Finding the Right Metric Nut is No Easy Task

With all of the nuts in the world, it can be hard to figure out which one is right for your assembly. To help you along with selecting the proper product for your project, here’s a brief rundown of some of the most common metric nuts and their applications.

  1. Metric All Metal Nuts
    alll metalThese general purpose nuts are commonly found on cars, farming machinery, and in metal working industries. They’re very tough, reusable, and provide a solid connection.

  1. Metric Hex Nuts
    metric hex nutMetric hex nuts are probably the most common type of nut in the world. These metric nuts are available in a wide variety of materials, strengths, and finishes. Their six-sided design makes them easy to turn with socket and box wrenches and provides a powerful grip.


  1. Metric Jam Nuts
    metric jam nutA jam nut works by “jamming” against a heavier metric nut. Jam nuts are thinner than full form metric nuts and act as a “lock” to keep either nut from loosening. This type of nut provides a great support system for your other metric nuts.


  1. Metric Nylock Nuts
    metric nylock nutThese metric nuts have a nylon collar at the back end. Once the bolt threads reach the surface, it creates a high-friction bond, keeping the screw or bolt from working loose under vibration.


  1. Metric Square Nuts
    metric square nutA great reusable metric nut, square nuts have more surface area which provides more holding power when tightened. They’re also more resistant to rounding or stripping, making them great for applications where they need to be reused.


  1. Metric Wing Nuts
    metric wing nutFor places where hand tightening is acceptable, you can’t beat a wing nut. These metric nuts can be quickly installed and removed using only your fingers.


  1. Metric Knurled Nuts
    metric knurled nutA close cousin of the wing nut, these metric nuts can be installed and removed by hand.


  1. Metric Hex Castle Nuts
    metric hex castle nutFrequently found in automotive and machinery applications, these metric nuts are positively locked in place using a cotter pin. The top of a metric castle nut is slotted. The slots align with a hole drilled in the mounting bolt. A cotter pin is inserted in one side of the slot, through the bolt, and out the other side of the slot. Once inserted, the cotter pin prevents the nut from loosening or tightening.


  1. Metric Insert Nuts
    metric insert nutThese metric nuts have a serrated edge along the bottom edge. The serrations bite into the mating material, creating a strong bond that resists loosening.


  1. Metric Weld Nuts
    metric weld nutWeld nuts are designed to be permanently welded to a mating surface, allowing other materials to be screwed or bolted in place. Made from bare steel, these metric nuts require little preparation prior to welding.


  1. Metric Dome/Acorn Nuts
    metric dome nutAcorn nuts screw onto the end of bolts or screws and provide a finished, snag-free product. The acorn nut covers the end of the bolt or screw, making for a safer, better-looking finish.


  1. Metric Keps/External Star Nuts
    metric kep nutMetric Kep nuts have an integral serrated washer. The washer spins independently of the nut, allowing it to bite deeply into the mating surface during installation.


Many Metric Nuts, One Purpose

The wide variety of metric nuts all share a common purpose—holding things together. When you’re installing, building, or repairing, you want things to stay where you put them. To find the perfect metric nut for your project, contact Mr. Metric.

About the author

Mr. Metric is the spokesperson for, an online store for metric fasteners. Get $7.50 flat shipping with no minimum orders, plus advice and best practices for using metric fasteners in any application.

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