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About Nuts, Materials, and Finishes
More
Metric Medium-Strength Steel Nylon-Insert Locknuts—Class 8

Made from medium-strength steel with a nylon insert, these Class 8 metric locknuts are strong enough to use on most machinery and equipment that’s prone to vibration and temperature changes. The nylon insert also won’t damage the threads on your bolt. All are reusable, but their holding power lessens with each use. Pair them with compatible Class 8.8 metric bolts.
Most of these locknuts meet ISO 7040 or ISO 10511 (formerly DIN 982 or DIN 985), which are international standards for dimensions. The ISO standards are functionally equivalent to the DIN standards with slight differences in width, height, or tolerances.
Zinc- and zinc yellow-chromate plated steel locknuts are a good option in dry environments. The zinc plating prevents the steel from corroding until the plating wears away.
For technical drawings and 3-D models, click on a part number.
Metric 18-8 Stainless Steel Nylon-Insert Locknuts

Made from 18-8 stainless steel, these locknuts have good chemical resistance and may be mildly magnetic. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use. Metric 18-8 stainless steel is also known as A2 stainless steel. These locknuts meet either DIN 982 or DIN 985, which are no longer active standards, but are still a common reference point for designers.
For technical drawings and 3-D models, click on a part number.
Thread | ||||||||
---|---|---|---|---|---|---|---|---|
Size | Pitch, mm | Wd., mm | Ht., mm | Insert Max. Temp., °F | Specifications Met | Pkg. Qty. | Pkg. | |
18-8 Stainless Steel | ||||||||
M3 | 0.5 | 5.5 | 4 | 220° | DIN 985 | 100 | 000000000 | 00000 |
Metric Super-Corrosion-Resistant 316 Stainless Steel Nylon-Insert Locknuts

Made from 316 stainless steel, these locknuts have excellent resistance to chemicals and salt water. The nylon insert grips the bolt to resist loosening without damaging threads. They're reusable, but their holding power lessens with each use. Metric 316 stainless steel is also known as A4 stainless steel. Nuts may be mildly magnetic. All meet DIN 982 or DIN 985, which are no longer active standards, but are still a common reference point for designers.
For technical drawings and 3-D models, click on a part number.
Thread | ||||||||
---|---|---|---|---|---|---|---|---|
Size | Pitch, mm | Wd., mm | Ht., mm | Insert Max. Temp., °F | Specifications Met | Pkg. Qty. | Pkg. | |
316 Stainless Steel | ||||||||
M3 | 0.5 | 5.5 | 4 | 220° | DIN 985 | 50 | 000000000 | 00000 |
Metric Low-Profile Low-Strength Steel Nylon-Insert Locknuts

With a shorter hex height than standard DIN 985 locknuts, these nylon-insert locknuts meet international ISO 10511 dimensional standards and are easy to install in tight spaces. The nylon insert grips the bolt thread to keep them from loosening without damaging the threads, so they're good for use on machinery and equipment that's prone to vibration. These locknuts can be removed and reinstalled; however, their holding power weakens with each use. Use them for light duty fastening applications, such as securing access panels. Made of zinc-plated steel, they won't corrode in wet environments.
For technical drawings and 3-D models, click on a part number.
Thread | ||||||||
---|---|---|---|---|---|---|---|---|
Size | Pitch, mm | Width, mm | Height, mm | Insert Maximum Temperature, °F | Specifications Met | Pkg. Qty. | Pkg. | |
Zinc-Plated Steel | ||||||||
M3 | 0.5 | 5.5 | 3.9 | 245° | ISO 10511 | 25 | 000000000 | 00000 |
Metric Steel Locknuts with External-Tooth Lock Washer

Also known as Keps and K-lock nuts, these locknuts have a free-spinning tooth lock washer that grips the material surface instead of threads for easy installation and mild vibration resistance. Height includes the thickness of the washer. A zinc plating provides corrosion resistance in wet environments.
For technical drawings and 3-D models, click on a part number.
Metric Stainless Steel Locknuts with External-Tooth Lock Washer


These locknuts have good chemical resistance and may be mildly magnetic. Also known as Keps and K-Lock nuts, they have a free-spinning tooth lock washer that grips the material surface instead of threads for easy installation and mild vibration resistance. Height includes the thickness of the washer.
Black-oxide stainless steel nuts have a dark surface color.
For technical drawings and 3-D models, click on a part number.
Metric Steel Nonmarring Locknuts with Spring-Lock Washer

A conical washer acts as a spring to add tension between the nut and the material surface for easy installation and mild vibration resistance. They have a smooth rim to resist scratching materials when tightened. Also known as Keps and K-lock nuts. Height includes the thickness of the washer.
Zinc-plated locknuts have an outer layer of zinc that provides corrosion resistance in wet environments.
Black oxide locknuts are mildly corrosion resistant and have a dark surface color.
For technical drawings and 3-D models, click on a part number.
Metric Medium-Strength Steel Top-Lock Distorted-Thread Locknuts—Class 8

