EMI/RFI grounding washers are manufactured from knitted wire mesh stocking that is formed into a resilient metal washer by compressing in a close-tolerance forming die. The grounding washer can be supplied in various diameters and thicknesses to satisfy the many requirements as indicated in the Applications shown in Figures 1 through 4.
By varying the weight of the stocking mesh inserted into the compression die, the density of the washers can be varied, thus increasing or decreasing unit resilience, depending on the needs of the specific application. Washers with a metal density of 15 to 20 percent will “flow” under compression and thus will fill a gap or seam under minimal pressure (10 psi).
A grounding washer with a metal density of 30 to 40 percent provides a snug fit around a shaft or rod, but when compressed against the wall of a metal enclosure (as shown in Figure 3) will act as a slip-ring thus grounding the rotating shaft to enclosure. This eliminates the possibility of the shaft acting as an antenna to radiate or pick up unwanted noises.
The all-metallic construction of the grounding washers that can be supplied in varying alloys makes them especially effective in hostile environments of temperature or chemicals.
Design Data
Applications
Figures 1 through 4 show some of the possible mounting methods for grounding washers.
Available Sizes
Table 1 — Grounding Washer Diameters
|
Part Number
|
O.D.
|
I.D.
|
| 2501-70005-xx |
0.218 |
0.062 |
| 2501-70007-xx |
0.375 |
0.250 |
| 2501-70009-xx |
0.030 |
0.000 |
| 2501-70010-xx |
1.000 |
0.500 |
| 2501-70015-xx |
0.234 |
0.109 |
| 2501-70020-xx |
0.500 |
0.250 |
| 2501-70027-xx |
0.635 |
0.500 |
| 2501-70076-xx |
1.120 |
0.810 |
| 2501-70078-xx |
0.906 |
0.593 |
| 2501-70079-xx |
2.322 |
2.202 |
| 2501-70084-xx |
1.370 |
1.120 |
| 2501-70092-xx |
0.750 |
0.228 |
| 2501-70094-xx |
0.062 |
0.000 |
| 2501-70106-xx |
1.425 |
1.043 |
| 2501-70108-xx |
1.437 |
1.063 |
| 2501-70109-xx |
1.437 |
1.083 |
| 2501-70110-xx |
1.437 |
1.102 |
| 2501-70115-xx |
0.255 |
0.150 |
| 2501-70117-xx |
0.885 |
0.625 |
| 2501-70118-xx |
0.630 |
0.550 |
| 2501-70119-xx |
1.380 |
1.250 |
| 2501-70120-xx |
0.380 |
0.250 |
| 2501-70121-xx |
0.880 |
0.810 |
| 2501-70122-xx |
0.635 |
0.375 |
| 2501-70134-xx |
0.937 |
0.687 |
| 2501-70135-xx |
0.625 |
0.469 |
| 2501-70136-xx |
1.620 |
1.125 |
| 2501-70137-xx |
2.130 |
1.600 |
| 2501-70138-xx |
2.130 |
1.600 |
| 2501-70144-xx |
0.875 |
0.375 |
| 2501-70145-xx |
0.345 |
0.185 |
| 2501-70150-xx |
2.125 |
1.812 |
| 2501-70158-xx |
1.500 |
1.000 |
| 2501-70160-xx |
2.950 |
2.875 |
| 2501-70170-xx |
2.642 |
2.562 |
| 2501-70180-xx |
0.910 |
0.790 |
| 2501-70200-xx |
0.750 |
0.250 |
| 2501-70300-xx |
0.225 |
0.130 |
| 2501-70310-xx |
0.410 |
0.250 |
| 2501-70320-xx |
0.350 |
0.175 |
| 2501-70350-xx |
0.906 |
0.344 |
| 2501-70360-xx |
0.550 |
0.200 |
| 2501-70500-xx |
0.875 |
0.344 |
| 2501-70501-xx |
0.875 |
0.315 |
| 2501-70502-xx |
0.275 |
0.180 |
| 2501-70503-xx |
0.300 |
0.150 |
| 2501-70504-xx |
0.240 |
0.187 |
| 2501-70600-xx |
1.370 |
0.750 |
| 2501-70650-xx |
2.625 |
0.450 |
| 2501-70700-xx |
0.500 |
0.200 |
| 2501-70710-xx |
0.450 |
0.170 |
| 2501-70720-xx |
1.250 |
0.315 |
| 2501-70730-xx |
1.880 |
0.680 |
| 2501-70740-xx |
1.000 |
0.300 |
| 2501-70750-xx |
1.800 |
0.480 |
| 2501-70755-xx |
1.100 |
0.315 |
| 2501-70756-xx |
0.900 |
0.480 |
| 2501-70800-xx |
0.394 |
0.323 |
| 2501-70950-xx |
1.375 |
1.125 |
Table 2 shows
washer sizes that can readily be supplied from existing tooling.
Thickness can be varied from .032 to .125.
Tolerances
Table 2
|
Sizes
|
O.D.
|
I.D.
|
Up to 1
(Up to 25.40) |
+0.015, -0.000
(+0.38) |
+0.000, -0.015
(-0.38) |
1 to 2
(25.40 to 50.80) |
+0.020, -0.000
(+0.51) |
+0.000, -0.020
(-0.51) |
2 to 3
(50.80 to 76.20) |
+0.025, -0.000
(+0.63) |
+0.000, -0.025
(-0.63) |
3 to 4
(76.20 to 101.60) |
+0.030, -0.000
(+0.76) |
+0.000, -0.030,
(-0.76) |
Over 4
(101.60) |
+0.040, -0.000
(+1.02) |
+0.000. -0.040
(-1.02) |
Materials
Grounding washers can be supplied using knit wire mesh of the
following materials:
Table 3
|
Code
|
Description.
|
| -31 |
Monel per QQ-N-281 Class A |
| -32 |
Aluminum |
| -33 |
Silver Plated Brass per QQ-W-321 (3% Silver by Weight) |
| -34 |
Tin Plated Copper Clad Steel per ASTM B520 |
