In order to extend the tool life or increase the working efficiency, it is especially important to improve the surface friction conditions, so more and more high-efficiency cutting materials are used. CVD thin coatings and PVD coatings have greatly improved the surface properties of the tool, and until now this effect is far from exhaustive. Using modern analytical techniques, the microstructure of the tool surface can be clearly observed for better optimization. The surface structure of the tool is achieved through a predetermined process program, which can now be functionally designed according to the optimum tool performance.

The most common surface modification treatment is the surface coating of the material. The compounding of carbides, nitrides and oxides of high hardness metals allows adjustment of the properties of individual compounds, particularly in terms of improved wear resistance, oxidation wear resistance, diffusion wear and bond wear. Of course, the introduction of other materials into the surface (such as by injection) can also have a lasting effect on the surface properties of the material.

In addition to mechanical occlusion, the adhesion mechanism between the chip and the tool is mainly represented by friction. Through a material modification treatment method - depositing a soft coating on the surface of the tool - one can effectively improve the friction performance.

In addition, surface topography can be modified, such as by polishing or purposeful roughing (in order to form a lubricating oil bath). Polishing is a traditional, mechanically reduced friction method that is particularly suitable for cutting tools that do not add lubricant to the cutting zone. Polishing is a method of reducing friction in most cases.

The periodic surface structure can be formed by a polishing process. Structural elements of a certain shape can also be obtained by a lithographic method or a laser. These methods are currently not common in machining compared to sheet metal processing. A theoretical basis for this approach is that microstructuring reduces heat transfer between the chips and the tool and reduces the thermal load on the tool.

Polishing of PVD coatings. The polishing process belongs to the modification of the surface topography. There are various polishing methods for the ground or coated surface. In addition to the Troywa polishing method for high-volume parts, there are also brushing and sandblasting methods commonly used in tool production. These methods are not novel and have been used for many years in the production of cutting inserts, such as broccoli-like surface structures for polishing CVD thick coatings. The polished cutting insert showed very uniform wear after 6 minutes of cutting. Unpolished inserts show parallel microscopic cracks, which cause the wear strip to widen quickly and prematurely fail the tool.

These polishing methods are now also commonly used in PVD coatings. As seen on the surface of a PVD coated orifice processing insert, a structure referred to as a "droplet" in the PVDARC process can be seen. These droplets act like stones in the riverbed, hindering the elimination process of the chips, which is particularly disadvantageous in hole processing. If the chips can be removed quickly and with less friction, the contact time between the chips and the tool is reduced and the amount of heat transferred to the tool is also reduced. Unobstructed chip removal eliminates cutting forces and prevents chipping and clogging in the drill bit and milling pocket. The quality of the polishing depends on the choice of polishing method and the adjustment of the process parameters.

The polishing process can extend the life of the tool, taking a twist drill as an example. A measuring instrument developed for final inspection that measures the friction in the chip flute. The reduction in friction is related to the surface condition. The polished bit groove has a friction coefficient of only 25% unpolished. The treated bit allows for higher cutting and drilling depths.