Explore our flagship industrial products manufactured to the highest global standards with zero compromises on raw material integrity.
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.
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, flat washers, 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).
Understanding the strict mechanical standards governing industrial flat washers to optimize load dispersion, prevent galvanic corrosion, and maintain bolt tension.
Flat washers are not mere spacers; they are high-precision components designed to distribute the clamping force of threaded fasteners over a larger surface area. By distributing this load, washers protect matching surfaces from compression damage, bridge oversized holes, and maintain constant clamping friction, preventing loosening. At Sinsun Hardware, we manufacture flat washers that adhere strictly to international standards, providing structural integrity in high-torque bolted joints.
Our manufacturing scope encompasses three primary international standards: DIN 125 (German Standard for plain washers), ISO 7089 (International Standard equivalent to DIN 125 Type A), and ASME B18.22.1 (North American Standard for plain washers). Understanding the mechanical properties, nominal diameters, clearances, and tolerances defined by these specifications is critical for engineers when selecting fasteners for heavy-duty applications.
| Standard | Common Types / Forms | Typical Nominal Sizes | Standard Material Options | Hardness Ratings (HV / HRC) | Primary Industrial Use Cases |
|---|---|---|---|---|---|
| DIN 125 Type A | Plain washers without chamfer | M1.6 to M150 | Carbon Steel, SUS 304/316, Brass | 140 HV / 200 HV / 300 HV | General machinery assembly, electrical framing, standard bolting systems. |
| ISO 7089 | Plain washers (Normal series, Product grade A) | M1.6 to M64 | Medium Carbon, Stainless Steel A2/A4 | 200 HV / 300 HV | Automotive engineering, petrochemical joints, global structural frameworks. |
| ASME B18.22.1 | Type A (Narrow, Wide, Regular) & Type B | #0 (0.060") to 3.0" nominal | SAE 1008/1045, Alloy Steel, Stainless | Rc 38-45 (Hardened series) | North American structural steel, oil & gas piping systems, heavy construction. |
The performance of a bolted assembly depends heavily on the surface pressure underneath the bolt head or nut. If this pressure exceeds the yield strength of the joined components, embedment occurs, leading to clamping force loss (preload relaxation) and joint failure. Sinsun Hardware manufactures washers with precise thickness control (±0.02mm) and premium thermal processing to ensure that flat washers maintain their flat shape under high torques, preventing the localized deformation associated with low-quality, stamp-pressed alternatives.
Sinsun Hardware controls the entire manufacturing chain, ensuring quality from steel billet selection to final heat treatment.
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. By managing this initial metallurgical stage in our four spheroidizing furnaces, we ensure consistent microstructures, preventing inner crack formation during high-speed cold heading.
This internal control guarantees that the steel wire is processed with uniform mechanical characteristics, resulting in high dimensional accuracy and consistent flatness in every washer batch we deliver to global markets.
At SINSUN, we combine German-engineered multi-station cold heading machines with precision Taiwanese production technology. Our advanced stamping presses process flat washers from annealed metal strips, ensuring outer and inner concentricity with clean, burr-free edges.
This machinery maintains a surface roughness profile of Ra ≤ 0.4μm, providing a smooth load-bearing surface that optimizes torque control during subsequent assembly.
SINSUN operates four dedicated heat treatment lines, allowing for precise and controlled processing time to achieve consistent hardness and enhanced product durability. Our in-house tempering and quenching lines eliminate manufacturing stresses, stabilizing steel microstructures to yield target hardness ratings of up to 300 HV.
This capability prevents washer dishing or bending when torqued with Class 8.8, 10.9, or 12.9 high-tensile structural bolts.
From digital dimensional inspection to salt-spray tests, our quality assurance team conducts 12+ checks. Washers can be coated in hot-dip galvanized (HDG), yellow zinc, black oxide, or geomet, guaranteeing rust resistance that exceeds 1,000+ hours in salt spray chambers.
This treatment makes our washers suitable for demanding outdoor structural and marine applications.
Sinsun Hardware flat washers are utilized globally to support structural integrity in infrastructure projects, automotive plants, and heavy equipment assemblies.
In heavy steel construction, high-tensile bolts require washers that comply with ASME B18.22.1 or DIN 125 Type A to distribute dynamic loads on bridges, railway structures, and structural frameworks. Our washers prevent bolt head embedment, securing high-strength structural joints against wind, vibration, and thermal expansion.
Automotive assembly lines require fasteners with tight tolerances to withstand continuous vibration. Sinsun's washers, manufactured to ISO 7089 standards with ±0.02mm dimensional precision, prevent mating surface scoring and maintain clamping torque under thermal cycling.
Offshore wind towers and solar tracker assemblies face harsh environmental conditions. Sinsun provides customized washers with hot-dip galvanized and geomet coatings, guaranteeing 1,000+ hours of salt-spray resistance to prevent galvanic corrosion between aluminum and steel components.
From our founding in 2006 to our 2025 technology upgrades, discover the milestones that have established us as a global partner in the fastener industry.
Sinsun began with a singular focus: to build a factory dedicated to self-tapping screws. This foundational specialization established our core expertise from the ground up, directing our manufacturing expansion into broad industrial fasteners.
We expanded beyond domestic supply, establishing our export department to distribute screws, nuts, and flat washers to markets in North America, South America, and Europe.
We added four spheroidizing furnaces and built our wire drawing workshop. Controlling raw materials allowed us to guarantee dimensional and mechanical consistency across all fastener products.
We imported multi-station cold heading machinery from Germany and incorporated Taiwanese processing technology, improving dimensional tolerances to ±0.02mm.
Annual output reached 36,000 tons, shipping over 1,100 containers globally to support international infrastructure and distribution partners.
We launched our automated warehouse with an 18,000+ pallet capacity, reducing turnaround times and ensuring order processing within critical project timelines.
We installed four advanced continuous heat treatment lines, expanding control over product hardness (up to HRC 28-32) and ensuring on-schedule delivery.
We supply flat washers and fasteners tailored to the specific regulatory requirements and environmental conditions of your market.
Our fasteners comply with RoHS and REACH regulations. We provide EN 10204 3.1 material certificates to guarantee full traceability, which is critical for structural and public works projects within the EU.
We manufacture flat washers to ASME B18.22.1 specifications (narrow, regular, and wide variations). These washers are designed to fit SAE and ASTM structural bolt grades, maintaining unified national coarse (UNC) thread clearance standards.
With customized packaging options (OEM box designs and shipping crates) and logistics coordination from our 12,000 sqm warehouse, we support import documentation, customs clearance, and port routing.
Sinsun Hardware is adopting digital technologies to transform traditional metal processing into a connected, data-driven manufacturing flow.
We are integrating AI-driven optical sorting systems into our manufacturing lines. These machines screen washers at high speeds, detecting deviations in flatness, thickness, and hole concentricity down to the micron level to ensure zero-defect batches.
We are researching thin-film anti-corrosion finishes that offer high salt-spray resistance without using heavy metal hexavalent chromium compounds. This initiative is designed to support the sustainable sourcing policies of our global partners.
We are implementing IoT sensors in our 12,000 sqm warehouse to track material movement from receipt to dispatch. This integration provides clients with real-time shipment updates, helping them manage their supply chains more efficiently.
Find answers to common questions about material selection, dimensions, mechanical standards, and manufacturing processes.
Submit your design drawings or reference standards (DIN 125, ISO 7089, ASME B18.22.1). Our engineering team will review your specifications and provide a quotation.
Browse our additional industrial items including anchor systems, structural bolts, and heavy-duty deck screws.
