Self-tapping thread inserts (also known as self-tapping thread inserts or self-tapping screw inserts) are fasteners that can be directly screwed into the substrate to form a high-strength internal thread without pre-tapping. They also enhance thread strength and repair damaged threads. Based on their structural design, material, and application scenarios, they are mainly classified as follows:
Classification by Structural Type: The head design of the self-tapping thread insert determines its self-tapping method and applicable scenarios, mainly divided into the following categories:
Slotted Type (Type 302): The insert head has a cutting groove, which cuts through the groove to achieve self-tapping. Suitable for most general applications, it is easy to install and is one of the most widely used types.
Three-Hole Type (Type 307, Type 308): The head has three evenly distributed self-tapping holes, which act as cutting edges, distributing cutting force more evenly. Suitable for harder or thin-walled materials (such as aluminum alloys and cast iron). The Type 308 is an extended version of the Type 307; the only difference is the length. It is suitable for applications requiring deeper thread embedding.
Flange type (307H/308H, 337H/338H, etc.): Based on the three-hole or slotted type, an added flange provides a larger support surface, significantly improving tensile and torsional resistance, suitable for high-load or vibration environments.
Blind hole type (337/338 series): Three cutting holes are blind holes to prevent chips from falling into the mounting holes, suitable for precision parts or enclosed spaces requiring high cleanliness.
Pin locking type (317/318 series): Locking is achieved by inserting a pin conforming to DIN1437 standards, providing excellent anti-loosening and vibration resistance, suitable for high-vibration environments.
Stainless steel (e.g., SUS303, 304, 316, 316L): Passivated, highly corrosion-resistant, suitable for high-strength substrates such as cast iron and stainless steel, or for use in humid or corrosive environments.
