Black Zinc Plated Nuts | McMaster-Carr

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29 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.

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.
Black-Zinc-Plated Steel



	M3 × 0.5 mm	5.5	3	Class 8	7.1	100	93825A210	000000


	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.

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.
Black-Zinc-Plated Steel



	4-40	1/4"	1/8"	0.281"	100	90328A101	00000


	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

Thin-Profile Nylon-Insert Locknuts

About half the height of standard-profile locknuts, these fit in spaces with low clearance. You can also use them as jam nuts by threading them against a hex nut to hold it in place. The nylon insert grips the screw to prevent loosening from moderate vibration without damaging threads. However, the insert may become brittle if exposed to high temperatures. These locknuts are reusable a handful of times, but the holding power decreases with each use.

Low-Strength Steel

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

	Wd.	Ht.	Insert Max. Temp., ° F	Pkg. Qty.		Pkg.
Black-Zinc-Plated Steel



	6-32	5/16"	1/8"	220	25	94627A110	00000


	8-32	11/32"	11/64"	220	25	94627A120	0000
	10-24	3/8"	11/64"	220	25	94627A130	0000
	10-32	3/8"	11/64"	220	25	94627A140	0000
	12-24	7/16"	13/64"	220	25	94627A150	0000
	1/4"-20	7/16"	13/64"	220	25	94627A160	0000
	5/16"-18	1/2"	1/4"	220	10	94627A170	0000
	3/8"-16	9/16"	17/64"	220	10	94627A180	0000

Low-Strength Steel Square Nuts

Large flat sides make these nuts easy to grip with a wrench and keep them from rotating in channels and square holes. About half the strength of medium-strength steel square nuts, use them in light duty fastening applications, such as securing access panels.

Black-Zinc-Plated Steel—Black-zinc-plated steel square nuts resist corrosion in wet environments and have a black finish that blends in with dark surfaces.

	Wd.	Ht.	Specs. Met	Pkg. Qty.		Pkg.
Black-Zinc-Plated Steel



	1/4"-20	7/16"	3/16"	—	100	94859A111	000000


	5/16"-18	9/16"	7/32"	—	50	94859A122	00000
	3/8"-16	5/8"	1/4"	—	50	94859A133	00000


	Black-Zinc-Plated Steel—Class 5



			M4 × 0.7 mm	7 mm	3 mm	DIN 557	25	96887A118	0000


			M5 × 0.8 mm	8 mm	4 mm	DIN 557	25	96887A119	0000
			M6 × 1 mm	10 mm	5 mm	DIN 557	25	96887A121	0000
			M8 × 1.25 mm	13 mm	6.5 mm	DIN 557	10	96887A122	0000
			M10 × 1.5 mm	17 mm	8 mm	DIN 557	10	96887A123	00000
			M16 × 2 mm	24 mm	13 mm	DIN 557	1	96887A125	0000