Technical

Annealing

First, place the raw materials that need processing into a high-temperature furnace. Strictly follow the specified requirements for high-temperature treatment. Then, gradually cool the material down to 550 degrees Celsius, allowing the product to naturally reach room temperature. This process can adjust the crystalline structure, reduce hardness, and improve the work ability of the wire at room temperature.

Pickling

After annealing, these materials are transported to the pickling area. The annealed material is placed in a hydrochloric acid tank for pickling, followed by rinsing with water to remove any hydrochloric acid residue from the wire surface. To create a tighter oxide film for the subsequent production step, oxalic acid is used to enhance the metal’s reactivity. Next, the material is immersed in a phosphate solution, allowing it to react with the steel surface and form a compound that adheres to the screw surface, creating a protective film. Finally, the surface is rinsed again to remove any remaining residue, and lubricating oil is applied to enhance lubrication and remove any oxide film from the wire, preparing it for screw formation.

Wire Drawing

After removing the oxide film, these materials are ready for formal production. They will enter our wire drawing workshop, where mechanical drawing processes are used to precisely reduce the diameter of the material to the desired wire gauge specified by the customer. This process is suitable for large screws, nuts, and threaded rods.

Heading

After straightening the material to the required wire diameter, it’s time for heading. In the bolt manufacturing process, heading involves a two-step operation. First, the product is heated in specialized equipment, with heating time and temperature set according to the product specifications. Next, the heated material is transferred to a forming machine where it is shaped using molds. Finally, a swaging machine compresses the material to achieve the desired diameter. The design can be customized based on customer requirements, with common head types including P-head, B-head, F-head, and T-head. Additionally, popular groove types include cross-slots, single-slots, flower-shaped slots, and internal hexagonal slots.

Drilling

After heading, the semi-finished product is sent to our drilling workshop. The purpose of drilling is to create the dovetail shape required for penetrable steel plates, which is a crucial step. Parameters such as concentricity and blade width are strictly controlled during this process.

Threading

After drilling, the semi-finished product is sent to our wire threading workshop. In this specialized area, we use machinery to progressively reduce the diameter of the already formed semi-finished product to achieve the desired thread dimensions for the screws.

Heat Treatment

After threading, our products are already in their preliminary form. However, to enhance material mechanical properties, relieve residual stresses, and improve metal machinability, we need to subject the products to a heat treatment process. This process includes cleaning, high-temperature carburizing, and quenching.

Surface Treatment

Finally, based on customer requirements, we can choose whether to apply surface treatments. If requested, we can create protective layers on the product surface through methods such as electroplating, hot-dip galvanizing, or mechanical zinc plating.

Wear Washers

Based on different screw requirements, some products also need to be assembled with various types of washers. Using specialized automatic washer-insertion machines, the washer assembly process for bolts is completed, resulting in a fully assembled product.

Product Testing

After production is completed, our inspection personnel sample the products and conduct comprehensive inspections on aspects such as appearance, dimensions, threads, and mechanical performance. Qualified finished products are then transported to the packaging line and ultimately stored for sale. Of course, during the production process mentioned above, specialized employees also perform first-piece inspections, regular quality checks, and production supervisor inspections to ensure the quality of our products.