Metric Nuts

Metric Coupling Nuts are extra-long hex nuts with right-hand coarse machine screw threads at each end. Use to "couple" two threaded rods to extend their length or connect a threaded rod to a hanger bolt. Length varies with size, which is about three times their size. They are also called Extension Nuts and Hex Spacers.

Metric Flange Nuts are similar to and often used with Flange Bolts and are available with coarse and fine machine screw threads. A large protruding circular flange, the diameter of which exceeds that of the hex section, accommodates oversized holes. Choose from smooth (non-serrated) and serrated bearing surfaces; serrations provide resistance to loosening.

Metric Hex Nuts remain the most common type of nut in use. They are full size and comparable to inch series Finished Hex Nuts. Their coarse and fine machine screw threads mate with the external threads of bolts, screws, studs, threaded rods, etc. The Class (strength grade) of a nut should be the same as or greater than that of the mating bolt/screw.

Metric Jam Nuts are thin hex nuts. They have coarse and fine machine screw threads, like hex nuts, but their reduced thickness (height) results in a reduction in strength. They are used with small machine screws to save space or to "jam" against another nut to create a locking action.

Metric Keps Nuts are hex nut/lock washer assemblies. Aside from the captive and free-spinning lock washer, the hex nut resembles a regular hex nut with coarse machine screw threads. They are a reusable and low-cost one-piece alternative to installing separate lock washers and nuts; they "lock" when seated and tightened. They are the same as K-Lock Nuts.

Metric K-Lock Nuts are hex nuts with free-spinning, non-removable lock washers. The hex nuts have coarse machine screw threads and mate with external threads. "Locking" occurs when they are seated and tightened. The two-piece assembly replaces separate nuts and washers, which saves time. They are equivalent to Keps Nuts.

Metric Lock Nuts make up a family of hex nuts that have some sort of "locking" feature. They include All Metal Prevailing Torque, K-Lock and Nylon Insert. Each type is suited for different applications. All are hex nuts with coarse machine screw threads; some are available with fine thread.

Metric Machine Screw Nuts are smaller than full-size hex nuts. Since there isn't a metric nut that's equivalent to inch series Machine Screw Nuts, the best option is to use a metric Jam Nut. They are the same width as like-sized hex nuts but are thinner—their thickness is about 0.5 times their nominal size instead of 0.8 times. Available in coarse and fine machine screw threads.

Metric Nylon Insert Lock Nuts use a captive undersized non-metallic (nylon) insert to create prevailing torque that results in rotational resistance. While the nylon insert acts as an effective gas and moisture seal, it alone is responsible for the temperature and chemical limitations of the nuts. Still, they are popular in many applications even though reuse is limited. Thread galling may occur with stainless steel nuts. Coarse and fine machine screw threads are available. Also called Nylock Nuts and Stop Nuts.

Metric Prevailing Torque Lock Nuts have a "locking" element that prevents the nuts from free spinning after the element engages the mating threads. For All Metal nuts, thread deformation creates the prevailing torque, which may cause thread galling. For Nylon Insert nuts, an undersized nylon washer is used; thread galling may occur with stainless steel Nylon Insert nuts. Both are installed one-way—the locking element threads on last. All Metal nuts are impervious to the chemicals that affect Nylon Insert nuts and can withstand higher temperatures. Reuse of both is limited since the prevailing torque declines each time the nut is installed and removed.

Metric Weld Nuts are available as hex nuts with three weld projections and square nuts with four projections. Choose from coarse and fine machine screw threads.

Metric Wing Nuts have two rounded tip wings, opposite each other, and a cone-shaped nut with coarse machine screw threads. Found in low-torque applications that are frequently adjusted or disassembled, use finger pressure to tighten and loosen.