Large OD Flat Fender Washers
Thin materials need fender washers. We manufacture them.
Prevent bolt pull-through on sheet metal and fiberglass.
DIN 9021 fender washers. Factory direct. Ready to ship.
Get a Quick QouteFender Washers – DIN 9021 Large OD Washers for Thin Materials | Sinsun
Need fender washers to prevent bolt pull-through on sheet metal, fiberglass, and plastic? Sinsun manufactures DIN 9021 fender washers — large OD flat washers that distribute load over wider surfaces. Steel, stainless, aluminum, and nylon options. Factory direct. Request a quote.
Sinsun Fender Washers – Large Outer Diameter Flat Washers for Load Distribution & Surface Protection
Premium Sinsun fender washers feature oversized outer diameter designs for maximum load spread. We manufacture standard, heavy and stainless fender washers to prevent bolt pull-through on sheet metal, plastic and wood substrates for automotive, signage and construction B2B projects.
Reliable Screw Washers – Definition, Industrial Uses & Sinsun Advantages
Large OD Flat Washers
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Stainless Steel Fender Washers
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Thick Fender Washers
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Aluminum Fender Washers
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Heavy-Duty Thick Fender Washers
Send inquiry Now| Nominal Bolt Size (M) | Inner Diameter (d₁) min (mm) | Outer Diameter (d₂) nom (mm) | Thickness (s) (mm) | Hardness Class | Suitable Bolt Grade |
| M3 | 3.2 | 9 | 0.8 | 140 HV | ≤ 6.8 |
| M4 | 4.3 | 12 | 1 | 140 HV | ≤ 6.8 |
| M5 | 5.3 | 15 | 1 | 140 HV | ≤ 6.8 |
| M6 | 6.4 | 18 | 1.6 | 140 HV / 100 HV* | ≤ 8.8 |
| M8 | 8.4 | 24 | 2 | 140 HV / 100 HV* | ≤ 8.8 |
| M10 | 10.5 | 30 | 2 | 140 HV / 100 HV* | ≤ 8.8 |
| M12 | 13 | 37 | 2.5 | 140 HV / 100 HV* | ≤ 8.8 |
| M14 | 15 | 44 | 2.5 | 140 HV / 100 HV* | ≤ 8.8 |
| M16 | 17 | 50 | 3 | 100 HV | ≤ 6.8 |
| M20 | 21 | 60 | 3 | 100 HV | ≤ 6.8 |
| M24 | 25 | 72 | 4 | 100 HV | ≤ 6.8 |
| M30 | 31 | 90 | 4 | 100 HV | ≤ 6.8 |
| M36 | 37 | 110 | 5 | 100 HV | ≤ 6.8 |
*Fender washers ≤16mm are available in Class 140 HV; >16mm are Class 100 HV per DIN 9021 standard requirements. Class 100 HV washers are suitable for bolts/screws of Property Class 6.8 and below and nuts of Class 6 and below. Use Class 140 HV with bolts/screws below Class 8.8 and nuts below Class
| Nominal Bolt Size (inch) | Inner Diameter (d₁) (inch) | Outer Diameter (d₂) (inch) | Thickness (s) (inch) |
| #6 | 0.149 | 0.562 | 0.032 |
| #8 | 0.174 | 0.625 | 0.04 |
| #10 | 0.199 | 0.75 | 0.04 |
| 1/4″ | 0.281 | 1 | 0.051 |
| 5/16″ | 0.343 | 1.125 | 0.064 |
| 3/8″ | 0.406 | 1.25 | 0.064 |
| 7/16″ | 0.469 | 1.375 | 0.08 |
| 1/2″ | 0.531 | 1.5 | 0.08 |
| 9/16″ | 0.594 | 1.75 | 0.088 |
| 5/8″ | 0.656 | 1.875 | 0.1 |
| 3/4″ | 0.812 | 2.25 | 0.1 |
| 5/8" | 0.656 | 1.312 | 0.1 |
| 3/4" | 0.812 | 1.469 | 0.1 |
| 7/8" | 0.938 | 1.75 | 0.12 |
| 1" | 1.062 | 2 | 0.125 |
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Primary Function:
Specialized for uniform load distribution over soft substrates, thin sheet metal and oversized mating surfaces. Effectively eliminates bolt pull-through, surface denting and local stress concentration to protect fragile assembly components. -
Outer Diameter (OD) Specification:
Manufactured with oversized outer diameter, typically 3 times or larger than the inner diameter. This exclusive structural design delivers maximum coverage area compared to standard flat washers for superior pressure dispersion. -
Thickness Feature:
Adopts thinner gauge metal construction than conventional flat washers, with adjustable thickness based on standard sizes and actual application scenarios. Balances lightweight performance and basic structural rigidity for universal fastening needs. -
Available Raw Materials:
