--- title: "What Are Bearing Lock Nuts (KM Series) Used For?" description: "Bearing Lock Nuts (KM Series) (DIN 981) are used for setting and holding a rolling bearing on a threaded shaft seat, used together with a matching tab washer." url: https://engineeringhardware.com/applications/bearing-lock-nuts-km/ source: Engineering Hardware & Fasteners --- # What Are Bearing Lock Nuts (KM Series) Used For? Nuts · DIN 981 · Application guide Typical applications, the industries that specify bearing lock nuts (km series), and how to choose the right size, material and finish for the joint. Bearing Lock Nuts (KM Series) are used for setting and holding a rolling bearing on a threaded shaft seat, used together with a matching tab washer. They are manufactured to DIN 981, and the choice of size, property class and finish is driven by the load in the joint and the environment it sits in. - **Primary duty:** Setting and holding a rolling bearing on a threaded shaft seat, used together with a matching tab washer - **Governing standard:** DIN 981 - **Size designation range:** KM4 to KM12 - **Category:** Nuts Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation. ![What Are Bearing Lock Nuts (KM Series) Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/06/Slotted-Round-Nut-—-GB-T-812-Series-069-—-GB-T-812.webp) The primary duty of Bearing Lock Nuts (KM Series) is setting and holding a rolling bearing on a threaded shaft seat, used together with a matching tab washer. Below: the sectors that specify them in volume, the checklist used to select the right size and material for the application, installation notes, and the known limits of the type. Stocked across roughly 4 to 12, they cover general to heavy-duty work. ## Typical Applications for Bearing Lock Nuts (KM Series) The most common settings where these are specified: - **Vibration-prone equipment:** where a locking or flanged style resists loosening. - **Frames & weldments:** captive or welded options for repeatable assembly. - **General machine building:** fastening covers, brackets, motors and sub-assemblies on production equipment. - **Maintenance & repair (MRO):** a stocked size for servicing existing plant where the original fastener spec must be matched. - **Fabrication & metalwork:** bench and on-site assembly of steel frames, enclosures and weldments. Product catalog ## Related Bearing Lock Nuts (KM) products [![DIN6923 Hot Sale Flange Lock Nut Self-Locking Nut Flange Nut](https://img.engineeringhardware.com/DIN6923-Hot-Sale-Flange-Lock-Nut-Self-Locking-Nut-Flange-Nut.webp)](https://engineeringhardware.com/product/din6923-hot-sale-flange-lock-nut-self-locking-nut-flange-nut/) Nylon-Insert & All-Metal Lock Nuts ### [DIN6923 Hot Sale Flange Lock Nut Self-Locking Nut Flange Nut](https://engineeringhardware.com/product/din6923-hot-sale-flange-lock-nut-self-locking-nut-flange-nut/) Hexagon Head · GB **US$0.62 – 0.82**MOQ 50,000 pieces [![DIN985 DIN982 M5 M6 M8 M10 M12 M14 M16 M20 Carbon Steel Nylon Lock Nut](https://img.engineeringhardware.com/DIN985-DIN982-M5-M6-M8-M10-M12-M14-M16-M20-Carbon-Steel-Nylon-Lock-Nut.webp)](https://engineeringhardware.com/product/din985-din982-m5-m6-m8-m10-m12-m14-m16-m20-carbon-steel-nylon-lock-nut/) Nylon-Insert & All-Metal Lock Nuts ### [DIN985 DIN982 M5 M6 M8 M10 M12 M14 M16 M20 Carbon Steel Nylon Lock Nut](https://engineeringhardware.com/product/din985-din982-m5-m6-m8-m10-m12-m14-m16-m20-carbon-steel-nylon-lock-nut/) Hexagon Head · DIN **US$0.012 – 0.036**MOQ 10,000 pieces [![China Galvanized Nylon Lock Nuts Stainless Steel DIN985 Hex Blue Lock Nuts](https://img.engineeringhardware.com/China-Galvanized-Nylon-Lock-Nuts-Stainless-Steel-DIN985-Hex-Blue-Lock-Nuts.webp)](https://engineeringhardware.com/product/china-galvanized-nylon-lock-nuts-stainless-steel-din985-hex-blue-lock-nuts/) Nylon-Insert & All-Metal Lock Nuts ### [China Galvanized Nylon Lock Nuts Stainless Steel DIN985 Hex Blue Lock Nuts](https://engineeringhardware.com/product/china-galvanized-nylon-lock-nuts-stainless-steel-din985-hex-blue-lock-nuts/) Hexagon Head · DIN, ANSI, GB, JIS, GOST, BSW **US$0.0012 – 0.006**MOQ 10,000 pieces [![DIN985 Nylon Nut M2 M2.5 M3 M4 M5 M6 M8 Customized Aluminum Nylon Lock Nuts](https://img.engineeringhardware.com/DIN985-Nylon-Nut-M2-M2-5-M3-M4-M5-M6-M8-Customized-Aluminum-Nylon-Lock-Nuts.webp)](https://engineeringhardware.com/product/din985-nylon-nut-m2-m2-5-m3-m4-m5-m6-m8-customized-aluminum-nylon-lock-nuts/) Nylon-Insert & All-Metal Lock Nuts ### [DIN985 Nylon Nut M2 M2.5 M3 M4 M5 M6 M8 Customized Aluminum Nylon Lock Nuts](https://engineeringhardware.com/product/din985-nylon-nut-m2-m2-5-m3-m4-m5-m6-m8-customized-aluminum-nylon-lock-nuts/) ASME/ANSI B18.2.2; DIN985, DIN982 · Copper **US$0.012**MOQ 1,000 pieces [![Metric DIN 985 Blue White Zinc Plated Steel Hexagon Nylock Self Locking Hex Nut](https://img.engineeringhardware.com/Metric-DIN-985-Blue-White-Zinc-Plated-Steel-Hexagon-Nylock-Self-Locking-Hex-Nut.webp)](https://engineeringhardware.com/product/metric-din-985-blue-white-zinc-plated-steel-hexagon-nylock-self-locking-hex-nut/) Nylon-Insert & All-Metal Lock Nuts ### [Metric DIN 985 Blue White Zinc Plated Steel Hexagon Nylock Self Locking Hex Nut](https://engineeringhardware.com/product/metric-din-985-blue-white-zinc-plated-steel-hexagon-nylock-self-locking-hex-nut/) Hexagon Head · DIN, ANSI, GB, JIS, GOST, BSW **US$0.024 – 0.06**MOQ 10 pieces [![White Blue Zinc Plated Black Oxide Hex Flange Nylon Lock Nut](https://img.engineeringhardware.com/White-Blue-Zinc-Plated-Black-Oxide-Hex-Flange-Nylon-Lock-Nut.webp)](https://engineeringhardware.com/product/white-blue-zinc-plated-black-oxide-hex-flange-nylon-lock-nut/) Nylon-Insert & All-Metal Lock Nuts ### [White Blue Zinc Plated Black Oxide Hex Flange Nylon Lock Nut](https://engineeringhardware.com/product/white-blue-zinc-plated-black-oxide-hex-flange-nylon-lock-nut/) Hexagon Head · DIN, ANSI, GB, JIS, GOST, BSW **US$0.012 – 0.12**MOQ 1 piece [View all Nylon-Insert & All-Metal Lock Nuts →](https://engineeringhardware.com/fastener-products/nuts/nylon-insert-all-metal-lock-nuts/) [Full product catalog](https://engineeringhardware.com/products/) ## How to Specify Bearing Lock Nuts (KM Series) for Your Application - **Size:** Match the nominal size to the mating thread or hole. This product spans 4–12; check the full table below for the exact dimensions of each size. - **Locking & grade:** Match the strength grade to the bolt, and choose a locking style (nyloc, all-metal, serrated flange) if the joint sees vibration. - **Environment:** For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient. - **Standard:** This product is supplied to DIN 981. Quoting the standard on your order guarantees interchangeable dimensions between suppliers. ## Installation & Assembly Practice - Run the nut down by hand before applying the wrench to catch cross-threading early. - Tighten the nut rather than the bolt head where access allows — the torque-to-preload relation is more consistent. - For locking