How to measure and specify expanded metal - News

When measuring and specifying expanded metal, it's crucial to follow a systematic approach to select the most suitable mesh pattern for your application. Expanded metal comes in a variety of designs, each with unique characteristics and applications.

Our customers sometimes find themselves confused over what measurements they should provide in order to select the most suitable mesh pattern for their application. Ian Hutchinson, Product Manager at The Expanded Metal Company, provides a guide on how to measure and specify expanded metal…

For more aluminum expanded mesh information, please contact us. We will provide professional answers.

Raised or Flattened Mesh: What is the Difference?

When measuring expanded metal mesh, the first thing to consider is whether the mesh is raised or flattened. Both have a unique set of terminologies with regard to their respective measurements.

The original form of expanded metal is always of a raised appearance and is characteristic of the unique slit and stretch motion employed to manufacture the product, which presents angular strands inclined from the plane of the sheet.

Raised mesh is championed for its angular appearance which not only gives it strong aesthetic appeal but offers practical benefits: it offers grip underfoot, has the ability to direct air, liquid, and light, and provides a key when used as a substrate.

Common applications for raised mesh include walkway ramps, security fencing, decorative building cladding for interiors and exteriors, and laths for render and plaster.

A secondary process is often applied to expanded metal which utilizes heavy rolls to flatten the angular strands. The end result is a sheet which is completely two-dimensional with its strands in the same plane as the sheet. Flattened mesh is often championed when a flush finish is required.

Common applications for flattened meshes include security partition meshes, conical air filters, and machine guards.

How to Measure Raised Mesh

The key measurements for a raised mesh are Longway Pitch (LWP), Shortway Pitch (SWP), Strand Width (SWDT), and Strand Thickness (STK).

LWP, measured horizontally from either knuckle to knuckle or center to center, is derived from the size of tooling used within the production process.

SWP, measured vertically from either knuckle to knuckle or center to center, is manifested through the overall expansion applied during manufacture.

SWDT is a measurement of the width of the resulting angular strand created during manufacture.

STK, is a measurement of starting raw material thickness. Contrary to belief, the expanding process does not directly alter material thickness. Strand Thickness should not be confused with the overall height or depth of expanded metal. Typically, mesh height can be as much as 1-2x the measurement of SWDT.

How to Measure Flattened Mesh

The key measurements for a flattened mesh are Longway Aperture (LWA), Shortway Aperture (SWA), Strand Width (SWDT), and Strand Thickness (STK).

LWA is measured horizontally from internal aperture point to point.

SWA is measured vertically from internal aperture point to point.

SWDT is a measurement of the width of the resulting angular strand created during manufacture.

STK is a measurement of starting raw material thickness.

While the expanding process does not alter material thickness, the flattening process does. It is common to observe a 10-20% reduction in material thickness after the flattening process. As the mesh is completely two-dimensional after flattening, the overall height measurement of the mesh is akin to starting material thickness with a further allowance of 10-20% reduction.

How to Specify Sheet Size and Orientation

Expanded metal mesh exhibits different mechanical and aesthetic properties when the sheet size is oriented at opposing angles.

When specifying sheet dimensions, one should also consider the orientation of the diamonds in relation to sheet size. The terminology employed to describe orientation is Longway Mesh (LWM) and Shortway Mesh (SWM).

For example, when raised mesh is used as a walkway ramp platform, the surface grip is strongest when the diamonds run left-to-right underfoot.

Alternatively, it is common within the security fencing industry to mount expanded mesh fencing panels with the diamonds longways pointing to the sky. This creates narrower openings and inhibits the ability to climb and scale the fence.

The below illustration provides a clear explanation of how 2440mm LW x 1220mm SW differs from 1220mm LW x 2440mm SW despite being dimensionally the same.

View an example of our 2076F flattened steel mesh at a horizontal orientation here and view the same mesh at a vertical orientation here.

You can also view our 2089 raised steel mesh at a horizontal orientation here and at a vertical orientation here.

For more support and to discuss your requirements further, contact us.

