Tapping refers to the machining process that focuses on creating internal threaded holes in a workpiece to promote the fastening and attachment of different parts. The technique uses a simple tool with various cutting teeth that aid it in creating the internal threads. 

Like other machining processes, the procedure is suitable for creating internal threads in various material types, including metals, alloys, plastics, composites, etc. This versatility makes it a mainstay in multiple industries.

This article explores all you need to understand about tapping, including its working principles, advantages, and shortcomings. Read ahead!

What is Tapping?

Tapping is a machining process that involves creating internal threaded holes in sheet metal and workpieces. Generally, the threading is usually formed into a pre-punched, drilled, or extruded hole using an appropriate tool. Threaded features are essential for enabling the assembly and securing of components using machine screws and bolts. Whenever you notice a screw and bolt connection, there’s likely a hole with appropriate threading and tapping to such an application. 

The tapping process uses a machining tool – tap. It consists of a screw with straight or spiral flutes machined into it, making it suitable for creating the required internal threads. Like many other machining processes, tapping may be performed manually using a tap wrench attached to a  drill press or a more sophisticated device, like a CNC machine. The latter ensures better precision and dimensional accuracy of the part, making it the more appropriate method for applications with strict tolerance specifications.

The tap creates permanent threads, which is crucial for the assembly of smaller parts and components to create a larger structure. While manual tapping may prove efficient and effective for a few holes, a tap drill or one incorporated into a CNC machine is more effective for more robust applications that require several holes. 

Moreover, the higher accuracy it guarantees ensures proper securing, fastening, and creating tight connections of the metal parts fittings. Therefore, like any manufacturing process, good tool selection is critical to the success of tap machining.

Understanding the Working Principles of Tapping 

As we earlier defined, tapping is a machining process that involves creating internal threads in a pre-drilled hole. The technique, which could also follow a manual procedure, creates these threads in full spectrum small-sized holes.

However, before fitting the tap into the hole, ensure that the workpiece is secured correctly, clamping it to prevent any unnecessary controversies during tapping. Ensuring that the workpiece remains stable during tapping increases the possibility of a successful tapping project. The tap consists of flutes or grooves along its length, which facilitate chip evacuation and guide the tap into the hole. 

The machinist inserts the tap into the hole at a helix angle, which occurs between the tap’s axis and the cutting face. Setting the tap in this configuration allows it more access for better machining as it makes subtle cuts along the hole, generating the internal threading. Therefore, as the tap rotates, the cutting edge interacts with the walls of the pre-drilled hole, creating sharp cuts and removing pieces of material, creating the thread. The process is relatively the same, regardless of whether it’s manually operated or uses a CNC machine

The cutting action of the tap involves shearing away the material, with the flutes aiding the chop evacuation, preventing chop clogging, and promoting efficient tapping. You may need to taper the tip of the tap, which reduces the entire length of the cutting teeth, enabling multi-pass cutting in a single rotation.

Also, ensure proper lubrication to reduce tool wear, friction and reduce temperature buildup and snagging—all of these result in smoother tapping and overall machining experience. Optimizing the alignment of the tap with the pre-drilled hole is also a practice to adapt when tapping, as it prevents tap breaking and prevents the formation of defective threads. 

Types of Tapping

We already hinted that tapping can be performed manually or using a CNC machine. Below, we explore the two kinds of tapping machining.

Manual Tapping

Like any manual manufacturing process, it involves using a mechanical hand tool, requiring skill and expertise on the part of the machinist. The operation starts with clamping the workpiece to ensure it remains in position during the process. 

Afterward, the machinist selects the right tap based on factors such as the intended depth, size, and material type that best suits the intended thread and applications. Then, the tap is attached to an appropriate wrench and a suitable cutting compound to the tap to optimize the tapping process. Now, upon application of force to the wrench and rotation, it results in making cuts that will create internal threads.

Tapping on a CNC Device

While manual tapping is effective, precision and accuracy are not guaranteed. This is what tapping with a CNC machine provides. This operation involves making internal threads in a workpiece using a tap attached to a CNC machine, such as a lathe.

Like in the manual tapping, the process starts by securing the workpiece in a chunk. The machinist then inserts the tap into the CNC’s turret (tool holder). However, the operator must have customized the CNC device with the required codes and programs that the tapping process requires. Therefore, the CNC machine controls the tap as it removes pieces of the material, making internal cuts in the pre-drilled hole as it creates the intended threads.

The main distinction between both processes is the automation and independence that the CNC machine offers, which makes it a more precise machining operation.

