McMaster-Carr logo
    Filter by
    System of Measurement
    Thread Pitch
    Industrial Info Snippet
    Attribute Image
    Fastener Strength Grade/Class
    Industrial Info Compare
    Face Style
    Hex Nut Profile
    Thread Spacing
    Industrial Info Compare
    Thread Type
    Fastener Strength Rating
    Specifications Met
    Industrial Info Compare
    Thread Direction
    Drive Style
    Industrial Info Snippet
    Thread Fit
    Industrial Info Snippet
    Attribute Image
    U.S.–Mexico–Canada Agreement (USMCA) Qualifying
    DFARS Specialty Metals
    Industrial Info Compare
    Spanner Wrench Style
    Export Control Classification Number (ECCN)
    Industrial Info Snippet
    Forward
    Enter e-mail addresses in the fields below
    Message
    Cancel
    Print
    How can we improve?
    Comments
    E-mail address (if you would like a response)
    17 Products

    Nylon-Insert Locknuts

    Versatile yet economical, these are the most commonly used locknuts. The nylon insert grips the screw to prevent loosening from moderate vibration without damaging threads. However, the insert may become brittle if exposed to high temperatures. These locknuts are reusable a handful of times, but the holding power decreases with each use.
    High-Strength Steel
    Image of Product. Front orientation. Locknuts. Nylon-Insert Locknuts.
    Rated Grade 8, Grade C, or Class 10, these locknuts are about 25% stronger than medium-strength steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.
    Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Fastener Strength
    Grade/Class
    Insert Max.
    Temp., ° F
    Specs. Met
    Pkg.
    Qty.
    Pkg.
    Zinc-Plated Steel
    M30 × 2 mm4630Class 10
    		185DIN 985, ISO 10511194645A124000000
    M30 × 3.5 mm4630Class 10
    		185DIN 985194645A33000000
     
    Medium-Strength Steel
    Image of Product. Front orientation. Locknuts. Nylon-Insert Locknuts.
    These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.
    Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Fastener Strength
    Grade/Class
    Insert Max.
    Temp., ° F
    Specs. Met
    Pkg.
    Qty.
    Pkg.
    Zinc-Plated Steel
    M30 × 2 mm4630Class 8
    		185DIN 985, ISO 10511190576A366000000
    M30 × 3.5 mm4630Class 8
    		185DIN 985, ISO 10511190576A1500000
     
    Low-Strength Steel
    Image of Product. Front orientation. Locknuts. Nylon-Insert Locknuts.
    Rated Grade 2, Class 6, or lower, these locknuts are about half as strong as medium-strength steel nuts. Use them with screws that have a similar strength rating to avoid stripping threads during installation.
    Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Insert Max.
    Temp., ° F
    Pkg.
    Qty.
    Pkg.
    Zinc-Plated Steel
    M30 × 3.5 mm4630185190631A12600000
     
    Corrosion-Resistant Stainless Steel
    Image of Product. Front orientation. Locknuts. Nylon-Insert Locknuts.
    18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.
    316 Stainless Steel—Our most corrosion-resistant nuts, these hold up in just about any environment. They won't degrade from exposure to weather, salt water, and most chemicals.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Insert Max.
    Temp., ° F
    Specs.
    Met
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    M30 × 3.5 mm4630185DIN 985193625A750000000
     
    316 Stainless Steel
    M30 × 3.5 mm4630185DIN 985194205A38000000
     

    Bearing Locknuts

    Image of System. Front orientation. Contains Annotated. Bearing Nuts. Bearing Locknuts.
    Image of Product. Carbon Steel. Front orientation. Bearing Nuts. Bearing Locknuts, Chamfered Face, Carbon Steel.

