Stainless steel external expansion screw

Stainless steel external expansion screws, commonly known as stainless steel expansion anchor bolts, are mechanical anchoring fasteners designed for securing structures and equipment to concrete or solid masonry substrates. The fastening mechanism relies on an expansion sleeve that expands against the wall of the drilled hole when the nut is tightened, creating a strong frictional and mechanical anchoring effect. Stainless steel expansion screws are widely used in structural installations where corrosion resistance, reliable anchoring strength, and long-term durability are required.

ZSD Screw manufactures stainless steel external expansion screws through controlled machining and assembly processes, ensuring dimensional accuracy and stable anchoring performance. Production dimensions and design principles are based on commonly used industrial anchor standards such as DIN 933 and installation practices widely applied in construction fastening systems. Stainless steel materials used in these anchor assemblies follow the mechanical property requirements defined in ISO 3506 to ensure consistent strength and corrosion resistance in structural environments. Quality inspection includes thread verification, sleeve dimensional inspection, and assembly checks to maintain reliable expansion performance.

Standard sizes are produced according to common construction anchoring specifications. Custom anchor lengths and configurations can be manufactured according to installation requirements or engineering drawings.

Type: External Expansion Screw / Expansion Anchor Bolt
Head Type: External Hex Head
Diameter Range: M6 – M24
Length Range: 40 mm – 200 mm
Thread Type: Metric
Expansion Mechanism: Sleeve Expansion
Tolerance: According to standard specifications or customer drawings.

Materials Available: Stainless Steel 304 (A2)、Stainless Steel 316 / 316L (A4). Other corrosion-resistant stainless steel materials can be supplied upon request depending on service environment requirements.

Strength Grades: Stainless steel expansion screws generally follow material classifications defined in ISO 3506 such as A2-50、A2-70、A4-70、A4-80, which define the tensile strength characteristics of stainless threaded components used in anchoring assemblies. For reference across general fastening systems, carbon steel threaded fasteners commonly use strength grades 4.8、8.8、10.9、12.9、14.9 according to ISO 898-1. ZSD Screw maintains controlled production processes and inspection procedures to ensure consistent anchoring reliability and fastening stability.

Surface Treatment: Stainless steel expansion screws primarily rely on the inherent corrosion resistance of stainless alloys. Depending on installation environments, the following surface finishing processes may be applied: Passivation treatment、Electropolishing、Cleaning and protective oil treatment. Additional surface finishing or special treatments can be arranged according to environmental conditions or project specifications.

Applications: In mechanical equipment manufacturing, stainless steel external expansion screws are commonly used for fixing machine bases, equipment frames, mounting brackets, and structural supports onto concrete foundations. The expansion anchoring mechanism helps provide reliable load transfer and stable installation for industrial equipment.

In electronic equipment and industrial electronics, these expansion anchors are used for securing control cabinets, industrial enclosures, cable management systems, and mounting frames to concrete or masonry walls. Stable anchoring performance helps maintain structural support and installation safety for electronic and automation equipment.

In the new energy sector, stainless steel expansion screws are widely applied in photovoltaic mounting structures, inverter support frames, battery storage installations, and renewable energy equipment mounting systems. Corrosion-resistant stainless materials are particularly suitable for outdoor installations exposed to moisture and temperature variation.

In conventional and renewable power generation facilities, expansion anchor bolts are used to secure generator bases, auxiliary equipment frames, cable tray supports, and pipeline brackets to concrete structures. Reliable anchoring strength is important for maintaining equipment stability under vibration and operational loads.

In the automotive and transportation industries, stainless steel expansion screws are used in maintenance facilities, vehicle service infrastructure, equipment installation points, and structural support systems where mechanical equipment must be anchored securely to concrete foundations.

In heavy industry and engineering equipment manufacturing, stainless steel expansion anchors are widely used for installing steel structures, processing equipment bases, conveyor supports, lifting equipment frames, and industrial infrastructure. Their durable mechanical anchoring capability supports safe and stable equipment installation in demanding industrial environments.

304-A2:  Moderate work hardening rate, suitable for general cold working and deep drawing processes. It has good cold workability and is widely used in the production of hexagon screws, nuts and washers.

316-A4: Added with molybdenum, it has stronger corrosion resistance than 304. It is especially suitable for applications in seawater and chemical media, with enhanced corrosion resistance and pitting resistance.

Notes：1. If the nickel content is lower than 8%, the minimum manganese content must be 5%.
2. When the nickel content is greater than 8%, there is no limit on the minimum copper content.
3. If the chromium content is lower than 17%, the minimum nickel content shall be 12%.
4. For austenitic stainless steel with a maximum carbon content of 0.03%, the maximum nitrogen content can reach 0.22%.
5. For products with larger diameters, to meet the specified mechanical properties, a higher carbon content may be specified in the manufacturer’s instructions; however, for martensitic steel, the carbon content shall not exceed 0.12%.