M4 Helicoils | McMaster-Carr

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U.S.–Mexico–Canada Agreement (USMCA) Qualifying

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Export Control Classification Number (ECCN)

EAR99

Tensile Strength

200,000 psi

Military Specification

MIL-I-8846

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53 Products

About Threaded Inserts

Choose the right threaded insert for your application and learn how to install it securely.

Helical Threaded Inserts


Pronged	Prongless

Restore, reinforce, or create threads in metal. The tough coils on these inserts expand once installed to anchor in a tapped hole. Also known as Heli-Coil inserts, they're often used in engine heads and machinery housings where strong connections are critical. Unlike threadlocking inserts, you can remove and reuse them without them losing their strength.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

Prongless—Without a prong to break off and retrieve, these inserts save time and avoid leftover debris in holes.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

Nickel—More resistant to acids and salt water than stainless steel inserts.

	Inserts								Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Prong Break-Off Tools		Inserts with Installation Tools
	Thread Size	Installed Lg., mm	Drill Bit Size, mm	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each	No. of Inserts Included		Each
Pronged







				18-8 Stainless Steel

				M4 x 0.7 mm	4	19 Ga.	0.166"	DIN 8140, SAE MA3279-104	10	91732A649	00000	91709A359	000000	91709A527	000000	90261A190	0000000	92955A160	0000000	10	91732A421	000000


				M4 x 0.7 mm	6	19 Ga.	0.166"	DIN 8140, SAE MA3279-154	10	91732A656	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000	10	91732A944	00000
				M4 x 0.7 mm	8	19 Ga.	0.166"	DIN 8140, SAE MA3279-204	10	91732A776	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000	10	91732A431	00000
				M4 x 0.7 mm	10	19 Ga.	0.166"	DIN 8140, SAE MA3279-254	10	91732A781	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000	10	98356A154	00000
				M4 x 0.7 mm	12	4.2	4.2 mm	SAE MA3279-304	10	91732A185	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000	10	98356A155	00000




						Nickel

						M4 x 0.7 mm	4	4.25	4.25 mm	—	1	94264A140	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000	—	———	0


						M4 x 0.7 mm	6	4.25	4.25 mm	—	1	94264A143	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000	—	———	0
						M4 x 0.7 mm	8	4.25	4.25 mm	—	1	94264A147	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000	—	———	0


						Prongless







										18-8 Stainless Steel

										M4 x 0.7 mm	4	19 Ga.	0.166"	NA0276M4-10	10	91990A413	0000	91709A359	00000	91709A527	00000	91049A624	000000	———	0	—	———	0


										M4 x 0.7 mm	6	19 Ga.	0.166"	NA0276M4-15	10	91990A416	0000	91709A359	00000	91709A527	00000	91049A624	000000	———	0	—	———	0
										M4 x 0.7 mm	8	19 Ga.	0.166"	NA0276M4-20	10	91990A419	0000	91709A359	00000	91709A527	00000	91049A624	000000	———	0	—	———	0

Extraction Tools

Remove installed helical inserts.

For Pronged Helical Inserts—Place the tip into pronged inserts and lightly strike the tool’s head. Then, turn the tool counterclockwise with pressure to extract the insert.

For Prongless Helical Inserts—Remove prongless inserts without damaging threads or the surface of your material. These tools also back out or adjust inserts that are installed too deep.

		Each
For Pronged Helical Inserts



	3-48, 3-56, 4-40, 4-48, 5-40, 5-44, 6-32, 6-40, 8-32, 8-36, 8-40, M2.5, M3, M3.5, M4	90254A310	000000


	For Prongless Helical Inserts



			M4	91049A366	000000

Helical Insert Taps

Match the size of helical inserts so they fit tightly when installed in the hole.

High-Speed Steel—These taps resist heat and wear to stay sharp.

Plug Chamfer—Our go-to chamfer type. With a longer taper than a bottoming chamfer, they are easier to turn but won't thread as close the bottom of a hole.

Bottoming Chamfer—Cut all the way to the bottom of blind holes with taps that have the shortest taper. Since these require the most force to turn, they’re often used to finish holes started by taper- or plug-chamfer taps.

