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What are the different types of thread manufacturing process?

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Threads, as an integral part of mechanical engineering, are widely used in various equipment and products. The diversity and complexity of their manufacturing processes also reflect the exquisite skills of modern machinery manufacturing. This article will introduce in detail several different types of thread manufacturing processes and explore their respective characteristics and application scenarios.

What is threading in manufacturing process?

Threading is one of the most important applications of CNC machining centers. It is a subtractive processing method used to make external and internal threads of different sizes. This machining is performed by the circular motion of a rotating tool calibrated for the required thread depth and density.The main function of threads is to act as a coupling agent between two mechanisms. During the coupling process, movement occurs between the parts.Threads are made up of different parts. These parts include crest, base, helix angle, pitch, and flanks.

The principle is to process spiral thread lines on the workpiece through the relative movement of the cutting tool and the workpiece. During the machining process, the movement path, pressure and cutting depth of the tool need to be controlled to ensure that the processed thread meets the design requirements.

Main Parameters For Thread

Main ParametersElaborate
Helix angleThe helix angle in machining is the angle between the thread axis and the helix in a straight thread, or the angle formed by the tapered helical area of ​​the thread in a tapered thread.
RootThis is the bottom of the thread. It is the adjacent area of ​​a projected cone or cylinder.
Cremation The crest is the top of the thread. It is the farthest region of the projected cone or cylinder. The crest is also the thread surface that connects the flanks.
FlankThis threaded portion connects the root and crest of the tooth. Theoretically, the intersection of the tooth flank surface and the axial plane is a parallel line.
PitchThe diameter of the pitch is theoretically equal to the diameter of the cylinder or cone. Thread pitch is a measurement of the distance between adjacent thread areas. The parallel areas measured must correspond.

Different types of thread manufacturing processes

1.cutting method

The cutting method is The process or production of high-volume threaded parts using automated multi-axis machine tools. It is the most efficient and economical processing method for processing threaded parts. Continuous protrusions and grooves with the same cross-section formed on the surface of a cylinder along a spiral are called threads.

Advantages of cutting method

  • High efficiency: Thread cutting method is the most efficient method for processing threaded parts, especially suitable for mass production.
  • Economical: Due to its high efficiency, the thread cutting method performs well in cost control and is one of the most economical processing methods.
  • High precision: The thread cutting method can ensure the high precision of the thread and is suitable for occasions with high requirements for thread precision.
  • Strong versatility: The tools and equipment used in the thread cutting method are highly versatile and can process internal and external threads of various shapes, sizes and different precisions.

disadvantages of cutting method

  1. High technical requirements for workers: Since the thread cutting method involves complex machine tool operations and tool adjustments, it requires high technical levels of workers.
  2. Large initial investment: In order to achieve efficient and high-precision thread cutting, more funds need to be invested to purchase automatic multi-axis machine tools and other related equipment.
  3. Not suitable for small batch production: Since the thread cutting method is mainly suitable for large batch production, for small batch production, its economy and efficiency may not be as good as other processing methods.
Threading tools

2.Rolling method

The rolling method is a forming process that uses a roller or rolling tool to apply pressure on the workpiece to plastically deform the workpiece material to form the desired thread shape. Rather than removing material to create threads, this method uses the material’s ability to plastically deform to permanently press the roller’s shape onto the workpiece.

Advantages of Rolling method

  • High surface quality: The surface roughness of the thread rolling method is smaller than that of traditional processing methods such as turning, milling and grinding, and can produce a smoother and more precise thread surface.
  • Improved strength and hardness: The strength and hardness of the rolled thread surface can be increased due to cold work hardening, making the threaded connection stronger and more reliable.
  • High material utilization rate: Compared with cutting processing, the thread rolling method can save 15 to 20% of material, especially in mass production, this advantage is more significant.
  • High productivity: The productivity of thread rolling method is exponentially higher than that of cutting processing, and it is easy to realize automation, which improves production efficiency.
  • The rolling mold has a long life: The rolling mold has a long life, which reduces the frequency of mold replacement and reduces production costs.

