M28 Washers | McMaster-Carr

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FDA Compliant 21 CFR 177.2600

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5 Products

Oversized Washers

These washers have exaggerated diameters to cover large holes and to compensate for uneven mounting surfaces. They are also thicker than general purpose washers, so they bridge wide gaps when used as spacers.

Steel

Image of Product. Front orientation. Washers. Oversized Washers.

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

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


	M28	28.0	42.0	4.4 to 5.6	DIN 1440, ISO 8738	5	000000000	000000

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.

Rubber

Resist leaks better than metal sealing washers, but are more susceptible to wear and tear. Reuse these washers a handful of times, as long as the material isn't damaged.

Weather-Resistant EPDM—The best choice for outdoor use, these washers withstand long-term exposure to sunlight, rain, and ozone. However, they can't handle oil, grease, or fuel like Buna-N washers can.

					Temp. Range, ° F
	For Screw Size	ID, mm	OD, mm	Thk., mm	Min.	Max.	Color	Food Industry Std.	Pkg. Qty.		Pkg.
Weather-Resistant EPDM


		M28	29.000	50.000	1.190 to 1.950	-50	300	White	FDA Compliant 21 CFR 177.2600	5	000000000	000000

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.

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


	M28	28.300	35.900	1.3 to 1.7	DIN 7603	5	000000000	000000

	Cellulose-Filled Copper


			M28	28.300	33.900	2.3 to 2.7	DIN 7603	5	000000000	00000

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
				M28	28.000	50.000	1.000	7.000	2.500	5.000	Not Rated	DIN 462	DIN 1804	000000000	00000