High-durability wholesale industrial screws, rivets, nails, and specialty connection systems manufactured to ISO tolerances.
Within mechanical design and architectural structures, fasteners play a double role: they must ensure the structural integrity of structural assemblies while delivering a clean, polished appearance. In markets ranging from premium automotive engineering and high-traffic public infrastructure to residential glazing assemblies, standard industrial nuts leave unsightly threads exposed. This vulnerability leads to both galvanic corrosion and aesthetic degradation.
ODM Decorative Cap Nuts (often referred to as Acorn Nuts or Domed Cap Nuts) solve this engineering challenge. By enclosing the threaded end of the bolt within a smooth, custom-forged dome, these specialized fasteners shield connections from atmospheric moisture, industrial cleaning chemicals, and mechanical abrasions. Choosing a reliable ODM manufacturing partner allows global procurement groups and industrial OEMs to order custom dimensional heights, specialized metallic alloys, and specific architectural coatings suited for their projects.
Established in 2006, Sinsun Hardware 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 massive 30,000 sqm integrated facility that includes modern production zones, a 12,000 sqm smart warehouse (with over 18,000 pallet capacity), and multi-language customer support centers. Our yearly supply of over 8,500 containers consistently services key global markets such as the Middle East, Southeast Asia, South America, and Russia.
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).
We specialize in offering unique fastening solutions 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.
A 30,000 sqm integrated manufacturing plant operating 200+ multi-station cold heading machines, shipping 8,500+ containers globally each year.
Guaranteed dimensional precision of ±0.02mm and surface roughness parameters kept strictly below Ra ≤ 0.4μm for high-finish components.
Specialized protective coatings tested to exceed 1,000+ hours of continuous salt spray exposure in simulated marine testing chambers.
How regional architectural guidelines and unique environmental challenges dictate custom cap nut configurations.
Architects in coastal areas face salt-spray corrosion risks. Using custom 316 Stainless Steel (A4 grade) decorative cap nuts ensures glass canopy supports remain structurally sound and free from tea-stain rust lines.
Tier-1 automotive suppliers use brass and chrome-plated cap nuts to secure exposed engine manifolds and motorcycle exhaust pipes. These components resist thermal expansion fatigue and keep their finish under high engine temperatures.
In washdown zones, exposed threads can catch organic material and lead to bacterial growth. Smooth, dome-shaped cap nuts prevent debris buildup, making high-pressure cleaning routines much more effective.
Sinsun Hardware's manufacturing approach connects early-stage metallurgy with post-production processing. We use an in-house development cycle to turn raw steel coils into high-tolerance, decorative fasteners.
We source raw carbon steel (C1022A) from XING TAI Steel and process it in our gas-fired annealing furnaces. This step changes the steel's internal microstructure, increasing ductility and ensuring it responds well to cold forging without developing micro-cracks.
Using multi-station, cold heading machines imported from Germany, wire is cut and forged into the body of the cap nut. This mechanical process maintains grain flow integrity, which gives the finished product high tensile strength compared to machined components.
For custom ODM pieces, the internal thread profiles are cut with precision Taiwanese tapping equipment to meet international standards (including metric M3-M24 and imperial UNC/UNF sizes). The outer dome cap is joined to the nut body using automated welding systems, creating a clean finish.
We operate four continuous-mesh belt heat treatment lines with a daily capacity of 20 tons. Proper heating and oil-quenching cycles give the cap nuts a uniform hardness of HRC 28-32 and a tensile strength exceeding 1,000 MPa, preventing thread stripping under high load.
To achieve a high-end decorative finish, parts go through polishing processes to lower surface roughness to Ra ≤ 0.4μm. Depending on the installation environment, we offer several coating options:
From our founding in 2006 to state-of-the-art automated manufacturing facilities.
