Expanded Metal Terminology
|Expanded Metal Style
Designation: Expanded metal mesh products are designated by a
series of numbers that identify a given style. The first number
is the nominal diamond dimension Short Way of Design (SWD).
The second number used in conjunction with the first number
MAY specify the gauge of metal, weight per hundred square foot,
or may have some other significance. Therefore, the word "GAUGE"
SHOULD NEVER BE ADDED TO THE STYLE DESIGNATION. Grating products
are designated by weight per square foot of the finished
Expanded Metal Strands: The individual slit metal strips, or slides
of an expanded metal pattern. Strand thickness in standard expanded
metal mesh is the gauge or thickness of the sheet or coil from which
the expanded metal was produced. In flattened expanded metal,
it is the overall thickness of the finished sheet. Strand width
in standard expanded metal mesh is the amount of metal fed into the
expanding machine, which is slit and stretched with each stroke
of the upper die. In flattened expanded metal, it is as the
name implies, the width of the strand.
Open Area: The amount of open area to determine the amount
of light or air passage.
SWD: The distance from a point on a bond to a corresponding
point on the following bond measured across the Short Way of
Design. This distance is also sometimes referred as "pitch SWD".
LWD: The distance from a point on a bond to a corresponding
point on the following bond measured across the Long Way of
Design. This distance is also sometimes referred as "pitch LWD".
SWO: Short Way of Opening, the distance measured from
the inside of the bond across to the inside of the bond SWD.
LWO: Long Way of Opening, the distance measured from
the inside of the bond across to the inside of the
Bond: The intersection of two strands and it is always
the width of two strands.
Overall Thickness: The actual measurement of the thickness
of the mesh measured at the bond.
Standard Expanded Metal: Expanded
metal mesh as it comes off the machine. The strands and bonds
are set at a uniform angle to the plane of the sheet. This
adds strength and rigidity, allows air circulation, distributes
the load on the metal to the supporting frames as well as making
a skid resistant surface. Standard expanded metal is abbreviated
Flattened Expanded Metal: Manufactured
by passing the standard expanded metal mesh sheet through a cold roll reducing
mill parallel to the LWD. By flattening the sheet, the
bonds and strands are turned down to produce a smooth and flat
surface, reducing the overall thickness and elongating the diamond
pattern (LWD). Cross roll flattening is done by passing
the expanded metal sheet through a cold roll reducing mill parallel
to the SWD. The result is the same except the diamond
pattern SWD is elongated. Flattened expanded metal mesh is
Grating: Grating is a standard
expanded metal pattern produced from heavier gauge low carbon
steel plates. The strands and openings are considerably larger
than the other meshes. Ideal for use whenever a strong,
durable and lightweight surface is required. Although
used primarily for pedestrian traffic, grating can accommodate
heavier loads when properly supported.
Expanded Metal Decorative Patterns: Specially
designed expanded metal mesh for use in architectural and decorative
applications. These design can be used to provide privacy
and to control light and air while allowing visibility.
Sunscreens, room dividers and building facades are only a
few of the possible design possibilities. Available in
carbon steel, aluminum and other alloys in a wide range of patterns
and gauges. Most of these patterns are produced on a special
order basis only.
Projection Mesh Grating:
Features small tooth-like projections on the upper surface of the expanded metal mesh. These projections provide an excellent non-slip surface where additional anti-skid surfacing is desired.
Normal dimension Short Way of Design (SWD) of expanded metal.
Actual dimension SWD and Long Way of Design (LWD). Measured from a point to a corresponding point on the expanded metal design.
Gauge thickness of expanded metal.
Amount of metal fed under dies to produce the expanded metal strand.
Bond Side Shearing:
This cut is made along the length of the sheet on the center line of the bond over the specified length. In most cases it is not practical to attempt to bond side shear in either regular or flattened expanded metal because of camber.
The process of cutting a piece of expanded metal parallel to the short way of the diamond.
End Random Shearing:
The process of shearing a piece of expanded metal to a specified length (LWD). This cut normally leaves open diamonds at both ends but accomplishes close tolerance (plus or minus 1/8 inch) when both ends are sheared.
End Bond Shearing:
The process of shearing a piece of expanded metal to a specified length (LWD). A plus or minus 1/8 inch-tolerance applies when both ends are sheared. One end is cut on the bond parallel to the SWD. The other end usually has open diamonds. NOTE: When end bond shearing is requested for both ends, the sheet is sheared at the center line of the bond over the specified width. A tolerance minus 0 plus 1/2 diamond applies. It is possible to end bond shear, but extraordinary care must be exercised to maintain the squareness of the sheet.
