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Bolts that back out under vibration are a frustrating and sometimes costly problem for mechanics, fabricators, and DIYers alike. Whether you're assembling automotive body panels, securing machinery guards, or building metal frames, a standard bolt without a locking feature can work loose over time. These Phillips hex flange bolts with hex nuts solve that problem at the fastener level — the serrated flange variant bites into the mating surface as you tighten, delivering built-in vibration resistance without a separate lock washer.
Each set includes one hex flange bolt and one matching hex nut. Available in five thread diameters — M3, M4, M5, M6, and M8 — with lengths ranging from 5mm (3/16") to 60mm (2-3/8"). Two flange face styles are offered: Serrated (radial teeth for locking action) and Without Teeth (smooth, for flat bearing surface applications). Pack sizes of 1 Set or 5 Set are available. All threads follow the ISO metric coarse-pitch standard.
Typical applications include automotive panel and engine cover fastening where Phillips hex flange bolts with serrated faces prevent loosening from engine vibration, machinery and equipment assembly where a combined bolt-and-nut set simplifies BOM management, and general metal fabrication and DIY builds where the wide flange distributes clamping load across a larger surface area than a standard hex bolt head.
| Thread Sizes Available | M3, M4, M5, M6, M8 |
|---|---|
| Thread Standard | ISO metric coarse pitch (per ISO 68-1) |
| Head Style | Hex Flange (wide bearing flange with hex drive) |
| Drive Type | Phillips (PH) cross-head + Hex wrench/socket |
| Flange Face Options | Serrated (radial locking teeth) / Without Teeth (smooth flat face) |
| Available Lengths | 5mm (3/16") — 60mm (2-3/8"); see variant options for full range by size |
| Included Hardware | 1 hex flange bolt + 1 matching hex nut per set |
| Pack Sizes | 1 Set, 5 Set |
| Flange Diameter (approx.) | Typically 1.7–1.9× thread diameter — contact us to confirm for specific sizes |
| Material / Finish | Contact us to confirm |
| Compatible Fasteners | Matched ISO metric hex nuts (included); standard metric washers |
| Recommended Use | Automotive panels, machinery guards, equipment frames, metal fabrication |
A general rule is to select a length so that at least two-thirds of the shank engages the mating material or nut. For a standard hex nut, the nut height is typically about 0.8× the thread diameter — so an M6 nut is roughly 5mm (3/16") tall. Measure your total stack thickness (material + nut) and add a few millimeters of thread engagement beyond the nut. Lengths in this listing run from 5mm (3/16") to 60mm (2-3/8").
The Serrated flange has radial teeth machined into the underside of the flange face. These teeth bite into the mating surface as the bolt is tightened, creating mechanical resistance to loosening from vibration — similar to a built-in lock washer. The Without Teeth (smooth) flange distributes clamping load over a wider area without the locking action, making it suitable for softer materials or surfaces where marring must be avoided.
Hex flange bolts are generally used in medium-duty applications including automotive body panels, engine covers, machinery guards, and equipment frames. The serrated variant is particularly well-suited for vibration-prone environments. For safety-critical structural joints, always verify the bolt grade and torque specification against your engineering requirements. Contact us to confirm the material grade if needed.
Corrosion resistance depends on the material finish. If you need outdoor or wet-environment performance, look for zinc-plated or stainless steel variants. Contact us to confirm the specific surface treatment for this listing before use in exposed or corrosive environments.
These bolts follow the ISO metric thread standard. M3, M4, M5, M6, and M8 are all standard metric coarse-pitch threads (per ISO 68-1). The included hex nuts are matched to the same metric thread, so no additional hardware is needed. They are not compatible with UNC/UNF (imperial) threads.
These bolts use a Phillips (PH) cross-head drive on the top, allowing installation with a Phillips screwdriver or bit. The hex head also accepts a standard metric hex wrench or socket for higher-torque installation. For M3–M4, a PH1 or PH2 bit is typically used; for M5–M8, a PH2 or PH3 bit is generally appropriate. Always use the correct bit size to avoid cam-out.
Yes. Each ‘1 Set’ includes one hex flange bolt and one matching hex nut. The ‘5 Set’ option includes five bolt-and-nut pairs. Select your preferred quantity from the Pack of Quantity variant above.
Choose the Serrated flange when your application involves vibration, engine components, automotive panels, or any joint that may loosen over time — the teeth provide built-in locking action without a separate lock washer. Choose the Without Teeth (smooth) flange when working with softer materials like aluminum, plastic, or finished surfaces where the serrations could cause surface damage, or when a flat bearing surface is required.
