Combination Tooth Internal-External Lock Washers: Dimensions & Specifications

Combination Tooth Internal-External Lock Washers Drawing

Combination Tooth Internal-External Lock Washers (ASME B18.21.1 2009)

 

Nominal Washer Size

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A

B

C

 Inside Diameter (ID)

 Outside Diameter * (OD)

Thickness (TH)
Max Min Max Min Max Min
4 0.112 0.123 0.115 0.475 0.460 0.021 0.016
6 0.138 0.150 0.141 0.510 0.495 0.028 0.023
8** 0.164 0.176 0.168 0.506 0.494 0.028 0.023
8 0.164 0.176 0.168 0.610 0.580 0.034 0.028
10 0.190 0.204 0.195 0.610 0.580 0.034 0.028
1/4 0.250 0.267 0.256 0.760 0.725 0.040 0.032
5/16 0.312 0.332 0.320 0.900 0.865 0.040 0.032
3/8 0.375 0.398 0.384 0.985 0.965 0.045 0.037
7/16 0.438 0.464 0.448 1.070 1.045 0.050 0.042
1/2 0.500 0.530 0.512 1.260 1.220 0.055 0.047
5/8 0.625 0.663 0.640 1.410 1.380 0.060 0.052

 

*Industry standards allow for washers with larger outside diameter dimensions.
**ITW Shakeproof specification, not ASME B18.21.1


Description


A circular washer with twisted prongs or teeth protruding from both the washer's inner as exterior edges
(see diagram above).

Applications/
Advantages

Lockwasher preferred in the following circumstances: (1) where a bigger bearing surface is desired;
(2) for optimum electrical connection; (3) where the hole is over-sized or out- of-round;(4) as an insert between two adjustable parts where a longitudinal or rotational adjustment is required.

Material

Steel: SAE 1050 - 1065 spring steel. 
18-8 Stainless: SAE 301 - 305 stainless steel.
Hardness

Steel: Rockwell C40 - 50.
18-8 Stainless: Annealed 88 minimum Rockwell B, 1/4 hard through full hard Rockwell C20 - 45.
Plating

Steel: See more information above on the plating of steel lock washers.
Stainless: Stainless lock washers are usually plain or furnished with a black oxide conversion finish.