Advantages of Tapping

While tap machining focuses explicitly on creating internal threaded holes in metal components, below are more advantages of this process.

High Precision Accuracy

Taping creates threaded features with high accuracy, especially those integrated into CNC machines. Regardless of thread depth, pitch, and diameter, this machining process is capable of producing consistent and high-quality threaded holes with extreme precision, making it suitable for applications with strict tolerances, such as parts for the aerospace and automotive industries. 

Cost Effective

Tapping is an effective means of creating internal threaded features, especially in comparison to similar processes such as thread milling. It is a simple technique suitable for making threads in various material options. Moreover, manual tapping is also efficient, an even more cost-effective process for creating high-quality threadings. 

Quick and Efficient for Creating Internal Threads

Tapping is a quick and highly efficient machining process, especially for small-scale production. Besides, utilizing the technique with a suitable CNC device makes it ideal for large-volume projects. Therefore, tapping is an effective means of resting internal threadings quickly.

High Versatility

Tapping is a highly versatile process, suitable for vast material options, including sheet metals and ingots. The technique suits metals and alloys like aluminum, steel, composites, plastic, and even wood. This makes it suitable for diverse industrial applications. Also, it fits the threading of holes with varying sizes and design specifications. 

Little Material Wastes

Generally, machining processes generate material waste since they involve removing pieces of the material. However, tapping creates minimal waste, and the machining process is targeted towards threading a pre-made hole. This feature makes it a more efficient method and promotes sustainability.

Reduced Machine Setup

Compared to other machining methods, tapping does not require an elaborate machine setup, which ensures a faster manufacturing lead time. Also, the process is more flexible, permitting more diverse applications.

Shortcomings and Challenges of Tap Machining 

Even with the vast benefits it offers to machining, there are some shortcomings and challenges to this technique. Let’s get right into them.

Tool Wear and Breakage

Taps can experience tool wear, tear,  and breakage. This is particularly likely to happen after high-volume tapping. Tool wear may also occur when working on more abrasive and more challenging alloys, like titanium and hardened steel. Therefore, there is a need for frequent tool replacement lubrication to guarantee production efficiency.

Limited to Threaded Holes

Tap machining is specific for creating threaded holes. Therefore, compared to other machining processes, its applications are limited to these particular features. When fabricating non-threaded holes, features, and complex geometries, you’d require the services of other machining processes. 

Material Compatibility

While tapping is a versatile machining process, it may be challenging when working with overly hard alloys, requiring specialized taps or alternative threading methods. Such materials increase the tendency of tool wear, limiting the effectiveness of the tapping. 

Chip Evacuation Issues

Chip removal is important to maintain tapping accuracy and to prevent tap breakage, especially when dealing with long or deeper threads. However, evacuation of these chips may be challenging, particularly when tapping blind holes, limiting the efficiency of the process. 

Other possible challenges include distortion due to high-temperature build-ups and difficulty in creating threads of larger sizes and those near the edges of metal sheets, as it may alter the parts’ structural integrity.

Applications of Tapping

Tap machining benefits various manufacturing industries, especially when fabricating large structures with smaller components. Below are the applications of this machining technique. 

  • Automotive Industry: Tapping offers applications for creating internal threaded holes that aid in fitting engine parts, chassis, car body, and panels. It also benefits brake, exhaust, and transmission systems. 
  • Aerospace Industry: It allows the fitting and fastening of various components using threaded holes. This includes fuselage panels, engine parts, and other structural elements. 
  • Medical Industry: Tappingbsuitsbyhe manufacture of medical devices where precision and reliability benefits. Threaded holes suit components such as surgical instruments, implants, and diagnostic equipment, ensuring secure assembly and functionality. 
  • Consumer Goods and Electrical Equipment: Tapping suits the production of electronic gadgets and an extensive range of consumer goods. It makes threaded holes for fasteners and products like power tools, recreational devices, and furniture. It also suits making threaded holes in metal enclosures and connectors. 
  • Die and Tooling Manufacturing: Tapping helps fabricate various manufacturing tools. Some tool parts, such as dies, require threaded holes to suit specific applications, such as creating jigs, fixtures, and cutting edges. Tapping aids the acquisition of precision and functionality of these manufacturing parts.

Manufacturing Tips to Ensure Quality Tapping

Tapping is an effective machining technique that creates top-notch internal threads for various applications. Below are expert tips to ensure a high-quality tapping procedure. Let’s get right into them.

Tool Selection 

Appropriate tool selection is critical for the success of any manufacturing process. Factors such as material hardness, strength, thickness, and thread type are criteria to consider when selecting the right tools for tapping. Ensure you choose the most appropriate tool to ensure efficient and high-quality tapping.

