Machine Tap DIN 376 Form B HSSE - UNF 9/16 x 18

UNF (Unified National Fine): This refers to an American fine thread, standardized according to ANSI. The thread has a finer pitch than a standard coarse thread, which results in a stronger connection. The nominal size 9/16 x 18 indicates the outer diameter (9/16 inch) and the number of threads per inch (18).

DIN 376: This standard from the German Institute for Standardization regulates the dimensions of machine taps with a reinforced shank. It ensures that the tool is precise and reliably meets industrial standards.

Form B: Form B describes the chamfer geometry of the tap. It has a chamfer of 3.5 to 5 threads. This geometry is ideal for through holes because it allows for easy guidance in the bore and pushes the chips forward out of the hole.

HSSE: Stands for "High Speed Steel with Cobalt." This is a high-quality, cobalt-alloyed high-speed steel. It offers higher hardness, toughness, and hot hardness resistance compared to conventional HSS, making it ideal for machining difficult-to-cut materials.

Through Holes: A through hole is a bore that passes completely through the workpiece. In contrast to a blind hole, the chips can be removed forward through the hole during the threading process, which simplifies the work process.

Follow these steps to use the machine tap correctly:

1. Preparation: Ensure the workpiece is securely clamped. Drill a core hole with the correct diameter for a UNF 9/16 x 18 thread.
2. Tool Clamping: Clamp the machine tap firmly into the chuck of your machine (e.g., a drill press or a CNC machine).
3. Lubrication: Apply cutting oil or a suitable lubricant to the tap and into the bore. This extends the life of the tool and ensures a clean cut.
4. Threading: Start the machine at the correct speed. Begin to guide the tap slowly and evenly into the bore. The Form B chamfer pushes the chips forward out of the hole.
5. Cleaning: After the threading process, carefully clean the thread of all chips and residues.
6. Inspection: Check the cut thread with a suitable thread gauge to ensure the correct tolerance (2B).

1. What is the difference between a machine tap and a hand tap?

Machine taps are designed for use in machines that ensure a uniform rotational movement. Hand taps are used by hand with a tap wrench and are usually available in sets (taper, plug, and bottoming taps).

2. Can I use this tool for blind holes?

No, Form B is intended for through holes as it removes chips forward. For blind holes (bores that do not go completely through the workpiece), you should use a tap with Form C or D (with spiral flutes) which removes the chips backward.

3. What does tolerance 2B mean?

Tolerance 2B is an American standard tolerance class for internal threads. It is between Class 1B (loose fit) and 3B (tight fit) and is the most commonly used class for general applications.

4. What materials can I use this tap in?

Thanks to the HSSE alloy, this tap is suitable for a variety of materials, including alloyed and unalloyed steels with a strength of up to 1200 N/mm², stainless steels, cast iron, and non-ferrous metals.

5. How do I choose the right lubricant?

The choice of lubricant depends on the material to be machined. Special cutting oil is often recommended for steels, while an emulsion or spirits is suitable for aluminum. Lubrication is crucial to reduce tool wear and improve thread quality.

6. Why is Form B ideal for through holes?

The straight flute form of Form B guides the chips cleanly and efficiently forward out of the bore. This prevents chip build-up and tap breakage, which is particularly advantageous for deep through holes.