finger access
- 18″ minimum distance from hazard to mesh surface
- Framed edges to prevent sharp contact points
- Quick-release fasteners for maintenance access
Security Fencing and Barriers
The expanded metal security fencing provides an impediment made of facilitates climbing in critical industry, data centers, and high-risk applications. While it is possible to cut the mild steel chain-link fabric with the use of bolt cutters since it has a linking design continues, expanded metal is distinctly cut-resistant.
Security Pattern Selection
- Small mesh patterns (1/2″ SWD) prevent tool passage and climbing
- Heavy strand widths (#9 and heavier) resist cutting and breaching
- Vertical diamond orientation (LWD vertical) improves climb resistance
- Topping with barbed wire or razor ribbon for maximum security
Typical Installations
- Data center perimeter security
- Utility substation fencing
- Airport and transportation security
- Correctional facilities
- Critical infrastructure protection
Architectural Facades and Screens
The in-stock expanded metal becomes the favorite material for making diffusion screens, cages, facades, guardrails, etc. The very nature of the material makes the whole thing look good. With windows covered with screens like these, light mottled to produce an effect which is visually interesting due to continuous pattern and shadow play.
There was a need for parking garage screening for a mixed-use development in Portland, Oregon, wherein it was required that the design meet the city’s guidelines while also providing security and ventilation. The mesh cost $280,000 and had a lead time of 14 weeks. The design team re-aligned to go with 1/2″, #16 flatted expanded aluminum with a custom bronze anodized finish. The expanded metal was bought at $95,000 and delivered in 4 weeks. The continuous diamond pattern, while complex in design, lent aesthetic interest by its random intertwined pattern; often 65% open gave natural ventilation in accordance with the client’s wish. The anodized aluminum, being maintenance-free, began developing a nice little patina that would still make the façade more attractive at no additional cost. The considerable savings of $185,000 thereby allowed the developer to enhance the finishes of the lobby, and quicker delivery kept the idea on schedule for tenant occupancy.
Architectural Considerations
- Flattened Mesh provides a less vertical look than raised.
- Anodization or powder coating with aluminum is for weather protection.
- Selection of patterns affects diffusion of light and visibility.
- Panel sizes are limited to a maximum of 4′ x 10′ or 5′ x 12′ generally.
- Mounting systems incorporate fixturing, clips, or housing frames.
Interested in architectural applications? Explore our (architectural wire mesh design guide)
Walkways, Platforms, and Grating
Expanded metal gratings offer a low-cost and slip resistance material for walking on industrial platforms, mezzanine floors, and maintenance walkways. The higher surface of the grating forms traction even if wet or oily.
Design standards include:
- Minimum of 13 # line width for walking by persons
- Maximum safety requires an SWD of 0.5″ for protecting the heel
- Support may range from 4′ to 6′ centimeters
- For better resistance to skidding
- Hot-dip galvanizing is used for industrial environments
Verifying Load Capacity
Always confirm the actual load capacity following manufacturer’s data specific to the pattern used. Remember to account for point loads due to equipment, maintenance materials, and potential loads.
Filtration and Screening
Despite being suitable neither for fine particulate pick-up nor for other filtration applications, expanded metal plays pivotal filtering roles in industrial systems:
- Support screens: They provide structural backup to filter media
- Pretreatment screens: These take care of larger debris before passing it for fine filtration
- Dewatering screens: These are useful to separate solids from liquids into different kinds of processing applications
- Air intake screens: They protect HVAC from down to process equipment-filtered emanations.
EMI/RFI Shielding
Expanded metal provides effective electromagnetic interference shielding when properly grounded. The continuous metal construction creates a Faraday cage effect that blocks electromagnetic radiation.
Shielding Applications
- Computer room enclosures
- Test chamber shielding
- Medical equipment housing
- Secure communications facilities
- Aerospace and defense applications
Aluminum and copper expanded metal are preferred for shielding due to their conductivity. Effectiveness depends on mesh size relative to wavelength of radiation being blocked.
Expanded Metal vs Wire Mesh: Selection Guide
When to Choose Expanded Metal
Cost-Driven Decisions
Expanded metal typically costs 30-50% less than equivalent welded wire mesh. When budgets are constrained and expanded metal meets technical requirements, it’s the economical choice.
Structural Applications
Choose expanded metal when:
- Load-bearing capacity is critical
- Impact resistance is required
- Continuous structural integrity is essential
- No connection point failures can be tolerated
Availability Requirements
Standard expanded metal patterns are typically available from stock with immediate delivery. When lead times are critical, expanded metal may be the only practical option.
