Carriage Bolts/Round Head Bolts Manufacturers

What We Supply in This Product Family

Round head bolts carry a hemispherical dome that sits flush or slightly proud of the workpiece, so the joint reads cleanly on visible surfaces and presents no sharp edge to operators or end users. The square neck under the head bites into timber or a square punched hole and stops the bolt from turning while the nut is tightened from the opposite side.

We produce the full family rather than a single profile: plain round head bolts, square-neck carriage bolts, short square-neck screws, large round head shoulder bolts, nib bolts and tension-control button head bolts. Threads are rolled in metric coarse and inch series, and we hold the head-to-shank transition, neck squareness and under-head fillet as controlled characteristics because they decide whether the bolt seats and locks correctly in service.

Our Round Head and Carriage Bolt Range

Materials, Finishes and Critical Specifications

Carbon steel and stainless steel are our standard material routes for this family, with low-alloy steel available where a strength grade is called out on the drawing. The specification points that decide fit and service life are consistent across profiles:

• Head geometry — dome diameter, head height and under-head radius, which set bearing area and the visual finish on exposed faces.
• Neck form — square neck width, depth and squareness for anti-rotation in timber or punched plate; nib position for keyed seating.
• Thread — metric coarse or inch series, rolled for grain flow and consistent flank contact with the mating nut.
• Length — measured under the head, with the unthreaded shank length controlled where the bolt passes through a timber or plate stack.
• Mechanical properties — grade-dependent tensile and hardness values verified against the specified standard.
• Finish — zinc plating, nickel plating and blackening for appearance and basic corrosion resistance; hot-dip galvanizing for outdoor and structural work.

Because the head is the visible element, we treat plating thickness and surface condition as appearance-critical, not only as corrosion protection. Where a customer supplies a sample or a reference part, we match head profile and finish against it before production.

Where Round Head Bolts Fit Best

The smooth dome and the square neck solve two different problems at once, which is why this family appears across very different industries. The head protects hands, fabric and painted surfaces and gives a finished look; the neck transfers torque into the workpiece so the bolt can be tightened from one side only.

• Timber and outdoor structures — decking, fencing, pergolas, playground equipment and street furniture, where DIN 603 carriage bolts are the common specification.
• Furniture and consumer hardware — visible joints on seating, shelving and flat-pack assemblies that must look clean after installation.
• Rail transportation and vehicle bodywork — panel and body fastening where a low-profile head avoids snagging and the neck resists vibration loosening.
• Agricultural and construction machinery — guards, panels and attachments that are assembled in the field with access from one side.
• Mining and ground-engaging equipment — ASME B18.10 round head bolts on wear parts and heavy plate.
• Electrical and power accessories — pole-line and cabinet hardware where a tamper-resistant head is preferred.

Our wider Bolts range covers hexagon, flange, countersunk, square head, T-head, U-bolt and foundation profiles, so a project that mixes head styles can be consolidated into one supply program instead of several. Matching Nuts in the same grade and finish are quoted alongside the bolts.

Configuration Options We Build To

Most round head bolt enquiries are not a catalogue pick. We configure the part around the joint, the installation method and the finish requirement:

• Diameter and length combinations outside the standard table, including non-preferred lengths to reduce the number of part numbers on a bill of materials.
• Full thread or part thread, with shank length set to the thickness of the timber or plate stack.
• Neck depth and width adjusted for the receiving material, including short-neck variants for thin sections.
• Nib or double-nib heads for keyed anti-rotation instead of a square neck.
• Shoulder bolts with a controlled unthreaded bearing diameter for pivot applications.
• Grade selection from commercial carbon steel through to higher-strength low-alloy and stainless grades.
• Finish selection matched to indoor appearance or outdoor exposure, with plating thickness agreed before production.
• Custom head marking, thread tolerance class and packaging format for OEM and distributor programs.

Quality Control and Acceptance

We operate a total quality management process with inspection after each production step and a final inspection of finished goods against the customer's requirements and the referenced international standard. Our laboratory is equipped with a spectrometer, coordinate measuring machine and X-ray flaw detector, which lets us monitor chemical composition, mechanical properties, non-destructive soundness and geometric dimensions in-house.

