Types of Taps for Threading

1. Perkenalan

In manufacturing, precision is the cornerstone of quality and reliability.

One of the most critical processes that ensure this precision is threading, where taps play an indispensable role in creating internal threads within holes.

These tools are not just essential for machining but also vital for repair and maintenance tasks.

By exploring the various types of taps, aplikasi mereka, and how to choose the right one.

Dalam panduan ini, we will explore the various types of taps available for threading, their specific uses, and the key factors to consider when selecting the right tap for your project.

Understanding these options will ensure you achieve the best possible results in terms of precision, daya tahan, dan efisiensi.

2. What Are Taps for Threading?

Taps are tools designed to cut or form internal threads within a hole. These threads create a fitting for fasteners such as screws and bolts, which are essential for joining components.

Thread allows parts to fit together securely, providing strength and stability in various mechanical applications.

Threading Basics

Threading involves creating helical ridges on a cylindrical surface. Internal threads, produced by taps, must be precise to ensure proper engagement with external threads such as those on screws or bolts.

Precision in thread creation is crucial for maintaining the integrity and functionality of assembled parts.

Components of a Tap

A typical tap consists of several parts:

• Shank: The portion of the tap that fits into the tool holder.
• Flutes: Grooves that allow for chip removal during the tapping process.
• benang: The cutting edges that form the internal threads.
• Point: The part of the tap that initiates the cutting process.

3. Types of Taps for Threading

3.1 Hand Taps

Hand taps are designed for manual use, typically in repair or small-scale projects. These taps are operated by hand using a tap wrench, making them ideal for lower-volume tasks.

Subtypes:

• Taper Tap: This tap has a gradual chamfer (7-10 utas), which makes it ideal for starting threads in soft to medium materials. It’s commonly used in hand threading.

• Plug Tap: Featuring a medium chamfer (3-5 utas), this tap is used for threading partially through a hole or in blind holes.

• Bottoming Tap: With a minimal chamfer (1-2 utas), a bottoming tap is used for cutting threads all the way to the bottom of blind holes, making it perfect for full thread depth.

3.2 Machine Taps

Machine taps are designed for use with powered equipment like CNC machines. These taps are suitable for mass production and high-precision threading operations.

Subtypes:

• Spiral Point Taps: These taps push chips forward and are ideal for through holes. The spiral design helps prevent chip clogging and makes for a cleaner, faster cut.

• Spiral Flute Taps: These taps pull chips backward and are designed for blind holes. They are effective in removing chips without causing a material buildup in the hole.

• Straight Flute Taps: Simple these taps are used for general-purpose applications. They are commonly used for both blind and through holes in materials like steel and aluminum.

3.3 Forming Taps (Roll Taps)

Forming taps don’t cut the material but instead displace it to create the threads. This method is often used for softer materials like aluminum, kuningan, dan tembaga.

Pro:

• No chips are produced, reducing the need for chip removal.
• Stronger threads are formed due to material displacement, which improves the thread’s strength and durability.
• Longer tool life compared to cutting taps.

3.4 Pipe Taps

Pipe taps are specifically designed to cut threads on pipes and pipe fittings. They are essential for applications like plumbing, gas, and industrial piping systems.

Common Types:

• Tapered Pipe Taps: Used to create leak-tight seals, such as NPT threads, which are tapered for pressure-tight joints.

• Straight Pipe Taps: Used for general-purpose applications, such as BSP threads, where the fit does not require the tapering effect.

3.5 Specialty Taps

These taps are designed for specific applications that require unique thread forms or functions.

Types include:

• Thread Repair Taps: Used for cleaning up or repairing damaged threads, such as those found in worn-out nuts or bolts.
• Acme Taps: These taps are used for creating Acme threads, commonly used in lead screws and power transmission systems.
• Buttress Taps: Ideal for threads designed to handle high axial loads in one direction, often used in applications requiring significant force or pressure.
• Tandem Taps: Allow multiple threading stages to be done in a single pass, improving the efficiency of the threading operation.

4. Materials Suitable for Different Taps

The choice of tap material depends on the workpiece material. Here are some common considerations:

• Logam: Baja, baja tahan karat, aluminium, kuningan, tembaga, dan titanium. Each of these requires different tap materials, such as HSS for softer metals and carbide for harder alloys.
• Plastik: Materials like ABS, PVC, and nylon require taps made from HSS or carbide for cutting clean threads.

