Tech Focus The advantages of deep drilling with indexable inserts
Even in deep drilling with single-lip drills, both when boring and drilling, the trend is moving towards tools with indexable inserts. The range of advantages is vast compared to soldered tools, with improvements in bore quality and performance being particularly noticeable.
For holes with depths starting at about 20 x D, single-lip drills are clearly superior to other drilling tools. The gradients are lower, the surfaces of significantly better quality. These are important reasons why this type of tool is often used for applications with less deep bores, but the highest quality requirements. Experts refer to this as “precision drilling.” The quality can be increased even further if single-lip drills with indexable inserts are used. This fact often remains unknown because indexable inserts are not nearly as common in deep drilling as, for example, in milling, turning or short-hole drilling.
“Single-lip drills with indexable inserts have both performance and quality benefits,” says Dr. Thomas Bruchhaus, tool expert at TBT Tiefbohrtechnik in Dettingen/Erms. “If only one of these aspects is important to the user, we recommend indexable inserts with single-lip drills. And this is happening more and more often, because the cost pressure and the demands on the quality of the cutters are constantly increasing.”
While the quality of the bore is of less importance than machining time for cooling or lubricating bores in the field of mould-making or the automotive industry, the plastics industry, for example, attaches great importance to extremely smooth surfaces. Both requirements can be fulfilled very well by the insert-type single-lip drill.
As a full-service provider for deep drilling, TBT has continued to expand its tool range in recent years. Single-lip drills with indexable inserts for full boring are currently available from a diameter of 12 mm. With small diameters, there is no space to clamp the indexable inserts and guide strips; as such, these are still manufactured exclusively with soldered cutting edges. Drilling with single-lip drills is a less common type of machining; the tools are almost always made by TBT according to customer requirements.