Provides a bearing surface thus minimizing surface wear
Distributes fastener loads evenly to minimize surface deformation (when tightening fasteners)
Conducts electricity
May cover large clearance holes
Has more compression strength and can handle higher forces than non-metallic
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Aluminum 5712
Light weight — 1/3 the weight of steel
Good sealing capability
Non-magnetic
Good electrical conductor (30% copper)
Good heat conductor (70 btu/hr/sq ft/°F/ft)
May be anodized to increase corrosion resistance and is available in a wide variety of colors
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Beryllium Copper 5718
Good electrical conductor (17-22% copper)
May be heat treated for higher strength
Corrosion resistant
Non-magnetic
Good heat conductor (68 btu/hr/sq ft/°F/ft)
Good vase metal for plating
Excellent spring material
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Brass 5714
Good electrical conductor (26% copper)
Non-magnetic
Excellent plating base
Corrosion resistant — especially in a marine environment
Good heat conductor (70 btu/hr/sq ft/°F/ft)
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Copper 5716
Excellent electrical conductor (100% copper)
Excellent sealing capability
Corrosion resistant
Good plating base
Excellent thermal conductivity (225 btu/hr/sq ft/°F/ft)
Non-magnetic
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Phosphor Bronze 5720
Good bearing surface
Non-magnetic
Good electrical conductor (15% copper)
High strength
High temperature resistance
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Steel 5702
Least expensive metallic washer
Good plating base
Fair electrical conductor (12% copper)
Most commonly used material
Highest strength for cost
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Stainless Steel 5710
Excellent corrosion resistance
May be passivated for increased corrosion resistance
High strength
Low magnetic permeability — can vary with alloy and temper
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Titanium 5706
Extreme high temperature applications
Corrosion resistant
Quite expensive
High strength to weight ratio
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| Covers large
clearance holes.
|
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| The terms washer, shim and spacer are essentially interchangeable and often dictated by personal preference. |
| |
| |
| Covers large clearance holes. |
| |
| The terms washer, shim and spacer are essentially interchangeable and often dictated by personal preference. |
| Non-Metallic Flat Washers | |||||||
| A flat disc with centrally located hole. Electrical and thermal insulation or isolation. Sealing — because they can conform to the surface configuration. Cushioning — because of elastic or plastic properties. Protects surface finishes. ______________________________________________ ______________________________________________ Acetal 5614 Good electrical insulator (400-465 v/mil) Low water absorption rate Good cold flow resistance High strength for a non-metallic Good bearing qualities High toughness ______________________________________________ ______________________________________________ Fibre 5602 Low cost Fair electrical insulator (150-250 v/mil) Fair mechanical properties Good thermal conductivity for a non-metallic (.25 btu/hr/sq ft/°F/ft) Good cold flow resistance Not recommended for humid environments ______________________________________________ ______________________________________________ Fibreglass • Epoxy 5621 Good electrical insulator (400 v/mil) High mechanical strength at room temperature Low water absorption rate Good dimensional stability Not recommended for extremely high compression applications ______________________________________________ ______________________________________________ • Melamine 5621 Good thermal conductivity for a non-metallic (.29 btu/hr/sq ft/°F/ft) Best mechanical properties of fibreglass Good electrical insulator (350 v/mil) particularly in humid environments Good dimensional stability Non recommended for extremely high compression applications ______________________________________________ ______________________________________________ Kapton 5611 Excellent electrical insulator (700 v/mil) Good for high temperature applications High dimensional stability ______________________________________________ ______________________________________________ Mica 5624 Excellent electrical insulator (3000-6000 v/mil) Excellent for high temperature applications Relatively expensive to fabricate Material tends to flake and chip ______________________________________________ ______________________________________________ Mylar 5622 Extremely good electrical insulator (4000 v/mil) Less expensive alternate to Kapton for lower temperature applications Good dimensional stability ______________________________________________ ______________________________________________ Neoprene 5613 Cushioning properties Excellent abrasion resistance Good oil & gasoline resistance Excellent flame resistance Excellent sealing qualities Resilient — tear resistant ______________________________________________ ______________________________________________ Nylatron (Molybdenum disulfide impregnated nylon) 5615 Excellent anti-frictional properties Heat resistant to 400°F Stronger than nylon and better dimensional stability Not recommended for an electrical insulator ______________________________________________ ______________________________________________ Nylon (Polyamide) 5610 Good electrical insulator (385 v/mil) High strength Good anti-fractional properties Heat resistant to 300°F ______________________________________________ ______________________________________________ Phenolics |
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