5. Geometric Features of Taps

The geometry of the tap impacts the final thread quality and performance:

• Thread Size and Pitch: These dimensions determine compatibility with fasteners.
  Misalnya, a fine pitch may be needed for precision joints, while a coarse pitch is preferred for load-bearing applications.
• Flute Design: Taps can have straight or spiral flutes, which affect chip removal. Spiral flutes are typically used for deeper holes or blind holes.
• Pelapis: Taps are often coated with materials like titanium nitride (Timah) or black oxide to enhance wear resistance and prolong tool life.

6. Choosing the Right Tap for Your Project

Selecting the right tap involves several key considerations:

• Workpiece Material: Match the tapping material (HSS, cobalt, karbit) with the material being threaded.
• Type of Thread: Determine whether you need a basic thread, a tapered pipe thread, or a more specialized thread like Acme or buttress.
• Precision and Tolerance: If you require precise, high-performance threads, consider taps with coatings or those designed for high-precision applications.
• Volume Produksi: Untuk lari besar, machine taps and rolling taps are more efficient, while manual taps might be better suited for small projects or repairs.

7. How to Use a Tap for Threading?

Using a tap for threading is a precise process that requires careful attention to ensure clean, accurate threads are formed.

Whether you’re working with a hand tool or a machine, the steps involved are generally the same.

Melangkah 1: Clamping the Workpiece

Before starting any threading operation, make sure the workpiece is securely clamped to avoid any movement during the process.

If you are using a CNC machine, the part will be secured using the appropriate fixtures or vice. For manual tapping, use a vice or clamping tool to hold the workpiece steady.

• Tip: Ensure the hole to be tapped is drilled accurately to the correct size. The diameter of the hole should match the tap size to avoid issues with thread formation.

Melangkah 2: Drilling the Hole

Before tapping, you must drill a pilot hole (also called a “tapping hole”). The hole diameter will vary depending on the type of thread you intend to cut and the size of the tap.

• Tip: Use the right drill bit for the type of thread and material you are working with. A tap drill chart can help you determine the correct hole size for the tap you’re using.
• Catatan: For blind holes (holes that don’t go all the way through the material), ensure that the hole is slightly deeper than the required thread depth to avoid bottoming out the tap.

Melangkah 3: Lubrication and Preparation

Once the hole is drilled, apply the appropriate tapping lubricant or cutting fluid to the hole. This reduces friction, helps with chip removal, and prolongs the life of the tap.

• Tip: For harder materials, seperti baja, consider using a heavy-duty tapping fluid. For softer materials, seperti aluminium, a light oil or water-based coolant can suffice.

Melangkah 4: Tapping the Hole

Berikutnya, insert the tap into the hole and begin turning. The process will depend on whether you’re using a hand tool or a machine:

Manual Tapping:

• Insert the Tap: Place the tap into the drilled hole and make sure it’s aligned straight.
• Turning the Tap: Turn the tap slowly and steadily. Use a tap wrench to rotate the tap.
  Apply pressure gently, ensuring that the tap enters the hole at a consistent, perpendicular angle.
• Back the Tap Occasionally: Every quarter to half turn, back the tap out slightly to help clear any chips from the flutes and prevent the tap from binding.

Machine Tapping (CNC):

• Align the Tap: For CNC machines, set the tap on the programmed path and ensure the machine is set to the correct speed and feed rate.
• Automated Process: The CNC machine will automatically feed the tap into the hole and reverse direction to clear chips during the tapping process.

Melangkah 5: Removing the Tap

Once the desired depth is reached, carefully remove the tap from the hole. If you’re using a hand tool, rotate the tap wrench in reverse to back the tap out, keeping the threads intact.

• Tip: Be cautious not to twist the tap too forcefully. For tough materials, it may take some time for the tap to exit without damage.
  Applying too much force can cause the tap to break or the threads to be deformed.

Melangkah 6: Cleaning and Final Inspection

After removing the tap, clean the hole and the threads. Inspect the threads for uniformity and accuracy. A good tap job will produce clean, sharp threads with no burrs or defects.

• Tip: Check the threads with a thread gauge or a matching bolt to ensure proper fit and function.

Melangkah 7: Post-Tapping Processing

Tergantung pada aplikasinya, you may need to deburr the edges of the newly threaded hole. You may also want to clean the part to remove any lubricant or cutting fluid residue.

• Tip: Use a brush or a rag to clean the part thoroughly. For high-precision applications, a light surface finish or additional post-processing may be required to ensure perfect thread integrity.

8. Advantages of Using the Right Tap

• High-Quality Threads: Proper tap selection ensures that threads are precise, tahan lama, and capable of bearing the expected loads.
• Efficiency and Longevity: The right tap reduces tool wear and minimizes downtime, increasing production efficiency.
• Penghematan Biaya: A well-chosen tap reduces the need for repairs or rework, leading to cost savings in the long run.

