In modern industrial assembly, sealing against atmospheric moisture, aggressive chemicals, and pressurized gases is a key requirement. An OEM Neoprene Bonded Sealing Washer represents a composite solution: a structural metal backing (typically carbon steel, galvanized steel, stainless steel, or aluminum) pressure-bonded to a synthetic elastomer (Polychloroprene or Neoprene) sealing element. Under torque, the metallic washer distributes the clamping load evenly, while the neoprene element deforms elastically to fill the microscopic voids between the fastener head and the substrate. This prevents leakage and galvanic corrosion.
The performance of these sealing elements depends on the quality of the vulcanization bond. Lower-quality factories use cold-curing or basic adhesive applications, which can result in separation under high-temperature cycles or severe mechanical shear. Sinsun Hardware employs advanced hot-vulcanized bonding techniques. By cross-linking the polymer chains of the neoprene directly to the chemically-prepared surface of the metal disc under high pressure, we ensure that our bonded washers resist delamination, even when torque reaches design limits.
Additionally, modern environmental regulations demand that materials comply with RoHS and REACH standards. As a leading OEM factory, we source our chemical compounds with trace traceability, ensuring that the neoprene backing contains no hazardous plasticizers or prohibited chemical compounds. This makes our sealing solutions suitable for sensitive global projects, including architectural cladding, solar installations, and marine structures.
Established in 2006, Sinsun Hardware has grown to become the largest self-tapping screw and industrial fastener production base in Northern China. Operating from our integrated facility, we manage a 12,000 sqm smart warehouse with a capacity of over 18,000 pallets. Supported by multi-language customer support teams, we export over 8,500 containers annually to key global markets in the Middle East, Southeast Asia, South America, Europe, and Russia.
Our manufacturing capability is backed by German-imported machinery and Taiwanese engineering processes. We produce more than 20,000 SKUs of nails, screws, wires, and rivets. Each batch undergoes 12+ quality control checks to verify dimensions, mechanical performance, and coating quality. Our products feature high surface finishes (Ra ≤ 0.4μm), salt spray resistance of over 1,000 hours, tight dimensional tolerances (±0.02mm), high tensile strength (1,000+ MPa), and controlled hardness ranges (HRC 28-32).
Global procurement teams now focus on material durability under harsh conditions. Standard washers can fail due to temperature shifts or UV exposure. Specifying high-grade Neoprene (Polychloroprene) ensures the seal remains flexible from -40°C to 120°C. Sinsun's bonded washers are designed to resist ozone degradation and acid rain, making them suitable for long-term outdoor use.
Pairing different metals, such as steel screws on aluminum roofing, can lead to galvanic corrosion. Neoprene bonded washers act as an electrical insulator, separating the metal fastener from the metal panel. Sinsun offers various combinations, including stainless steel (304/316) and galvanized carbon steel, to prevent chemical degradation in marine and industrial environments.
Industrial procurement relies on predicting long-term costs. While standard washers have a lower initial cost, premature sealing failures can lead to leaks, product degradation, and structure damage. Sinsun's OEM solutions offer high-durability products that lower maintenance and replacement costs over the project's life cycle.
Sinsun Hardware controls quality starting from the raw materials. We source steel directly from Xingtai Iron and Steel, a major manufacturer of high-quality alloy steel wire rods. By bringing wire processing in-house—including spheroidizing annealing and precision wire drawing—we maintain consistent control over the metallurgy of our fasteners. This vertical integration reduces reliance on external suppliers and allows us to offer steady pricing and lead times amid market changes.
In 2025, Sinsun added four continuous, atmosphere-controlled heat treatment lines. This upgrade improves our heat-treating capacity, ensuring consistent tensile strength and hardness (HRC 28-32) across large production runs. Additionally, our testing laboratory performs systematic checks, including microhardness profiles, torque testing, and salt spray exposure (tested to 1,000+ hours in line with ASTM B117), to ensure every batch meets international standards.
For custom OEM/ODM packaging, our 12,000 sqm warehouse uses semi-automated packing lines. We support customized box designs, private labeling, barcode scanning, and direct shipping container configurations. These logistics setups help streamline our clients' intake and distribution processes.
Sinsun began operations with a focus on self-tapping screw production, building our manufacturing base and tooling expertise from the ground up.
We established our dedicated Export Department, expanding from domestic sales to supplying international hardware distributors and construction groups.
Installed four spheroidizing annealing furnaces and wire drawing systems, allowing us to manage quality starting from the raw material steel rods.
Upgraded our production with multi-station cold heading machinery and expanded our product range to include self-drilling and bonded washer assemblies.
Achieved an annual production output of 36,000 tons and shipped over 1,100 export containers to global markets.
Opened our 12,000 sqm finished-goods warehouse, maintaining consistent stock levels to reduce lead times for key product categories.
Added four continuous atmosphere-controlled heat treatment lines. This expansion increases production capacity, ensures consistent mechanical performance, and provides reliable shipping schedules for large-volume orders.
Used to seal fasteners on corrugated roofing panels. The neoprene layer conforms to the panel shape, sealing out rainwater and preventing leaks in commercial warehouses and industrial plants.
Solar arrays on metal roofs face constant wind vibration and thermal changes. Bonded washers provide a seal that absorbs vibration, helping to maintain fastener torque and prevent water intrusion over decades of operation.
HVAC systems operate with internal pressure changes and moisture condensation. Neoprene bonded washers prevent air and condensation leaks through mounting holes, maintaining system efficiency.
Sinsun Hardware hosts monthly visits for international clients and purchasing teams. We display our entire production process, including wire drawing, cold heading, thread rolling, vulcanized washer assembly, heat treatment, and packaging. We also participate in global trade shows to meet clients, share industry insights, and discuss customized fastening solutions.
Neoprene (Polychloroprene) offers good resistance to oils, chemicals, and mechanical tear, making it a reliable general-purpose sealing material. EPDM (Ethylene Propylene Diene Monomer) provides higher resistance to UV rays, ozone, and extreme outdoor weather. The choice depends on the environmental exposure and chemical contact of your specific application.
We use a hot-vulcanization bonding process. Rather than relying on standard glues, the neoprene compound is cured under high heat and pressure directly onto the chemically cleaned and primed metal backing. This forms a durable bond that resists shear and compression during installation.
We supply carbon steel (with electro-galvanized or hot-dip galvanized finishes for rust resistance), stainless steel (Grades 304 and 316 for marine and highly corrosive settings), and aluminum backings. These options can be matched to the fastener and substrate materials to minimize the risk of galvanic corrosion.
Yes. Sinsun's bonded washers are designed to distribute the clamping force evenly. However, it is important to follow the specified torque limits for the fastener size; over-tightening can squeeze out or damage the neoprene sealing lip, which may compromise the seal's long-term performance.
We offer customization for the outer and inner diameters, metal backing thickness, rubber thickness (standard is 1.5mm to 3.0mm), metal material grade, and plating finishes. We can also customize the packaging and labeling to suit your distribution requirements.
Get in touch with Sinsun Hardware's engineering sales team to receive detailed material test reports, free product samples, or a comprehensive quote for your custom manufacturing needs.
