--- title: "What Are Self-Tapping Screws Used For?" description: "Self-Tapping Screws (ISO 7049 / DIN 7981) are used for fixing into sheet, timber or plastic by forming their own thread as they are driven, without a tapped…" url: https://engineeringhardware.com/applications/self-tapping-screws/ source: Engineering Hardware & Fasteners --- # What Are Self-Tapping Screws Used For? Screws · ISO 7049 / DIN 7981 · Application guide Typical applications, the industries that specify self-tapping screws, and how to choose the right size, material and finish for the joint. Self-Tapping Screws are used for fixing into sheet, timber or plastic by forming their own thread as they are driven, without a tapped hole. They are manufactured to ISO 7049 / DIN 7981, and selection is driven by the size designation, the fit and tolerance the assembly requires, and the service environment. - **Primary duty:** Fixing into sheet, timber or plastic by forming their own thread as they are driven, without a tapped hole - **Governing standard:** ISO 7049 / DIN 7981 - **Size designation range:** ST2.2 to ST9.5 - **Category:** Screws Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation. ![What Are Self-Tapping Screws Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/06/Self-Tapping-Screws-—-DIN-7976-／-ISO-1481-Applications1.webp) Application guide for Self-Tapping Screws to ISO 7049 / DIN 7981. The core duty of the type is fixing into sheet, timber or plastic by forming their own thread as they are driven, without a tapped hole. The typical industries, the how-to-specify checklist, assembly practice and the exclusion cases are set out below. Stocked across roughly 2.2 to 9.5, they cover general to heavy-duty work. ## Typical Applications for Self-Tapping Screws The most common settings where these are specified: - **Electronics & enclosures:** mounting PCBs, panels and lids where the drive style and head height matter. - **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. ## How to Specify Self-Tapping Screws for Your Application - **Size:** Match the nominal size to the mating thread or hole. This product spans 2.2–9.5; 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 ISO 7049 / DIN 7981. 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 Self-Tapping 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 Self-Tapping 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 self-tapping screws outside the standard range? A non-standard screw is quoted from the drawing; where one already exists in the catalog, the special is usually a variation on its tooling. 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 ST2.2 Self-Tapping Screws to ISO 7049 / DIN 7981. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Nominal diameter (mm):** 2.2 - **Pilot hole (mm):** 1.7 - **Pitch (mm):** 0.71 - **Head diameter dk (mm):** 4.2 - **Head height k (mm):** 1.4 - **Plate thickness (mm):** 0.5~1.0 - **Notes:** Cross-recess pan-head self-tapping ## Dimensions & Specifications (ISO 7049 / DIN 7981) | Size | Nominal diameter (mm) | Pilot hole (mm) | Pitch (mm) | Head diameter dk (mm) | Head height k (mm) | Plate thickness (mm) | Reference standard | Notes | | --- | --- | --- | --- | --- | --- | --- | --- | --- | | ST2.2 | 2.2 | 1.7 | 0.71 | 4.2 | 1.4 | 0.5~1.0 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST2.9 | 2.9 | 2.3 | 0.94 | 5.6 | 1.7 | 0.6~1.6 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST3.5 | 3.5 | 2.8 | 1.27 | 6.9 | 2.1 | 0.8~2.0 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST3.9 | 3.9 | 3.1 | 1.29 | 7.5 | 2.3 | 0.9~2.5 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST4.2 | 4.2 | 3.4 | 1.41 | 8.2 | 2.5 | 1.0~2.5 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST4.8 | 4.8 | 3.9 | 1.59 | 9.5 | 2.9 | 1.2~3.0 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST5.5 | 5.5 | 4.5 | 1.81 | 10.9 | 3.3 | 1.5~3.5 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST6.3 | 6.3 | 5.1 | 1.81 | 12.5 | 3.8 | 2.0~4.0 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST8.0 | 8.0 | 6.7 | 2.12 | 16.0 | 4.8 | 2.5~5.0 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | | ST9.5 | 9.5 | 8.0 | 2.12 | 19.0 | 5.7 | 3.0~6.0 | ISO 7049 / DIN 7981 | Cross-recess pan-head self-tapping | 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 drive type do Self-Tapping Screws use? Drive depends on the head style — socket (hex key), cross (Phillips/Pozi) or slot. A recessed drive resists cam-out when driven with power tools; check the product head style on this page. ### What material should Self-Tapping 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 Self-Tapping Screws made to a recognized standard? Yes — they are manufactured to ISO 7049 / DIN 7981, so dimensions are interchangeable between suppliers when you quote the standard on your order. ### What are Self-Tapping Screws used for? Fixing into sheet, timber or plastic by forming their own thread as they are driven, without a tapped hole. They are supplied to ISO 7049 / DIN 7981. ### Can I get a quote for Self-Tapping 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: [Self-Tapping Screws — specifications & sizes](https://engineeringhardware.com/fastener/self-tapping-screws/) ### Self-Tapping Screws Specification Guides ### Related Fastener Applications