MATERIALS AND PLATING – The charts on the following pages show the availability of washers in the more popular materials. Many of these washers are available in other non-ferrous materials and non-metallics. In the appropriate materials availability columns, standard dash reference numbers are used for AN, MS and NAS parts as well as for some commercial parts to indicate the availability of these parts in the designated materials and finishes. For commercial parts, an “X” designation is used. (See figure 2.)

METRIC WASHERS – The many metric flat washers available from WCL are designated with an (M-) prefix for the metric screw or bolt size in the “Size” column. Metric washers are available in either DIN or ANSI/ASME B18.22M specifications and the relevant specification is indicated in the particular “Reference” column. (Example of M6 see Figure 2.) Material thicknesses on metric parts generally conform to conventional U.S. washer manufacturing tolerances unless the parts have been stamped from material produced to metric thickness.

WCL PART NUMBERS – Example: The Type A part shown in Figure 2 is expressed as follows:

– Washers are grouped by type and listed by size, first by I.D., then by O.D., then thickness. (See Figure 2).

SYMBOLS AND ABBREVIATIONS – In the appropriate materials availability columns for the parts on the following pages, standard dash numbers are used for AN, MS, and NAS parts, and for some commercial references, to indicate the availabili­ty of these parts in designated materials and finishes. Other non-ferrous and non-metallic washers are also available, see pages 31-35.

EXAMPLE – Here is a listing for one of the MS parts that appear among the 1/4″ diameter metallic flat washers on Page 17. In addition to the nominal dimensional data and basic part specifications, the listing shows the availability of this part in steel plated in the thickness specified (X), and in additional thickness as indicated by the * after the X. This specific part is also available in stainless steel, passivated and plated, as indicated by the appropriate dash numbers.

Figure 2

SizeI.D.O.D.ThicknessReference Part NumberSteel PlatedStainless Steel Pass. AN-MS-NAS Dash NumbersStainless Steel Plated AN-MS-NAS Dash NumbersBrass Plain AN-MS-NAS Dash NumbersBrass Plated AN-MS-NAS Dash NumbersAluminum Alloy Plain AN-MS-NAS Dash NumbersAluminum Alloy Chem Treat AN-MS-NAS Dash NumbersAluminum Alloy Anodize AN-MS-NAS Dash Numbers 
1/40.2660.6250.049TYPE AX*X*X*

The Type A washer, shown here is available in steel, brass and aluminum alloy plain in the designated thickness, and also additional thicknesses designated by an (*) asterisk next to the X.

“AVAILABLE” – This designates standard commercial parts in the predominant dimensions shown and in the materials designated by an “X” in the appropriate columns. Call for availability.

REFERENCE PART NUMBERS – Washers listed in the charts on the following pages are referenced to appropriate
commercial and government part numbers. The following observations on these particular references may be of help.

AMERICAN NATIONAL STANDARD WASHERS – Designated by ASME B18.22.1, these washers are of two types:A and B. Many washers are available in either narrow (-N), regular (-R), or wide (-W) series.

AN 960 – Most AN960 steel washers now in stock are made to Revision 21, which specifies steel to MIL-S-7952. Some remaining stock is made to Revision 18, which may still be used in accordance with the government’s “phase-in, phase-out” policy on most specification revisions. The entire 960 series will eventually be replaced by the NAS 1149 specification, which is now recommended for use in new designs. AN960 washers are stocked, in accordance with the specification, with CAD II plating. AN960 washers are also stocked in other materials and platings, including : Stainless Steel, passivated (-C) and black oxide (-XC); Brass (-B);Aluminum, plain (-D);Aluminum with a Chemical Film (-JD); and Aluminum Anodized (-KD).

AN 961– washers, having the same dimensions as the AN960 washers, appear in the Brass column and are available with either a Tin (-T or a Silver (-S) finish. Note the AN letters are not in the column and are designated by “961-1016.” (See Figure 3 Brass Plated column.)

AN 970 – washers have oversized outside diameters and are stocked in Steel, plated Cad II (yellow) or, commercially, with a zinc finish. (See Figure 3 for example in Steel and Stainless, AN 970-10 & -C10).

NAS 620 – washers are used to mount small items with vent radii and other interferences, most commonly found in electronic components. Stocked in steel, stainless steel, brass and aluminum.

NAS 1149 – this new specification was introduced in 1992 to eventually replace the AN960 specification which is now classified, per revision 21, as “inactive for new design.” This means that on all new products NAS1149 washers may be specified. AN960 washers may continue to be ordered and used in the ongoing production or repair of already designed products. NAS1149 duplicates most of the AN960 parts, but additional, material options permit specification of Titanium and other special high strength alloy materials. Selected NAS1149 parts are referenced in the following charts as an indication of the availability of this series. WCL stocks many of these washers and can supply detailed information and prints when requested. Boeing is one particular used who requires this series. (See Figure 3).

Figure 3

SizeI.D.O.D.ThicknessReference Part NumberSteel PlatedStainless Steel Pass. AN-MS-NAS Dash NumbersStainless Steel Plated AN-MS-NAS Dash NumbersBrass Plain AN-MS-NAS Dash NumbersBrass Plated AN-MS-NAS Dash NumbersAluminum Alloy Plain AN-MS-NAS Dash NumbersAluminum Alloy Chem Treat AN-MS-NAS Dash NumbersAluminum Alloy Anodize AN-MS-NAS Dash Numbers 
5/80.641.3120.01STK STDX

MS 15795 – designates general purpose washers and the Dash Numbers show Stainless Steel, Brass and Aluminum. Other materials are available, as well as conventional plated steel. Not specifically listed, but also available from stock are Copper (-500 series) and Nickel Copper alloy (-400 series). The NASM series supercedes the MS15795, but the part numbers remain the same.

MS 27183 – specifies general purpose washers in Steel, grades 1008 through 1020 ASTM-A109, #4 temper with Cadmium II plating. This series is also available commercially with zinc and other finishes. MS27183 supersedes MS 15795-200 series.

MS 51496 – these Army and Air Force customer numbers have a reduced outside diameter (narrow series) and are made from Stainless Steel, 20 HRC minimum, passivated, with a 2.0 magnetic permeability or less. This specification may be subject to modification by the Committee on MIL Specifications as a result of difficulties experienced in meeting some dimensional, material and hardness requirements.

MS 9321 and MS 9549 – made from AMS 5510 stainless steel in a variety of sizes.

MS 14151 – washers are made from Stainless Type 304 and are normally used in electrical and other non-corrosive applications.

MS 16212 – specifies a medium series washer made from non-magnetic Stainless having minimum tensile strength of 50, 000 psi.

N 400, N 401, N 402 – this series of washers are General Electric reference numbers for flat washers. Many of these G.E. part numbers cross over to MS series, but have tighter tolerances. WCL supplies MS series to G.E.’s tighter tolerances.

OTHER REFERENCED PART NUMBERS – washers meeting other specific OEM references are also shown. These include Martin Marietta, Boeing, Ordnance, etc. WCL offers many other Mil Spec parts, see High Strength-Heat Treated and Non-Metallic sections for numbers that fall under these categories.