MANUFACTURING INC.
MANUFACTURING INC.
In CNC machining, threading is often essential for assembling parts. CNC tapping is a key method used to create these threads. This process involves using a rotating tool called a tap, which is fed into a drilled hole to form internal threads. It’s known for being efficient, reliable, and cost-effective, especially when working with small thread sizes. CNC tapping is used across many industries such as aerospace, automotive, and medical devices.
In this article, we’ll explain what CNC tapping is, how it works, the tools and techniques involved, and its advantages and disadvantages. We’ll also explore its common uses and how it differs from threading.
CNC tapping is a process used to cut threads inside holes with high accuracy. These threads are necessary for fitting screws or bolts. The operation relies on pre-programmed CNC machines to control the movement of the tap, ensuring that the threads meet precise specifications.
The tap, which is the main tool, cuts the thread as it turns into the hole. There are two broad types of taps—hand taps and power taps. Hand taps, including taper, plug, and bottoming taps, are used for manual tasks. For CNC operations, power taps are more efficient. These include spiral point taps, spiral flute taps, and roll taps.
Before tapping can begin, the hole must be drilled to the correct size. Once that’s done, tapping can proceed in the following steps:
1. Selecting the right tap based on the material, hole size, thread type, and fit requirements is essential for achieving accurate threads.
2. The CNC machine settings are configured for speed and depth. Once set up, the machine feeds the tap into the hole.
3. The tap rotates at a controlled speed—typically between 40 to 60 rpm. The CNC system manages the entire operation and alerts the operator when it’s complete.
4. After the threads are formed, chamfering the hole is often done to remove sharp edges.
Lubrication is also an important part of the process. It reduces friction, cools the cutting area, removes chips, and prevents overheating.
Choosing the correct type of tap is crucial for thread quality. Here are the most common types:
– Spiral Point Taps: These taps have a pointed end and are great for through holes. They push chips forward and are suitable for most general-purpose applications.
– Spiral Flute Taps: These taps have grooves that carry chips upward, making them ideal for blind holes and harder materials.
– Roll Taps (Form Taps): Rather than cutting, these taps form threads by displacing material. They work well for high-volume production and create smooth, strong threads.
There are several approaches to tapping based on hole type and material:
– Through Hole Tapping: The hole goes all the way through the material, allowing chips to escape easily. Spiral taps work well here.
– Blind Hole Tapping: The hole doesn’t go all the way through, requiring better chip control. Spiral flute or peck tapping is often used.
– Rigid Tapping: The tap’s motion is synchronized with the spindle, offering high accuracy but a greater risk of breakage if misaligned.
– Floating Tapping: The tap can move slightly to adjust for misalignment, reducing breakage risks.
– Self-Reversing Tapping: The tap automatically reverses at the end of the cycle, saving time.
– Peck Tapping: The tap moves in and out in small steps to clear chips from deep blind holes.
– Form Tapping: Threads are formed without cutting, using taps that reshape the material.
Advantages:
– High Productivity: Tapping is faster and more efficient than manual threading.
– Consistent Quality: Tapping produces uniform threads with tight tolerances.
– Reduced Scrap: Better control leads to fewer errors and waste.
– Repeatability: Once programmed, the process can be repeated with consistent results.
– Versatility: Can be used for different thread sizes and types.
– Safer Operation: Removes the operator from direct involvement, lowering the risk of injury.
Disadvantages:
– High Initial Cost: CNC machines and tooling require significant investment.
– Complex Programming: Time is needed to create and test accurate CNC programs.
– Tap Breakage: Taps can break due to misalignment or high feed rates.
– Setup Time: Aligning parts and setting up the machine can be time-consuming.
– Limited Flexibility: Once a cycle is programmed, it’s harder to switch tasks quickly compared to manual methods.
CNC tapping is widely used in many industries:
– Automotive: For engine parts, transmission housings, and cylinder heads.
– Aerospace: For precision parts in jet engines and aircraft structures.
– Medical Devices: For tools, implants, and diagnostic equipment.
– Electronics: For tiny threads in enclosures and circuit boards.
– Plumbing: For tapping threads in fittings, valves, and pipe connectors.
– Mold & Die Making: For precisely threaded inserts in dies and molds.
– Oil and Gas: For heavily threaded components like pipes and valves.
– Optics: For finely threaded parts in lenses and mounts.
– Pneumatics and Hydraulics: For threading cylinder ends and fittings.
While both tapping and threading create threads, they serve different purposes:
– Tapping is used to create internal threads using a tap. It involves cutting and creates chips that need to be removed.
– Threading uses a die to form external threads, like those on bolts or rods. It reshapes the material without removing it, making it faster and stronger.
Tapping is generally more precise for internal threads, while threading is faster and better for external threads. The choice depends on the specific need.
– Choose the right tap for the material and application.
– Secure the workpiece firmly to avoid movement.
– Set the correct spindle speed and feed rate.
– Use lubricants to cool and remove chips.
– For blind holes, use peck tapping to clear debris.
– Ensure threads meet quality standards using inspection gauges.
CNC tapping is a powerful tool in modern manufacturing. It enables the creation of accurate, repeatable internal threads in a wide range of parts and materials. With the right tools, machine settings, and attention to detail, CNC tapping can deliver high-quality results across many industries.
Understanding the CNC tapping process is key to achieving high-quality, precision-threaded components. At Interscope Manufacturing Inc., we specialize in CNC machining and prototyping services. With over 35 years of industry experience, we offer reliable solutions for a wide range of threading and component needs. Get in touch with us today for a fast, accurate quote!
