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【2】Size: M3-M64.
【3】Surface treatment: Natural color, passivated, customizable.
【4】Packaging methods: Bagged, Boxed, Cardboard box, Pallet.
【5】Execution standards: GB, DIN, ISO, ANSI, JIS, etc.
【6】Optional services: Customize、OEM/ODM、Testing (salt spray testing,etc)
Stainless steel external hex bolt and nut assemblies are complete fastening sets consisting of a hexagon head bolt and a matching hex nut, typically used together with washers to create secure threaded connections. These assemblies are widely applied in structural, mechanical, and equipment installations where reliable clamping force, corrosion resistance, and long-term durability are required. Stainless steel bolt and nut assemblies are especially suitable for outdoor installations, humid environments, and equipment exposed to chemical or marine conditions.
ZSD Screw manufactures stainless steel external hex bolt and nut assemblies through controlled cold forging, precision thread rolling, and standardized nut forming processes. Production follows internationally recognized dimensional standards such as DIN 933, DIN 931, ISO 4017, ISO 4014, and hex nut standards such as DIN 934. Stainless steel material properties are produced according to ISO 3506 to ensure consistent tensile strength and corrosion resistance. Quality control procedures include dimensional inspection, thread gauge verification, and batch traceability to maintain stable fastening performance.
Standard bolt and nut assemblies are manufactured according to DIN and ISO specifications. Custom sizes, thread types, and assembly configurations can be produced based on customer drawings or project requirements.
Type: External Hex Bolt and Nut Assembly
Diameter Range: M3 – M64
Length Range: 8 mm – 300 mm
Thread Type: Metric / UNC / UNF
Thread Form: Full Thread / Partial Thread
Standard: DIN 931 / DIN 933 / ISO 4014 / ISO 4017 / DIN 934 / ISO 4032
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 bolt and nut assemblies are typically manufactured according to ISO 3506 with common property classes including A2-50、A2-70、A4-70、A4-80, which define tensile strength and mechanical performance for stainless threaded fasteners. For reference across general mechanical fastening systems, carbon steel fasteners commonly use strength grades 4.8、8.8、10.9、12.9、14.9 according to ISO 898-1. ZSD Screw maintains production inspection and mechanical verification to ensure stable fastening quality and reliable assembly performance.
Surface Treatment: Stainless steel bolt and nut assemblies generally rely on the natural corrosion resistance of stainless alloys. Depending on application requirements, 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 hex bolt and nut assemblies are widely used for assembling machine frames, gearbox housings, motor mounts, pumps, compressors, and structural brackets. The bolt-and-nut combination allows adjustable clamping force and reliable structural fastening under vibration and cyclic mechanical loads.
In electronic equipment and industrial electronics, these assemblies are commonly used in control cabinets, industrial enclosures, mounting frames, electrical panel structures, and equipment support systems. Stainless steel materials provide corrosion resistance and stable fastening performance for long-term operation of automation and electronic equipment.
In the new energy sector, stainless steel bolt and nut assemblies are widely applied in photovoltaic mounting structures, solar panel frames, inverter brackets, battery rack systems, and energy storage equipment installations. Their corrosion resistance and reliable clamping performance support stable operation in outdoor renewable energy environments.
In conventional and renewable power generation facilities, stainless steel fastening assemblies are used in generator frames, turbine housings, cooling system structures, pipeline support installations, and auxiliary equipment mounting points. Secure threaded connections help maintain structural stability under vibration, temperature variation, and continuous operational loads.
In the automotive and transportation industries, stainless steel hex bolt and nut assemblies are used in body structure connections, electrical system mounting brackets, exhaust assemblies, and auxiliary equipment installations. Reliable dimensional accuracy and corrosion resistance support durable fastening performance in vehicle manufacturing and maintenance.
In heavy industry and engineering equipment manufacturing, these assemblies are widely applied in construction machinery, marine equipment, steel structures, and large mechanical installations. Stainless steel materials help provide long-term corrosion resistance and structural reliability in demanding industrial environments such as offshore equipment, processing facilities, and infrastructure projects.
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%.
Custom Fasteners Manufacturer: ZSD Screw specializes in manufacturing custom non-standard fasteners according to customer drawings and samples.We support: Special dimensions and tight tolerances. Special thread forms. High strength and special materials. Small batch and mass production. Our experienced engineers provide professional technical support from design to production.
Quality Control & Certifications: Quality is strictly controlled throughout the entire production process.Inspection includes: Raw material inspection. Dimensional measurement. Thread gauge inspection. Salt spray test. Torque test. Hardness testing. Tensile strength testing Certifications: ISO 9001. IATF 16949. EN standards. ASTM standards.
Why Choose ZSD Screw: More than 16 years manufacturing experience. Complete production process (cold heading, CNC machining, heat treatment) . Strong custom fastener capability. Stable quality and competitive factory price. The delivery time of the source factory is short and controllable. Professional technical services and long-term after-sales service.
Please send us your drawings or specifications. Our engineers will provide professional fastening solutions and quotations within 24 hours.
A: We are a certified source factory located in SuZhou, China, with 16+years of expertise. Unlike trading companies, we operate our own cold-heading and thread-rolling lines, offering you factory-direct pricing, total quality control, and transparent production timelines.
A: It represents the highest quality standard in the automotive industry. For you, this means Automotive-Grade precision, 100% batch traceability, and a "Zero Defect" management philosophy applied to every fastener we produce, regardless of your industry.
A: Absolutely. Customization is our core strength. Our engineering team works with CAD, SolidWorks, and 3D Step files. From specialized head types to complex multi-station parts, we provide a one-stop solution from rapid prototyping to mass production.
A: Beyond our IATF protocols, we utilize high-speed automated optical sorting machines. These systems inspect 100% of the batch for dimensional accuracy, thread integrity, and surface defects, ensuring we meet your strict PPM (Parts Per Million) requirements.
A: Yes. As an IATF-certified partner, we provide full PPAP Level 3 packages, including Control Plans, PFMEA, and ISIR. Every shipment is accompanied by a 3.1 or 3.2 Material Test Report to verify chemical and mechanical compliance.
A: For standard stock items, there is no MOQ—you can order by the box. For custom parts, the MOQ depends on the specifications. We offer free samples for quality evaluation (customer covers shipping), which can be fully refunded upon mass production orders.
A: Stock items are shipped within 24-72 hours. Standard production typically takes 20-30 days, while complex custom projects (including tooling) take 35-45 days. We provide a firm delivery commitment with every quotation.
A: Yes. We offer DDP services globally (USA, Europe, Southeast Asia, etc.). We handle all freight, customs clearance, and import duties, delivering the goods directly to your door so you can focus on your business without logistics headaches.