    Carbon Steel

    With a nylon insert that grips your threaded shaft or spindle without damaging its threads, these locknuts—also called shaft nuts—hold bearings, bushings, gears, and pulleys prone to vibration tightly in place. They come as one piece, so you can easily clamp them onto your shaft or spindle. But, since they aren’t made entirely of metal, they don’t stand up to heat as well as all-metal locknuts. Slots in their sides mean you can tighten and loosen them with a spanner wrench or spanner socket. Their face is also chamfered to help keep the size and weight of your assembly at a minimum. All meet international standards for bearing locknut dimensions.
    Zinc-Plated Carbon Steel—Zinc-plated carbon steel locknuts resist rusting from some moisture, but you shouldn’t use them with salt water or chemicals. They are strong and resist wear, though they don’t stand up to corrosion as well as 303 stainless steel locknuts.
    Carbon Steel—All carbon steel locknuts are strong and resist wear, though they don’t stand up to corrosion as well as 303 stainless steel locknuts.
    303 Stainless Steel—303 stainless steel locknuts resist corrosion better than carbon steel locknuts but aren’t as strong. They withstand washdowns and chemicals.
    Thread Spacing—When choosing your thread spacing, consider the precision of your application. The finer the threads, the more control you have when making adjustments.
    Locknuts
    Sockets
    Thread
    Carbon Steel
    Zinc-Plated
    Carbon Steel
    303
    Stainless Steel
    Size
    Spacing
    OD,
    mm
    Wd.,
    mm
    Insert Max.
    Temp., ° F
    Specs.
    Met
    Each
    Each
    Each
    Each
    Chamfered Face
    M30 × 1.5 mmExtra Fine
    		4411210————03552N35000000———0———0
    M30 × 1.5 mmExtra Fine
    		4511.5160ISO 2982-26343K38000000———06343K680000005510N1530000000
     

    Steel-Insert Locknuts for Extreme Vibration

    Image of Product. Bottom orientation. Locknuts. Steel-Insert Locknuts for Extreme Vibration.
    The most secure hold of all the locknuts we offer. The tab on the insert stops the nut from rotating, even under extreme vibration. These locknuts are ideal for equipment with constant motion or jarring starts and stops, including conveyors, shakers, and compactors. In fact, they're so secure that they're even used to fasten components on roller coasters. These locknuts are also reusable, but their holding power decreases after the first use, so you should use a new nut for the strongest possible hold.
    Material Certificate Icon
    Certificates with a traceable lot number are available for these products. Download certificates from ORDER HISTORY after your order ships.
    Medium-Strength Steel
    These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.
    Steel—Best for dry environments since moisture will cause these nuts to rust.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Fastener Strength
    Grade/Class
    Each
    Steel
    M30 × 3.5 mm4627Class 8
    		93520A229000000
     

    Top-Lock Distorted-Thread Locknuts

    Image of Product. Front orientation. Locknuts. Top-Lock Distorted-Thread Locknuts.
    Irregularly shaped threads at the top of these locknuts grip the screw for a stronger hold than nylon-insert locknuts. Although the threads prevent the nut from backing out due to vibration, they also increase the effort to install and remove. To get these nuts off, you may need special tools, such as an impact wrench or propane torch. Nuts are not reusable.
    High-Strength Steel
    Rated Grade 8, Grade C, or Class 10, these locknuts are about 25% stronger than medium-strength steel nuts. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.
    Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Fastener Strength
    Grade/Class
    Pkg.
    Qty.
    Pkg.
    Zinc-Plated Steel
    M30 × 2 mm4630Class 10
    		199183A46000000
    M30 × 3.5 mm4630Class 10
    		199183A2400000
     
    Medium-Strength Steel
    These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.
    Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Fastener Strength
    Grade/Class
    Specs.
    Met
    Pkg.
    Qty.
    Pkg.
    Zinc-Plated Steel
    M30 × 3.5 mm4630Class 8
    		DIN 980V193795A31200000
     

    Locknuts for use with Cotter Pins

    Use these locknuts to secure rotating parts subjected to mild vibration, such as the wheels on carts and hand trucks. They’re not recommended for use on parts exposed to high vibration because the pin can shear under prolonged stress. These nuts are reusable, but you'll need a new cotter pin (not included) with each use.
    Medium-Strength Steel
    Image of ProductInUse. Front orientation. Locknuts. Locknuts for use with Cotter Pins.
    Image of Product. Front orientation. Locknuts. Locknuts for use with Cotter Pins.
    These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.
    Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.
    Steel—Best for dry environments since moisture will cause these nuts to rust.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Fastener Strength
    Grade/Class
    For Cotter
    Pin Dia., mm
    Specs.
    Met
    Pkg.
    Qty.
    Pkg.
    Zinc-Plated Steel
    M30 × 3.5 mm4633Class 8
    		6.3DIN 935193760A114000000
     
    Steel
    M30 × 3.5 mm4633Class 8
    		6.3DIN 935193760A12100000
     
    back to top