ASME B18.21.1:2009 pdf download Washers: Helical Spring-Lock , Tooth Lock , and Plain Washers Inch Series
2.6Coiling: Helical Spring-Lock Washers
Washers shall be coiled to form a helix.The gap andrelationship of the severed ends shall be such as to pre-vent washers from tangling and to ensure that washerscompress flatly.
2.7 Processing: Helical Spring-Lock Washers
2.7.1 Finishes: Helical Spring-Lock Washers.Unlessotherwise specified by the purchaser, lock washers shallbe supplied with a plain (as-processed) finish, not platedor coated. Where corrosion preventative treatment isrequired, washers shall be plated or coated as specifiedby the purchaser. When helical spring-lock washers areto be furnished with coatings over 0.0005 in. thick andare to be used with bolts or screws also having thickercoatings, they are to be coiled to limits of 0.020 in. inexcess of those specified in Tables 1 through 4 for mini-mum inside diameter and maximum outside diameter.Heavy coating of washers under / in. nominal size isnot recommended.
2.7.2 Embrittlement: Helical Spring-Lock Washers.Electroplating carbon and boron steel-lock washers isnot recommended because of the possibility of hydrogenembrittlement failures. When the purchaser specifieselectroplated lock-washers they must be baked afterplating using times and temperatures suitable for reliev-ing potentially trapped hydrogen. All lots of electro-plated lock-washers shall be tested by compressing themto a flat condition for a minimum of 48 hr, within whichtime they must not fracture.Compression shall beaccomplished between parallel flat surfaces.
2.8 Workmanship: Helical Spring-Lock Washers
The flat surfaces (faces) of helical spring-lock washersshall be free from such surface imperfections as knurling,serrations, die marks, deep scratches, loose scale, burrs,or other irregularities that would affect serviceability.Moderate feed roll marks shall be permissible on theouter periphery.
2.9 Twist Tests: Helical Spring-Lock Washers
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.A90-deg maximum segment of the free end of the washershall be gripped in wrench jaws so at least 25% of thewasher is exposed when twisting, as shown in Fig. 2.Edges of the wrench jaws shall be in a plane parallel tothe vise. Movement of the wrench that increases the freeheight of the spring-lock washer shall twist carbon steel,boron steel, and alloy steel washers through an angleapproximating 90 deg, and corrosion resistant steel andnonferrous washers through an angle approximating45 deg with no sign of fracture.
3 GENERAL DATA FOR TOOTH-LOCK WASHERS3.1 Application: Tooth-Lock Washers
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 Design: Tooth-Lock Washers
The selection of Type A or Type B tooth designs asshown in Fig. 3 and in Tables 6 through 10 shali be atthe manufacturer’s option unless a specific design isdesignated by the purchaser.
The number of teeth, the length of the teeth, the widthof the rim, and the thickncss of the washer over the teeth(free height) shall be optional with the manufacturer. Theprojection of the teeth on both sides of the washer shallbe relatively uniform.
3.3 Styles and Dimensions: Tooth-Lock WashersDimensions for the various types of washers are asfollows; internal tooth-lock washers (Table 6), heavyinternal tooth-lock washers (Table 7), external tooth-lockwashers (Table 8), external tooth countersunk washers(Table 9), and internal / external tooth lock washers(Table 10).
3.4 Material and Hardness: Tooth-Lock Washers3.4.1 Material Composition: Tooth-Lock Washers.Washers shall be made from material meeting thechemi-cal composition requirements of one of the followingstandards:
(a)Carbon Steel. SAE J403 1050-1065(UNS G10500-
G10650).
(b) Stainless Steel. SAE J405301-305 (UNS S30100-S30500) or SAE J405 316(UNS S31600).
(c)Stainless Steel.SAE J405 410 (UNS S41000).
(d)Copper Alloy. ASTMB 591 Type 425(UNSC42500).Other materials and grades shail be as agreed uponby the supplier and purchaser.
3.4.2 Hardness: Tooth-Lock Washers. Washers thatare manufactured from carbon steel that show evidenceof decarburization, or parts that were plated, shall havethese surface layers removed before checking. Duringthis operation,care shall be exercised to prevent thesurface temperature of the washer from exceeding 250°E.lt is recommended that the lighter, more sensitive depthreading HRA scale be used in lieu of HRC when testingwashers of a thin section. Hardness requirements appli-cable to washers of the respective materials shall be asfollows. Refer to ASTM E 140 for hardness conversions:(a)Carbon Steel. 40 HRC to 50 HRC,392 HV to 513HV.(b) Stainless Steel 301-305. Annealed 88 minimumHRB, 1%4 hard through full hard 20 HRC to 45 HRC.(c)Stainless Steel 410.40 HRC to 50 HRC,392 HV to513 HV.
(d) Copper Alloy.Temper HO6 minimum.
3.5 Designation: Tooth-Lock Washers
Nominal washer sizes are intended for use with com-parable screw or nut sizes.Fasteners conforming to thisStandard shall be designated by the following data, in
ASME B18.21.1:2009 pdf download
