Flexi Shields
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The Spira-Shield patented spiral is the basis for all of our unique high shielding EMI gasketing solutions. The spiral is wound out of spring temper beryllium copper for excellent spring memory and compression set resistance. The spiral is tin plated for superior conductivity and shielding properties. The edge plated version exhibits excellent corrosion resistance against aluminum when exposed to humid or salt-fog environments. See below for ordering information.

Application Information

This high-shielding gasket provides up to 165 dB of shielding and is well known for solving shielding problems that no other gasket can solve, and is perfect for military and aerospace projects. However, the cost is competitive enough that this gasket is also perfect for many commercial applications that require high-shielding.

Materials:
Spiral: Tin/lead plated beryllium copper. (See Options for RoHS compliance).
Electroplated, 90% tin, 10% lead per AMS-P-81728 (edges unplated).
Cord: 80 durometer PVC (hard plastic) optional. May require additional lead time.
Refer to Material Specifications for more information.

Shielding Quality:
This gasket offers shielding quality up to 165 dB. The shielding quality may vary depending on your specific application. Refer to Shielding Quality  for more complete performance data.

Compression Force:
Spira-Shield gaskets come in three different resiliencies shown below. Optimal compression of the gasket is 25% of the diameter of the spiral. Since the force to compress the gasket is a function of the cube of the thickness of the beryllium copper ribbon, the compression forces shown are approximate.

Standard Force: ~30 pounds per linear inch compression.
Moderate Force: ~10 pounds per linear inch compression.
Low Force: ~1.5 pounds per linear inch compression.

Mounting:
This gasket is groove mounted. Refer to Groove Mounting Techniques for detailed mounting information.

Available Options

Custom Sizes:
We can manufacture Spira-Shield gaskets in any size diameter, from .034” up to approximately 1.5”. There are no special charges involved, but the functional length of the part may be small at very large diameters. Please contact us with your requirements.

Plating:
Plating options can be specified by adding a prefix before the part number:
E: Edge tin/lead plating (includes edges) for high humidity or salt-fog environments
IW: RoHS compliant tin plating (Example: IWMS-08)
EIW: RoHS compliant edge tin plating for high humidity or salt-fog

Specify plating by choosing the desired prefix from the table.

Example: EIWLS-12; RoHS edge tin plated, Low Force

Material
Force
Tin/lead Plating
RoHS Tin
Edge Tin/Lead
RoHS Edge Tin
Beryllium
Copper
Standard
Moderate
Low
SS (default)
MS
LS
IWSS
IWMS
IWLS
ESS
EMS
ELS
EIWSS
EIWMS
EIWLS

Additional plating options are available by special request including: Reflow edge tin plating (R), Gold (G) and Sulfamate Nickel (N). Refer to Material Compatibility for more information.

Cord Insert:
Moderate and low force gaskets come standard with PVC cord. The cord acts as a mechanical stop to protect the spiral from over-compression during use and handling. Specify “no cord” in the moderate and low force gaskets as follows:
NC: No Cord (Example: MS-08 NC)
All Standard Force gaskets come without cord (no NC required).

Special Cord:
Special cords can be specified as follows (may not be available in all sizes and may include extra charges and lead time).
-F: Solid Fluorosilicone Cord (Example: MS-08-F)
-O: Space Qualified Silicone (non-outgassing)
-S: Solid Silicone Cord
-T: Thermal Plastic Rubber Cord

Ordering Information:
Spira-Shield is sold by the foot and typically packaged on spools except in small quantities. It can also be ordered cut-to-length in specific sizes or you can cut it yourself using a sharp pair of scissors. Custom o-rings are also available. (See Custom Gaskets for more information.)

Spira-Shield Part Numbers
(Tin/Lead Plated Beryllium Copper)
Recommended Groove Dimensions
Diameter Standard* Force Moderate Force Low Force Depth (L)
+.002"
-.000"
Width (G)
+.007"
-.005"
Width (W)
+.000"
-.002"
.034" ± .002" SS-02 MS-02 NC** -- .023" .046" .033"
.047" ± .002" SS-03 MS-03 NC** -- .035" .063" .045"
.063" ± .003" SS-04 MS-04 LS-04 .046" .094" .060"
.070" ± .003" SS-.070 MS-.070 LS-.070 .053" .094" .067"
.078" ± .003" SS-05 MS-05 LS-05 .059" .109" .075"
.094" ± .004" SS-06 MS-06 LS-06 .070" .125" .090"
.103" ± .004" SS-.103 MS-.103 LS-.103 .077" .141" .099"
.109" ± .004" SS-07 MS-07 LS-07 .082" .156" .105"
.125" ± .004" SS-08 MS-08 LS-08 .094" .171" .121"
.139" ± .005" SS-.139 MS-.139 LS-.139 .104" .187" .134"
.141" ± .005" SS-09 MS-09 LS-09 .105" .187" .136"
.172" ± .005" SS-11 MS-11 LS-11 .128" .234" .165"
.187" ± .006" SS-12 MS-12 LS-12 .140" .250" .181"
.250" ± .007" SS-16 MS-16 LS-16 .185" .343" .240"
.312" ± .009" SS-20 MS-20 LS-20 .234" .422" .300"
.375" ± .011" SS-24 MS-24 LS-24 .280" .500" .364"
.500" ± .015" -- MS-32 LS-32 .375" .656" .485"
* Standard Force gaskets come without a cord.
** This part cannot come with a cord.

See our Part Number Matrix for assistance with part numbers, options and product comparisons.

drawing of shield
Spira-Shield in a regular O-ring groove.

See  Groove Mounting Techniques for complete mounting details.

More information is also available on Dovetail Groove Cutters.

Spira Shield (second image)
Spira-Shield in a dovetail groove.