styles, note that nyloc inserts are single-use in critical joints and lose grip above roughly 120 °C. ## Common Selection Mistakes with Bearing Lock Nuts (KM Series) - Pairing a high-class bolt with a lower-class nut — the nut strips before the bolt reaches proof load; the nut class must meet or exceed the bolt class. - Using a plain nut with a spring washer in severe vibration instead of a prevailing-torque locking nut. - Re-using nyloc nuts in critical joints. ## Where Bearing Lock Nuts (KM Series) Are Not the Right Choice Not on their own — they need a matching bolt or stud — and a plain nut is not a substitute for a locking type under heavy vibration. Custom manufacturing · Made to drawing ## Need a bearing lock nuts (km series) outside the standard range? Thread, height, across-flats, property class, locking feature and flange form can all be varied, including thread sizes the standard series does not run to. Made by cold heading or tapping. Minimum order from 2,000 pieces; samples within 7 days of drawing approval. [Custom nut manufacturing](https://engineeringhardware.com/custom/nuts/)[Send a drawing](https://engineeringhardware.com/custom/nuts/#rfq) ## Technical Drawing Dimensioned line drawing of KM0 Bearing Lock Nuts (KM Series) to DIN 981. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Thread size:** M10x0.75 - **Outer diameter D (mm):** 18 - **Nut height m (mm):** 4 - **Slot width (mm):** 3 - **Slot depth (mm):** 2 - **Matching tab washer:** MB0 ## Dimensions & Specifications (DIN 981) | Size | Thread size | Outer diameter D (mm) | Nut height m (mm) | Slot width (mm) | Slot depth (mm) | Matching tab washer | Reference standard | | --- | --- | --- | --- | --- | --- | --- | --- | | KM0 | M10x0.75 | 18 | 4 | 3 | 2 | MB0 | DIN 981 | | KM4 | M20x1.0 | 32 | 6 | 4 | 2 | MB4 | DIN 981 | | KM6 | M30x1.5 | 45 | 7 | 5 | 2 | MB6 | DIN 981 | | KM8 | M40x1.5 | 58 | 9 | 5 | 2.5 | MB8 | DIN 981 | | KM10 | M50x1.5 | 70 | 9 | 6 | 2.5 | MB10 | DIN 981 | | KM12 | M60x2.0 | 80 | 11 | 6 | 3 | MB12 | DIN 981 | Inside the plant ## Manufactured in our own plant This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided. 1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift. 2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g. 3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1. 4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227. ## Frequently Asked Questions ### What material should Bearing Lock Nuts (KM Series) be for outdoor use? For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate. ### Are Bearing Lock Nuts (KM Series) made to a recognized standard? Yes — they are manufactured to DIN 981, so dimensions are interchangeable between suppliers when you quote the standard on your order. ### What are Bearing Lock Nuts (KM Series) used for? Setting and holding a rolling bearing on a threaded shaft seat, used together with a matching tab washer. They are supplied to DIN 981. ### Which industries use Bearing Lock Nuts (KM Series)? They are commonly specified in general machine building, maintenance & repair (mro) and fabrication & metalwork, among other sectors. ### Can I get a quote for Bearing Lock Nuts (KM Series) in the size and material I need? Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time. ## Related Pages Product page: [Bearing Lock Nuts (KM Series) — specifications & sizes](https://engineeringhardware.com/fastener/bearing-lock-nuts-km/) ### Bearing Lock Nuts (KM Series) Specification Guides ### Related Fastener Applications