I. Standards and Specifications
Compliant with the German industrial standard DIN 478, the current latest version is DIN 478:2016-08. Previous versions include the 1985 edition, etc. This standard clearly stipulates key contents such as product size tolerances, material requirements, performance indicators, surface treatment and marking. It is classified under the category of bolts, screws and studs in the international standard classification.

II. Structural Characteristics
The integrated structure adopts "square head + integral flange (pad)". The head is square-shaped, and the screw part has threads. The flange (pad) between the square head and the screw is integrally formed. The square head is convenient for tools such as wrenches to apply force, and it can provide a large torque; the integral flange does not require an additional washer and can directly increase the contact area. The structure is compact and the operation is convenient and fast.

III. Size Specifications
The specifications are classified by nominal diameter (M), covering a range from M2 to M100, etc. Some common specifications are concentrated in M3 to M33. The core size parameters include nominal diameter, pitch, screw length, width of the square head's opposite sides, outer diameter and thickness of the flange (pad), and each parameter has a strict tolerance range. For example, the M12 specification usually corresponds to a specific pitch and square head size.

IV. Materials and Properties
• Materials: The mainstream materials include carbon steel, alloy steel, and stainless steel (such as 304, 316, 430, etc.). Other metallic materials like copper, brass, and aluminum alloys can also be used.
• Performance: The high-strength material can achieve performance levels such as 8.8 and 10.9. The nominal tensile strength of the 10.9 grade product reaches 1000 MPa, and the yield strength is 900 MPa. The integral flange can effectively disperse the tightening pressure, protect the surface of the workpiece, and the overall structure possesses reliable load-bearing capacity and connection stability.

V. Surface Treatment
Carbon steel and alloy steel are typically treated with processes such as blue-white zinc, colored zinc, and blackening oxidation. The blackening treatment can form an oxide film, providing both anti-rust and wear-resistant properties.
• Stainless steel materials usually retain their natural color. Some can undergo passivation treatment to enhance corrosion resistance; copper or brass materials can be treated with acid washing and other methods to improve their rust resistance.

VI. Application Domains
It is widely applicable in fields such as mechanical manufacturing, fixed parts of CNC machine tool holders, automotive manufacturing, new energy equipment, and rail transportation. It is particularly suitable for connection scenarios that require a large tightening force, allow the nail head to protrude, and need to simplify the assembly process (without the need for additional washers), such as component positioning and equipment assembly parts.