In high-stress industrial applications, the stability of threaded joints determines the structural integrity and safety of the entire assembly. Standard hex nuts often fail under conditions of continuous vibration, thermal cycling, and heavy load changes. This is where the engineering superiority of Flange Lock Nuts comes into play.
Flange lock nuts integrate a circular, wide flange base directly beneath the hexagonal head. This integrated structure serves as a built-in washer, distributing the clamping pressure over a significantly larger surface area. This reduces the pressure exerted on the mating surface, eliminating the risk of material deformation and structural embedding over time.
The self-locking mechanism is typically achieved via specialized features: either a prevailing torque design (which deforms the threads to create high friction) or integrated serrations on the bottom of the flange. These serrations physically bite into the mating material, requiring higher breakaway torque than tightening torque. This ensures the joint remains firmly tightened under extreme dynamic stress.
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Sinsun Hardware, established in 2006, is a leading manufacturer and global supplier of high-quality fasteners. As Northern China's largest producer of Self-Tapping Screws, we operate from a gigantic 30,000 sqm integrated facility that includes modern production zones, a 12,000 sqm smart warehouse (18,000+ pallet capacity), and multi-language customer support centres. Our yearly supply of over 8,500 containers consistently services key global markets such as the Middle East, Southeast Asia, South America, and Russia.
At SINSUN, our quality control begins at the source. We start with premium raw materials from XING TAI Steel, then perform in-house spheroidizing annealing and precision wire drawing in our own plant. This end-to-end control, supported by our advanced drawing machines and gas-fired furnaces, ensures superior microstructure, consistency, and performance in every fastener we produce.
Our production prowess is driven by German-imported machinery, precision Taiwanese technology, and a dependable staff of trained specialists. We offer over 20,000 SKUs of nails, screws, wires, and rivets, each undergoing 12+ stringent quality checks to assure outstanding polish (Ra ≤ 0.4μm), corrosion resistance (1,000+ hours salt spray), dimensional accuracy (±0.02mm), high strength (1,000+ MPa), and consistent hardness (HRC 28-32).
At SINSUN, we combine German-engineered multi-station cold heading machines with precision Taiwanese production technology. Our specialized processes, including tail-gripping for drill screws, ensure every fastener is manufactured with utmost accuracy and consistency in our state-of-the-art production facility.
We specialise in offering unique fastening solutions that are tailored to your specific needs. Our technical team works directly with clients from design to manufacturing, providing support for unusual materials, coatings, dimensions, and performance requirements to ensure that each custom order matches exact specifications.
Explore our journey of expansion, from establishing exports in 2012 and integrating German technology in 2018, to achieving a 36,000-ton annual output and adding advanced heat treatment lines by 2025.
Sinsun began with a singular focus in 2006: to build a factory dedicated to self-tapping screws. This foundational specialization established our core expertise from the ground up, maintaining our commitment to quality production.
The year 2012 marked a pivotal step for Sinsun with the establishment of our Export Department. From that point forward, our specialized self-tapping screws began reaching customers across the world, expanding our mission beyond borders.
In 2015, Sinsun expanded its control over quality by adding four spheroidizing furnaces for raw material processing and in-house wire drawing capabilities. This strategic upgrade moved our production beyond screw manufacturing, beginning with precise control from the raw material stage to ensure superior consistency.
Our production capability was enhanced in 2018 with new German multi-station cold heading machines. Concurrently, we grew our product line to include a variety of drill tail screws. This dual development strengthened our specialized manufacturing foundation.
Sinsun's growth in 2021 was defined by two key metrics: reaching 36,000 tons in annual production and fulfilling international orders with over 1,100 export containers. This period underscored our capacity to deliver at scale to a global market.
To ensure timely delivery for our clients, we operate a 1,200-square-meter ready-stock warehouse as of 2023. This facility is dedicated to supporting efficient daily distribution and meeting your routine supply needs.
The addition of four heat treatment lines in 2025 significantly boosts our production capacity. This directly translates to greater consistency in product quality and stronger guarantees for on-schedule delivery, meeting your project needs with confidence.
We integrate cold forming, carbonization heat treatment, and precision packaging in a single facility to ensure traceability.
SINSUN operates four dedicated heat treatment lines, allowing for precise and controlled processing time to achieve consistent hardness and enhanced product durability. This in-house capacity ensures both exceptional fastener quality and reliable delivery schedules.
