I. Definitions

1. Differences Between Screw, Nut, Bolt, Screw Bolt, and Stud Bolt

Any component with external threads can be called a "screw".

Nut: Typically hexagonal in shape, with internal threads in its inner hole. It pairs with bolts to fasten related parts.

Bolt: Usually has a hexagonal head and a shank with external threads.

Screw: Smaller in size, with heads (e.g., flat head, cross head) and a shank with external threads.

Stud Bolt: Properly called a "double-ended stud"—it has external threads on both ends and a smooth shank in the middle. The longer threaded end connects to deep holes, while the shorter end pairs with a nut.

2. Common English Terms

screw；bolt；fastener

3. Definition of Thread

A thread is a shape with uniform helical protrusions on the external or internal surface of a solid.

II. Functions

Fastening and Connection: Applies to most current screw products.

Displacement: E.g., micrometers used for dimension measurement.

Sealing: E.g., sealing pipe connections.

III. Thread Development History

Machine Thread: Drill and tap a hole in the workpiece first; the tapped internal thread matches the screw’s external thread, allowing assembly with low torque.

Self-Tapping Thread: Drill a hole in the workpiece first (no tapping needed), assembled with high torque.

Self-Drilling Thread: Used directly on the workpiece—drilling, tapping, and thread formation are completed in one step.

IV. Processing Methods

1. Turning

Shapes material by removing excess material.

Advantages: High machining precision; no mold restrictions.

Disadvantages: High production cost; slow processing speed.

2. Forging

Shapes material by applying external force to deform it.

Advantages: Fast production speed; low cost; suitable for mass production.

Disadvantages: Shaping is limited by molds; high mold costs for complex products.

V. Introduction to Basic Screw Configurations