Hex Nut Lock Washers | McMaster-Carr

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82 Products

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Corrosion Resistant

Won't rust in wet and outdoor environments

26 products

Hex Nut Profile

Standard

The most common profile of locknut

79 products

Hex Nut Profile

Narrow

20% narrower than other nuts to fit in cramped spaces

3 products

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Assortment

A range of sizes to fasten a variety of parts

2 products

Locknuts with External-Tooth Lock Washer

To save on assembly time, these locknuts combine a hex nut with a free-spinning lock washer, so you can twist them into place by hand. Once the nut is against your material surface, tighten it down with a wrench or socket to get the teeth to bite. Although these nuts install more quickly than nylon-insert locknuts, they don't hold up as well against vibration and can mar your material. As long as the washer stays intact, you can reuse them. Also known as Keps and K-lock nuts.

Medium-Strength Steel

These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

Black-Zinc-Plated Steel—The dark zinc plating withstands occasional exposure to moisture while creating a finished look.

	Wd., mm	Ht., mm	Fastener Strength Grade/Class	Washer OD, mm	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	M3 × 0.5 mm	5.5	3.3	Class 8	7.1	100	93825A110	000000


	M4 × 0.7 mm	7	4.1	Class 8	8.5	100	93825A120	00000
	M5 × 0.8 mm	8	5.2	Class 8	9.5	100	93825A130	00000
	M6 × 1 mm	10	6.2	Class 8	12	100	93825A140	00000
	M8 × 1.25 mm	13	8.5	Class 8	15.5	25	93825A160	0000
	M10 × 1.5 mm	17	9.7	Class 8	20.1	10	93825A170	00000


	Black-Zinc-Plated Steel



			M3 × 0.5 mm	5.5	3	Class 8	7.1	100	93825A210	00000


			M4 × 0.7 mm	7	4.1	Class 8	8.5	100	93825A220	00000
			M5 × 0.8 mm	8	5.2	Class 8	9.5	100	93825A230	00000
			M6 × 1 mm	10	6.2	Class 8	12	50	93825A240	00000
			M8 × 1.25 mm	13	8.5	Class 8	15.5	25	93825A250	00000
			M10 × 1.5 mm	17	9.7	Class 8	20.1	10	93825A260	00000

Low-Strength Steel

Rated Grade 2, Class 6, or lower, these locknuts are about half as strong as medium-strength steel nuts. Use them with screws that have a similar strength rating to avoid stripping threads during installation.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

Black-Zinc-Plated Steel—The dark zinc plating withstands occasional exposure to moisture while creating a finished look.

	Wd.	Ht.	Washer OD	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	4-40	1/4"	7/64"	0.281"	100	90675A005	00000


	5-40	5/16"	9/64"	0.344"	100	90675A245	0000
	6-32	5/16"	9/64"	0.344"	100	90675A007	0000
	8-32	11/32"	5/32"	0.375"	100	90675A009	0000
	10-24	3/8"	5/32"	0.406"	100	90675A011	0000
	10-32	3/8"	5/32"	0.406"	100	90675A195	0000
	12-24	7/16"	3/16"	0.5"	50	90675A255	0000
	1/4"-20	7/16"	15/64"	0.5"	100	90675A029	0000
	1/4"-28	7/16"	15/64"	0.5"	100	90675A215	0000
	5/16"-18	1/2"	21/64"	0.578"	100	90675A030	00000
	5/16"-24	1/2"	5/16"	0.592"	50	90675A225	00000


	3/8"-16	9/16"	25/64"	0.656"	100	90675A031	00000
	3/8"-24	9/16"	25/64"	0.656"	100	90675A235	00000
	1/2"-13	3/4"	31/64"	0.891"	10	90675A265	0000


	Black-Zinc-Plated Steel



			4-40	1/4"	1/8"	0.281"	100	90328A101	0000


			6-32	5/16"	9/64"	0.344"	100	90328A102	0000
			8-32	11/32"	5/32"	0.375"	100	90328A103	0000
			10-24	3/8"	5/32"	0.406"	100	90328A104	0000
			10-32	3/8"	5/32"	0.406"	100	90328A105	0000
			1/4"-20	7/16"	7/32"	0.5"	100	90328A106	00000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

Black-Oxide 18-8 Stainless Steel—Typically chosen for their appearance, these nuts have a dark, matte coating to create a finished look. They resist rust in wet and outdoor environments, but won't hold up to the harsh chemicals that 316 stainless steel can.

	Wd.	Ht.	Washer OD	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	4-40	1/4"	1/8"	0.281"	100	96278A005	000000


	4-48	1/4"	1/8"	0.281"	100	96278A101	00000
	6-32	5/16"	9/64"	0.344"	100	96278A007	00000
	8-32	11/32"	11/64"	0.375"	100	96278A009	00000
	10-24	3/8"	11/64"	0.406"	100	96278A011	00000
	10-32	3/8"	11/64"	0.406"	100	96278A411	00000
	12-24	7/16"	11/64"	0.506"	50	96278A111	00000
	1/4"-20	7/16"	15/64"	0.5"	50	96278A511	00000
	1/4"-28	7/16"	15/64"	0.5"	50	96278A515	00000
	5/16"-18	1/2"	21/64"	0.578"	25	96278A519	0000
	5/16"-24	1/2"	21/64"	0.578"	25	96278A523	00000