disadvantages of Rolling method

  • There are requirements for the workpiece material: the thread rolling method requires that the hardness of the workpiece material does not exceed HRC40, and it needs to have good plasticity and cold fluidity. Materials such as cast iron are not suitable for thread rolling due to poor fluidity.
  • High requirements for blank dimensional accuracy: The accuracy of the blank diameter is crucial to the success of thread rolling. Exceeding or falling below the predetermined blank diameter may result in defective threads.
  • High requirements for rolling molds: The precision and hardness of rolling molds are very demanding, and it is difficult to manufacture molds. In addition, the cost of rolling molds is relatively high.
  • Not suitable for processing threads with asymmetrical tooth shapes: Due to the limitations of the rolling mold, the thread rolling method is not suitable for processing threads with asymmetrical tooth shapes.
What is the difference between cut threads and rolled threads?

3.Forging method

Forging method is a process that applies pressure to metal materials through forging equipment to cause plastic deformation to form the desired thread shape. During the forging process, the metal material is subjected to huge deformation stress, and its internal structure and performance are significantly improved. At the same time, the shape and size of the material also change to form the required thread shape.

Advantages of Forging method

  1. Improved material performance: During the forging process, metal materials are subject to huge deformation stress, which can eliminate defects and inclusions in the material, making the forgings have a more uniform structure and a more solid structure. In addition, the grain size of the metal can also be refined, thereby improving the material’s mechanical properties, wear resistance and service life.
  2. High material utilization rate: Compared with the casting process, the thread forging method does not need to melt the metal material first and then shape it, so it can greatly improve the material utilization rate. It is estimated that the forging process can save 15 to 20% of materials compared to the casting process.
  3. High precision of parts: The thread forging method uses molds to control the shape and size of parts, so it can produce threaded parts with higher precision and more complex shapes.
  4. Wide scope of application: The thread forging method is suitable for processing various metal materials, including not only common materials such as iron, copper, and aluminum, but also high-temperature alloy materials and high-strength steel materials such as titanium, nickel, and zirconium. Therefore, it can meet a wide range of industrial production needs and is widely used in shipbuilding, aerospace, automobile manufacturing and other industries.

disadvantages of Forging method

  1. Higher cost: Due to the high manufacturing and maintenance costs of forging equipment and molds, the production cost of the thread forging method is also relatively high. In addition, for thread processing of some special materials, special forging equipment and molds may be required, further increasing the cost.
  2. Longer processing cycle: Compared with rapid processing methods such as cutting, the thread forging method has a longer processing cycle. This is because the forging process requires sufficient plastic deformation of the metal material to form the required thread shape, which requires a certain amount of time and pressure.
  3. There are certain requirements for materials: the thread forging method requires the metal material to have good plasticity and cold fluidity in order to form the required thread shape during the forging process. If the material has poor plasticity and cold fluidity, it may result in forging failure or inaccurate thread shape.
  4. Great wear and tear on the mold: During the forging process, the mold will be subject to strong impact and friction from the metal material, so the mold will wear out quickly. Molds need to be replaced and maintained regularly to ensure processing accuracy and production efficiency.

Common methods of thread processing

1.Thread Milling

Thread milling is a method for cutting threads into a part or workpiece, but with a tool that has a limited contact area with the workpiece. For internal threads inside holes, the thread milling cutting tool has a smaller diameter than the hole and rotates at a relatively high speed as it moves in a circular path around the circumference of the hole. In this way, thread milling is different from tapping, as a tapping tool has a diameter that matches the hole to be threaded, and is in contact with the workpiece along its entire circumference while tapping the hole.

What Are The Advantages Of Thread Milling?

  1. A single thread milling cutting tool can be used to create inside and outside threads, left- and right-hand threads, and threads of different diameters. 
  2. Because a thread milling cutter is not in contact with the workpiece along its entire circumference (like a tap would be), the engagement with the material to be cut is significantly lower. Therefore a lower power and torque is required to drive the tool.
  3. Due to the lower engagement with the workpiece, the wear on the thread milling cutting tool is significantly lower than an equivalent tap. 
  4. Thread milling can be used on materials that are difficult to machine. Particularly for these materials, single tooth cutters could be used, to limit the forces to the minimum. This limits distortion of the workpiece, as well as chatter and risk of breakage of the tool.

