M6 Grease Nipple Overview
An M6 grease nipple is the smallest hydraulic-type grease fitting in the DIN 71412 family: a 6.5 mm conical head on an M6 x 1.0 thread. IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006, supplies M6 nipples in straight (H1), 45-degree (H2), and 90-degree (H3) forms for bearings, linkages, and lube points on industrial, mobile, and marine equipment. A spring-loaded internal valve keeps grease in until a coupler pushes it open.
M6 Grease Nipple Specifications
| Parameter | Standard M6 Nipple | Options |
|---|---|---|
| Thread | M6 x 1.0 mm, ISO metric per DIN 13, class 6g | M6 x 0.75 on request |
| Head | Conical head per DIN 71412, 6.5 mm diameter | |
| Internal valve | Ball or pin type, 2.5 mm diameter | |
| Spring | AISI 304 wire, 0.3 mm wire diameter, 2.5-3.0 N/mm | AISI 316 spring |
| Opening pressure | 15-25 PSI (1.0-1.7 bar) typical | Heavy-duty 40-60 PSI |
| Working pressure | Up to 150 bar (2,175 PSI) | Up to 400 bar (5,800 PSI), heavy-duty pin-valve type |
| Unit weight | Steel 2.5-3.0 g; brass 2.7-3.2 g; SS316 2.6-3.0 g | H2/H3 angled types 3.5-4.0 g |
| Temperature | Zinc-plated steel -40°C to +120°C | SS316 -60°C to +300°C (limited by grease and seal); brass -40°C to +200°C |
| Thread length | 6 mm | 8.5 / 14 / 21 / 31 mm extended |
| Hex size | SW7 (7 mm across flats) | |
| Overall length | H1 straight 15 mm; H2 45-degree 20.2 mm; H3 90-degree 18 mm | H1 extended: 17.3 / 24 / 29 / 41 mm |
| Materials | Zinc-plated steel, 8-12 micron coating per ASTM B633, blue or yellow passivation | SS316 (A4); brass CW614N (CZ121); nickel plating 15-20 micron |
M6 Nipple Configurations
| Form | DIN 71412 shape | Overall length | Unit weight | Best for |
|---|---|---|---|---|
| H1 straight | Shape A | 15 mm (extended 17.3 / 24 / 29 / 41 mm) | 2.5-3.0 g | Open access, head-on grease gun approach |
| H2 45-degree | Shape B | 20.2 mm | 3.5-4.0 g | Diagonal approach paths |
| H3 90-degree | Shape C | 18 mm | 3.5-4.0 g | Flush mounting, right-angle approach |
M6 Grease Nipple Applications
- Industrial machinery: bearing housings, slides, and pivot pins on conveyors and machine tools.
- Mobile and agricultural equipment: implement pivots, steering linkages, chassis points.
- Marine and washdown areas: deck fittings and hinges in stainless 316.
- Galvanic-sensitive or non-magnetic assemblies: brass CW614N against brass hardware.
Installation and Selection
Tighten M6 nipples to 3-5 Nm (2.2-3.7 ft-lb) in steel or cast iron housings, 2-3 Nm in aluminum; above 8 Nm you risk damage. Allow at least 6 mm engagement, one thread diameter. Seal with PTFE tape or medium-strength sealant; avoid anaerobic threadlocker on fine threads.
For self-tapping styles, drill a 5.6-5.8 mm pilot hole in steel and confirm fit in your material first. Use a standard four-jaw or push-in hydraulic coupler head for the 6.5 mm conical head; lock-on and twist-lock couplers also engage it. A DIN 3402 ball-head coupler does not fit. The same head pairs with the four-jaw coupler on our pneumatic grease gun control handle. Our grease fitting types guide maps common head styles.
To line up material, thread length, and pack size, request a quote with your M6 specification.
M6 Nipple Maintenance
Wipe the head clean before coupling so grit is not driven past the valve. Check for thread weeping at service and re-seat or re-seal as needed. A deformed head or a valve that no longer holds grease means replacement, not reuse.
M6 Grease Nipple FAQ
What is an M6 grease nipple?
An M6 grease nipple is a DIN 71412 hydraulic-type fitting with an M6 x 1.0 thread, a 6.5 mm conical head, and a spring-loaded internal valve. It threads into a tapped lube point and takes a standard hydraulic coupler for high-pressure grease injection.
How does DIN 71412 differ from DIN 3402, 3404, and 3405 heads?
DIN 71412 is the conical hydraulic head for high-pressure couplers; DIN 3402 ball, DIN 3404 button, and DIN 3405 flat heads each use different coupler geometry. Cross-reference does not guarantee interchangeability – confirm coupler fit before ordering.
Should I choose the straight, 45-degree, or 90-degree M6 nipple?
Pick H1 straight for head-on access, H2 45-degree for diagonal approaches, and H3 90-degree where the point sits flush or only a right-angle approach is possible.
What torque is correct for an M6 grease nipple?
3-5 Nm (2.2-3.7 ft-lb) in steel or cast iron, 2-3 Nm in aluminum, with a 7 mm wrench; above 8 Nm you risk stripping the thread. If it weeps at correct torque, clean and reseal with PTFE tape.
Why will grease no longer go into my M6 nipple?
Usually a dry or mis-seated coupler, a blocked valve, hardened grease, or a seat burr. Wipe the head and verify the coupler locks on squarely; our grease nipple troubleshooting guide walks through the checks.
Zinc-plated steel, stainless 316, or brass – which material should I pick?
Zinc-plated steel covers general indoor and chassis duty, -40°C to +120°C. Stainless 316 suits marine and high-temperature service, -60°C to +300°C; the grease and seal also set the practical limit. Brass CW614N fits galvanic-sensitive or non-magnetic assemblies, -40°C to +200°C.
When do I need an extended thread M6 nipple?
Specify 8.5, 14, 21, or 31 mm threads when the tapped hole sits deep in a boss, passes through an adapter plate, or must clear structure; the standard 6 mm suits flush surfaces.
What if the coupler slips or leaks on the conical head?
Slipping means worn coupler jaws or a damaged head seat; leaking under pressure means a partially locked coupler. Replace worn jaws, hold the coupler square, and inspect the head – a deformed head will not seal, so replace the nipple.
Does any standard hydraulic coupler fit an M6 DIN 71412 nipple?
Only couplers made for the 6.5 mm conical head: four-jaw or push-in hydraulic heads, plus lock-on and twist-lock variants. DIN 3402 ball-head couplers seal on a different surface and will not seat here.
Can I remove and reuse an old M6 grease nipple?
We do not recommend it. Removal often distorts the fine thread and may dent the head, so a reused nipple can leak or loosen. Part cost is minor next to a weeping lube point – fit a new nipple after any removal.
Bulk and Custom Orders
M6 nipples ship in 5-10, 25-50, and 100-500 piece packs; larger bulk is open for discussion. Nickel plating, AISI 316 springs, M6 x 0.75 threads, and extended threads combine per order. Contact our team to confirm lead time and bulk pricing, or write to inquiry@isohitech.com.