						Drill Bit			Plug Chamfer		Bottoming Chamfer
	For Insert Size	Thread Lg.	Overall Lg.	For Insert Thread Type	No. of Flutes	Size	Decimal Size Equiv.	Shank Type		Each		Each
High-Speed Steel







				Uncoated

				M4	7/8"	2 3/8"	Metric	3	19 Ga.	0.166"	Square	91709A359	000000	91709A527	000000

Lubricant-Free Seize-Resistant Helical Threaded Inserts

No lubricant means no mess or particles to contaminate environments such as clean rooms and labs. These inserts are made of Nitronic 60 stainless steel, which prevents sticking or binding that wears out the threads. They're ideal for parts that require frequent disassembly for inspection or repair. Also known as Heli-Coil inserts.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

	Inserts							Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Prong Break-Off Tools
	Thread Size	Installed Lg., mm	Drill Bit Size, mm	For Max. Hole Dia., mm	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Pronged







				Nitronic 60 Stainless Steel

				M4 x 0.7 mm	4	4.25	4.25	5	93914A111	00000	91709A359	000000	91709A527	000000	90261A190	0000000	92955A160	0000000


				M4 x 0.7 mm	6	4.25	4.25	5	93914A128	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000
				M4 x 0.7 mm	8	4.25	4.25	5	93914A145	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000
				M4 x 0.7 mm	12	4.25	4.25	5	93914A411	00000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000

Easy-Start Helical Threaded Insert Installation Tools

These tools compress the diameter of your insert so it fits easily into a tapped hole. They’re the best choice for preventing misaligned or damaged threads—just make sure you have space to turn the crank. Screw or slide an insert onto your tool and drive it between a quarter-turn and half-turn below the surface. Also known as prewinders.

Threaded Insert Installation Tools with Depth Stop


Crank Handle	Threaded Drive

Ensure consistent installation across multiple inserts. Set your desired installation depth, and the stop will prevent you from driving your insert any further.

Threaded Drive Helical Insert Tool—These tools align each coil of your insert perfectly with the thread pitch of your tapped hole for easy installation.

	Mfr.	Handle Style	Helical Insert Tool Drive Type	For Use With		Each
Metric Thread



	M4 × 0.7 mm	—	Crank	Threaded	Helical Inserts, Screw-Locking Helical Inserts	1338N55	000000


	M4 × 0.7 mm	Heli-Coil	Crank	Threaded	Helical Inserts, Screw-Locking Helical Inserts	90261A190	000000

Helical Threaded Inserts with Installation Tools

Drill Bit, Installation Tool

and Through-Hole Tap

Quickly restore stripped threads—these inserts come with through-hole taps and installation tools. The tough coils on these inserts expand once installed to anchor in a tapped hole.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	For Max. Hole Dia.	No. of Inserts Included	Includes		Each
Pronged







	18-8 Stainless Steel

	M4 x 0.7 mm	4	4.2	0.172"	10	Drill Bit Installation Tool Through-Hole Tap	91732A421	000000


	M4 x 0.7 mm	6	4.2	0.172"	10	Drill Bit Installation Tool Through-Hole Tap	91732A944	00000
	M4 x 0.7 mm	8	4.2	0.172"	10	Drill Bit Installation Tool Through-Hole Tap	91732A431	00000
	M4 x 0.7 mm	10	4.2	0.172"	10	Drill Bit Installation Tool Through-Hole Tap	98356A154	00000
	M4 x 0.7 mm	12	4.2	0.172"	10	Drill Bit Installation Tool Through-Hole Tap	98356A155	00000

Helical Threaded Insert Removal Tools

To remove installed helical inserts, place the tip of these tools into the insert and lightly strike the tool’s head. Then, turn the tool counterclockwise with pressure to extract the insert.

Narrow Profile—The tip of these tools has a narrower angle than standard removal tools to reduce the chance it will dig into your material’s surface when you strike the tool.

	Mfr.		Each
Standard Profile



	2-56, 3-48, 3-56, 4-40, 4-48, 5-40, 6-32, 6-40, 8-32, 8-36, M2, M2.2, M2.5, M3, M3.5, M4	—	90254A111	000000


	4-40, 4-48, 5-40, 6-32, 6-40, 8-32, 8-36, 10-24, 10-32, 12-24, 1/4"-20, 1/4"-28, 3/8"-16, M3, M3.5, M4, M5, M6, M7, M8, M9, M10	—	90254A112	00000
	6-32, 6-40, 8-32, 8-36, 10-24, 10-32, 12-24, 1/4"-20, 1/4"-28, 5/16"-18, 5/16"-24, 3/8"-16, 3/8"-24, 7/16"-14, 7/16"-20, 1/2"-13, 1/2"-20, 9/16"-12, 9/16"-18, 5/8"-11, 5/8"-18, 3/4"-10, 3/4"-16, 7/8"-9, 7/8"-14, 1"-8, 1"-12, 1"-14, M4, M5, M6, M7, M8, M9, M10, M12, M13, M14, M15, M16, M18, M20, M22, M24	—	90254A113	00000