An irregularly shaped thread at the top of the nut grips the bolt for a stronger hold than nylon-insert locknuts. They thread on from the bottom of the nut, allowing more threads to engage the bolt before tightening for easier installation than center-lock distorted thread locknuts. The strength of the bolt should match the strength of the nut to prevent damaging threads. They're not reusable. Comparable in strength to Class 8.8 bolts, they're suitable for fastening most machinery and equipment. A zinc or zinc yellow-chromate plating provides corrosion resistance in wet environments.
For technical drawings and 3-D models, click on a part number.
Thread | |||||||
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Size | Pitch, mm | Wd., mm | Ht., mm | Specifications Met | Pkg. Qty. | Pkg. | |
Zinc-Plated Steel—Class 8 | |||||||
M3 | 0.5 | 5.5 | 3.7 | DIN 980V | 50 | 000000000 | 000000 |
Metric Stainless Steel Flex-Top Locknuts for Heavy Vibration

Made from stainless steel, these locknuts resist chemicals and may be mildly magnetic. Threads at the top of the nut expand to grip the bolt on all sides for a stronger hold than distorted-thread locknuts. The strength of the bolt should match the strength of the nut to prevent damaging threads.
18-8 stainless steel locknuts have good chemical resistance.
316 stainless steel locknuts have excellent resistance to chemicals and salt water.
For technical drawings and 3-D models, click on a part number.
Metric Medium-Strength Steel Serrated Flange Locknuts—Class 8

Strong enough for use in most machinery and equipment, these medium-strength metric nuts have serrations on the underside of the flange. The serrations prevent the nuts from loosening in applications with mild vibration.
Also known as collar nuts, they do not require a washer, which saves assembly time. Instead, the flange spreads the holding force across a wide area. Because the flange makes them wider than standard nuts, they may not fit into tight spots.
Zinc-plated steel nuts have a layer of zinc on the outside that prevents the steel from rusting in wet environments, extending the life of the nut.
To ensure compatibility with other parts and tools, some nuts meet ISO 4161 (formerly DIN 6923).
For technical drawings and 3-D models, click on a part number.
Thread | Flange | ||||||||
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Size | Pitch, mm | Wd., mm | Ht., mm | Dia., mm | Thick., mm | Specifications Met | Pkg. Qty. | Pkg. | |
Zinc-Plated Steel—Class 8 | |||||||||
M3 | 0.5 | 5.5 | 4 | 8 | 0.7 | DIN 6923, ISO 4161 | 100 | 000000000 | 00000 |
Metric 18-8 Stainless Steel Serrated Flange Locknuts

These flange locknuts have good chemical resistance and may be mildly magnetic. They have serrations that grip the material surface instead of the threads for easy installation and mild vibration resistance. The flange distributes pressure where the nut meets the material surface, eliminating the need for a separate washer. Height includes the flange. Metric 18-8 stainless steel is also known as A2 stainless steel.
For technical drawings and 3-D models, click on a part number.
Thread | Flange | ||||||||
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Size | Pitch, mm | Wd., mm | Ht., mm | Dia., mm | Thick., mm | Specifications Met | Pkg. Qty. | Pkg. | |
18-8 Stainless Steel | |||||||||
M3 | 0.5 | 5.5 | 4 | 8 | 0.7 | DIN 6923 | 100 | 000000000 | 00000 |
Metric Super-Corrosion-Resistant 316 Stainless Steel Serrated Flange Locknuts

Made from 316 stainless steel, these flange locknuts have excellent resistance to chemicals and salt water. They have serrations that grip the material surface instead of the threads for easy installation and mild vibration resistance. The flange distributes pressure where the nut meets the material surface, eliminating the need for a separate washer. Height includes the flange. Metric 316 stainless steel is also known as A4 stainless steel. Nuts may be mildly magnetic.
For technical drawings and 3-D models, click on a part number.
Thread | Flange | ||||||||
---|---|---|---|---|---|---|---|---|---|
Size | Pitch, mm | Wd., mm | Ht., mm | Dia., mm | Thick., mm | Specifications Met | Pkg. Qty. | Pkg. | |
316 Stainless Steel | |||||||||
M3 | 0.5 | 5.5 | 4 | 8 | 0.7 | DIN 6923 | 25 | 000000000 | 00000 |
Nylon-Insert Press-Fit Locknuts for Sheet Metal

These press-fit nuts have a nylon insert that grips threads to resist loosening and knurls on the bottom of the nut that hold them firmly in place. Press them into a drilled or punched hole with an installation tool or an arbor press. Installation requires access to both sides of the panel.
Zinc-plated steel locknuts are a good option in dry environments. The zinc plating prevents the steel from corroding until the plating wears away.
For technical drawings and 3-D models, click on a part number.
Thread | |||||||||
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Size | Pitch, mm | Drill Bit Size | For Min. Panel Thick., mm | Flange Dia., mm | Head Ht., mm | Insert Max. Temp., °F | Pkg. Qty. | Pkg. | |
Zinc-Plated Steel | |||||||||
M3 | 0.5 | 6 mm | 1.5 | 7 | 3 | 250° | 10 | 000000000 | 00000 |