Forming and Fabrication
Expanded metal can be bent, rolled, and formed like sheet metal. For curved guards, cylindrical shapes, or complex fabrications, expanded metal offers superior workability compared to wire mesh.
When to Choose Wire Mesh
Fine Filtration
Woven wire mesh provides filtration down to 20 microns—far finer than expanded metal’s practical minimum of approximately 500 microns. For fine particle retention, wire mesh is the only viable option.
Flexible Uses
Woven wire meshes are so flexible that they bend over edges and irregular shapes. The feature is highly desired for applications that need to wrap around, stretch, or be joined into a flexible manner.
Visual Preference
Woven architectural meshes provide the aesthetics not possible with expanded metal. Woven wire meshes are often specified for high-end building surfaces due to their look of elegance.
Varying Airspace
Wiremesh offers a range of graded spacing with an accurate aperture size. Wire meshes would be the product of choice for applications requiring objective optical reflection or regulated airflow.
Cost Comparison
| Application | Expanded Metal | Welded Wire Mesh | Cost Advantage |
|---|---|---|---|
| Machine guarding | $8-15/sq ft | $15-28/sq ft | 40-50% savings |
| Security fencing | $12-20/sq ft | $20-35/sq ft | 35-45% savings |
| Walkway grating | $18-30/sq ft | $30-50/sq ft | 35-40% savings |
| Architectural screen | $25-45/sq ft | $60-120/sq ft | 55-65% savings |
Costs vary by material, pattern, quantity, and finishing. Use for comparative guidance only.
Performance Comparison
| Characteristic | Expanded Metal | Welded Wire Mesh | Woven Wire Mesh |
|---|---|---|---|
| Structural strength | Excellent | Good | Fair |
| Impact resistance | Excellent | Moderate | Poor |
| Finest opening | ~500 microns | ~25 microns | ~20 microns |
| Cost | Low | Medium | High |
| Lead time | Short | Medium-Long | Medium |
| Formability | Excellent | Limited | Good |
| Corrosion resistance* | Equal | Equal | Equal |
*Assuming equivalent materials and coatings
Ready to source specialty wire mesh? See our (wire mesh suppliers guide).
Specifications and Standards
ASTM F1267 Standard
ASTM F1267 is the primary standard specification for expanded metal. This standard covers:
Material Requirements
- Steel grades and mechanical properties
- Stainless steel specifications
- Aluminum alloy specifications
- Coating requirements for galvanized products
Dimensional Tolerances
- SWD and LWD tolerances (typically ±5%)
- Strand width tolerances
- Overall sheet size tolerances
- Thickness specifications for flattened mesh
Testing Requirements
- Coating weight tests for galvanized products
- Tensile testing for material verification
- Dimensional verification procedures
When specifying expanded metal for construction or industrial applications, reference to ASTM F1267 ensures product consistency and quality.
Want detailed specifications for a specific mesh type? Explore our (wire mesh specifications guide)
Understanding Gauge and Thickness
Wire gauge systems can be confusing because different gauge standards apply to different materials:
Carbon Steel (Manufacturers’ Standard Gauge)
- 16 gauge: 0.0598″ nominal thickness
- 14 gauge: 0.0747″ nominal thickness
- 13 gauge: 0.0897″ nominal thickness
Stainless Steel (United States Standard Gauge)
- 16 gauge: 0.0625″ nominal thickness
- 14 gauge: 0.0781″ nominal thickness
Aluminum (Birmingham Wire Gauge)
- 0.125″ (1/8″): Common for architectural applications
- 0.080″: Medium weight industrial
- 0.063″ (1/16″): Light duty screening
Always specify actual decimal thickness rather than gauge number to avoid confusion between material types.
Opening Size and Percent Open Area
Measuring Openings
Diamond openings in expanded metal are specified by SWD and LWD. The actual clear opening is slightly smaller than these dimensions due to strand width.
Approximate clear opening = SWD – Strand Width
Percent Open Area Calculation
Percent open area = (Open Area / Total Area) × 100
Standard expanded metal ranges from 30% to 80% open area:
- Heavy security mesh: 30-40% open area
- Industrial guarding: 60-70% open area
- Light screening: 75-80% open area
Specification Writing Guidelines
Complete Specification Example
“Expanded metal mesh shall be 3/4″ #9 flattened, carbon steel, hot-dip galvanized after fabrication per ASTM A123, minimum G90 coating weight. Mesh shall conform to ASTM F1267. Sheet size: 48″ x 96″ ±1/4″. Strand width: 0.125″ ±0.010″. SWD: 0.923″ ±0.046″. LWD: 2.100″ ±0.105″.”
