Thread machining is one of the most important applications for a computer numerically controlled machining center. Indirectly, the machining quality and efficiency of the thread will have a direct impact on the machining quality of parts and the overall productivity of the machining center.

There are several thread processing methods that are commonly used in CNC machining centers, and they are summarized in the following section. This will allow technicians to make reasonable choices when it comes to thread processing methods in order to increase the efficiency of the manufacturing process.

1. Select the processing method.
1.1 The classification and characteristics of tap processing are discussed.
The most commonly used processing method for threaded holes is to use a tap to process them. It is primarily used for threaded holes with small diameters (d  30) and with low requirements for hole position accuracy, as described above.

Flexibility of tapping method for threaded holes was first introduced in the 1980s. This technique involves clamping and compensating the tap with a flexible tapping chuck, and using the tapping chuck to compensate the feed error caused by a misalignment of the machine tool's rotational speed and spindle speed in order to ensure the proper pitch. The flexible tapping chuck has a complex structure, is expensive, is easily damaged, and has a low processing capacity. CNC machining centers have steadily improved in performance over the years, and the rigid tapping function has evolved into the standard 3D Printing Services configuration for CNC machining centers.

As a result, rigid tapping has surpassed all other methods of thread machining as the primary method.

In other words, the tap is clamped with a rigid spring collet, and the spindle feed is consistent with the spindle speed controlled by the machine tool. Spring tapping chucks have several advantages over other types of taping chucks, including their simplicity of construction, lower cost and wide range of applications. Furthermore, it can also clamp other tools such as the end milling cutter, drill bit and other cutting tools, which can lower the cost of the cutting tools. At the same time, rigid tapping can be used for high-speed cutting, which increases the service efficiency of the machining center while simultaneously lowering the manufacturing cost.

1.2 Determination of the threaded bottom hole prior to tapping the hole
The way a threaded bottom hole is processed has a significant impact on the service life of the tap as well as the quality of the thread processing. In most cases, the diameter of a threaded bottom hole drill bit is close to the upper limit of the threaded bottom hole diameter tolerance. For example, if the bottom hole diameter of an M8 threaded hole is 6.7 + 0.27mm, choose a drill bit diameter of 6.9mm to match the bottom hole diameter.
The machining allowance of the tap can be reduced, the load on the tap can be reduced, and the service life of the tap can be extended in this manner.

the taps are chosen in 1.3
When selecting taps, it is important to remember that the corresponding taps must be chosen in accordance with the materials being processed. It is important to note that the tool company produces various types of taps for use with various processing materials, and that special care should be taken in the selection process.
Because the tap, in comparison to the milling cutter and boring cutter, is extremely sensitive to the material being processed. For example, using a tap designed for processing cast iron to process aluminum parts is likely to result in thread dropping, disorderly threading, and even tap breaking, all of which will result in the scrapping Investment Casting Services of the finished workpiece.

Second, pay close attention to the difference between a through-hole tap and a blind hole tap in terms of appearance. When a through-hole tap is used, the front guide is very long, and the chip removal is done with a front chip. When the blind hole is opened, the front guide is short, and the chip removal is done with the rear chip. A through-hole tap used to machine blind holes cannot guarantee the depth of threads that will be machined in the holes.

If a flexible tapping collet is used, it should be noted that the tap handle diameter and the square width should be identical to the tap collet diameter; the diameter of the tap shank for rigid tapping should be the same as the diameter of the spring jacket, unless otherwise specified.
For the most part, only a reasonable selection of taps can ensure that the processing runs smoothly.

2. Thread milling as a technique
Thread milling has a number of distinct characteristics.
Thread milling is performed using a thread milling tool in conjunction with a three-axis linkage of a machining center, which includes arc interpolation on the x- and y-axes as well as linear feed on the z-axis. Large hole threads and threaded holes in difficult-to-machine materials are the primary applications for thread milling, which is a type of milling machine.
There are several characteristics that it possesses in particular:
(1) processing speeds that are fast, efficient, and precise are important. The material of the cutting tool is typically cemented carbide, and the cutting speed is rapid. Because the manufacturing accuracy of the cutter is high, the accuracy of the milling threads is also high.
(2) Milling tools are useful in a wide variety of situations. A single tool can be used for both left- and right-hand threads as long as the pitch is the same, which helps to reduce the overall cost of the tool by eliminating the need for multiple tools.
(3) Milling is less difficult to remove chips from and cool than tap, and the cutting condition is better than tap when using milling. Specifically, it is well suited for thread processing of challenging materials such as aluminum, copper and stainless steel, and in particular for thread processing of large parts and components made of precious metals, as it can ensure high thread processing quality while also alloy steel ensuring safety of the workpiece during processing.
Due to the lack of a tool front-end guide, it is particularly well suited for machining blind holes with short thread bottom holes and holes without tool return grooves, among other things.

2.2 Thread milling tools are classified according to their shape.
Thread milling tools are classified into two types: machine clamp cemented carbide blade milling cutters and integral cemented carbide blade milling cutters. Machine clamp cemented carbide blade milling cutters are the most common type. The clamping tool is useful in a wide variety of situations. When processing holes, it can handle both holes with thread depths less than or equal to the blade length and holes with thread depths greater than or equal to the blade length. When milling holes with thread depths less than the length of the tool, an integral cemented carbide milling cutter is typically used.
3. Use the snap method
The characteristics of the snap method are as follows:
It is possible to find large threaded holes on box parts from time to time. When a tap and thread milling cutter are not available, a method similar to lathe pick-up can be used instead of them. Thread turning tool installation on the boring bar is required to bore the thread.

Precautions to be taken when using the buckle picking method
(1) Following the start of the spindle, there shall be a delay time to ensure that the spindle reaches the rated speed before continuing.
(2) If the tool being retracted is a hand-ground thread tool, reverse tool Plastic 3D Printing retraction cannot be used because the tool cannot be ground symmetrically and therefore cannot be reversed. The spindle orientation must be chosen, the tool must be moved radially, and then the tool must be retracted before the process can continue.
(3) The cutter bar must be manufactured with precision, with the position of the cutter groove being consistent throughout the process. It is not possible to use multi cutter bar machining in the event of inconsistency. It will buckle at random if this is not done.
(4) Even if it is a very fine buckle, it cannot be picked with a single knife because doing so will result in tooth loss and poor surface roughness on the buckle. At least two knives must be divided in this manner.
(5) The processing efficiency is low, making it only suitable for single-piece, small-batch production, special pitch threads, and the absence of a suitable tool.