What Are The Disadvantages Of Thread Milling?

  1. In some applications, the main drawback of thread milling is that it is slower than tapping. If the hole can be threaded easily and reliably with a tap, then thread milling will simply take longer to complete that thread.  
  2. More sophisticated machinery is required for thread milling compared to tapping. A CNC machine is essential for thread milling, it cannot be carried out without one.
Thread cutting on lathe

2.Thread Turning

Thread turning is a method used to create screw-like grooves, known as threads, on a cylindrical object or inside a hole. This process is usually done on a machine called a lathe.During thread turning, the workpiece (the rod or tube) spins, while a special cutting tool moves along it. This tool cuts the threads into the surface of the workpiece, similar to the threads you see on a bolt or the inside of a nut.

What Are The Advantages Of Thread Turning ?

  1. High precision: Thread turning can achieve high precision. Since the relative position of the workpiece and the tool is relatively stable during the turning process and is not prone to shaking, the machined threads have high accuracy.
  2. Strong versatility: Thread turning equipment has strong versatility and is suitable for thread processing with a variety of different specifications and requirements. Whether it is non-standard threads, large pitch threads or locking threads, they can all be processed on a lathe.
  3. High material removal rate: Turning is a commonly used method in high-precision thread processing. It has a high material removal rate and is suitable for thread processing of various materials.
  4. High production efficiency (for internal threads): When turning internal threads, the process flow is relatively simple. You only need to clamp the workpiece and set appropriate tools and tool path parameters, and the processing efficiency is high.

What Are The Disadvantages Of Thread Turning ?

  1. Low productivity: Compared with other processing methods, such as milling, thread turning has low productivity. This is mainly because the turning process requires multiple tool passes and requires high technical level of workers.
  2. High technical requirements for workers: Thread turning requires high technical level of workers, requiring workers to have rich processing experience and skills.
  3. Difficulty in processing (for internal threads): Compared with external threads, turning internal threads is more difficult. A higher level of technology and experience is required, and residual burrs are easily produced after processing, requiring subsequent processing.
  4. Tools are easy to wear: Due to the particularity of the thread structure and the complexity of the process, the tools are easy to wear when turning threads, which affects the machining accuracy and surface quality.
  5. High processing costs (for special materials): For some special materials, such as titanium alloys, due to their special properties, problems such as tool sticking, material diffusion, and elastic recovery are prone to occur during turning processing, resulting in greatly increased processing costs.

3.Thread Rolling

Thread rolling is a type of threading process which involves deforming a metal stock by rolling it through dies. This process forms external threads along the surface of the metal stock. Internal threads can be formed using the same principle, specifically termed thread forming. In contrast with other widely used threading processes such as thread cutting, thread rolling is not a subtractive process. This means it does not remove metal from the stock.

What Are The Advantages Of Thread Rolling ?

