Steel wire is a type of wire that has undergone high-temperature rolling in a steel plant and has yet to be processed at room temperature. Its appearance resembles wire coils stacked together, and it is the primary material for making fasteners, with iron as the main component. Other common materials include copper-based, aluminum-based, and titanium-based wire.
    Fasteners are typically made of carbon steel, which is a common material. Alloy steel is another type of steel that is used for this purpose. Carbon steel mainly comprises iron, with a small amount of carbon (between 0.02% and 2%) and very few other metals. Based on the carbon content, carbon steel is categorized into high-carbon steel (0.6%~2%), medium-carbon steel (0.3%~0.6%), and low-carbon steel (0.02%~0.3%). Typically, the strength of the bolt increases with a higher carbon content unless otherwise specified.

    In Taiwan, a popular machine for forming screw heads is called “1 Die 2 Blow.” There are variations of this machine, such as “2 Die 2 Blow,” “3 Die 3 Blow,” and even “6 Die 6 Blow,” depending on the screw’s size and complexity. The term “Die” refers to the tool used for pressing, which determines the length and thickness of the screw during formation. The term “Blow” refers to the action of the punch, which primarily determines the shape of the head.
    Take the “1 Die 2 Blow” machine as an example; after feeding the wire material into the machine, the wire is first cut to the desired length using a cutting machine. Then, the wire is struck by the first punching die against the fixed die, preparing it for shaping. Next, the second punching die is used to achieve the final shape of the wire. Finally, the finished product is pushed out of the fixed die.
    The technology used in heading machines is cold forging, which differs from hot forging. Cold forging is performed at room temperature through multiple striking and shaping processes, resulting in a higher strength than hot forging.

    After the heading machine shapes the screw at the head part, the next step is to process the screw rod. We know that screws are used to connect with other objects (such as nuts) by utilizing the threads on the rod. Self-tapping screws can be used without the need for nuts. They can lock into materials such as wood by using their threads. Both examples indicate that forming the screw threads (thread rolling) is essential for producing the screw.
    The typical method for thread rolling involves using two parallel thread-rolling die plates, with each plate’s pitch corresponding to the screw thread pitch and angle equal to the screw’s helix angle. After placing the screw in between, it is clamped and fixed. The two plates achieve rapid thread formation through relative motion.
    Different from thread rolling for screws, the thread formation for nuts is generally referred to as thread tapping, and the principle is similar to that of screws.

    Once the heading and thread rolling steps are completed, the screw is roughly formed. The subsequent heat and surface treatments vary depending on each customer’s requirements. Regarding heat treatment, heating the screw to the appropriate temperature and cooling it will change its mechanical properties, such as hardness and toughness. Different methods are applied based on the wire material and its carbon content, including quenching, tempering, annealing, and normalizing. These methods can be used in combination to achieve the desired properties. For example, the screw can be quenched first to increase its hardness and then tempered to enhance its toughness and reduce the brittleness caused by quenching.

    Let’s say that heat treatment improves the internal mechanical properties of screws (although there is also a heat treatment process for the surface of screws). Surface treatment aims to improve the external properties of screws. Regarding external surface treatment, there are two critical purposes to consider. The first is to enhance the aesthetics of newly finished screws and their corrosion resistance and anti-rust capabilities.
    Regarding the first purpose of aesthetics, carbon steel screws generally have a black appearance. Electroplating is a popular surface treatment method, with options such as zinc plating and trivalent chromium plating (the hexavalent chromium process involves toxic substances) available for surface materials. Zinc plating can come in different colors, such as silver-white, blue-white, or even colored zinc. Trivalent chromium plating can produce different colors depending on the subsequent passivation treatment.
    The corrosion resistance and anti-rust capabilities of screws are also important aspects of surface treatment. Carbon steel screws undergo oxidation-reduction reactions with oxygen in the air, forming hydrated iron oxide and surface imperfections. As a result, surface strategies such as zinc plating are commonly employed to protect the underlying iron layer.

    After completing all the above processes, although the screws are roughly finished, if the production process is not perfect, it may result in defective products. The optical inspection stage checks the screw heads and thread diameters to weed out non-compliant screws. In addition, optical inspection reduces the potential for inaccuracies in manual inspection and lowers labor costs, thus becoming an essential method adopted by Way Fast collaborating manufacturers. Additionally, the process can speed up production when paired with an automatic screw-feeding machine.

    Packaging is the final process in manufacturing screws before they are shipped. It can be done using an automatic packaging machine, which allows users to automatically set the number of screws and place them into packaging containers. If customers have specific requirements, devices can also label the packaging. The packaged boxes are then systematically arranged onto pallets with the help of a carton sealing machine, preparing them for transport from the manufacturing facility or storage in a warehouse.

    Finally, after introducing the complete basic manufacturing process of screws, the most important thing is understanding your needs and finding a suitable company to purchase from. Way Fast has served in this industry for many years and specializes in the following products. For more information, please feel free to inquire and refer.

If you need any further assistance, feel free to ask!

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WFI product range:

• Material: Carbon Steel, Alloy Steel, Stainless Steel, Alum Alloy, Plastic, etc.
• Class: CL.8.8, CL.9.8, CL.10.9, CL.12.9, Brass, Alum, etc.
• Size: Diameter M1.0~M100
• Torx® / Torx Plus® Remform® / Plastite® Delta PT® / PT® / Duro PT® MAThread® / MATpoint® (GM “M-Point”) Taptite II® / Taptite 2000® / Duo-Taptite®.
• SEMS, Knurl Bolt, Clinch Stud, Welding Stud, Shoulder Bolt, Thread Forming Screw, Special Bolt & Screw to Print.
• Weld Nut, Conical Nut, Hex Flange Nut, Special Nuts to Prints, Open-Die Items, Rubber Components, Brass Insert & Turning Products, Washers (Flat, Conical, Bonded Washers, etc.), Blind Rivet.