Flange Head Screws Selection Guide | Hebei Wotu Fastener Manufacturing Co., Ltd.
Flange head screws suit assemblies where the screw head needs to spread load without a separate washer. The built-in flange gives a wider bearing surface, helps protect the mating part, and can reduce parts handling on production lines.
The main decision is not only diameter and length. Buyers also need to match the flange style, drive type, thread form, material, coating, and tip design to the base material and tightening method.
Brand: Hengzuan Surface: Color zinc plated, optional blue-white zinc plated, black oxide treatment Specifications: Chinese national standard ST4.2/ST4.8/ST5.5 specifications, rod length 13~50mm in stock, supports nonstandard length customization Packaging: 25kg export cartons, full wooden pallets wrapped with film, supports neutral packaging, private-label customization
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Brand: Wotu Surface: zinc plated Specifications: in stockM6/M8/M10/M12/M14/M16/M20 Chinese national standardfull range of specifications, support nonstandard thickness, tooth pitch customized Matching: can be matched with bolts of the same specification, flat washer, spring washer complete set of shipment Packaging: 25kg cartons, whole wooden pallets
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Brand: Hengzuan Surface: color zinc plated, can be customizedblue-white zinc plated Specifications: in stock 4.8/5.5 common wire diameter, rod length 16~125mm full range of specifications, supports nonstandard customized Packaging: 25kg cartons, whole wooden pallets, support neutral packaging, private-label customization
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Brand: Hengzuan Surface: blue and white zinc plated, color zinc plated can be customized on request Specifications: in stock 4.2/4.8/5.5/6.3mm mainstream wire diameter, length 20mm~165mm full range of specifications, nonstandard rod length, drill point size can be customized Packaging: 25kg export cartons, full pallets wrapped with film, supports neutral export packaging, customer private-label customization
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Brand: Wotu Surface: blue and white zinc plated, customized color zinc plated, Dacromet anti-corrosion coating available Specifications: ST5.5, ST6.3 mainstream specifications, rod length 20mm~125mm, full size range in stock, support nonstandard customization, drilling to adapt to steel sheet 2-6mm Packaging: 25kg cartons, whole wooden pallets
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Brand: Hengzuan Surface: blue and white zinc plated, can be customized color zinc plated, black oxide plated Specifications: Comply with GB/T15856.2 Chinese national standard, in stock ST3.5/ST4.2/ST4.8/ST5.5 mainstream wire diameter, rod length 13mm~50mm full range of specifications, nonstandard length customization on demand, drilling applicable plate thickness 2~5mm Packaging: 25kg export cartons, full pallets wrapped with film, supports neutral export packaging, private-label customization
Read MoreSelection criteria
Useful flange head screw selection depends on the assembly: bearing area under the head, drive access, thread engagement, point style, coating, and whether the flange must protect the surface or resist loosening. A drawing, sample, or current fastener specification usually removes more uncertainty than a general product name.
| Criterion | What To Check | Why It Matters | Buyer Tip |
|---|---|---|---|
| Flange style and bearing surface | Confirm whether the head has a flat flange, serrated flange, or another under-head form, and ask for a drawing or standard reference. | The flange spreads load over a wider area than a plain screw head, but serrations can bite into the mating surface and may mark coatings or thin sheet. | Ask: Is the flange intended to replace a washer, and should the underside be smooth or locking-serrated for this assembly? |
| Drive type and installation access | Match the drive to the available tool and access space, such as hex, socket, Phillips, or combination drive. | A flange head screw often needs controlled seating pressure; the wrong drive can cam out, strip, or slow assembly on the line. | Ask: What driver bit or socket will operators use, and is there enough clearance around the head for that tool? |
| Thread type for the base material | Specify machine thread, self-tapping thread, or self-drilling/self-tapping form based on whether the mating part is tapped, pre-drilled, or untreated sheet. | The flange head does not determine how the screw forms or engages the joint; thread choice affects pull-out resistance, hole preparation, and installation torque. | Ask: Is the screw going into a tapped hole, nut, sheet metal, plastic, or wood-based material? |
| Material and surface finish compatibility | Define the screw material and coating needed for the environment, appearance, and mating metals; verify if finish samples or coating details are available. | Coating choice affects corrosion resistance, friction during tightening, color matching, and the risk of surface damage under the flange. | Ask: Will the screw be used indoors, outdoors, or in contact with treated material or dissimilar metals? |
| Head height, flange diameter, and length definition | Review the dimensional drawing and confirm whether length is measured from under the flange or from the top of the head according to the relevant screw form. | Small dimensional differences can affect flushness, clearance, clamp area, and how much thread engages the mating part. | Ask: Can you confirm the required flange diameter, head height limit, total length definition, and minimum thread engagement? |
A flange head screw is different from a standard pan head or hex head screw because the head includes an integrated collar. That flange can improve clamp distribution and help cover oversized or slotted holes, but it also needs enough flat contact area around the hole. If the part has a recess, curved surface, or limited clearance, the flange diameter can become a fit problem.