SINSUN: Raw Material Spheroidizing Annealing Facility
Precision Multi-Station Cold Heading Production Line
Continuous In-House Heat Treatment Systems
SINSUN: 12,000 sqm Intelligent Warehouse & Logistics Hub
Global Fastener Exhibition Stand & Client Interactions
Comprehensive Fastener Testing & Verification Lab
Global supply chains depend on speed, material availability, and cost efficiency. Sinsun Hardware combines raw steel sourcing, cold forming, heat treatment, surface coating, and packaging within one central facility in Northern China.
By processing raw steel from nearby mills (such as Ansteel Group and Xingtai Steel), we avoid shipping delays and transit costs. Having four continuous heat treatment lines and an automated packing facility on-site allows us to move parts quickly through production. This structure helps protect our buyers from local supply interruptions and provides consistent shipping schedules for high-volume orders.
We deliver clear engineering support, batch traceability, and dependable production logistics for every order.
We work with you from early design and alloy selection through to stress analysis and torque limit testing. Our engineering team provides custom samples and design support to ensure the fastener matches your installation setup.
From the raw steel coil to the finished, boxed product, each production run is logged. Our testing lab documents mechanical checks, chemical analyses, and salt spray testing for every shipment.
Using an ERP-managed warehouse, we coordinate stock levels and production steps to keep orders moving. This structured tracking helps us maintain an on-time shipping rate of over 99%.
We offer specialized surface treatments, from cosmetic physical vapor deposition (PVD) to industrial zinc diffusion coatings and high-performance rust protectants, matching the needs of different environments.
Our fasteners are manufactured to meet major international standards (ISO, DIN, ANSI, JIS). This compliance helps simplify entry into global markets, including North America, Europe, South America, and Asia.
Our production setup handles both low-volume prototype builds and large-scale bulk orders, helping procurement teams manage their inventory levels effectively.
Real-world examples of Sinsun engineering solutions in demanding industrial environments.
How Sinsun handles orders from the first concept to final shipping.
We review your application, assembly challenges, and environmental conditions to determine the right fastener design.
Our engineering team outlines proposed solutions and provides a detailed quotation detailing material grades, coatings, and delivery timelines.
We produce and deliver initial pre-production prototypes for your mechanical validation and assembly line testing.
Upon sample approval, mass production begins using cold-forging and automated thread-tapping machinery.
Every production batch goes through quality checks, including torque and dimensional verification, and is prepared with full material certs.
Your orders are packed and shipped via our logistics network. Our team remains available for any follow-up questions or support.
Answers to common technical, material, and ordering questions about our decorative cap nuts and custom fastener services.
We offer flexible ordering options. While our plants are set up for efficient high-volume production runs, we also accommodate smaller MOQs for prototype testing, specialized architectural projects, and initial contract evaluations.
Yes. Custom manufacturing to client blueprints is one of our primary services. We produce components that comply with ISO, DIN, ANSI, and JIS standards, and can accommodate custom thread pitches or dome shapes.
We use Statistical Process Control (SPC) throughout production. We test raw materials, perform in-process checks, and conduct final dimension audits. Detailed quality inspection reports are available for every shipment.
Lead times depend on the complexity of the part, ordered quantity, and required surface treatments. Standard configurations generally ship within 4 to 6 weeks. We provide clear schedule estimates with every quote.
Yes. As a standard part of our production workflow, we provide physical pre-production samples to ensure fit, appearance, and mechanical performance match your requirements before mass production starts.
For high-moisture or coastal installations, we recommend A4-grade (SUS316) stainless steel or duplex alloy steels with a polished or passivated finish. These materials resist chloride-induced corrosion and protect against rust spots.
The smooth dome covers sharp thread ends that could snag clothing, cause injury to operators, or damage moving parts. This makes them a useful choice for exposed installations, such as on playground equipment, vehicles, and food processing lines.
Explore our wider catalog of industrial fasteners, including structural anchors, staples, concrete screws, and lag bolts.
SINSUN
