Special bolt manufacturing

In Lemec, we are your ally in the manufacture of special bolts, producing metal parts by cold heading for long series and bar turning for short series. We offer an unbeatable quality-price ratio and we work to order, following your drawings and technical specifications.

As an auxiliary industry, we focus on providing you with customized manufacturing solutions for your industrial projects.

Ball joints

Bushings

Rivets

Nuts

Screws

Pins

Small Shafts

Wire Terminals

Bolts

Spacers

Special bolts

At Lemec, we manufacture special bolts for virtually any industrial application and in different geometries and alloys.

Cylindrical bolts

Our machines are capable of manufacturing cylindrical bolts in one or more diameters and with cross holes.

Square bolts

Our square bolts provide a robust and durable fastening.

Hexagonal bolts

The hex bolts we manufacture are perfect for applications that require a tight fit.

Bolts of different alloys

We offer a wide variety of bolts in different alloys to meet various industry applications.

Aluminum bolts

Aluminum bolts are lightweight and strong, suitable for applications requiring low weight and corrosion resistance.

Brass bolts

Brass gives the bolts significant corrosion resistance, while providing an aesthetic appearance. They are ideal for specific applications where both factors must be combined.

Steel bolts

We manufacture steel bolts, due to their durability and capacity to withstand high loads, ideal for safety and bodywork applications.

Stainless steel bolts

At Lemec, we manufacture stainless steel bolts. These offer excellent corrosion resistance, making them perfect for corrosive environments in very critical anchoring applications.

Copper bolts

For applications in electrical installations where continuity and conductivity are crucial.

Lemec: Customized solutions in bolt manufacturing.

At Lemec, we have the capability to produce high quality bolts to your exact specifications. Whether you need bolts for doors, hinges, car bodies or any other application, our production processes
guarantee parts with great durability and excellent performance. Trust Lemec for all your bolt manufacturing needs.

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Frequently Asked Questions

What is a bolt?

A bolt is a fastening element with a head and a threaded shank that passes through the parts to be joined and is secured with a nut (usually with washers). Its function is to generate preload to keep the assembly stable against tension, shear, and vibration. Variants include through bolts, anchor bolts, and studs (threaded at both ends, without a head).

What is the difference between a bolt and a screw?

Bolt: works with a nut; the thread is not formed in the substrate. Ideal when joining multiple parts or different materials.

Screw: threads into a tapped hole in the component itself; does not use a nut.

In design, the bolt prioritizes preload of the assembly and nut–washer compatibility, while the screw depends on the strength of the substrate’s thread.

How does a manufacturer of special bolts approach production depending on series size and geometry?

• Cold heading/cold stamping + thread rolling: optimal for long series, high repeatability, and better fatigue resistance due to preserved fiber continuity.
• Screw machining/turning and auxiliary machining: ideal for custom bolts in short/medium runs and complex geometries (special heads, grooves, holes, tapers, precise chamfers).
• Heat treatments according to strength class, and anti-corrosion coatings (zinc plating, zinc-nickel, nickel plating) depending on environment and galvanic compatibility.

Rolled vs. machined threads: when is each recommended and how does it affect bolt performance?

Rolled threads (roll forming): induce compressive stresses, preserve grain flow, and improve fatigue resistance and surface finish; the best option for long runs and standardized thread pitches, requires ductile material and tooling.

Machined threads (turning/milling/tapping): offer maximum flexibility for special geometries, difficult materials, or short/medium runs; parameters must be carefully controlled to avoid micro-notches.

In both cases, defining standard and tolerance (e.g., M – 6g/6H, UNC/UNF), usable thread length, lead-in chamfer, and run-out control is key for proper assembly and tightening.

How is service durability ensured in special bolts: corrosion, anti-loosening, and traceability?

• Corrosion: select material (stainless steel A2/A4) or coatings (zinc plating, zinc-nickel, zinc flake, nickel plating) depending on environment and galvanic compatibility. For bolts ≥ 10.9, consider hydrogen embrittlement mitigation (e.g., baking after galvanizing if applicable).

• Anti-loosening: depending on vibration: self-locking nuts, serrated/wave washers, anaerobic adhesives, torque–angle tightening, or holes for pins/wire-locking in custom bolts.

• Traceability/quality: class marking (8.8/10.9/12.9) and manufacturer, batch/heat number, certificates (e.g., 3.1), coating thickness checks, torque–tension testing (K factor), and, depending on sector, PPAP/control plans.