Several Thread Machining Methods When Making Prototyping

by xiaolong luo cnc machining shop

Thread cnc machining is one of the important applications of CNC machining centers. The quality and efficiency of threadmachining directly affect the quality of parts and the production efficiency of the machining center.

With the improvement of the performance of CNC machining centers and tool performance, the method of threadmachining is also continuously improved, and the accuracy and efficiency of threadmachining are also gradually improved. In order to enable the technical staff to reasonably choose the threadmachining method in themachining process, improve production efficiency and avoid quality accidents, several screwmachining methods commonly used in practice in CNC machining centers are summarized as follows:

Tapmachining method

1. Classification and characteristics of tapmachining

Tapping is the most commonly used method formachining threaded holes. It is mainly applicable to threaded holes with smaller diameters (D <30) and lower hole position accuracy.

In the 1980s, all tapped holes were developed using a flexible method, that is, taps were flexibly tapped, and clamping and tapping chucks could be axially compensated to compensate errors caused by uneven spindle speeds. Axial advance to ensure correct pitch.

The flexible tapping chuck has a complicated structure, high cost, easy damage and lowmachining efficiency. In recent years, the performance of CNC machining centers has gradually improved, and the rigid tapping function has become the basic configuration of CNC machining centers.

Therefore, rigid tapping has become the main method of threadmachining.

The rigid tap is used to clamp the tap, so that the spindle speed is controlled by the machine tool to maintain consistency.

Compared to the flexible tapping chuck, the spring chuck has a simple structure, a low price and a wide range of applications. In addition to clamping taps, it can also clamp tools such as end mills and drills, which can reduce tool costs. At the same time, rigid tapping can be used to perform high-speed cutting, improve the efficiency of the machining center, and reduce manufacturing costs.

2. Determine the bottom hole of the thread before tapping

The cnc machining shop of the thread bottom hole has a great influence on the service life of the tap and the quality of the threadmachining. In general, the diameter of a tapped hole drill bit is close to the upper limit of the tolerance of the tapped hole diameter. 

For example, M8 tapped hole bottom hole Ф6.7 + 0.27mm diameter, choose some diameter 6.9mm diameter. This can reduce the machining allowance of the tap, reduce the load on the tap, and increase the service life of the tap.

3. Click to select

When selecting a tap, first select the corresponding tap according to the differentmachining materials. The tool company produces different types of taps according to the differentmachining materials. Pay special attention when selecting.

Because taps are more sensitive to the material being processed than milling and boring tools. For example, the use of cast iron taps to process aluminum parts can easily lead to thread teeth, random buckles, or even broken taps, resulting in scrapped workpieces. Secondly, we should pay attention to the difference between a through hole tap and a blind hole tap. The front end guide rail of the through-hole tap is long, and the chip removal is the front chip removal. 

The blind guide has a short front guide and the chip removal is the rear guide. It is impossible to guarantee the depth of thread precision machining by using a through-hole tap to process blind holes. In addition, if a flexible tapping chuck is used, the diameter and width of the tapping handle should be the same as those of the tapping chuck; the diameter of the rigid tapping shank should be the same as the diameter of the spring sleeve. In short, only a reasonable choice of taps can ensure the smoothmachining.

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Created on Dec 10th 2019 02:39. Viewed 238 times.

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