New indexable insert technology greatly benefits thread turning

The precise fixation of indexable inserts in the tool holder is one of the main challenges facing the processing industry today. Clamping the blade firmly in the tool has always been a top priority, especially when it comes to high productivity and high quality parts, more attention is paid to eliminating the phenomenon of micro-movement of the cutting edge. The slight movement of the cutting edge during the cutting process often leads to prematurely shortened tool life, erratic performance and unsatisfactory machining results. Especially in profiling turning and thread turning processes, it is more obvious.

Recently, a new breakthrough has been made in indexable insert technology. A method has been found to fix the insert on the tool bar more stably, which has significantly improved the stability during the cutting process. At the same time, this technological breakthrough opened the door to a harder and more durable blade material, which reliably shortened the processing cycle time.

In the case of wrong thread profile

As far as thread processing of screw clamping arbor is concerned, thread profile error is the most important cause of quality problems, specifically caused by deviations in tolerance or surface accuracy. The thread profile error is mainly caused by the micro displacement of the indexable insert during the thread turning process, which can produce more negative results. The generation of unqualified profile will limit the cutting parameters and shorten the service life of the insert. The main consequence of the instability of the insert is the breakage of the cutting edge, especially the crack at the nose radius. Using traditional tools and choosing appropriate fastening screws or clamping methods will improve the stability to a certain extent. However, the improvement of the tool holder to achieve more stable clamping of the blade still needs continuous discussion.

The most sensitive moments during thread turning are when cutting in and ending cutting out. When the sharp cutting edge starts to cut in or exits cutting after the end of the pass, the strength and direction of the cutting force will suddenly change greatly, which will have a great impact on the blade. At the above two moments, the blade is most prone to displacement. The tip of the thread profile on the insert forms a lever for the thread, forcing the cutting edge to slightly change position, deforming the supporting point in the tool holder seat and increasing instability. The cutting force acting on the insert in different directions will cause the insert in the seat to move back and forth until an unqualified thread is produced. In fact, thread turning inserts are replaced more often due to displacement than due to actual tool wear.

In order to avoid time-consuming machine setup and minimize or eliminate the generation of scrapped parts, simple, fast and accurate positioning of the blade in the tool holder is very important. Repeatability is also very important when positioning and fixing the blade in the tool holder. Under normal circumstances, due to the risk of obvious cutting marks on the thread surface, it is possible to avoid blade displacement during each pass as much as possible. If the blade needs to be replaced during the thread cutting process, the precise positioning of the blade is critical to maintaining and achieving acceptable machining results. Combined with this, considering the impact on machine downtime, repeatability between two passes is also very important.

For many reasons, the quality of the positioning and locking of the thread turning insert in the insert groove plays a decisive role in achieving high production efficiency, safe operation and consistent part quality. With the past blade locking and positioning solutions, it is impossible to fasten the blade in the blade slot in many cases. Methods such as clamping force, shim clamping, and simple indexing have all meant compromises, and the limitations of blade manufacturing methods have hindered the possibility of non-traditional solutions.