ASME B18.21.1 pdf download LOCKVWASHERS (INCH SERIES)
2.7.1 Finishes. Unless otherwise specified by thepurchaser, lock washers shall be supplied with a plain(as processed) finish, not plated or coated. Wherecorrosion preventative treatment is required,washersshall be plated or coated as specified by the purchaser.When helical spring-lock washers are to be furnishedwith coatings over 0.0005 in. thick and are to be usedwith bolts or screws also having thicker coatings, theyare to be coiled to limits of 0.020 in. in excess ofthose specified in Tables 1 through 4 for minimuminside diameter and maximum outside diameter. Heavycoating of washers under ‘/4 in. nominal size is notrecommended.
2.7.2 Embrittlement. Carbon and boron steel-lockwashers that are electroplated or coated may be subjectto embrittlement and shall be suitably treated to mini.mize such embrittlement. Plated washers shall not fracture after having been compressed flat for a minimurnof 48 hr.
The flat surfaces (faces) of helical spring-lock washersshall be free from such surface imperfections asknurling, serrations, die marks, deep scratches, loosescale, burrs,or other irregularities that would affectserviceability. Moderate feed roll marks shall be permissible on the outer periphery.
2.9 Twist Tests
The washer shall be gripped in vise jaws. The endsof the washer shall be free, and an axis passing throughthe slot shall be parallel to and slightly above the topof the vise so less than 50% of the washer is gripped.A 90 deg maximum segment of the free end of the washer shall be gripped in wrench jaws so at least25% of the washer is exposed when twisting, as shownin Fig. 2. Edges of the wrench jaws shall be in aplane parallel to the vise. Movement of the wrenchthat increases the free height of the spring-lock washershall twist carbon steel, boron steel, and alloy steelwashers through an angle approximating 90 deg, andcorrosion resistant steel and nonferrous washers throughan angle approximnating 45 deg with no sign of fracture
3 GENERAL DATA FOR TOOTH-LOCKWASHERS
The tooth-lock washers covered in this Standard areintended for general application. The tooth-lock washersserve to increase the friction between the screw andthe assembly. Internal tooth-lock washers are preferredwhere it is desirable to provide a smooth periphery.
3.2 Tooth DesignThe Type A and Type B tooth designs shall beoptional.
Dimensions of internal tooth-lock washers, heavyinternal tooth-lock washers, external tooth-lock washers.and internal/external tooth lock washers shall be asspecified in Tables 6 through 10.
3.4 Material and Hardness
3.4.1 Material Composition. Washers shall bemade from material meeting the chemical compositionrequirements of one of the following standards: