Questions About Threads
Knowledge

Questions About Threads

Screws and bolts are common threaded fasteners with external threads. They are generally used for fastening a combination of multiple components. Unlike welding, the locking mechanism is easy to adjust and can be disassembled. If a fastener has external threads and is not used with a nut, it is a screw (such as wood screws, self-tapping screws, etc.) If it is used with a nut, it is a bolt (such as flat head bolts, non-slip bolts etc.). There are different kinds of threads which are used for different applications.
Published: May 10, 2022
Questions About Threads

What Is a Thread?

A thread is a uniform helical protrusion on a cross-section of the outer or inner surface of a material. The cross-section or the protruding material follows an inclined plane. The threaded parts are screwed together to provide a strong connection.

Thread Classifications

According to their structure and use, threads can be classified as:

  1. Ordinary threads (fastening threads): The protruding tooth profile is triangular. Ordinary threads can be categorized as coarse, fine or superfine, according to the pitch.
  2. Sealing threads: The threads are tapered, becoming tighter as they are screwed in. They are often used for pipe connections.
  3. Transmission threads: Special threads may be trapezoidal, rectangular, or saw-tooth shaped.
  4. Special threads: Special purpose threads for special purposes.
  5. Thread sizes can be given in the following units:

    1) Metric thread: ISO metric thread consists of symmetrical V-shaped threads, the sides are at an angle of 60° to each other, and the thread depth is 0.614 × pitch. The marking of metric threads starts with the letter M, followed by the outer diameter of the thread and then the pitch, in mm. For example, M8x1 is a metric thread with an outer diameter of 8 mm. which when rotated 360 ° will advance 1 mm.

    2) Inch thread: Inch thread is commonly known as "Wheel thread" and is marked with W*N. Inch thread pitch indicates how many threads per inch, for example, a 1/8”-40 bolt has an outer diameter of 1/8″ (3.175mm) and has 40 threads per inch), However screws and bolts may sometimes be marked with their outside diameter and length. For example, 1/4"x1.25 means a screw with a 1/4" OD and is 1.25" long.

    3) American thread: Screws are generally marked with a serial number, such as #2-56; #4-40; #6-32; #8-32; #10-24. For example, #8-32 is a size 8 screw with 32 threads per inch.

Thread Terms

External thread: A thread formed on the outer surface of a cylinder or cone.

Internal thread: A thread formed on the inner surface of a cylinder or cone.

Major diameter: The diameter of an imaginary cylinder or cone tangent to the external thread crest or internal thread root.

Minor diameter: The diameter of an imaginary cylinder or cone tangent to the root of the external thread or the crest of the internal thread.

Pitch Diameter: The diameter of an imaginary cylinder or cone that is halfway between the major diameter and the minor diameter. It can also be referred to as a mid-diameter cylinder or mid-diameter cone.

Right-hand thread: A thread that is screwed in when turned clockwise.

Left-hand thread: A thread that is screwed in when turned counterclockwise.

Tooth profile angle: On the thread profile, the angle between two adjacent flanks.

Pitch: The axial distance between the corresponding two points on the center diameter line of two adjacent teeth.

Marking Recognition of Threads

There are many specifications and types of fasteners. To distinguish them clearly, their composition is given in a defined order called mark identification as shown below.

  1. Marking of screws or bolts: Name, standard number, nominal diameter × thread diameter × nominal length - material - wrenching form - surface treatment.
  2. Marking of nuts or washers: name, standard number, nominal diameter x thread pitch - material - surface treatment.
  3. Marking of the retaining rings: name, standard number, nominal size.
  4. Pin marking: name, standard number, nominal diameter x nominal length - material - surface treatment.
Published by May 10, 2022 Source :SOIC

Further reading

You might also be interested in ...

Headline
Knowledge
Precision in Rotation: Indexing Plates in Metal Machining
Rotary Indexing Plates are precision components of milling machines that facilitate the precise angular positioning of workpieces and cutting tools. They are used in both metal machining and woodworking, and while they share a fundamental purpose, there are notable differences in their design, capabilities, and applications due to the distinct characteristics of the materials and processes involved.
Headline
Knowledge
Sheet Metal Fabrication Machines: An Overview
Sheet metal machines are widely used in various manufacturing industries for shaping, cutting, and forming sheet metal into different components. Some of the industries that extensively utilize sheet metal machines include light industries such as electrical and medical equipment, all the way up to heavy industries such as automotive, rail, oil and gas, as well as wind power generation.
Headline
Knowledge
The Significance of Planing Machines in the Machining Tool Industry
Metal and wood planing machines are essential tools in the machining industry. Wood planers use a rotating cutterhead equipped with sharp blades to smooth and size workpieces, ensuring uniformity in woodworking projects. Metal planers use a cutting tool mounted on a reciprocating tool head to remove excess material from metal surfaces, achieving precise dimensions in components. Both types of planning machines enhance efficiency, precision, and the overall quality of finished products. Understanding the key features of the various types of planing machines will help you choose the right machine best suited for your machining needs.
Headline
Knowledge
Stamp Press Technology and Manufacturing in Taiwan
Nestled in the heart of East Asia, Taiwan has emerged as a powerhouse in the global stamp press industry, with a robust manufacturing ecosystem, and cutting-edge technology. With a rich manufacturing tradition and a focus on precision engineering, Taiwanese companies meet the demands of diverse sectors, ranging from electronics and automotive to medical devices and aerospace, supplying high-quality stamp press solutions to a diverse range of markets worldwide.
Headline
Knowledge
Introduction to Stamp Press Technology
Stamp press technology, also known as stamping or pressing, is a manufacturing process that utilizes a press to shape or cut materials into desired forms. This process involves the use of a die and a punch to form or cut the material, creating intricate shapes with high precision. Widely employed for mass production due to its speed, accuracy, and repeatability, this process is a crucial part of modern manufacturing.
Headline
Knowledge
Mechanical Reducers in Industrial Manufacturing
Speed reducers are powerful mechanical devices generally used in machining tools to multiply the force or torque generated by an input power source, thereby increasing the usable force, enhancing the performance and precision of the machining tool. They are also used in material handling systems such as conveyor belts and lifting mechanisms to control the speed of material transfer and manage heavy loads efficiently. By multiplying the available output force, they enable the use of a reduced input power source, resulting in cost savings for machine tool investments. When choosing the appropriate speed reducer, the torque, speed, and horsepower of the input, as well as the mounting configuration, efficiency, and required lifetime all need to be considered. The quality of the machine chosen will also be reflected in the amount of backlash, transmission error, torsional rigidity, and inertia experienced during machining.
Headline
Knowledge
Introduction to Stamp Press Technology
Stamp press technology, also known as stamping or pressing, is a manufacturing process that utilizes a press to shape or cut materials into desired forms. This process involves the use of a die and a punch to form or cut the material, creating intricate shapes with high precision. Widely employed for mass production due to its speed, accuracy, and repeatability, this process is a crucial part of modern manufacturing.
Headline
Knowledge
Innovations in Sawing Technology
The traditional image of saws as just cutting tools is being reshaped by cutting-edge advancements that integrate automation and robotics in sawing technologies, paving the way for greater precision and efficiency of sawing technology in manufacturing.
Headline
Knowledge
The Fundamentals of Drilling Machines
Drilling machines play a pivotal role in the manufacturing industry, using rotary motion to create precise holes in a variety of materials. Whether it's metal, wood, plastic, or composites, drilling machines are versatile and essential for producing components in countless applications.
Headline
Knowledge
Hybrid Milling in Manufacturing: Integrating Additive and Subtractive Processes
The integration of additive manufacturing (AM) and subtractive milling processes has emerged as a transformative manufacturing process known as hybrid milling. This technique combines the strengths of both 3D printing and traditional subtractive milling, opening up new possibilities and diverse applications for creating complex geometries with improved material efficiency.
Headline
Knowledge
Features and Mechanics of Industrial Saws
Industrial saws shape raw materials into precise components that form the backbone of countless products. Understanding the mechanics of sawing, examining the fundamental principles, cutting mechanisms, and essential aspects of safety and maintenance will ensure the most efficient and safe operation of industrial saws.
Headline
Knowledge
Understanding the Diversity of Industrial Saws
Industrial saws play a pivotal role in processing a wide range of materials with precision and efficiency. Taiwan is a major supplier of industrial saws to the automotive, aerospace, and construction, as well as the metal fabrication industries. This article aims to provide a comprehensive understanding of the diverse industry of industrial saws, exploring their types, structures, applications, and the crucial role they play in various industries.
Agree