  • High thread strength: Thread rolling is usually done in relatively low temperatures making it a cold working process. Cold working is known to produce parts with higher strengths without the need for secondary heat treatment. This makes rolling suitable for threading materials that do not respond to heat treatment. Rolled threads are 10 to 20 percent stronger than cut or ground threads.
  • Good surface finishes: Thread rolling inherently imparts smooth and burnished threads without the need for secondary polishing processes. The high compressive forces that deform the metal remove any unevenness on the surface of the thread. Rolled surfaces have a surface roughness of approximately 8 to 24 microinches Ra while cut threads typically have 64 to 125 microinches Ra. Rolled threads are also free of tears, chatter marks, cutting marks, and burrs.
  • Precision threading: Since the dies used in thread rolling are mirror images of the threads to be generated and there is no material being removed from the stock, the process can produce parts with high precision and accuracy over long runs. This is true provided that the dies are accurate and made with sufficient hardness.
  • Lower coefficient of friction: Good surface finish leads to a lower coefficient of friction. A lower coefficient of friction provides more uniform and consistent tightening of nuts and bolts or better power transmission for lead screws.
  • Lower production lead times: Thread rolling is generally faster than thread cutting. Rolling speeds depend on the type of material, thread profile, size and capacity of the machine, and method of feeding the metal stock. For reciprocating dies, thread rolling can produce 30 to 40 parts per minute with stock diameters ranging from 5/8 to 1 1/8. For cylindrical dies, 10 to 30 parts per minute for sizes ranging from 1 to 1 ½ inch.
  • Lower cost brought by the efficient use of material: Since thread rolling is a deformative process, no amount of material is removed throughout the process. This leads to better energy utilization since there is no need to collect and recycle wasted materials.
Schematic representation of the thread rolling process and its motion: a Two rolling dies , b Motion in finite element modeling using two rolling dies c Three rolling dies

What Are The Disadvantages Of Thread Rolling ?

  • Not practical for hard materials: Thread rolling is mostly done on malleable metals. Even though it is possible, thread rolling is not done for metals above 40 Rockwell C. Beyond this hardness level, thread grinding is more practical. Rolling hard materials significantly decreases tool life.
  • More expensive tooling: Dies used for rolling must be hard and precise. Any deformity of the die will result in poor dimensional accuracy of the threads. Because of the required hardness, precisely fabricating the dies are difficult.
  • Stock diameter must be precise: There must be the right amount of material that will flow to be displaced and raised above the original surface. The diameter of the stock must be calculated and verified by trial especially when producing accurate threads. To get the right diameter, the stock may require a preliminary turning process.

4.Thread grinding

Thread grinding is a process that uses equipment to shape a grinding wheel into the precise shape of a thread. It cuts a specific pattern into the workpiece, which slowly rotates while moving axially. The grinding wheels are monitored and re-dressed (dressed) throughout the process to ensure the highest precision of the threads. In addition, grinding wheels are capable of grinding heat-treated parts, eliminating any distortion that may occur during heat treatment. Therefore, it is mainly used for precise and precise tool and gauge work for the production of different threaded components.

What Are The Advantages Of Thread grinding ?

  1. Smoother surfaces and greater precision: The result of thread grinding is a better, smoother texture. At the same time, accuracy is improved as it creates more consistent threads than other methods.
  2. Better Cut Control: Thread grinding also provides greater control over helical cuts, which means there is little room for error.
  3. It’s suitable for tough and rigid materials: Thread grinding is ideal for tough materials.

What Are The Disadvantages Of Thread grinding ?

  1. High grinding heat: During the grinding process, the friction between the abrasive grains and the workpiece surface will generate a large amount of heat, which may cause the surface temperature of the workpiece to rise, thereby affecting the dimensional accuracy and surface quality of the workpiece.
  2. High processing cost: Due to the complexity of grinding equipment, consumption of grinding wheels, and limitations in processing efficiency, the processing cost of thread grinding is relatively high.

5.Thread crushing

A nut or screw type thread grinding tool made of soft material such as cast iron is used to grind the machined threads of the workpiece in the forward and reverse direction to improve the pitch accuracy. Hardened internal threads are also usually ground to eliminate deformation and improve accuracy.

6.Tapping and Threading

Tapping is the process of screwing a tap into a pre-drilled bottom hole in a workpiece with a certain torque to produce internal threads.

Threading is the process of cutting external threads on a bar (or tube) workpiece with a plate. The accuracy of tapping or threading depends on the accuracy of the tap or plate. Although there are many ways to process internal and external threads, the internal threads of small diameters can only be processed by taps. Tapping and threading can be done by hand, or by lathe, drill press, tapping machine or threading machine.

Cylindrical mold thread rolling

Thread processing applications

Threads play a vital role in various industries, and each industry has different applications that rely on threads. Let’s explore some common thread applications across different industries.