Random Side Shearing:
The process of cutting a piece of expanded metal parallel to the LWD dimension of the sheet, which usually leaves open diamonds. Standard tolerance SWD is plus or minus 1/8 inch when both sides are sheared.
The process of cutting a piece of expanded metal parallel to the long dimension of the diamond.
When all four sides of a sheet of expanded metal are sheared, the maximum tolerance will be plus or minus 1/16 inch per foot of width.
Standard Expanded Metal:
Also called regular, unflattened or raised expanded metal. Expanded metal as it comes from the press. The strands and bonds are set at a uniform angle to the plane of the sheet, adding strength and rigidity as well as a skid-resistant surface.
Standard expanded metal that has been passed through a cold roll mill. The bonds and strands are turned down to produce a smooth, flat surface. The flattening process reduces the original gauge of the base metal, and the strand width increases slightly.
Machine Run to Size:
Expanded metal as it comes off the press with closed diamond edges.
Condition of the edge of an expanded metal sheet. Usually refers to "open" (random) or "closed" (bond) diamond edges produced from shearing.
The process of levelling expanded metal with a levelling roller after the expansion process.
The measurement of the shortest side of the sheet or cut-to-size expanded metal piece.
The measurement of the longest side of the expanded metal sheet or cut-to-size piece.
Stainless Steel Expanded Metal
The most widely used or the stainless and heat resisting steels.
Offers good corrosion resistance to many chemical corrodents
as well as industrial atmospheres. This material is also
less susceptible to carbide precipitation during welding and
to subsequent intergranular corrosion.
304-L Extra low carbon variation of 304 that avoids
harmful carbide precipitation due to welding. 304-L offers
the same corrosion resistance as 304 and, slightly lower mechanical
properties. This alloy is employed for extremely severe
conditions where intergranular corrosion may occur.
309 Good strength at high temperatures. Corrosion
resistance superior to that of 304. Oxidation resistance
to 2000 degrees F. High resistance to scale. Excellent
in resisting sulfite liquors, nitric acid, nitric-sulfuric mixtures,
acetic, citric and lactic acids.
310 Moderate strength at high temperatures.
Corrosion resistance better than 304. Excellent oxidation
resistance under constant or moderately cyclic conditions.
Higher alloy content improves the characteristics of this material
to that of 309.
316 Improved corrosion and pitting resistance as well
as better strength at higher temperatures than 304. This
material is a Molybdenum bering stainless that processes a greatly
increased resistance to chemical attack than that of the basic
316-L Low carbon variation of 316 to avoid carbide precipitation
due to welding Same corrosion resistance as 316.
321 Stabilized with titanium for weldments subject
to severe corrosion. No carbide precipitation. Excellent
resistance to a variety of corrosive media. Immune to
most organic chemicals, dyestuffs and many inorganic chemicals.
330 Austenitic alloy with excellent oxidation resistance,
especially under cyclic conditions. Resists sulfur free
furnace atmospheres containing carbon and nitrogen.
333 Superior strength at temperatures to 2000 degrees
F. Outstanding oxidation resistance, excellent resistance
to shock, dimensional stability, resistance to creep, distortion,
409 Lowest cost stainless. Used extensively
in automotive exhaust systems. Due to its combination
of low cost and good resistance to oxidation and corrosion this
material is a good alternative for use on parts where surface
appearance is not important. (MAGNETIC)
410 Heat treatable stainless used widely where corrosion
is not severe, i.e.:air, fresh water, some chemicals and food
430 This is the most popular of the non-hardenable
chromium stainless steels. It combines good corrosion
and heat resistance with good mechanical properties. Oxidation
resistance to 1500 degrees F. Widely used in both industrial
and consumer products. (MAGNETIC)
Aluminum Expanded Metal
1100 aluminum Commercially pure aluminum (99% min.).
Excellent corrosion resistance, workability and weldability
- high in thermal conductivity. Tensile strength range
14,000 to 24,000 psi.
3003 aluminum Alloyed with 1.2% manganese to provide a tensile
strength range of 17,000 to 30,000 psi. Also has excellent
workability, weldability and corrosion resistance.
5005 Alloyed with .8% magnesium. Tensile
strength range from 18,000 to 30,000 psi. Same excellent
workability, weldability and corrosion resistance as 1100 and
3003. Specified for applications that are comparable to
1100 and 3003 where anodizing is required.
5052 Alloyed with 2.5% magnesium. Tensile
strength range 31,000 to 44,000 psi. Very good corrosion
resistance, good workability, weldability and strength.
** Niles Expanded Metals stocks only 3003 aluminum