The button head and semi-circular head American machine screw are a kind of fastener that combines aesthetics and functionality. At the same time, button head and semi-circular head American machine screws are also two common types of screws, which are widely used in mechanical assembly, electronic equipment, automobiles and other fields. They have both similarities and differences in structure and application. The following is a detailed comparison.
1. Similarity
Thread standard: Both adopt the American unified thread standard and are compatible with the same nuts and threaded holes.
Material and surface treatment: Commonly used carbon steel, stainless steel, or alloy steel, the surface can be galvanized, nickel-plated or passivated.
Drive mode: Usually, hexagonal or cross and slot drives are used.
Functional use: Both are used in mechanical assembly, electronic equipment, automobiles, and other fields to provide fastening connection functions.
2. Differences
Head structure characteristics
Appearance: The button head is a low, cylindrical shape, with a slightly convex top and a straight side; the semi-circular head is hemispherical, and the height is slightly higher than the button head.
Height: Button head is lower, about 0.6 times the diameter; semi-circular head is higher, about 0.8 times the diameter.
Contact surface: The bottom of the button head has a small plane, and the contact area is larger; the semi-circular head is a pure arc surface, and the contact area is smaller.
Application scenarios
Button head: Suitable for occasions with limited space, the head is low and does not easily interfere. Because of the large contact surface, it can disperse pressure and is often used for soft materials.
Semi-circular head: Traditional general design, with a smoother appearance, mostly used in scenes that require beauty or reduce the risk of scratches. Because the head is higher, more installation space needs to be reserved.
Mechanical properties
Tensile strength: The semi-circular head has slightly stronger tensile strength due to more head material; the button head focuses on anti-shear.
Anti-loosening performance: The bottom plane of the button head can be matched with a gasket to enhance anti-loosening; the semi-circular head needs to rely on thread glue or elastic washers.
Other details
Countersink compatibility: Button head can adapt to shallow countersinks, semi-circular head requires standard countersinks.
Aesthetics: The semicircular head has a smoother appearance, and the button head has a strong sense of modernity.
3. Summary of selection suggestions
Choose a button head: compact space, low profile, or contact surface pressure dispersion.
Choose a semicircular head: focus on aesthetics, traditional design, or higher tensile strength requirements.
The two screws can be partially replaced in function, but the choice needs to be weighed according to the specific working conditions.
Through reasonable selection and standardized operation and application, button head semicircular head American machine thread screws can balance aesthetics and structural strength, and are an ideal choice for precision assembly.
