Can a forming tap be used for external threads?

Can a forming tap be used for external threads?

As a supplier of forming taps, I often encounter questions from customers regarding the application scope of our products. One of the most frequently asked questions is whether a forming tap can be used for external threads. In this blog post, I will delve into this topic, exploring the capabilities and limitations of forming taps in creating external threads.

Understanding Forming Taps

Before we discuss the use of forming taps for external threads, it's essential to understand what a forming tap is and how it works. A Thread Forming Tap is a cutting tool used to create threads in a pre-drilled hole by displacing the material rather than removing it. This process, known as cold forming, results in stronger, more accurate threads with improved fatigue resistance compared to traditional cutting taps.

Forming taps are typically made of high-speed steel (HSS) or carbide and are available in various sizes and thread profiles to suit different applications. They are commonly used in industries such as automotive, aerospace, and manufacturing, where precision and reliability are crucial.

Can a Forming Tap be Used for External Threads?

The short answer is yes, a forming tap can be used to create external threads. However, it's important to note that the process is different from using a forming tap for internal threads. When creating external threads, a forming tap is used in conjunction with a die holder or a threading machine.

The process of using a forming tap for external threads involves the following steps:

1. Select the appropriate forming tap: Choose a forming tap with the correct size and thread profile for the desired external thread.
2. Prepare the workpiece: The workpiece should be machined to the appropriate diameter and length, leaving enough material for the forming process.
3. Secure the workpiece: Use a vise or other clamping device to secure the workpiece in place.
4. Install the forming tap: Insert the forming tap into the die holder or threading machine and secure it tightly.
5. Apply lubricant: Apply a suitable lubricant to the workpiece and the forming tap to reduce friction and prevent damage to the tool.
6. Start the threading process: Rotate the forming tap slowly and steadily, applying gentle pressure to form the external thread.
7. Monitor the process: Check the progress of the threading process regularly to ensure that the thread is being formed correctly.
8. Finish the thread: Once the thread is fully formed, remove the forming tap from the workpiece and clean the thread to remove any debris or lubricant.

Advantages of Using a Forming Tap for External Threads

There are several advantages to using a forming tap for external threads, including:

1. Stronger threads: The cold forming process used by forming taps results in stronger, more accurate threads with improved fatigue resistance compared to traditional cutting taps.
2. Improved surface finish: Forming taps produce a smoother surface finish on the external thread, reducing the risk of corrosion and improving the overall appearance of the workpiece.
3. Increased tool life: Forming taps typically have a longer tool life than cutting taps, as they do not experience the same level of wear and tear during the threading process.
4. Reduced material waste: Since forming taps displace the material rather than removing it, there is less material waste during the threading process, making it a more environmentally friendly option.
5. Versatility: Forming taps can be used to create a wide range of external thread sizes and profiles, making them a versatile tool for various applications.

Limitations of Using a Forming Tap for External Threads

While there are many advantages to using a forming tap for external threads, there are also some limitations to consider, including:

1. Limited material compatibility: Forming taps are typically designed for use with ductile materials such as aluminum, brass, and mild steel. They may not be suitable for use with brittle materials such as cast iron or high-strength steels.
2. Higher initial cost: Forming taps are generally more expensive than cutting taps, due to the more complex manufacturing process and the use of higher-quality materials.
3. Requires specialized equipment: Using a forming tap for external threads requires the use of a die holder or a threading machine, which may not be available in all workshops.
4. Limited thread depth: Forming taps are typically limited to creating threads with a depth of up to 3 times the thread pitch. Deeper threads may require the use of a cutting tap.

Conclusion

In conclusion, a forming tap can be used to create external threads, offering several advantages over traditional cutting taps. However, it's important to consider the limitations of using a forming tap for external threads, such as limited material compatibility, higher initial cost, and the need for specialized equipment.

As a supplier of forming taps, we offer a wide range of products to suit different applications and requirements. Our team of experts is available to provide technical support and advice to help you choose the right forming tap for your needs.

If you are interested in learning more about our forming taps or would like to discuss your specific requirements, please contact us to arrange a consultation. We look forward to working with you to provide the best possible solutions for your threading needs.

References

• ASM Handbook, Volume 16: Machining, ASM International, 2008.
• Machinery's Handbook, 31st Edition, Industrial Press, 2012.
• Threading Tools: A Practical Guide, Sandvik Coromant, 2015.