Automotive Screws And Bolts Suppliers

The Bolts And Screws We Supply

Matching The Bolt To The Joint

The same drawing can call for a welded stud, a bolted joint or a locating shoulder. The table below shows how we map our range to the joint type, and which variables drive the configuration.

Materials, Property Classes And Surface Finishing

Finishing is done on our own line, which is why coating thickness and salt-spray hours are quoted together with the mechanical properties rather than sourced separately.

• Property classes: hex head bolts with captive washers in 8.8 and 10.9; round head weld studs from class 4.8 upward according to weld and load requirements. Where a bolt closes against a high-strength nut, our nut programmes run to class 12, with class 13–14 in pre-research for heavy-duty and high-performance engine applications.
• Base materials: carbon steel for structural and body joints, stainless steel for corrosion exposure, aluminium for weight-driven parts, brass where conductivity matters.
• Zinc systems: trivalent zinc plating qualified to 480 hours salt spray, and zinc-nickel alloy at 480 to 720 hours for underbody, wheel-arch and battery-adjacent hardware.
• High-temperature finishes: three grades rated for 300 °C, 550 °C and 650–700 °C service for exhaust and engine-periphery joints.
• Copper plating: applied to weld studs for stable arc initiation and low contact resistance.
• Black oxide: uniform appearance with light corrosion protection for interior trim and seat hardware.

Threads, Tolerances And Dimensional Control

Metric threads run from M3 to M24 on hex head bolts and M3 to M10 on round head weld studs. Head, shoulder, step and washer-face features are held within a 0.06 mm to 0.30 mm control window depending on what the feature does in the joint — a locating shoulder is checked tighter than a clearance face, and the washer face is checked for squareness as well as position.

Our MAT self-correcting thread places a guided lead on the first threads, so a slightly misaligned bolt is pulled into the correct thread path instead of cross-threading. On automated stations this reduces rejects at the nutrunner, and it is available on the nut side of a matched bolt-and-nut set. Thread gauging, run-out, shoulder diameter and step position are recorded as separate characteristics during production.

Tooling, Feeding And Automated Assembly

Most of our automotive bolt volume is installed by machine, so the features the line actually touches decide whether a part runs cleanly. We build cold heading and thread rolling tooling around the customer drawing and review the details that affect presentation and torque: head geometry for socket engagement and feeder orientation, crimp strength on captive washers so they survive vibration feeding, chamfer at the thread start, and ignition tip consistency on weld studs.

• Feeder trials and sample batches for line qualification before series release
• Bulk packaging, layer counting and labelling agreed to your call-off pattern
• Weld stud selection matched to the process — CD for smaller diameters and thin sheet with minimal backside marking, drawn arc for larger studs and heavier base material
• Matched nut, sleeve or stamping from the same plant when the joint crosses part families

Quality Control And Acceptance

Production is governed by our IATF 16949-2016 system. Work instructions are written for special and critical processes, and inspection runs at every step: incoming raw material analysis, in-process checks after heading, tapping, heat treatment and thread rolling, and finished-part mechanical performance and hardness testing. We also hold work safety standardization and environmental management system certification.

Acceptance characteristics are agreed part by part — thread and shoulder dimensions, hardness and property class, plating thickness, salt-spray hours, and weld quality on studs where the joint depends on it. Inspection results travel with the shipment so your incoming inspection can release the lot without re-testing every characteristic.

Information We Use To Prepare Your Proposal

Frequently Asked Questions

Which bolts and screws can you manufacture to a customer drawing?

Full thread and round head stud weld bolts, hex head bolts with crimped captive washers from M3 to M24 in classes 8.8 and 10.9, double step shoulder locating pivot bolts, and non-standard screws with modified heads, shanks, thread leads or coatings. The mating nut, sleeve or stamped bracket can come from the same plant.

What is the difference between capacitor discharge and drawn arc stud welding?

Capacitor discharge uses a short, low-energy arc, typically for studs up to about 10 mm diameter on thinner sheet, with minimal marking on the reverse side. Drawn arc uses a higher-energy arc for larger stud diameters and heavier base material. The ignition tip, weld base and plating are matched to whichever process your line runs.

Which finish gives 480 hours of salt spray?

Trivalent zinc plating is qualified to 480 hours in our finishing line. Zinc-nickel alloy extends this to 480–720 hours for underbody, wheel-arch and battery-adjacent parts. High-temperature grades for 300 °C, 550 °C and 650–700 °C are available where exhaust or engine heat rules out standard zinc.

How tight can a locating shoulder be held?

Shoulder, step and washer-face features are controlled within a 0.06 mm to 0.30 mm window, set by the function of the feature on your drawing. A pivot or locating diameter is normally the tightest characteristic on the part; clearance faces are allowed more room. Each is gauged and reported separately.

What do you need to quote a custom bolt programme?

A detail drawing with thread, shoulder and tolerance callouts; material and property class; finish and salt-spray target; the mating part and target torque; sheet thickness and access conditions; annual volume and call-off pattern; and the documentation you need for line release. With those, we return a configuration, tooling position and piece price.