The thread and point matter as much as the head. Machine screw threads suit tapped holes or nuts, self-tapping threads form or cut their mating thread, and self-drilling versions add a drill point for certain sheet-metal assemblies. Choosing the wrong version can cause poor thread engagement, damaged material, loose joints, or slow installation.
Start with the joint, not the screw name. Confirm whether the screw will fasten metal to metal, metal to wood, plastic, sheet material, or a pre-tapped component. The base material determines whether you need a machine thread, self-tapping thread, self-drilling point, or another thread form.
Check the head and drive against your assembly method. Hex flange heads work well where external driving and higher installation torque are preferred. Cross, six-lobe, or socket drives may be better where head clearance, tool access, or appearance matters. A serrated flange can resist loosening in some applications, but it may mark painted, plated, or softer surfaces.
Match finish and material to the service environment. Indoor dry assemblies may not need the same coating as outdoor, humid, or chemically exposed installations. If corrosion appearance, coating compatibility, or galvanic contact is important, ask which material and surface treatment options are suitable for the mating parts.
Avoid ordering from a vague description such as “flange screw” alone. Send the head style, drive, thread type, nominal size, length measurement method, material, coating, mating material, pilot-hole or drilled-hole condition, and any sample or drawing. Hebei Wotu Fastener Manufacturing Co., Ltd. can then confirm which details are needed before quoting or recommending an alternative.
| Criteria | Importance | Description | Example Options |
|---|---|---|---|
| Thread and point type | Usually the first functional decision | The base material and hole condition determine whether the screw needs a machine thread, self-tapping thread, self-drilling point, or another thread form. | A tapped metal part may need a machine screw thread, while some sheet-metal assemblies may require a self-tapping or self-drilling version. |
| Flange underside | Important for surface condition and loosening behavior | A plain flange spreads load with less surface marking, while a serrated flange may improve grip but can cut into coatings or softer materials. | A painted panel may call for a non-serrated flange if surface damage is unacceptable. |
| Drive style | Affects installation speed, access, and torque control | External hex drives can suit higher-torque installation with open tool access. Internal or recess drives may fit better where clearance or appearance matters. | A housing with limited side access may favor a recess drive rather than an external hex head. |
| Flange diameter and head clearance | Critical for physical fit | The flange must cover and clamp the hole area without interfering with edges, recesses, bends, nearby components, or tools. | A slotted hole may benefit from a wider flange, but a narrow channel may not have enough seating space. |
| Material and finish | Depends on the service environment | Material and coating choices affect corrosion behavior, surface appearance, and compatibility with the mating parts. | An indoor dry assembly may have different finish requirements than an outdoor bracket exposed to moisture. |
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It helps where the joint benefits from a wider bearing surface under the head, such as sheet-metal panels, brackets, housings, and assemblies with clearance holes. It can also reduce handling because a separate washer may not be needed, but the mating surface must have enough flat area for the flange to seat properly.
A serrated flange can add resistance to loosening by biting into the mating surface, which may suit some metal assemblies. A non-serrated flange is usually better where the surface finish must be protected or where marking, coating damage, or corrosion risk at the contact point is a concern.
They are similar in purpose because both increase the bearing area under the head, but the geometry can differ by standard, head height, flange diameter, drive style, and underside shape. Do not assume they are interchangeable unless the flange diameter, head clearance, drive access, and seating surface all match the assembly.
A frequent mistake is giving only the diameter and length while leaving out the thread type, drive, point style, coating, and flange diameter. Those missing details can change how the screw installs, how much clamp it provides, and whether it damages the mating material.
Send the nominal size, length measurement method, head and drive style, thread or point type, material, finish, mating material, hole condition, and quantity. If the part is replacing an existing fastener, a drawing, sample, or clear photo with dimensions helps confirm the correct match.
Send the screw size and length, head and drive style, thread or point type, mating material, coating requirement, and a drawing or sample if available.
