28mm Springs | McMaster-Carr

Squeeze these springs and they’ll push right back to their original length. When compressed, they apply steady pressure to keep components securely in place. Release the pressure and they snap back instantly, just like the tip of a ballpoint pen.

Corrosion-Resistant 302 Stainless Steel—Won’t corrode from exposure to moisture and mild chemicals, including ammonia often found in cleaning solutions. These springs are easier to compress than steel, but can’t handle as high a load.

Highly Corrosion-Resistant 316 Stainless Steel—Our most corrosion-resistant stainless steel springs won't degrade when exposed to salt water and harsh chemicals. They're easier to compress than steel, but can’t handle as high a load.

	OD, mm	ID, mm	Wire Dia., mm	Compressed Lg. @ Max. Load, mm	Max. Load, lb.	Spring Rate, lbf/mm	End Type	Specs. Met	Pkg. Qty.		Pkg.
Corrosion-Resistant 302 Stainless Steel



	28	4.8	3.2	0.8	19.1	5.9	0.66	Closed	DIN 2095	5	00000000	000000


	Highly Corrosion-Resistant 316 Stainless Steel



			28	4.8	3.2	0.8	20.4	5	0.67	Closed and Ground	—	1	00000000	0000

Extension Springs

Loop End

The farther you stretch these springs, the harder they pull to bring the two ends back together. They're commonly used to tension cable, return an air cylinder to its starting point, or hold a door closed.

Loop End—The most secure attachment method. With fully closed loops, there's no risk of slipping off.

Spring Steel—Strong and resilient, but best suited for dry environments since moisture will cause these springs to rust.

Minimum Load—The amount of force required to start extending the spring.

Maximum Load—The amount of force required to fully extend the spring.

					Load, lb.
	Lg., mm	OD, mm	Wire Dia., mm	Extended Lg. @ Max. Load, mm	Min.	Max.	Spring Rate, lbf/mm	Pkg. Qty.		Pkg.
Loop End







				Spring Steel

				28	7.5	0.7	70.2	0.38	3.46	0.07	2	00000000	000000

Extension Spring Stud Anchors

A black-oxide finish provides these steel anchors with mild corrosion resistance. Attach an extension spring to an anchor and then thread the anchor into your part for a secure connection.

	Thread
	Size	Min. Lg., mm	Spacing	Lg., mm	Dia., mm	Hole Dia., mm		Each
Black-Oxide Steel



		M5 × 0.8 mm	19	Coarse	28	5	3	0000000	00000

Corrosion-Resistant Extension Spring Stud Anchors

These stainless steel stud anchors offer excellent corrosion resistance. Attach an extension spring to an anchor and then thread the anchor into your part for a secure connection.

	Thread
	Size	Min. Lg., mm	Spacing	Lg., mm	Dia., mm	Hole Dia., mm		Each
18-8 Stainless Steel



		M5 × 0.8 mm	19	Coarse	28	5	3	000000000	000000

Swiveling Extension Spring Stud Anchors

A black-oxide finish provides these steel anchors with mild corrosion resistance. The head swivels 360° so the spring stays straight and properly coiled. Attach an extension spring to an anchor and then thread the anchor into your part for a secure connection. To make tightening easier, anchors have a hex socket on the bottom and wrench flats at the top of the threads.

	Thread
	Size	Min. Lg., mm	Spacing	Lg., mm	Dia., mm	Hole Dia., mm	Hex Size, mm		Each
Black-Oxide Steel



		M5 × 0.8 mm	19	Coarse	28	5	3	1.5	000000000	000000

Corrosion-Resistant Swiveling Extension Spring Stud Anchors

These stainless steel stud anchors offer excellent corrosion resistance. The head swivels 360° so the spring stays straight and properly coiled. Attach an extension spring to an anchor and then thread the anchor into your part for a secure connection. To make tightening easier, anchors have a hex socket on the bottom and wrench flats at the top of the threads.

Certificates with a traceable lot number are available for these products. Download certificates from ORDER HISTORY after your order ships.

	Thread
	Size	Min. Lg., mm	Spacing	Lg., mm	Dia., mm	Hole Dia., mm	Hex Size, mm		Each
18-8 Stainless Steel



		M5 × 0.8 mm	19	Coarse	28	5	3	1.5	000000000	000000

Slotted Spring Pins

End View

Squeeze these pins into holes and they expand slightly, creating tension to hold parts in place. They are often used as hinge pins and as fasteners for springs and power transmission components. An alternative to dowel pins, they're lighter in weight with a hollow center and don’t need a precise hole. Also known as roll pins.

Spring Steel—These pins won't deform from stress and vibration. Although they're stronger than stainless steel, they're best for dry environments since moisture will cause them to rust.

Corrosion-Resistant 18-8 Stainless Steel—The choice for wet and outdoor environments, these pins resist rusting. They are strong enough to join most components but won't withstand extreme stress and vibration as well as steel.

	Double Shear Breaking Strength, lbf	Min. Hardness	Specs. Met	Pkg. Qty.		Pkg.
Spring Steel







	3 mm Diameter

	28	3	0.3	780	Rockwell C42	DIN 7346, ISO 13337	50	000000000	000000


	28	3 to 3.1	0.6	1,400	Rockwell C42	ISO 8752	100	000000000	0000




			4 mm Diameter

			28	4	0.5	1,700	Rockwell C42	DIN 7346, ISO 13337	50	000000000	00000




					5 mm Diameter

					28	5	0.5	2,300	Rockwell C42	DIN 7346, ISO 13337	50	000000000	00000


					28	5 to 5.2	1	3,900	Rockwell C42	ISO 8752	100	000000000	00000




							6 mm Diameter

							28	6	0.75	4,000	Rockwell C42	DIN 7346, ISO 13337	25	000000000	00000




									8 mm Diameter

									28	8	0.75	5,300	Rockwell C42	DIN 7346, ISO 13337	25	000000000	00000




											12 mm Diameter

											28	12	1	10,700	Rockwell C42	DIN 7346, ISO 13337	5	000000000	0000




													13 mm Diameter

													28	13	1.2	14,800	Rockwell C42	DIN 7346, ISO 13337	5	000000000	00000




															16 mm Diameter

28															16	1.5	22,000	Rockwell C42	DIN 7346, ISO 13337	5	000000000	00000


Corrosion-Resistant 18-8 Stainless Steel







															3 mm Diameter

															28	3 to 3.1	0.6	Not Rated	Not Rated	DIN 1481, ISO 8752	10	000000000	0000




															5 mm Diameter

															28	5 to 5.2	1	Not Rated	Not Rated	ISO 8752	10	000000000	0000