types of metric thread taps

Types of Metric Thread Taps: A Comprehensive Guide to Cutting Tools

In the vast world of manufacturing and engineering, having the right cutting tools is essential to achieve precise and accurate results. One such indispensable tool is the metric thread tap. This article aims to provide a comprehensive guide to the various types of metric thread taps available in the market. So, whether you are a professional machinist, a DIY enthusiast, or simply someone curious about the different tools at your disposal, read on to optimize your understanding of metric thread taps.

I. Introduction to Metric Thread Taps

Before diving into the details about the different types of metric thread taps, it is crucial to comprehend the overall concept of this cutting tool. Metric thread taps are devices specifically designed for creating internal threads within a pre-drilled hole. These internal threads are commonly used in various applications, such as assembling mechanical components, fastening objects, or producing complex parts.

Metric thread taps come in various sizes, each corresponding to a specific thread pitch. The thread pitch refers to the distance between adjacent threads, usually measured in millimeters. This measurement allows engineers and machinists to select the appropriate tap size that matches the desired thread pitch requirement.

II. Common Types of Metric Thread Taps

1. Taper Tap (Starting Tap)

The taper tap, also known as the starting tap, is an essential tool in creating threads. It has a gradual taper from the shank to the cutting portion, allowing for easy alignment and smooth cutting. Taper taps are primarily used to initiate threading operations, especially in difficult materials or holes that lack a pre-drilled lead-in. Due to their tapered design, taper taps enable better chip evacuation and prevent tool breakage.

2. Plug Tap (Intermediate Tap)

The plug tap, or intermediate tap, is the most commonly used type of metric thread taps. It has a less pronounced taper compared to the taper tap, providing a balance between ease of use and efficient thread cutting. Plug taps are typically utilized after the taper tap to continue threading operations or create threads into an existing through-hole. They are also suitable for blind holes, where the depth of the tapped hole does not fully penetrate the material.

3. Bottoming Tap (Finishing Tap)

The bottoming tap, also known as the finishing tap, is specialized for creating full-depth threads. Unlike the taper and plug taps, the bottoming tap has a shorter cutting length and minimal taper. Because of this design, it allows for maximum thread engagement, ensuring a secure and complete threading process. This type of metric thread tap is ideal when you want to tap blind holes with a bottom surface, achieving threads that are flush with the material.

4. Spiral Point Tap

The spiral point tap, often referred to as the gun tap, possesses a unique cutting feature that sets it apart from the other types of metric thread taps. This tap design involves a spiral fluted body with ground edges and a single, forward-facing cutting edge. The cutting edge, positioned at the tip, performs the initial cutting action. However, what makes the spiral point tap distinctive is its spiral flute, which allows the chips to move forward along the tap, away from the cutting action. This design greatly improves chip evacuation and prevents chip clogging, making spiral point taps suitable for deep-hole threading applications.

5. Spiral Flute Tap

In contrast to the spiral point tap, the spiral flute tap, also known as the gun nose tap, excels in chip evacuation on blind-hole applications. Its spiral flutes extend all the way to the tap’s tip, effectively pushing the chips forward and out of the hole. This tap design reduces the chances of chip clogs, resulting in smoother cutting and better thread quality. Spiral flute taps are commonly used in softer materials like aluminum, brass, and plastics.

III. Choosing the Right Metric Thread Tap

Now that the different types of metric thread taps have been described, it is important to determine which tap is suitable for your specific application. Several factors should be considered when selecting the appropriate thread tap, such as material type, hole depth, thread pitch, and desired thread quality.

1. Material Type

Different materials pose various challenges during the tapping process. Softer materials like aluminum and brass are relatively easier to tap, often requiring standard taps. However, for harder materials such as stainless steel or hardened steel, the use of a specific tap type, such as high-speed steel (HSS) taps or cobalt taps, is recommended for optimal results.

2. Hole Depth

The depth of the hole also influences the choice of metric thread tap. For through-holes, where the tapped hole goes completely through the material, a standard plug tap can be employed. Conversely, for blind holes, where the threads do not penetrate the entire material thickness, using taper taps, plug taps, or bottoming taps, depending on the depth, is necessary.

3. Thread Pitch and Desired Thread Quality

The thread pitch, measured in millimeters, determines the fineness or coarseness of the threads. Choosing the correct thread pitch is crucial, as improper matching can result in weak threads or thread failure. It is imperative to consult thread pitch charts and guides to ensure the accurate selection of the corresponding tap size.

Additionally, when aiming for high thread precision, using metric fine thread taps may be required. These taps have a finer thread pitch, enabling tight and accurate thread formation, suitable for applications that demand a higher level of precision.

IV. Conclusion

Metric thread taps are essential cutting tools in the world of manufacturing and engineering. Understanding the different types of metric thread taps enables professionals and DIY enthusiasts to select the appropriate tool for each application, ensuring precise and reliable thread creation. Whether it be taper taps, plug taps, bottoming taps, spiral point taps, or spiral flute taps, each type serves a unique purpose in optimizing the threading process.

To maximize efficiency and accuracy in your projects, keep in mind the material type, hole depth, thread pitch, and desired thread quality. By considering these factors when choosing the right metric thread tap, you are well on your way to achieving exceptional threading results and enhancing your overall cutting tool expertise. So, go ahead and explore the world of metric thread taps – an indispensable tool for precision thread creation!