SINSUN offers flexible OEM and ODM packaging tailored to your needs. With a professional packaging team and a 12,000 m² warehouse, we provide custom packaging, 3D design previews, and full logistics support to deliver a seamless, worry-free experience from production to shipment.
Every month, we welcome clients from across the country for on-site factory visits, demonstrating our transparency and production strength. As a trusted industry partner, we actively participate in global exhibitions to connect, exchange insights, and showcase innovation — building lasting relationships based on quality and reliability.
Rapid industrialization has accelerated demand for lock nuts in automotive chassis, solar mounting racks, and heavy agricultural equipment. Structural joints require anti-loosening components that resist thermal expansion and shear loads, prompting massive infrastructure investments globally.
Chinese fastener factories offer high efficiency through localized supply chains. Sinsun manages everything in-house—from cold head forming and wire drawing to continuous heat treatment. This vertical setup minimizes external markups, maintains structural reliability, and delivers shorter lead times.
Modern procurement specialists prioritize material traceability (EN 10204 3.1 certification), anti-corrosion finishes (Geomet, Dacromet, or Trivalent zinc), and strict dimensional tolerances (ISO/DIN compliance) to guarantee error-free performance in high-speed automated assembly lines.
Automotive subframes and battery enclosure boxes in electric vehicles are exposed to continuous vibrational cycles. Flange lock nuts provide uniform load distribution, preventing torque loss and ensuring passenger compartment safety without the added weight of dual washers.
Solar trackers are installed in demanding outdoor environments. Wind loading forces structural hardware to withstand alternating shear loads. Serrated flange nuts are the industry standard for securing aluminum struts to structural support steel, resisting corrosion and high winds.
The industry is shifting toward chrome-free coatings such as Geomet and Zinc Flake, which offer 1000+ hours of salt spray protection without hydrogen embrittlement. Manufacturing is also shifting toward automated inspection lines, using optical sorting to reduce defect rates to zero PPM (Parts Per Million).
| Feature | Standard Hex Nut | Serrated Flange Lock Nut |
|---|---|---|
| Load Distribution | Localized under hex hex-points | Evenly distributed across wide flange |
| Washer Required | Yes (Flat / Spring Washers) | No (Saves assembly time and cost) |
| Vibration Resistance | Low (Requires threadlocker) | High (Serrations lock on mating face) |
| Breakaway Torque | Equal to tightening torque | Up to 30% higher than installation torque |
| Mating Face Protection | High scoring risk | Controlled grip design |
Prevailing torque flange lock nuts (such as nylon insert lock nuts or all-metal deformed thread nuts) rely on internal thread friction to resist rotation and do not damage the mating surface. Serrated flange lock nuts feature physical teeth on the bearing surface of the flange that bite into the mating joint. They provide higher resistance to loosening under extreme vibration but can score the mounting surface.
Our manufacturing processes conform to DIN 6923 (serrated and non-serrated hex flange nuts), ISO 4161, and ASME B18.16.4 standards. We provide fully traceable mill inspection reports covering mechanical performance, dimensional stability, and thread precision tolerances of ±0.02mm.
By sourcing raw steel wire from premium vendors like Xingtai Steel and conducting spheroidizing annealing in-house, we control the steel's internal microstructure. This prevents hydrogen embrittlement during surface treatment and ensures our Class 8 and Class 10 nuts achieve a tensile strength of over 1,000 MPa under high loads.
While standard flange nuts are reusable, serrated flange lock nuts should not be reused in critical applications. During installation, the serrations deform the mating material and can wear down, leading to reduced breakaway torque upon reinstallation. All-metal lock nuts can be reused, though locking effectiveness decreases with each cycle.
For extreme offshore or chemical environments, we recommend Stainless Steel (grade A4/316) flange nuts or carbon steel nuts coated with hot-dip galvanizing, Dacromet, or Geomet. These coatings easily survive 1,000+ hours in salt spray testing without red rust formation.
Our standard production MOQ is typically 1 ton per size, though we support lower volumes for items in our 12,000 sqm ready-stock warehouse. Standard lead times range from 20 to 30 days, supported by our four continuous heat treatment lines and automated packing systems.
Get in touch today for custom fasteners, technical drawings, or volume pricing. Our multi-language engineering support desk will reply within 12 hours.