Modify Tapping Speed and Feed Rates

Again, this depends on the strength and hardness of the material you are working with. When tapping very hard material, reduce the tapping speed and optimize the feed rate to reduce excessive heat build-up. 

Control Chip Evacuation

We already hinted that optimizing chip removal is essential for high-quality tap machining. Therefore, the machinist must monitor and control the chip evacuation to ensure optimization of the tapping process, especially for deeper and blind holes. Moreover, optimizing chip removal helps prevent clogging and promotes the precision and reliability of the procedure, which is essential for parts with dimensional accuracy specifications. 

Optimize Hole Diameter

Ensure that the hole you’d be tapping is accurate. The pre-drilled hole serves as a guide for the tap during machining. Therefore, it is vital to ensure the dimensional accuracy of the hole to guarantee successful tapping. 

Use Appropriate Lubricants and Cooling Agents

Lubrication and cooling is an essential aspect of any machining process. It helps prevent or reduce the tendency of tool wear and also reduces heat generation, limiting build-up. It also prevents friction and machining defects, improving the chances of creating high-quality internal threading. Moreover, it helps to improve the surface finish, ensuring smoother internal threads. 

Use Peck Tapping

Peck tapping is a technique for tapping, particularly for deeper holes. It involves intermittent removal and chip evacuation during the machining of the holes. This technique aids in the prevention of chip accumulation at the hole’s base, reducing the risk of tap breaking and ensuring high-quality internal threads.

How Do You Choose the Appropriate Tap for Tap Machining?

When selecting the right tapping tool, some factors require consideration. Below is an overview of some of those items that you need to factor in when choosing the appropriate tap. 

Material Consideration 

The material you are tapping requires careful consideration. You must factor in the material type, strength, and hardness before selecting the right tap tool. Hard materials will require more robust taps, such as those coated with carbide tips, to ensure proper tapping without breaking and enhanced thread quality. 

Hole Type and Diameter 

Whether you are machining a through hole or a blind hole, you also need to factor in the hole type when selecting the tap. Also, you need to factor in the intended thread size pitch and profile to ensure you choose a tap that best suits your application and design specifications. 

Tapping Methods 

The kind of tap you select for tap machining also depends on whether you will be tapping manually or using a CNC machine. Therefore, you should choose taps that are compatible with the tapping methods. Also, factor in parameters such as the direction of tap rotation to avoid tapping complications and defects.

Thread Quality and Tolerance

You should also consider the specified thread tolerance and quality when selecting taps for the internal threading. Also, evaluate the pull-out strength required for your application and ensure you do not exceed it. Exerting too much force during tapping or when pulling out the tap can cause tap breaking.

Tap Design 

The tap flute design plays a significant role in adding chip evacuation, which benefits the success of the tapping process. Taps with spiral flutes or spiral point taps are more effective in removing chips, especially from deep holes, preventing clogging and promoting smooth tapping. 

Other factors include the coating and surface treatment of the tapping tool. Ensure it is designed such that it reduces friction, promotes seamless tapping, and reduces heat generation.

Zintilon: Your Partner for High-quality Tapping and CNC Machining Services 

Besides having a detailed understanding of CNC and other sub-machining services, including tapping, partnering with a reliable service will save you a lot of hassle. These companies, such as Zintilon, will help you create your part to suit your specifications at competitive pricing.

Zintilon is an expert at offering high-quality CNC machining services. Our facilities boast of highly skilled engineers and machinists who are willing to work with your CAD files to give life to your fabrication. 

Besides tapping and other CNC machining operations, we also offer premium services in die casting, rapid prototyping, and related technologies. Partner with us today to guarantee a successful project.

Conclusion

Tapping is an important manufacturing process, especially for part assembly. The technique allows the creation of threaded holes that aid in the fastening and fitting of different parts together to create large fixtures and structures. When unsure of whether your fabrication requires tap machining services, don’t hesitate to go over this article.

FAQs

How Does Tapping Differ From Drilling?

While tapping and drilling involve working with holes, they are distinct machining processes. Tapping involves creating internal threading into pre-made holes, enabling the fastening and assembling of parts. On the other hand, drilling involves creating holes without threading. Therefore, tapping is only possible after drilling the holes in the workpiece.

Is Tapping Necessary?

Yes, tapping is crucial for making internal threaded holes for various applications. Tapping suits these applications, whether small, medium, or large threaded holes. It aids in creating high-quality threads, which benefits the fitting and assembling of various parts to form a large structure.

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