--- title: "What Are One-Way Security Screws Used For?" description: "One-Way Security Screws (Trade series (one-way clutch head)) are used for fixings in public or unsupervised places that must resist casual removal with ordin…" url: https://engineeringhardware.com/applications/one-way-security-screws/ source: Engineering Hardware & Fasteners --- # What Are One-Way Security Screws Used For? Screws · Trade series (one-way clutch head) · Application guide Typical applications, the industries that specify one-way security screws, and how to choose the right size, material and finish for the joint. One-Way Security Screws are used for fixings in public or unsupervised places that must resist casual removal with ordinary tools. They are manufactured to Trade series (one-way clutch head), 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:** Fixings in public or unsupervised places that must resist casual removal with ordinary tools - **Governing standard:** Trade series (one-way clutch head) - **Thread size range:** M3.5 to M8 - **Category:** Screws Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation. ![What Are One-Way Security Screws Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/09/Security-Screws-Drive-Detail.webp) Application guide for One-Way Security Screws to Trade series (one-way clutch head). The core duty of the type is fixings in public or unsupervised places that must resist casual removal with ordinary tools. The typical industries, the how-to-specify checklist, assembly practice and the exclusion cases are set out below. Stocked across roughly M3.5 to M8, they cover general to heavy-duty work. ## Typical Applications for One-Way Security Screws The most common settings where these are specified: - **Appliances & consumer goods:** high-volume assembly with power tools and consistent seating. - **Machine guarding & panels:** removable access covers that are opened for service. - **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. 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This product spans M3.5–M8; check the full table below for the exact dimensions of each size. - **Drive & head:** Pick the drive (socket, cross, slot) and head style for the tool access and seating surface; a recessed drive resists cam-out under power tools. - **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 Trade series (one-way clutch head). Quoting the standard on your order guarantees interchangeable dimensions between suppliers. ## Installation & Assembly Practice - Match the driver exactly to the recess (PH ≠ PZ; hex key sizes per ISO 2936) and keep the tool axial — side load is the main cause of stripped drives. - In tapped holes, engage a thread length of at least 1× the nominal diameter in steel, 2× in aluminum. - Set power tools to a torque that seats the head without embedding it into the mating surface. ## Common Selection Mistakes with One-Way Security Screws - Under-sizing the drive for the installation torque — a small recess at high torque strips before the screw is seated. - Using a countersunk head in thin sheet where the countersink removes most of the load-bearing material. - Specifying stainless in high-strength duty: A2-70 is roughly class 7 steel, not a 10.9 substitute. ## Where One-Way Security Screws Are Not the Right Choice Not for high-preload structural joints (use a property-class bolt and nut), and not in thin sheet where a self-drilling or self-tapping type suits better. Custom manufacturing · Made to drawing ## Need a one-way security screws outside the standard range? Thread size and pitch, length, property class, drive form, head geometry and head marking are all specifiable — the standard part is where it starts, not where it stops. Made by cold heading or warm forging. Minimum order from 2,000 pieces; samples within 7 days of drawing approval. [Custom screw manufacturing](https://engineeringhardware.com/custom/screws/)[Send a drawing](https://engineeringhardware.com/custom/screws/#rfq) ## Technical Drawing Dimensioned line drawing of M3.5 One-Way Security Screws to Trade series (one-way clutch head). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Pitch (mm):** 0.6 - **Head diameter dk (mm):** 7.0 - **Head height k (mm):** 2.4 - **Head form:** Pan - **Common length range (mm):** 10~40 - **Material:** Steel zinc / A2 - **Removable:** No — permanent ## Dimensions & Specifications (Trade series (one-way clutch head)) | Thread size | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Head form | Common length range (mm) | Material | Removable | | --- | --- | --- | --- | --- | --- | --- | --- | | M3.5 | 0.6 | 7.0 | 2.4 | Pan | 10~40 | Steel zinc / A2 | No — permanent | | M4 | 0.7 | 8.0 | 2.8 | Pan | 10~50 | Steel zinc / A2 | No — permanent | | M5 | 0.8 | 9.5 | 3.2 | Pan | 12~60 | Steel zinc / A2 | No — permanent | | M6 | 1.0 | 12.0 | 3.8 | Pan | 16~60 | Steel zinc | No — permanent | | M8 | 1.25 | 16.0 | 4.6 | Pan | 20~60 | Steel zinc | No — permanent | 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 One-Way Security Screws 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 One-Way Security Screws made to a recognized standard? Yes — they are manufactured to Trade series (one-way clutch head), so dimensions are interchangeable between suppliers when you quote the standard on your order. ### What are One-Way Security Screws used for? Fixings in public or unsupervised places that must resist casual removal with ordinary tools. They are supplied to Trade series (one-way clutch head). ### Which industries use One-Way Security Screws? They are commonly specified in general machine building, maintenance & repair (mro) and fabrication & metalwork, among other sectors. ### Can I get a quote for One-Way Security Screws 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: [One-Way Security Screws — specifications & sizes](https://engineeringhardware.com/fastener/one-way-security-screws/) ### One-Way Security Screws Specification Guides ### Related Fastener Applications