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China Suppliers Factory Flat Square Plate Washers 304/316 Stainless Steel Thick Washers for Construction

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Name: Square Flat Washer (Square Washer / Square Plate Washer / Flat Square Spacer)
, Material: AISI 304/316 Stainless Steel (corrosion resistant, rust resistant), Q235 Carbon Steel
, Standards: GB/T 97.1, JGJ 130, DIN 436, ISO 7091
, Grade: A2 (304 Stainless Steel) / A4 (316 Stainless Steel), Carbon Steel 4.8 Grade / 8.8 Grade
, Specifications: M4-M24 (customizable)
, Surface Treatment: Natural Polishing / Passivation Treatment (No Plating, Corrosion Resistant), Electro-galvanizing / Hot-dip galvanizing (optional, enhanced rust resistance)
, Design Features: Square structure design, precise center opening, optional thickening, corrosion-resistant stainless steel, smooth, burr-free edges
, Applications: Ideal for building curtain walls, railings and balustrades, construction engineering, outdoor and marine applications, and general assembly
, Delivery Time: 15-30 days after receiving advance payment
, Origin: China
, Brand: JGD
, Minimum Order Quantity: 10,000 pieces, negotiable
, Samples: Available
, Packaging: Boxed/Bulk/Pallet or customized packaging
, OEM: Available
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Discover premium quality square flat washers from leading suppliers and manufacturers in China. Our square washers, made from durable AISI 304/316 stainless steel and Q235 carbon steel, offer exceptional corrosion resistance and are designed for various applications. With customizable specifications ranging from M4 to M24, our factory ensures you receive the precise washers needed to meet your project requirements. Enjoy confident sourcing from our China-based factory, which adheres to international standards and delivers reliable products within a swift timeframe. Contact us today for samples and explore our OEM options tailored to your unique needs.

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    304 Stainless Steel Cross Recessed Countersunk Head Self-Tapping Screws01
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    304 Stainless Steel Cross Recessed Countersunk Head Self-Tapping Screws01

    Key Features

    Our self-tapping screws are crafted from food-grade 304 stainless steel and treated to achieve metric Grade 12.9 ultra-high strength, overcoming the traditional hardness limitations of standard stainless steel. Featuring a countersunk Phillips head design, these screws can be installed flush with the workpiece surface for a zero-profile finish, making them ideal for precision electronics and architectural decoration. We have optimized the thread geometry for different substrates (metal, wood) to ensure low-torque driving with high-torque clamping, effectively preventing stripping. As a superior alternative to standard Tek screws, these fasteners perform exceptionally well in thin sheet metal connections, providing an intelligent fastening solution that balances aesthetics with high load-bearing capacity.
    304 Stainless Steel Cross Recessed Countersunk Head Self-Tapping Screws01
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    304 Stainless Steel Cross Recessed Countersunk Head Self-Tapping Screws04

    Precision Manufacturing Process

    From wire rod to finished product, we strictly adhere to multiple international standards including ISO, DIN, ANSI, and GB. Utilizing multi-station cold forging technology, we ensure shank diameter tolerances are controlled within microns. Threads are formed through a precision thread rolling process to enhance fastening force. For non-standard requirements, we employ optical imaging sorters to reject minute defects like head cracks. In post-treatment, we offer a wide range of surface finishing options: from conventional zinc plating and nickel plating to highly corrosion-resistant Hot-Dip Galvanizing (H.D.G.), as well as decorative polishing and black anodizing. We even provide food-grade passivation treatment, ensuring every screw has a prolonged fatigue life in demanding environments.
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    Transparency & Customization

    As a source factory, we are committed to breaking down the information barriers of traditional trade. From mill certificates for raw materials to hardness grades (covering Grade 4.8 to Grade 12.9, as well as A2-70 and A4-80 marine-grade stainless steel), all test data is traceable. We support full-chain customization: dimensionally, we can adjust thread length and head thickness according to drawings; functionally, we can combine processes like sandblasting, electrophoretic coating (e-coating) , or chrome plating. Whether you need British Standard (BS) fasteners or require a special colored anodized finish, we offer small-batch sampling. This ensures that when you purchase fasteners from us, you not only receive high-quality products but also full transparency and control over the entire process, from material selection to packaging.
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    No Pre-Drilling · Rust Resistant · More Secure