	Narrow Profile



			3-48, 3-56, 4-40, 4-48, 5-40, 5-44, 6-32, 6-40, 8-32, 8-36, 8-40, M2.5, M3, M3.5, M4	Heli-Coil	90254A310	00000

Screw-Locking Helical Threaded Inserts


Pronged	Prongless

The irregularly shaped threads tightly grip screws to prevent them from loosening or backing out under vibration. Use these inserts to create or repair threads in pumps and other machinery that shakes and rattles. Also known as Heli-Coil inserts.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

Prongless—Without a prong to break off and retrieve, these inserts save time and avoid leftover debris in holes.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	Inserts								Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Prong Break-Off Tools
	Thread Size	Installed Lg., mm	Drill Bit Size	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Pronged







				18-8 Stainless Steel

				M4 x 0.7 mm	4	19 Ga.	0.166"	DIN 8140, SAE MA3329-104	10	90296A407	00000	91709A359	000000	91709A527	000000	90261A190	0000000	92955A160	0000000


				M4 x 0.7 mm	6	19 Ga.	0.166"	DIN 8140, SAE MA3329-154	10	90296A409	00000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000
				M4 x 0.7 mm	8	19 Ga.	0.166"	DIN 8140, SAE MA3329-204	10	90296A410	00000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000
				M4 x 0.7 mm	10	19 Ga.	0.166"	SAE MA3329-254	1	90296A418	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000


				Prongless







								18-8 Stainless Steel

								M4 x 0.7 mm	4	19 Ga.	0.166"	NA0276M4-L10	10	91630A256	0000	91709A359	00000	91709A527	00000	91049A624	000000	———	0


								M4 x 0.7 mm	6	19 Ga.	0.166"	NA0276M4-L15	10	91630A237	0000	91709A359	00000	91709A527	00000	91049A624	000000	———	0
								M4 x 0.7 mm	8	19 Ga.	0.166"	NA0276M4-L20	10	91630A239	0000	91709A359	00000	91709A527	00000	91049A624	000000	———	0

Helical Threaded Insert Assortments with Installation Tools

Repair damaged threads or create new ones. These convenient assortments include helical inserts, an installation tool for each thread size, a drill bit, and a tap. The inserts are also known as Heli-Coil inserts.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	Drill Bit Size	For Max. Hole Dia.		Each
Pronged







	18-8 Stainless Steel

	18	Drill Bit Installation Tool M4×0.7 mm Thread × 4 mm Installed Lg. (6 Each) M4×0.7 mm Thread × 6 mm Installed Lg. (6 Each) M4×0.7 mm Thread × 8 mm Installed Lg. (6 Each) Prong Break-Off Tool Through-Hole Tap	Coarse	11/64"	0.172"	91732A943	000000

Spring-Loaded Helical Threaded Insert Prong Break-Off Tools

Cleanly snap prongs off installed helical inserts with just one hand. Because they work faster than standard prong break-off tools, these are a good choice when you have many prongs to remove. Press your tool into an insert to trigger the spring-loaded punch and snap off the prong.

For Standard-Length Inserts—Use these tools for inserts that are 1 to 2 times as long as the diameter.

For Long Inserts—Use these tools for inserts that are 2 _1/2 to 3 times as long as the diameter.

	Mfr.		Each
For Standard-Length Inserts



	8-32, 8-36, 8-40, M4	—	92955A315	000000


	M4	Heli-Coil	92955A160	000000


	For Long Inserts



			8-32, 8-36, M4	—	92955A415	00000

Easy-Start Prongless Helical Threaded Insert Installation Tools

Install prongless (tangless) helical inserts more quickly and consistently than with standard tools. These tools compress your insert’s diameter and align each coil with the thread pitch, guiding it straight into a tapped hole. They’re the best choice for preventing misaligned or damaged threads. Just make sure you have space to turn the crank. Screw an insert onto these tools and drive them a quarter- to half-turn below the material’s surface. Also known as prewinders.