Key Elements to Include
- Pattern designation (SWD # strand)
- Raised or flattened condition
- Material specification
- Coating or finish requirements
- Reference standard (ASTM F1267)
- Dimensional tolerances
- Sheet or roll size
Installation Best Practices
Framing and Support Requirements
Expanded metal requires adequate framing and support to perform as designed. Unsupported spans exceeding manufacturer recommendations result in excessive deflection and potential failure.
Framing Materials
- Angle iron: L-1-1/2″ x 1-1/2″ x 1/8″ minimum for guards
- U-channel: Provides edge protection and mounting surface
- Flat bar: Used for backing and surface mounting
Support Spacing
Follow manufacturer load tables for specific patterns. General guidelines:
- Personnel loads: 4′ maximum span for light patterns, 6′ for heavy patterns
- Light equipment: 3′ maximum span
- Heavy loads: Engineering analysis required
Cutting and Fabrication
Cutting Methods
- Shearing: Clean cuts parallel to strand direction
- Band saw: For thicknesses over 1/8″
- Plasma/laser cutting: For complex shapes and patterns
- Abrasive cutoff: Field cutting with proper ventilation
Bending and Forming
Expanded metal can be brake-formed like sheet metal:
- Minimum bend radius: 2x material thickness
- Grain direction: Bend across LWD for best results
- Pre-heating: May be required for heavy material thicknesses
Welding Considerations
- MIG welding: Preferred for carbon steel
- TIG welding: Preferred for stainless steel and aluminum
- Ground preparation: Remove coatings before welding galvanized materials
- Fume extraction: Essential when welding galvanized steel
Fastening Methods
Framing Attachment
- Welding: Continuous or stitch welding to frame
- Bolting: Through-frame with flat washers
- Clinching: Mechanical attachment without heat
Mounting to Structures
- Self-tapping screws: For light-duty applications
- Through-bolts: With backing plates for security
- Toggle bolts: For hollow structure mounting
- Specialty clips: Manufacturer-specific mounting systems
Safety Considerations
Sharp Edge Hazards
Expanded metal edges can be sharp, particularly when cut. Safety measures include:
- Wearing cut-resistant gloves during handling
- Framing or edging cut edges
- Deburring cut edges before installation
- Using flattened mesh for high-contact applications
Load Verification
Before putting expanded metal platforms or walkways into service:
- Verify design loads with engineering calculations
- Test load capacity if specifications are uncertain
- Inspect support structures for adequate capacity
- Post load capacity signage for maintenance personnel
Electrical Safety
Expanded metal conducts electricity. When used around electrical equipment:
- Ensure proper grounding
- Maintain required clearances from energized components
- Use insulated mounting where electrical isolation is required
Conclusion
Expanded metal mesh occupies a unique position in industrial materials, combining the structural integrity of one-piece construction with cost efficiency that alternatives cannot match. The manufacturing process—simultaneously slitting and stretching sheet metal—creates a product that is paradoxically stronger than the original material while using zero raw material waste.
In terms of safety guarding, the expanded metal offers OSHA-compliant protection, which saves the end user 30-50% over welded wire mesh. When serving security purposes, continuous construction easily resists cuts and breaches. When used as an architectural screen, pattern, and finish can add visual appeal and be functional purpose. For walkways and platforms, the raised diamond pattern bestows skid resistance by its sheer design.
The crux of the specifications applicable to expanded metal lies in understanding pattern selection, where SWD, LWD, and strand width interact with each other in terms of strength factor, open area, and performance. Material choices could be any of the three–carbon steel, stainless steel, and aluminum, based on balancing the different aspects, cost attributes, and environmental exposure. While the need for a shaping–raised or flattened–would depend actually on surface profile and appearance.
When weighing the favorable aspects of expanded metal in comparison with the myriad wire mesh alternatives, do contemplate the total value translation, not just the material cost, but fabrication timing, structural performance, availability, and service life. Wherever expanded metal satisfies technical specifications, better fiscal value most certainly is assured.
Especially for the case of industrial mesh applications next, you will find the best full-fledged guide available to comprehend how expanded metal fits into mesh. Encompassing everything from fabricated work to ready-in-stock and available for niche markets like screening hoops, expanded metal mesh has a reputation of being hit upon here and there across various global industries.
