Thread Forming
What is thread forming?
Thread forming is a method where a thread tap shapes the thread profile in a workpiece without removing any material. This is different from traditional cutting tapping, where material is removed to form the thread in the workpiece. Threads produced by forming taps are generally stronger and have a smoother surface finish, making them particularly useful for many machine shops and machining operations.
Advantages of thread forming taps
Thread forming taps have several advantages over conventional cutting taps:
- Speed: Thread forming taps often operate faster than cutting taps.
- Deep holes: Capable of threading deep holes (up to 3.5 x D) without problems caused by chip removal.
- Long tool life: The tap often lasts longer, increasing cost-efficiency and reducing tool change downtime.
- Versatility: The same tool can be used for different materials and for both through and blind holes.
- Low risk of breakage: Robust design reduces the risk of tap breakage.
- Thread quality: Produced threads are precisely within tolerance and have a smoother surface finish.
- Chip-free thread hole: No chips, which reduces cleaning and maintenance costs.
- Stronger threads: Formed threads can be up to 100% stronger, as the material around the thread is more densely compressed.
Requirements for effective thread forming
Although thread forming offers many benefits, certain requirements must be met for effective use:
- Formable materials: The method is not suitable for all materials; the material's formability must be considered.
- Maximum tensile strength: The recommended maximum tensile strength is 1200 N/mm².
- Accurate hole diameter: The hole diameter must be precise to ensure successful threading.
- Effective lubrication: Lubrication must be effective to prevent overloading the tool and workpiece.
Basics of thread forming
In thread forming, the tap shapes the workpiece material around to form the thread. Because no material is removed but rather formed, the resulting thread is stronger and more durable. This method is often used on materials soft enough to be formed, such as steel, aluminum, copper, brass, and certain stainless steels.
Thread forming vs. cutting taps
Thread forming taps:
- No chips: Material is not removed, so no chips are produced.
- Material is formed: The thread is created by forming material, which results in a stronger thread.
- Fewer risks: Reduces the risk of tap breakage and offers longer tool life.
- Faster process: Allows higher machining speeds and better production output.
Cutting taps:
- Material is removed: Material is cut away to form the thread, producing chips.
- Suitability: Better suited for hard and difficult-to-form materials.
- Weaker thread: The thread may be weaker compared to threads made by forming.
- Chip removal: Chips must be removed, which can be problematic for deep or blind holes.
Summary
Thread forming is an efficient and versatile method that offers significant advantages compared to traditional cutting tapping. It enables the production of stronger and smoother threads without chip removal issues, extends tool life, and allows faster processing. In machine shops and machining operations, thread forming taps can improve productivity and quality, especially with softer and more formable materials. However, the need for proper lubrication and accurate pre-drilled holes must be taken into account to achieve optimal results.