Supports full industrial material options including Low Carbon Steel, 18-8/304 Stainless Steel, 316 Stainless Steel, Copper, Aluminum and Nylon/PVC. Diversified material grades match mechanical, corrosion and insulation requirements of different working environments. -
Common Surface Finishes:
Comes with multiple commercial finishes: Clear zinc plated, yellow zinc plated, plain unfinished and hot-dip galvanized. Different treatments enhance anti-corrosion, anti-rust and wear resistance for indoor and outdoor industrial applications.
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Mechanical Tensile Strength:
Reaches up to 600MPa for metal material models, delivering stable structural rigidity under standard and medium-high torque fastening conditions.
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Flatness Tolerance Standard:
Strictly controlled within 0.06mm, effectively eliminating warping and ensuring uniform load distribution during bolt fastening.
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Operating Temperature Range:
Works stably from -30℃ to 250℃, adapting to indoor, outdoor and alternating temperature industrial environments.
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Production Compliance:
Fully manufactured in accordance with ASME B18.21.1 industrial standards for global project compatibility.
Fender Washer Applications – Where Load Distribution Matters
Explore specific fender washer applications across automotive repair, marine hardware, HVAC systems, electrical enclosures, timber construction, and plumbing — each requiring large OD washers to prevent pull-through.
Outdoor Signage & Billboard Installation
In the hardware industry, fender washers are also called sign washers, which are ideal for repairing outdoor billboard and display brackets. Sinsun large diameter fender washers increase the stress area of signage bolt connections.They resist wind pressure and external impact, preventing loose fastenings or plate deformation due to long-term exposure to the elements. Stainless steel models are not affected by rust erosion, ensuring long-term stability and neat appearance for outdoor signage facilities.
Assembly of precision electrical and new energy equipment
Sinsun’s fender washers, made from stainless steel and lightweight aluminium, are suitable for fastening upcoming energy battery brackets, electronics cabinet panels and precision equipment shells. A flat structure without deformation protects fragile electrical components from damage.These washers reduce overall equipment weight while maintaining fastening stability. They avoid circuit failure and component damage caused by local stress deformation, and meet new energy industry assembly standards.
Repair of Automotive Body & Chassis Fastening
Sinsun heavy-duty fender washers are extensively used in automotive body panels and chassis bracket assembly. The ultra-wide outside diameter spreads out the bolt torque pressure to prevent thin car body sheet metal from denting and pulling-through damage.These compensate for irregular mounting gaps in automotive shells, and strengthen weak stress points. They ensure that the body is flat and that fastenings are tight and stable. They are critical auxiliary fasteners for auto-repairing and refitting projects.
Steel structures and civil decoration works
Sinsun fender washers protect thin decorative plates and light steel components in the installation of light steel keel, curtain wall decoration and indoor ceiling engineering. There is no localized pressure due to the evenly distributed load.They solve the problem of easy bolt sinking and plate cracking in fastening thin materials. Flat and smooth surface improves assembly aesthetics. Widely applicable for civil decoration and lightweight structure construction projects.
