China Flat Head Anchor Bolts Manufacturer & Factory

A flat head anchor bolt features a countersunk head profile (commonly angled at 60°, 80°, or 90°) with an internal drive socket (such as internal hex, Torx/star, or cross-recess). When tightened, the head sits entirely flush with or slightly below the surface of the anchored steel fixture plate. Standard hex or wedge anchors feature protruding nuts and threaded studs that pose trip hazards and interfere with low-clearance equipment, wheel traffic, or architectural glazing covers. Furthermore, the conical countersunk geometry generates balanced radial and axial load transfer directly into the base plate, eliminating the need for separate loose washers.

Effective embedment depth ($h_{ef}$) is measured from the concrete surface to the deepest point where mechanical expansion or undercut interlock transfers tension into the concrete substrate. In accordance with ACI 318 Chapter 17 (Concrete Capacity Design CCD Method), the nominal breakout strength of a single anchor in uncracked concrete is calculated as $N_{b} = k_{c} \cdot \lambda_{a} \cdot \sqrt{f'_{c}} \cdot h_{ef}^{1.5}$, where $k_{c}$ is 10 for cast-in and 7 for post-installed anchors, and $f'_{c}$ is specified compressive concrete strength. For flat head anchors, adequate anchor body length must be specified to ensure $h_{ef}$ reaches beyond surface aggregate layers, maintaining a minimum edge distance of $c_{min} \ge 1.5 \cdot h_{ef}$ to prevent premature edge spalling under shear.

Direct electrical contact between aluminum (anodic potential approximately -0.85 V) and carbon steel (cathodic potential -0.40 V) in the presence of an electrolyte causes accelerated sacrificial oxidation of the aluminum extrusion. To mitigate this in solar photovoltaic installations, Youlong provides three engineering solutions: (1) Pre-assembled non-conductive vulcanized EPDM or UV-stabilized polyamide isolating washers and sleeves; (2) Specifying Austenitic Stainless Steel A4-80 (AISI 316) anchors treated with non-reactive inorganic passivation films; or (3) Applying microscopic zinc-aluminum flake coatings (such as Geomet 500B), which provide controlled sacrificial protection without promoting violent galvanic couples against structural aluminum rails.

Accurate installation is vital to prevent anchor slipping or concrete over-cracking:

1. Drilling: Use a carbide hammer drill bit conforming to ANSI B212.15 or DIN 8035 to drill a cylindrical hole perpendicular to the base material to the specified embedment depth plus 1 bolt diameter.
2. Borehole Evacuation: Employ the 2x2x2 cleaning method: 2 cycles of compressed oil-free air blast, 2 cycles of wire brushing, and 2 final air blasts to remove all pulverized dust that would lubricate the expansion sleeve.
3. Insertion: Drive the flat head anchor through the fixture countersunk hole using a rubber mallet until the head sits true and level in the chamfer.
4. Calibrated Torquing: Tighten using a calibrated torque wrench to the exact manufacturer specification (e.g., M8: 15–20 Nm; M10: 30–35 Nm; M12: 50–60 Nm; M16: 120–140 Nm). Over-torquing can strip internal drive sockets or shear the concrete expansion cone.

Yes. Over 40% of our production volume comprises customized fasteners manufactured to client-provided CAD drawings or reverse-engineered samples. Our in-house tooling division fabricates specialized cold-heading dies, countersunk punch inserts, and rolling dies within 5 to 7 business days. We support non-standard head diameters, unique countersunk bevel angles (such as 82° for American architectural specs or 90° for DIN/ISO standards), extended threading lengths, custom knurling, and proprietary tamper-resistant internal drive pins (Security Pin Torx). Prototypes include initial PPAP Level 3 documentation prior to batch manufacture.

For standard catalog items and standard carbon steel / 304 stainless sizes (M6 through M20), we maintain an active buffer inventory with dispatch available within 48 to 72 hours. For custom OEM runs or specialized surface treatments (HDG, Dacromet), standard manufacturing lead times range from 15 to 25 calendar days depending on tonnage. Minimum order quantities start at 5,000 units for standard sizes and 1,000 kg for custom forged anchors. We support global commercial Incoterms including FOB Tianjin, CIF destination port, CFR, and DDP (Delivered Duty Paid) to the Americas, Europe, the Middle East, and Southeast Asia.