For round head bolts, the acceptance conversation usually centres on head profile and dome finish, neck squareness and depth, thread gauging, length under head, plating appearance and hardness or tensile results. We agree the inspection items, sampling basis and any third-party inspection requirement before the order is released, and we issue inspection records with the shipment. Certification documentation is available for the standards we produce to.

Production Capacity, Packaging and Delivery

Our plant runs 12 modern production lines, including a fully automatic shell moulding line and four heat treatment lines, with annual output exceeding 20,000 tons. That capacity supports large structural and OEM programs while remaining responsive to small and medium batch purchases, and it is backed by more than 100 employees including over 10 engineers and more than 50 technical professionals.

Packaging is treated as part of the product. We supply bulk export cartons, retail-ready blister packs, retail kits and custom boxes, with labelling and quantity per carton agreed to suit the sales channel. The facility sits within a short drive of Shanghai and Ningbo ports, so sea freight is our main shipping mode, with air freight arranged through Ningbo or Shanghai airports for urgent deliveries. DDP delivery to the customer's door is available where it simplifies the receiving process.

Information We Use to Configure Your Solution

A workable quotation for round head bolts depends on a small set of inputs. When these are clear, we can confirm the profile, material, finish and inspection plan without a round of clarification.

Custom Development, Spares and Serviceability

Customized production is our core business. We develop and manufacture from customer drawings or physical samples, and our engineering team reviews head form, neck geometry and thread before tooling is committed. For projects that mix standard and special parts, we consolidate the whole fastener list — bolts, nuts and washers — into one specification-led supply program so grades and finishes stay aligned across the assembly.

On serviceability, round head bolts are a replaceable element rather than a repairable one, so the practical requirements are dimensional consistency between production lots and continued availability of the same part number. We hold tooling for repeat programs and can supply replacement quantities in the same configuration, finish and packaging as the original release. Where a customer needs a documented part reference for maintenance manuals, we provide the drawing and standard designation used at production.

Frequently Asked Questions

Are you a round head bolt manufacturer or a trading company?

We are a direct manufacturer with our own production facilities and an international sales department handling export. Better Fastener began in 2001 as a washer factory and expanded in 2010 into a comprehensive fastener enterprise covering washers, nuts, bolts and spring nuts.

Which standards can you produce round head and carriage bolts to?

Our range covers DIN 603:2017 large round head square neck bolts, ASME/ANSI B18.5 round head bolts and square neck bolts, ASME/ANSI B18.5:2008 short square neck screws, ASME/ANSI B18.5 (T6) large round head shoulder bolts, ASME B18.10:2006 round head bolts, DIN 607:2010 nib bolts, ASME/ANSI B18.5 (T5) double nib bolts and ASME B18.2.6:2019 tension control button head bolts. Equivalent international specifications can be produced where the drawing is supplied.

What materials and finishes are available?

Carbon steel and stainless steel are standard, with low-alloy steel for higher strength grades. Finishes include zinc plating, nickel plating and blackening for appearance and basic corrosion resistance, plus hot-dip galvanizing for outdoor and structural applications.

Can you produce non-standard diameters, lengths or neck dimensions?

Yes. We develop from drawings or samples, including non-preferred lengths, adjusted neck depth and width, part-thread configurations and shoulder bolts with a controlled bearing diameter. Custom head marking and packaging are also available.

How is quality verified before shipment?

Inspection is carried out after each production process, and 100% of finished products pass a final inspection against customer requirements and the referenced standard. Our laboratory uses a spectrometer, coordinate measuring machine and X-ray flaw detector to check chemical composition, mechanical properties, internal soundness and dimensions.

What packaging and shipping options do you offer?

We supply bulk export cartons, retail blister packs, retail kits and custom boxes. Sea freight is the main mode from Shanghai and Ningbo ports, with air freight available for urgent deliveries and DDP delivery to the customer's door where required.