M4 Plungers | McMaster-Carr

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8 Products

Ball-Nose Spring Plungers

Align, position, and lock moving parts for most machining and assembly tasks. These spring plungers have a spring-loaded ball that compresses when a part presses against it, and then pops out into a notch or groove to hold the part in place. Unlike long-nose spring plungers, the ball rolls easily in and out of position, so they're a great fit for applications that require consistent, smooth movement, such as positioning parts in an assembly line and aligning fixtures and jigs when cutting or drilling.

Spring plungers are available with or without a threadlocker. Those with a threadlocker won't wiggle loose from vibration. Spring plungers without a threadlocker are easier to remove.

440C Stainless Steel Nose—The strongest, most wear-resistant stainless steel noses, these grind against hard metal surfaces without denting or scratching. However, they are not as corrosion resistant as 316 stainless steel.

Nylon Nose—Extra soft to avoid scratching delicate surfaces. Nylon is best for use on soft materials, such as aluminum. It will swell and weaken when exposed to moisture, however, so it should only be used in dry environments.

	Spring Plungers											Spring Plunger Drivers
		Nose, mm		Nose Force, lbf		Body		Drive Style
	Thread Size	Extended Lg.	Dia.	Extended	Compressed	Material	Lg., mm	Front	Back		Each		Each
440C Stainless Steel Nose


		M4 x 0.7 mm	0.8	2.5	0.9	2.3	18-8 Stainless Steel	9	Spring Plunger Driver	Slotted	85015A46	00000	3382A12	00000
		M4 x 0.7 mm	0.8	2.5	0.9	2.3	Steel	9	Spring Plunger Driver	Slotted	3391A31	0000	3382A12	0000

		Nylon Nose


				M4 x 0.7 mm	0.8	2.5	0.9	2.3	18-8 Stainless Steel	9	Spring Plunger Driver	Slotted	2277A51	00000	3382A12	0000
				M4 x 0.7 mm	0.8	2.5	0.9	2.3	Steel	9	Spring Plunger Driver	Slotted	2191A11	0000	3382A12	0000

Long-Nose Spring Plungers

Lock heavy moving parts securely in place. Often used in indexing applications, these have a longer nose than ball-nose spring plungers to withstand greater side forces without disengaging. The nose compresses when a part presses against it, and then pops out into deep notches or grooves for a strong hold.

Spring plungers are available with or without a threadlocker. Those with a threadlocker won't wiggle loose from vibration. Spring plungers without a threadlocker are easier to remove.

Acetal Nose—The best plastic for damp and wet environments, acetal won't swell or lose strength if exposed to moisture. These noses are extra soft to avoid scratching delicate surfaces. They are best for use on soft materials, such as aluminum.

	Spring Plungers											Spring Plunger Drivers
		Nose, mm		Nose Force, lbf		Body		Drive Style
	Thread Size	Extended Lg.	Dia.	Extended	Compressed	Material	Lg., mm	Front	Back		Each		Each
Acetal Nose


		M4 x 0.7 mm	1.5	1.5	1	3.6	18-8 Stainless Steel	15	Spring Plunger Driver	—	8339A12	00000	3382A12	00000
		M4 x 0.7 mm	1.5	1.5	1	3.6	Black-Oxide Steel	15	Spring Plunger Driver	—	8281A12	0000	3382A12	0000
		M4 x 0.7 mm	2.4	1.8	2.7	7.3	Black-Oxide Steel	15.9	—	Hex	2467A35	00000	———	0

Spring Plunger Drivers

Install spring plungers from the nose end without depressing the nose.

	For Spring Plunger Nose Type		Each
Steel


	8-32, M4	Ball, Long	3382A12	00000