M27 Washers | McMaster-Carr

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.

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



	M27	28.0	50.0	3.7 to 4.3	DIN 125	1	000000000	00000

Steel

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



	M27	30.0	50.0	3.4 to 4.6	DIN 126, ISO 7091	5	000000000	00000

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

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.

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



	M27	28.0	60.0	9.0 to 11.0	DIN 7349	1	000000000	00000


	Steel



			M27	30.0	98.0	5.0 to 7.0	DIN 440-R	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.

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



	M27	27.300	31.900	1.8 to 2.2	DIN 7603	10	000000000	000000


	M27	30.000	38.000	2.8 to 3.2	—	1	000000000	00000


	Aluminum



			M27	30.000	38.000	2.8 to 3.2	—	10	000000000	00000

Structural Washers

Distribute pressure under structural screws and nuts in columns, joists, and I-beams. These thick washers are tested and certified to meet industry standards for handling high-stress loads.

Steel

Image of Product. Front orientation. Washers. Structural Washers.

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

Corrosion-Resistant Galvanized Steel—These washers combine the strength of steel with the rust resistance of stainless steel. They're an economical alternative to 18-8 stainless steel in wet and outdoor environments, but they won't hold up to salt water and chemicals.

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.
Steel



	M27	28.0	50.0	4.4 to 5.6	ISO Class 10.9	DIN 6916, ISO 7416	1	000000000	00000


	Corrosion-Resistant Galvanized Steel



			M27	28.0	50.0	4.4 to 5.6	ISO Class 10.9	DIN 6916, ISO 7416	1	000000000	0000

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.

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

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

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



	M27	27.5	43.0	4.8 to 5.2	DIN 127B	5	000000000	000000


	Zinc-Plated Steel



			M27	28.5	43.0	4.8 to 5.2	DIN 127B	10	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



	M27	1.120"	1.650"	0.260" to 0.280"	1	000000000	000000


	Highly Corrosion-Resistant Zinc-Flake-Coated Steel



			M27	1.120"	1.650"	0.220" to 0.240"	1	000000000	00000


			M27	1.120"	1.910"	0.220" to 0.240"	1	000000000	00000

Heavy-Vibration-Resistant Spring Lock Washers for Socket Head Screws

Stop socket head screws from wiggling loose on equipment with constant, vigorous vibration, such as engines, turbines, and generators. These washers have a small diameter to fit under screws with narrow heads. Similar to a spring, they flatten under pressure to add tension between mating surfaces. As long as the washers aren't deformed or otherwise damaged, you can reuse them indefinitely without losing locking strength. Also known as conical washers and Belleville washers.

Stack multiple washers in the same direction to double or triple how much weight they can bear. Stack washers in opposite directions for better deflection, which means they compress further and withstand more shock and movement without loosening.

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.

Top-and-Bottom Serration—Adds friction for extra gripping power.

	ID	OD	Thk.	Overall Ht.	Serration Location	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	1 1/16", M27	1.126"	1.535"	0.071"	0.122"	Top and Bottom	5	000000000	000000


	Steel



			M27	1.126"	1.535"	0.071"	0.122"	Top and Bottom	5	000000000	00000

Heavy-Vibration-Resistant Spring Lock Washers

With a grip that's second only to wedge lock, these washers stop nuts and screws from wiggling loose under constant, vigorous vibration. They are ideal for engines, turbines, generators, and other heavy duty equipment. Similar to a spring, they flatten under pressure to add tension between mating surfaces. As long as the washers aren't deformed or otherwise damaged, you can reuse them indefinitely without losing locking strength. Also known as conical washers and Belleville washers.

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.

DIN 432—These washers have a small tab that presses up against the flats of your nut or screw for extra security.

	ID, mm	OD, mm	Thk., mm	Overall Ht., mm	Specs. Met	Pkg. Qty.		Pkg.
Highly Corrosion-Resistant 316 Stainless Steel



	M27	28.0	58.0	1.6	9.5	DIN 432	1	000000000	000000

Tension-Indicating Structural Washers

Fasten structural screws and nuts securely without overtightening. When you see orange dye, you'll know you've applied the correct tension, so you don't accidentally strip threads. These washers distribute pressure under fasteners in columns, joists, and I-beams. They are tested and certified to meet industry standards for handling high-stress loads.

Steel

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

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



	M27	28.4	54.4	4.0 to 7.0	ISO Class 10.9	ASME B18.2.6M, ASTM F959	1	000000000	00000


	Corrosion-Resistant Galvanized Steel



			M27	28.4	54.4	4.0 to 7.0	ISO Class 8.8	ASME B18.2.6M, ASTM F959	1	000000000	0000

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.

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

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.
Zinc-Plated Steel



	M27	28.5	38.9	4.8 to 5.2	DIN 7980	5	000000000	00000


	Black-Oxide Steel



			M27	28.5	38.9	4.8 to 5.2	DIN 7980	5	000000000	0000