    This stainless steel Phillips countersunk self-tapping screw, with its rust-resistant and corrosion-resistant material, one-step self-tapping design, and aesthetically pleasing countersunk head structure, has become the preferred solution for metal substrate fastening scenarios that is efficient, reliable, and aesthetically pleasing.
    Product Details

    Manufacturing Process

    Manufacturing Process

    • Multi Station Cold Heading Technology
    • Intelligent Heat Treatment System
    • Micron-Level Thread Rolling Process
    • Fully Automatic Optical Sorting
    • Environmentally Friendly Surface Treatment
    • Metallographic And Mechanical Joint Laboratory
    Quality Control System

    Quality Control System

    • Raw Material Source Locking
    • Furnace Number Batch Full Traceability
    • Third Party Material Certification
    • Process Parameters Open And Transparent
    • Salt Spray Test Real Time Monitoring
    • International Standard Compliance Declaration
    Customization Capability

    Flexible Customization Capability

    • Customizable head/slot Shapes
    • Extreme Application Of Special Materials
    • Breakthroughs In Extra Large/Long Specifications
    • Integrated Assembly Of Components
    • Customizable Surface Treatment Colors
    • Personalized Packaging And Labeling
    Technical Service

    Technical Service

    • On-Site Failure Analysis
    • Selection Calculation And BOM Optimization
    • Installation Tool Selection Guidance
    • Inventory Management (VMI) Trusteeship
    • Free Sample Making And Testing
    • International Standard Translation
    Stainless Steel Square Washers

    Multi-Material & Full-Size Series for All-Weather & Corrosion Resistance

    Our square flat washers are made of AISI 304/316 stainless steel or Q235 carbon steel, with strength grades including stainless steel A2 (304)/A4 (316) and carbon steel grades 4.8/8.8. The 316 stainless steel variant offers excellent chloride corrosion resistance, passing ≥720 hours of salt spray testing to withstand highly corrosive environments such as coastal bridges and ship decks. Carbon steel options with electro or hot-dip galvanizing balance high strength and rust protection. Available in sizes matching M4-M24 bolts, with custom thickened or non-standard options, they deliver reliable pressure distribution for curtain walls, outdoor railings, and more.

    Square Structure for Enhanced Load Distribution & Anti-Rotation Performance

    Manufactured to standards including GB/T 97.1, JGJ 130, and DIN 436, our square washers provide a larger contact area than traditional round washers on flat or irregular surfaces such as square tubes, channels, and wood. This effectively disperses bolt preload to prevent surface damage to workpieces. The square edges also enhance anti-rotation performance, eliminating washer rotation during nut tightening in applications like curtain wall keels and guardrail posts, significantly improving connection stability and reliability.

    Square Structure Washers
    Precision Machining Washers

    Precision Machining for Easy Installation & Versatile Application

    With precision center holes and smooth, burr-free edges, our washers can be easily slipped onto bolts or screws and locked with nuts without additional alignment adjustments, greatly improving assembly efficiency. Stainless steel washers with polished/passivated finishes are suitable for hygiene-sensitive applications without coating contamination, while galvanized carbon steel versions offer enhanced corrosion resistance for outdoor use. Widely applicable in construction projects, railings, and heavy equipment assembly, they provide excellent versatility for flat fastener matching needs.

    Application Scenarios

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    High-Quality Square Flat Washer Display Rack

    Frequently Asked Questions

    Q1: What materials are available for your square flat washers?
    A: We offer square washers in AISI 304 and 316 stainless steel for superior corrosion resistance, as well as Q235 carbon steel (grades 4.8/8.8) with galvanized finishes for high-strength applications.
    Q2: Why should I choose a square washer over a standard round one?
    A: Square washers provide a larger contact surface area, which better distributes load and prevents damage to the mounting surface. Their square edges also offer anti-rotation benefits during installation.
    Q3: Are your products tested for corrosion resistance?
    A: Yes, our 316 stainless steel washers undergo rigorous salt spray testing for ≥720 hours to ensure they can withstand harsh marine and coastal environments.
    Q4: Can you provide customized sizes or shapes?
    A: Absolutely. We offer flexible customization for head shapes, slot types, extra large or long specifications, and personalized packaging/labeling to meet specific project needs.
    Q5: Which international standards do your washers comply with?
    A: Our manufacturing process follows international standards including DIN 436, GB/T 97.1, and JGJ 130 to ensure global compatibility and safety.
    Q6: Do you provide technical support for selection?
    A: Yes, we provide comprehensive technical services including on-site failure analysis, selection calculations, BOM optimization, and guidance on installation tool selection.