--- title: "What Are Nylon Insert Hex Lock Nut Used For?" description: "Nylon Insert Hex Lock Nuts (GB/T 889 / ISO 7040) are used for the clamped counter-face of a bolted joint. Catalogued M3 to M36." url: https://engineeringhardware.com/applications/cad-svg-078-nylocnut/ source: Engineering Hardware & Fasteners --- # What Are Nylon Insert Hex Lock Nut Used For? Nuts · GB/T 889 / ISO 7040 · Application guide Typical applications, the industries that specify nylon insert hex lock nut, and how to choose the right size, material and finish for the joint. Nylon Insert Hex Lock Nuts are used for the clamped counter-face of a bolted joint. They are manufactured to GB/T 889 / ISO 7040, 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:** The clamped counter-face of a bolted joint - **Governing standard:** GB/T 889 / ISO 7040 - **Thread size range:** M3 to M36 - **Category:** Nuts Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation. ![What Are Nylon Insert Hex Lock Nut Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/06/Nylon-Insert-Hex-Lock-Nut-—-GB-T-889-ISO-7040-Series-078-—-GB-T-889-ISO-7040.webp) Application guide for Nylon Insert Hex Lock Nuts to GB/T 889 / ISO 7040. The core duty of the type is the clamped counter-face of a bolted joint. The typical industries, the how-to-specify checklist, assembly practice and the exclusion cases are set out below. Stocked across roughly M3 to M36, they cover general to heavy-duty work. ## Typical Applications for Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) 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. ## How to Specify Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) for Your Application - **Size:** Match the nominal size to the mating thread or hole. This product spans M3–M36; 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 GB/T 889 / ISO 7040. 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 Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) - 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 Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) 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 nylon insert hex lock nut 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 M3 Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) to GB/T 889 / ISO 7040. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Pitch (mm):** 0.5 - **Width across flats s (mm):** 5.5 - **Width across corners e (mm):** 6.01 - **Total height m (mm):** 4.0 ## Dimensions & Specifications (GB/T 889 / ISO 7040) | Size | Pitch (mm) | Width across flats s (mm) | Width across corners e (mm) | Total height m (mm) | Reference standard | | --- | --- | --- | --- | --- | --- | | M3 | 0.5 | 5.5 | 6.01 | 4.0 | ISO 7040 / DIN 985 | | M4 | 0.7 | 7.0 | 7.66 | 5.0 | ISO 7040 / DIN 985 | | M5 | 0.8 | 8.0 | 8.79 | 5.0 | ISO 7040 / DIN 985 | | M6 | 1.0 | 10.0 | 11.05 | 6.0 | ISO 7040 / DIN 985 | | M8 | 1.25 | 13.0 | 14.38 | 8.0 | ISO 7040 / DIN 985 | | M10 | 1.5 | 16.0 | 17.77 | 10.0 | ISO 7040 / DIN 985 | | M12 | 1.75 | 18.0 | 20.03 | 12.0 | ISO 7040 / DIN 985 | | M14 | 2.0 | 21.0 | 23.36 | 14.0 | ISO 7040 / DIN 985 | | M16 | 2.0 | 24.0 | 26.75 | 16.0 | ISO 7040 / DIN 985 | | M18 | 2.5 | 27.0 | 30.14 | 18.0 | ISO 7040 / DIN 985 | | M20 | 2.5 | 30.0 | 33.53 | 20.0 | ISO 7040 / DIN 985 | | M24 | 3.0 | 36.0 | 39.98 | 22.0 | ISO 7040 / DIN 985 | | M30 | 3.5 | 46.0 | 50.85 | 25.0 | ISO 7040 / DIN 985 | | M36 | 4.0 | 55.0 | 60.79 | 29.0 | ISO 7040 / DIN 985 | 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 Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) 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 Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) made to a recognized standard? Yes — they are manufactured to GB/T 889 / ISO 7040, so dimensions are interchangeable between suppliers when you quote the standard on your order. ### What are Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) used for? The clamped counter-face of a bolted joint. They are supplied to GB/T 889 / ISO 7040. ### Which industries use Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078)? They are commonly specified in general machine building, maintenance & repair (mro) and fabrication & metalwork, among other sectors. ### Can I get a quote for Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) 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: [Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) — specifications & sizes](https://engineeringhardware.com/fastener/cad-svg-078-nylocnut/) ### Nylon Insert Hex Lock Nut — GB/T 889 / ISO 7040 (Series 078) Specification Guides ### Related Fastener Applications