Electrical Enclosures, Switchgear & Control Cabinets
Sensitive electronics in control cabinets require non-conductive, non-magnetic mounting solutions. Sinsun nylon flat washers and plastic shoulder washers isolate PCB standoffs from metal chassis to eliminate short circuits and ground loops. Our captive finish washers for countersunk screws provide flush-mounted hardware that won’t snag cables or inhibit airflow in tight enclosures. Neoprene sealing washers with EPDM rubber gaskets for outdoor telecommunications cabinets and EV charging stations. These sealing washers meet IP65 and NEMA 4X ingress protection standards to prevent the ingress of dust and moisture at the cable entry points.
Fender Washer FAQ – Your Technical Questions Answered by Sinsun Engineers
Get quick answers to common screw washer questions—size selection, material suitability, torque retention, rust prevention, and bulk sourcing. Engineering support from Sinsun.
Q1: What purpose do Sunsun fender washers serve?
A: They distribute the bolt load over a large area to avoid damaging and pulling through thin material.
Q2: What is the main difference between a Fender washer and a flat washer?
A: Fender washers have large diameters for better coverage and even load distribution.
Q3: What size fender washer is for M8 and M10 bolts?
A: 8.4*30*1.5mm M8; 10.5*35*2.0mm M10 as standard specs.
Q4: Do I need thicker fender washers to mount signage?
A: Yes, heavy-duty models are resistant to wind pressure and will not deform structurally in the long run.
Q5: What fender washer is suitable for outdoor coastal environments?
A: 316 stainless steel fender washers are excellent for salt spray and corrosion resistance.
Q6 : Can aluminium fender washers handle heavy bolt torque?
A: They are for light loads. Thickened carbon steel models will be needed for heavier loads.
Q7. Do you have custom oversized Sunsu fender washers?
A: Yes, we can customise for special projects, such as outer diameter, thickness, special shapes sizes etc.
Q8: What surface treatments are used to make fender washers more durable?
A: Anti-rust and wear resistance performance can be effectively improved by galvanisation and passivation.
Q9: What use are fender washers in auto repairs?
A: The large surface area protects thin car body sheets from being dented by bolt pressure.
Q10: Do Sinsun fender washers conform to any flatness standards?
A: Tight flatness tolerance < .06mm to ensure no deformation after fastening.
Q11: Can you use fender washers to fill oversized mounting holes?
A: Yes, the large outer diameter covers oversized holes to shore up loose mounting points.
SINSUN
Top Competitive Advantages for B2B Procurement Sinsun Fender Washers
Unique strengths of Sinsun fender washers, flatness precision, scenario customisation, factory direct supply for global industrial buyers.
Get A Quick Qoute01
Ultra High Flatness Precision:
Special levelling technology is adopted to achieve ultra-low flatness tolerance. When the bolts are tightened, the bolt itself does not bend or warp, so the load is distributed evenly over the entire bolt and the surfaces of the workpieces are not damaged.
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Diversified Scenario Customisation：
We customise oversized outer diameters, special thicknesses and exclusive materials for automotive, signage and new energy exclusive scenarios beyond standard specs.
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03
Full Compliance to Industrial Standards:
All Products are fully compliant to ASME B18.21.1 international standards with complete certification documents, fully adaptable to global industrial engineering projects.
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04
Factory Direct Supply, Cost-effective:
We are professional manufacturer, we control the whole production chain.
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Ready to Secure Your Fender Washer Supply?
Tell us about your thin-material fastening challenge. What material are you fastening through — sheet metal, fiberglass, aluminum extrusion, plastic panel, or plywood? What bolt size and grade are you using? What environmental exposure does the assembly face — indoor, outdoor, coastal, chemical plant, or marine? Our engineering team will recommend the exact fender washer type, material, hardness class, and finish — and send you a factory-direct quote with DIN 9021 dimensional data within 24 hours.
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📧 Email: info@sinsunfastener.com
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🌐 Website: www.sinsunfastener.com
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🏭 Factory Location: Tianjin, China — Leading fastener export hub with direct sea access to Tianjin Port
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Sinsun — your global partner for fender washers that stop pull-through. Request a matched sample set or bulk pricing today.
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