	Handle Style	For Use With		Each
Metric Thread



	M4 × 0.7 mm	Crank	Helical Inserts, Screw-Locking Helical Inserts	91049A624	0000000

Replacement Tips

For Thread Size		Each
M4	91049A754	000000

Seize-Resistant Helical Threaded Inserts

Pronged

Install and remove screws repeatedly without sticking or binding. These inserts have a dry-film lubricant on their surface for smooth installation. They're ideal for parts that require frequent disassembly for inspection or repair. Also known as Heli-Coil inserts.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

Dry-Film-Lubricated 18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	Inserts								Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Prong Break-Off Tools
	Thread Size	Installed Lg., mm	Drill Bit Size	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Pronged







				Dry-Film-Lubricated 18-8 Stainless Steel

				M4 x 0.7 mm	4	19 Ga.	0.166"	DIN 8140, SAE MA3280-104, MIL-I-8846	1	91000A031	00000	91709A359	000000	91709A527	000000	90261A190	0000000	92955A160	0000000


				M4 x 0.7 mm	6	19 Ga.	0.166"	DIN 8140, SAE MA3280-154, MIL-I-8846	1	91000A034	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000
				M4 x 0.7 mm	8	19 Ga.	0.166"	DIN 8140, SAE MA3280-204, MIL-I-8846	1	91000A037	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000

Seize-Resistant Helical Threaded Inserts for Dissimilar Metals

Skip the primer. These inserts are coated to resist galvanic corrosion when used with aluminum or magnesium. The coating also prevents the screw from sticking or binding during installation. Also known as Heli-Coil inserts.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

Dry-Film-Lubricated 18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	Inserts								Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Prong Break-Off Tools
	Thread Size	Installed Lg., mm	Drill Bit Size	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Pronged







				Dry-Film-Lubricated 18-8 Stainless Steel

				M4 x 0.7 mm	4	19 Ga.	0.166"	—	1	93914A323	00000	91709A359	000000	91709A527	000000	90261A190	0000000	92955A160	0000000


				M4 x 0.7 mm	6	19 Ga.	0.166"	—	1	93914A329	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000
				M4 x 0.7 mm	8	19 Ga.	0.166"	DIN 8140	1	93914A334	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000

Screw-Locking Seize-Resistant Helical Threaded Inserts

Screws won't get stuck or come loose with these inserts. A dry film on the surface lubricates fasteners during insertion to prevent sticking and binding. Once installed, the irregularly shaped threads tightly grip screws to keep them in place under vibration. Also known as Heli-Coil inserts.

Installation requires a drill bit, a helical insert tap, and an installation tool.

Pronged—The prong attaches to an installation tool for precise control as you drive inserts in. Remove the prong with a punch or break-off tool before inserting a screw.

Dry-Film-Lubricated 18-8 Stainless Steel—The choice for wet and outdoor environments, these inserts resist rust and mild chemicals.

	Inserts								Through-Hole Taps		Closed-End Hole Taps		Installation Tools		Prong Break-Off Tools
	Thread Size	Installed Lg., mm	Drill Bit Size	For Max. Hole Dia.	Specs. Met	Pkg. Qty.		Pkg.		Each		Each		Each		Each
Pronged







				Dry-Film-Lubricated 18-8 Stainless Steel

				M4 x 0.7 mm	4	19 Ga.	0.166"	DIN 8140, SAE MA3330-104	1	91000A522	00000	91709A359	000000	91709A527	000000	90261A190	0000000	92955A160	0000000


				M4 x 0.7 mm	6	19 Ga.	0.166"	DIN 8140, SAE MA3330-154	5	91000A525	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000
				M4 x 0.7 mm	8	19 Ga.	0.166"	DIN 8140, SAE MA3330-204	5	91000A527	0000	91709A359	00000	91709A527	00000	90261A190	000000	92955A160	000000

Prongless Helical Threaded Insert Removal Tools

Remove prongless inserts without damaging threads or the surface of your material. These tools also back out or adjust inserts that are installed too deep.

Replacement Tips—Replacement tips (sold separately) come with one removal tip, two pins, and two springs.

	Removal Tools				Replacement Tips
	For Thread Size	For Use With		Each		Each
Metric Thread



		M4	Helical Inserts, Screw-Locking Helical Inserts	91049A366	0000000	91049A505	000000

Punch-Style Helical Threaded Insert Prong Break-Off Tools

Break the prong off of installed helical inserts. Place these tools inside the insert and hit the back with a hammer. Once removed, thread in your fastener.

For Thread Size	Handle Style	For Use With		Each
8-32, 8-36, M4	Straight	Helical Inserts, Screw-Locking Helical Inserts	1231N14	00000