9. Common Challenges in Threading

• Thread Galling: This can occur in softer metals, causing threads to seize and tear.
• Keausan pahat: Improper material choice or overuse can lead to tap wear and reduced thread quality.
• Poor Chip Evacuation: If chips aren’t effectively cleared, they can clog the threads, affecting the final result.

10. Find Thread Tap Size with a Chart

Selecting the correct tap size is essential to ensure that the threaded hole matches the fastener perfectly.

The drill size must correspond to the tap size, as mismatched sizes can lead to loose threads, damaged taps, or poorly fitting fasteners.

A thread tap size chart is a valuable tool to simplify this process and prevent errors.

Importance of the Correct Tap and Drill Sizes

• Oversized Holes: If the drill size is larger than the tap’s requirements, the resulting threads will not grip the fastener tightly.
• Undersized Holes: A smaller-than-recommended drill size can cause the tap to break or damage the workpiece due to excessive force during tapping.
• Precision Matters: The success of threading depends on precise alignment between the drill and tap sizes.

To correct improperly sized holes, permesinan yang membosankan can be used to enlarge the drilled hole before threading.

The Formula for Calculating Drill Size

While charts are handy, this formula can be used for quick estimations:

Drill Size = 78×Tap Size−132\frac{7}{8} \times \text{Tap Size} – \frac{1}{32}87×Tap Size−321

Misalnya:

• Untuk a 1/4-20 tap, substitute 1/4 into the formula: Drill Size=78×14−132=0.218\text{Drill Size} = \frac{7}{8} \times \frac{1}{4} – \frac{1}{32} = 0.218Drill Size=87×41−321=0.218 inci.

This result corresponds closely to the standard 7/32-inch drill size.

Thread Tap Size Chart Example

Here’s an example of a chart for commonly used UNC (Unified National Roarse) utas:

Thread Size (UNC)	Drill Size (Inci)	Drill Size (mm)
1/4-20	7/32	5.56
5/16-18	F (0.257″)	6.53
3/8-16	5/16	7.94
1/2-13	27/64	10.72

Untuk metric threads, the chart looks slightly different:

Thread Size (MISALNYA., M8 × 1.25):

• “M8” represents the nominal diameter (8 mm).
• “1.25” represents the thread pitch (distance between threads, in millimeters).

Thread Size (Metrik)	Pitch Thread (mm)	Drill Size (mm)
M1 × 0.25	0.25	0.75
M2 × 0.4	0.4	1.6
M3 × 0.5	0.5	2.5
M4 × 0.7	0.7	3.3
M5 × 0.8	0.8	4.2
M6 × 1.0	1.0	5.0
M8 × 1.25	1.25	6.8
M10 × 1.5	1.5	8.5
M12 × 1.75	1.75	10.2
M16 × 2.0	2.0	14.0

Tips for Using Tap-Size Charts

1. Match the Thread Standards: Ensure you are using the correct chart for the thread type, such as UNC, UNF, or metric threads.
2. Consider Material: Softer materials like aluminum may require a slightly smaller drill size for tighter threads, while harder materials like steel may need a slightly larger size.
3. Account for Tolerance: Use charts that specify tolerance ranges for precision-critical applications.
4. Always Test: Untuk aplikasi penting, test threading on a sample workpiece before machining the final part.

11. Kesimpulan

Understanding the different types of taps and their features is key to achieving precise, high-quality threaded connections.

By selecting the right tap for the job, you ensure optimal performance, daya tahan, dan efisiensi. Whether you’re working with metal, plastik, or a specific type of pipe,

choosing the proper tap will help improve the strength and longevity of your threads, making your projects more successful and cost-effective.

FAQ

What’s the difference between cutting and forming taps?

• Cutting Taps: Remove material to form threads. Suitable for a wide range of materials.
• Forming Taps: Displace material to create threads, resulting in stronger threads and no chips.

How can I prevent taps from breaking?

To prevent tap breakage:

• Use the correct tap size and type for the material.
• Apply proper lubrication to reduce friction.
• Avoid excessive force and maintain alignment during tapping.
• Clear chips frequently to prevent clogging.

How do I maintain and store taps?

• Pembersihan: Remove debris and chips after each use.
• Pelumasan: Apply rust-preventive oil if the tap is stored for an extended period.
• Penyimpanan: Store taps in a clean, dry environment, ideally in labeled compartments to avoid damage.