	3/8"-16	9/16"	25/64"	0.656"	25	96278A527	00000
	3/8"-24	9/16"	25/64"	0.656"	10	96278A531	0000
	1/2"-13	3/4"	7/16"	0.898"	10	96278A112	0000
	M3 × 0.5 mm	5.5 mm	3.3 mm	6.5 mm	50	90923A216	00000
	M4 × 0.7 mm	7 mm	4.1 mm	8.2 mm	50	90923A219	00000
	M5 × 0.8 mm	8 mm	5.2 mm	9.5 mm	25	90923A222	0000
	M6 × 1 mm	10 mm	6.2 mm	11.5 mm	25	90923A227	0000
	M8 × 1.25 mm	13 mm	8.5 mm	15.1 mm	5	90923A241	0000
	M10 × 1.5 mm	17 mm	9.7 mm	19.2 mm	5	90923A282	00000


	Black-Oxide 18-8 Stainless Steel



			M3 × 0.5 mm	5.5 mm	3.3 mm	6.5 mm	25	90923A231	0000


			M4 × 0.7 mm	7 mm	4.1 mm	8.2 mm	25	90923A232	00000
			M5 × 0.8 mm	8 mm	5.2 mm	9.5 mm	25	90923A233	00000
			M6 × 1 mm	10 mm	6.2 mm	11.5 mm	25	90923A234	00000

Locknuts with Spring-Lock Washer

The curved, spring-like washer grips surfaces more tightly than tooth-lock washers for better vibration resistance. These locknuts also install just as quickly since you can twist them into place by hand. Once the nut is against your material, tighten it down with a wrench or socket. The washer's smooth edges won't mar the surface like teeth can. As long as the washer stays intact, you can reuse these locknuts.

Medium-Strength Steel

These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

Black-Oxide Steel—Typically chosen for their appearance, these nuts have a dark, matte coating to create a finished look. They offer minimal corrosion resistance, so they're best for dry environments.

	Wd., mm	Ht., mm	Fastener Strength Grade/Class	Washer OD, mm	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	M3 × 0.5 mm	5.5	3.8	Class 8	8	50	91270A250	000000


	M4 × 0.7 mm	7	4.2	Class 8	10	100	91270A310	00000
	M5 × 0.8 mm	8	5.3	Class 8	12	100	91270A320	00000
	M6 × 1 mm	10	6.6	Class 8	14	50	91270A330	0000
	M8 × 1.25 mm	13	8.8	Class 8	18	50	91270A340	00000
	M10 × 1.5 mm	17	10.7	Class 8	22	10	91270A350	00000
	M12 × 1.75 mm	19	13.8	Class 8	25.5	25	91270A360	00000


	Black-Oxide Steel



			M3 × 0.5 mm	5.5	3.5	Class 8	10	50	91270A260	00000


			M4 × 0.7 mm	7	4.2	Class 8	10	50	91270A270	00000
			M5 × 0.8 mm	8	5.3	Class 8	12	50	91270A280	00000
			M6 × 1 mm	10	6.6	Class 8	14	25	91270A290	0000

Low-Strength Steel

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

	Wd.	Ht.	Washer OD	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	4-40	1/4"	9/64"	0.328"	25	95170A350	000000


	6-32	5/16"	9/64"	0.328"	25	95170A355	00000
	8-32	11/32"	3/16"	0.375"	50	95170A360	00000
	10-32	3/8"	3/16"	0.406"	25	95170A370	00000
	1/4"-20	7/16"	3/16"	0.5"	10	95170A390	00000


	Black-Oxide Steel



			4-40	1/4"	9/64"	0.328"	50	92087A110	00000


			6-32	5/16"	9/64"	0.328"	25	92087A120	00000
			8-32	11/32"	3/16"	0.375"	10	92087A130	00000
			10-32	3/8"	3/16"	0.406"	10	92087A140	0000
			1/4"-20	7/16"	3/16"	0.5"	10	92087A150	00000

Assortments of Locknuts with External-Tooth Lock Washer

With a range of sizes on hand, you can use these assortments to fasten a variety of parts. These locknuts combine a hex nut with a free-spinning lock washer, so you can twist them into place by hand and save on assembly time. Once the nut is against your material surface, tighten it down with a wrench or socket to get the teeth to bite. Although these nuts install more quickly than nylon-insert locknuts, they don't hold up as well against vibration and can mar your material. As long as the washer stays intact, you can reuse them. Also known as Keps and K-lock nuts.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

	Locknuts Included	Container Type		Each
Zinc-Plated Steel



	600	4-40 (100 Pieces) 6-32 (100 Pieces) 8-32 (100 Pieces) 10-24 (100 Pieces) 10-32 (100 Pieces) 1/4"-20 (100 Pieces)	Plastic Box	90740A106	000000


	18-8 Stainless Steel



			600	4-40 (100 Pieces) 6-32 (100 Pieces) 8-32 (100 Pieces) 10-24 (100 Pieces) 10-32 (100 Pieces) 1/4"-20 (100 Pieces)	Plastic Box	90625A500	00000

Narrow-Profile Locknuts with External-Tooth Lock Washer

Since they're about 20% narrower, these locknuts fit in tight spaces where standard-profile nuts won't fit. They combine a hex nut with a free-spinning lock washer, so you can twist them into place by hand and save on assembly time. Once the nut is against your material surface, tighten it down with a wrench or socket to get the teeth to bite. Although these nuts install more quickly than nylon-insert locknuts, they don't hold up as well against vibration and can mar your material. As long as the washer stays intact, you can reuse them. Also known as Keps and K-lock nuts.

Low-Strength Steel

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

	Wd.	Ht.	Washer OD	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	6-32	1/4"	1/8"	0.281"	100	90413A101	000000


	8-32	5/16"	9/64"	0.344"	100	90413A102	00000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

	Wd.	Ht.	Washer OD	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	6-32	1/4"	1/8"	0.287"	100	96278A113	000000