M42 Washers | McMaster-Carr

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For Bearing Nut Specifications Met

DIN 1804

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2.500 mm

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Minimum Temperature

14 Products

General Purpose Washers

Your go-to metal washer for every screw size. Washers take the pressure off nuts and screws to protect mounting surfaces.

Stainless Steel About Stainless Steel

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

Highly-Corrosion-Resistant 316 Stainless Steel—Superior to 18-8 stainless steel, these washers won't degrade when exposed to harsh weather, salt water, and most chemicals.

	ID, mm	OD, mm	Thk., mm	Specs. Met	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	M42	43.0	78.0	6.0 to 8.0	DIN 125, ISO 7089	1	000000000	00000


	Highly-Corrosion-Resistant 316 Stainless Steel



			M42	43.0	78.0	6.0 to 8.0	DIN 125, ISO 7089	1	000000000	0000

Steel

Zinc-Plated Steel—A common choice for areas with occasional exposure to moisture.

Steel—Best for dry environments since moisture will cause these washers to rust.

For Fastener Strength Grade/Class—If you require screws or nuts with a specific fastener strength rating, make sure your washer matches the grade or class.

	ID, mm	OD, mm	Thk., mm	For Fastener Strength Grade/Class	Specs. Met	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	M42	43.0	78.0	6.0 to 8.0	—	DIN 125, ISO 7090	1	000000000	00000


	M42	43.0	78.0	6.0 to 8.0	ISO Class 8.8	DIN 125, ISO 7089	1	000000000	00000


	Steel



			M42	45.0	78.0	5.8 to 8.2	—	DIN 126, ISO 7091	1	000000000	0000

Sealing Washers

Prevent leaks while distributing weight evenly under nuts and screws. These washers compress as you tighten to keep air and fluid in, and dust and contaminants out. Use them anywhere you need a tight seal, such as protecting electronics from moisture or keeping lubricants contained in machinery.

Metal

Also known as crush washers, these are made of soft metal that deforms under pressure to fill gaps around the nut or screw. Often found in oil drain valves, they withstand stress and wear better than plastic and rubber washers, but aren't as leak-resistant. Metal sealing washers are not reusable.

Copper—Softer than aluminum washers, these deform easily to create a tight seal with less effort. They resist rusting in corrosive environments, but will develop a green patina over time.

Cellulose-Filled Copper—The easiest washers to crush. These washers are embedded with cellulose, which makes them more flexible than other metal washers for a tighter seal. They resist rusting in corrosive environments, but will develop a green patina over time.

Aluminum—These washers are an economical alternative to copper. They have similar corrosion resistance but require more effort to crush.

	ID, mm	OD, mm	Thk., mm	Specs. Met	Pkg. Qty.		Pkg.
Copper



	M42	42.300	48.900	1.8 to 2.2	DIN 7603	1	000000000	000000


	Cellulose-Filled Copper



			M42	42.300	48.900	2.3 to 2.7	DIN 7603	1	000000000	00000


			Aluminum



					M42	45.000	53.000	2.8 to 3.2	—	5	000000000	00000

Plastic Washers

All of these washers are lightweight, nonconductive, and naturally rust resistant. They are commonly used in electronics and automation applications to take the pressure off screws and nuts and protect mounting surfaces.

Chemical-Resistant High-Temperature PTFE—The most chemical-resistant plastic washers we offer, these stand up to the widest range of harsh acids, bases, solvents, and corrosive cleaners, even at temperatures up to 500° F. Their slippery surface reduces friction between the washer, fastener, and mounting surface to prevent sticking when tightening and loosening. They are also good electrical insulators.

					Temp. Range
	For Screw Size	ID, mm	OD, mm	Thk., mm	Min.	Max., ° F	Color	Pkg. Qty.		Pkg.
Chemical-Resistant High-Temperature PTFE



		M42	43.0	78.0	1.4 to 1.8	Not Rated	500	White	1	000000000	000000

Bearing Spring Lock Washers for Slotted Bearing Nuts


	For Stepped Nuts

Designed for use with bearing nuts, these lock washers have a conical shape that presses like a spring against bearings, bushings, gears, and pulleys to hold them in place on your threaded shaft or spindle. They also have an inner tab that sits in the shaft or spindle’s keyway to prevent the nut from loosening.

Steel—Steel washers are strong and flexible.

DIN 462—DIN 462 and DIN 5406 washers meet international standards for lock washer dimensions. Pair DIN 462 washers with DIN 1804 bearing nuts, and DIN 5406 washers with DIN 981 bearing nuts.

					Tab, mm
	For Screw Size	ID, mm	OD, mm	Thk., mm	Wd.	Dp.	Overall Ht., mm	Hardness	Specs. Met	For Bearing Nut Specs. Met		Each
For Stepped Nuts







				Steel

				M42	42.000	62.000	1.200	8.000	2.500	5.000	Not Rated	DIN 462	DIN 1804	000000000	00000

Extreme-Vibration-Resistant Wedge Lock Washers

When it's critical to keep bolted assemblies secure, choose these two-piece lock washers with the tightest grip of all. They stop nuts and screws from loosening in heavy machinery that experiences jarring starts and stops, such as compressors and compactors. Serrations on the outside bite into the fastener and mating surfaces, while wedges on the inside lock the two pieces together. When the nut or screw starts to loosen, the wedges drive more tightly together to maintain tension. You can reuse these washers up to fifteen times, as long as the serrations and wedges are not worn down. They are comparable to NORD-LOCK® or Sherex TEC® washers.

Wedge Lock

Highly-Corrosion-Resistant 316 Stainless Steel—Superior to 18-8 stainless steel, these washers won't degrade when exposed to harsh weather, salt water, and most chemicals.

Highly-Corrosion-Resistant Zinc-Flake-Coated Steel—With 40 times the corrosion resistance of zinc-plated steel, these withstand rust as well as 316 stainless steel. They have been tested to extreme standards, including 1,000 hours of salt spray. They are similar to Magni-coated washers.

	ID	OD	Thk.	Pkg. Qty.		Pkg.
Highly-Corrosion-Resistant 316 Stainless Steel



	M42	1.700"	2.480"	0.260" to 0.280"	1	000000000	000000


	Highly-Corrosion-Resistant Zinc-Flake-Coated Steel



			M42	1.700"	2.480"	0.250" to 0.270"	1	000000000	00000

Split Lock Washers

Stop nuts and screws from loosening due to mild vibration. As you tighten, the uneven ends bite into the nut or screw so it won't back out. While they're not as vibration resistant as other lock washers, they are a great fit for electrical panels, light fixtures, and other light duty assemblies. Split lock washers are not reusable, and they only work with fasteners that have right-hand threads.

Zinc-Plated Steel—A common choice for areas with occasional exposure to moisture.

	ID, mm	OD, mm	Thk., mm	Specs. Met	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	M42	43.7	68.2	6.8 to 7.2	DIN 127B	1	000000000	000000

Split Lock Washers for Socket Head Screws

Stop socket head screws from loosening due to mild vibration. These washers have a small diameter to fit under screws with narrow heads, but are still thick enough to keep fasteners secure. While they're not as vibration resistant as other lock washers, they are a great fit for electrical panels, light fixtures, and other light duty assemblies. Split lock washers are not reusable, and they only work with fasteners that have right-hand threads. Also known as high-collar lock washers.

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

	ID, mm	OD, mm	Thk., mm	Specs. Met	Pkg. Qty.		Pkg.
Black-Oxide Steel



	M42	43.7	60.2	7.7 to 8.3	DIN 7980	1	000000000	000000