EXPANDING— An expanding press simultaneously slits and stretches base material to form a diamond pattern.

LEVELLING— Expanded metal is usually leveled after the expansion process by a leveling roller.

RAISED (abbreviated R)— Expanded metal as it comes from the press. The strands and bonds are set at a uniform angle to the plane of the sheet. This gives added strength and rigidity, as well as a skidding resistant surface.

FLATTENED (abbreviated F)— Expanded metal that has been cold-rolled after expansion, to provide a smooth, flat, and level sheet. The flattening process reduces the original gauge of the base metal and the strand width increases slightly. Some of the heavier expanded metals cannot be flattened.

SWD— Nominal dimension, Short Way of Design

LWD— Nominal dimension, Long Way of Design.

When referring to a sheet size the SWD is always referred to before the LWD. For example, a 4x8 sheet means 4-foot dimension is in the SWD direction and 8-foot dimensions are in the LWD direction.

SWO— Short Way of Opening

LWO— Long Way of Opening

STRAND THICKNESS— Gauge thickness of the base metal.

STRAND WIDTH— Amount of metal fed under dies to produce one strand.

EDGE CONFIGURATION— Condition of the edge of an expanded metal sheet. Usually refers to open (random) or closed (bond) diamond edges produced from shearing.

SHEARING— Cutting expanded metal to size to produce various sheet sizes. May be bond or randomly sheared.

In bond shearing, the shear line falls through the bonds. The result is an edge configuration of all closed diamonds. For bond shearing the resultant dimensions must be in a multiple of the full diamond dimensions.

In random shearing, the shear line falls at random points on the mesh pattern. Edges are open, and diamonds are not matched. Random shearing is necessary when the required overall dimensions are not a multiple of the full diamond dimensions.

Style Lbs. per 100 Sq. ft. Standard Sheet Size (ft.) Design Size (inches) Opening Size (inches) Strand Size (inches) Overall Thick-ness (in.) No. of Designs per ft. (%) Open Area Width Length SWD LWD SWD LWD SWO LWO Width Thickness SWD LWD

STANDARD

1/4—#20

86

4

8

.250

1.00

.125

.718

.072

.036

.135

48

12

45

1/4—#18

114

4

8

.250

1.00

.110

.718

.072

.048

.147

48

12

43

1/2—#20

43

4

8

.500

1.00

.438

.938

.072

.036

.140

24

10

80

1/2—#40 (18 ga.)

40

4

8

.500

1.20

.440

.938

.051

.048

.110

24

10

82

1/2—#18

70

4&6

8&10

.500

1.20

.438

.938

.088

.048

.172

24

10

72

1/2—#16

86

4&6

8&10

.500

1.00

.375

.938

.087

.060

.175

24

10

65

1/2—#13

147

4&6

8&10

.500

1.20

.312

.938

.096

.092

.204

24

10

57

3/4—#16

54

4&6

8&10

.923

2.00

.813

1.750

.101

.060

.210

13

6

78

3/4—#13

80

4&6

8&10

.923

2.00

.750

1.688

.096

.092

.205

13

6

76

3/4—#10 (13 ga.)

120

4&6

8&10

.923

2.00

.750

1.625

.144

.092

.290

13

6

72

3/4—#9 (10 ga.)

180

4&6

8&10

.923

2.00

.688

1.562

.150

.134

.312

13

6

68

1—#16

44

4

8

1.00

2.40

.938

2.062

.087

.060

.192

12

5

82

1 1/2—#18

20

4

8

1.33

3.00

1.313

2.625

.068

.048

.140

9

4

90

1 1/2—#16

40

4

8

1.33

3.00

1.250

2.625

.108

.060

.230

9

4

85

1 1/2—#13

60

4&6

8&10

1.33

3.00

1.188

2.500

.105

.092

.242

9

4

85

1 1/2—#10 (13 ga.)

79

4&6

8&10

1.33

3.00

1.188

2.500

.138

.092

.284

9

4

80

1 1/2—#9 (10 ga.)

120

4&6

8&10

1.33

3.00

1.125

2.375

<