Automobile industry

The automotive industry relies heavily on complex assembly processes. Threads provide strong and reliable connections to a variety of automotive components such as engines, braking systems, suspension components, drivetrains and steering components.

aerospace industry

The aerospace industry requires strong, precise and reliable connections. Even the slightest mistake can have disastrous consequences. Aircraft components such as engines, landing gear, hydraulics and flight control systems use different types of threads to provide safety and functionality.

construction industry

The construction industry is an important part of the normal functioning of society. Buildings require a variety of threaded components for strength and sturdiness. Additionally, engineers rely heavily on threaded connections when building infrastructure such as bridges and ports.

electronic industry

In today’s world, almost everyone owns a mobile phone. Other popular electronic products include computers, televisions, refrigerators and washing machines. These home electronics have one thing in common. They rely on screws and fasteners for efficient assembly and functionality.

Pipeline industry

Threaded connections are essential in the field of pipes. For example, threaded pipe is widely used in residential, commercial, and industrial piping. They create a waterproof connection, prevent leaks and promote smooth water flow.

What is the thread rolling process?

Why choose Longsheng for thread processing business?

Choosing Longsheng for thread processing may have the following advantages:

※Excellent technology: Longsheng is famous for its excellent technology in thread processing. This ensures high precision and efficiency in threading, making it a reliable choice for complex threading tasks.

※High quality assurance: Longsheng has a good reputation for high quality assurance. Its threading tools and machines undergo rigorous testing and quality checks to ensure they meet high standards, giving customers confidence in their efficiency and durability.

※Customer Support: Longsheng offers excellent customer support. They provide comprehensive after-sales service and technical support to help customers solve any problems they may encounter when using threading tools and machines.

※Innovation: Longsheng is committed to continuous innovation. They continually update their spinning technology to keep up with the latest industry trends and customer needs, ensuring they continue to be the leading choice in the market.

※Cost-effective solutions: Longsheng provides cost-effective solutions for thread processing. Their tools and machines are very competitively priced and offer excellent value for money, especially considering their advanced technology and high quality.

conclusion

The different types of thread manufacturing processes have their own characteristics and advantages. In practical applications, the appropriate thread manufacturing process should be selected according to specific needs and conditions to achieve efficient and precise thread processing. At the same time, with the continuous advancement of science and technology and the rapid development of industry, the thread manufacturing process will continue to be innovated and optimized, providing strong support for the development of the manufacturing industry.

FAQs

What are the common challenges in the thread manufacturing process?

Challenges faced in the thread manufacturing process mainly include high-precision requirements, complex shape processing, material diversity, common problems during processing, tool wear and replacement, programming and technical capabilities, and cost control. In response to these challenges, companies need to take corresponding measures and technical means to ensure the quality and efficiency of thread processing.

How to choose the right threading method for a specific product?

Selecting a thread manufacturing process suitable for a specific need requires a comprehensive consideration of requirements analysis, process evaluation, technical feasibility, cost-benefit analysis, sustainability and environmental impact, and subsequent handling and maintenance. Through detailed analysis and evaluation, the thread manufacturing process that best meets the actual situation and needs is selected to ensure product quality and production efficiency while reducing production costs and protecting the environment.

How does threading affect product quality and performance?

The impact of thread processing on product quality and performance is mainly reflected in aspects such as strength and load-bearing capacity, sealing, precision, surface quality, self-locking performance, production efficiency and cost, energy consumption and environmental protection. In actual production, it needs to be based on the product’s Select appropriate thread processing methods and parameter settings based on specific needs and characteristics to ensure that the strength, sealing, precision and self-locking performance of the product meet the requirements. At the same time, we also need to pay attention to the impact on production efficiency, cost and environmental protection.

What is the future development trend of thread processing technology?

The future development trend of thread processing technology will show the characteristics of high precision, high efficiency, intelligence, automation, environmental protection and sustainability, composite integration, digital networking and personalized customization. The development of these trends will promote continuous innovation and progress in thread processing technology and inject new impetus into the development of manufacturing industry.

resource

Threading (manufacturing)

Optimization of Double Thread Nuts Screwing Process

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