Pay attention to the suitability of choosing ppe

In order to prolong the life of the tool or improve its working efficiency, it is particularly important to improve the surface friction conditions, and therefore more and more efficient cutting material applications have emerged. The CVD thin coating and PVD coating have greatly improved the surface properties of the tool and until now this effect is far from being exhausted. Using modern analysis techniques, the microscopic structure of the tool surface can be clearly observed and better optimized. The surface structure of the tool is achieved through a predetermined process program. Functional design can now be performed based on the optimized tool performance.

The most commonly used surface modification method is the surface coating of the material. Through the compounding of carbides, nitrides and oxides of high hardness metals, the properties of individual compounds can be adjusted, particularly in terms of the ability to improve abrasion resistance, oxidation wear resistance, diffusion wear and adhesive 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.

The mechanism of adhesion between chips and tools is mainly mechanical friction except for mechanical occlusion. Through a material modification method - the soft coating deposited on the surface of the tool - can effectively improve the friction properties.

In addition, modification of the surface topography can be performed, such as by polishing or purposely roughening (in order to form lubricant grooves). Polishing is a traditional method of reducing friction by mechanical means. It is particularly suitable for cutting tools that do not add lubricant to the cutting area. Polishing is, in most cases, an effective method of reducing friction.

Periodic surface structures can be formed by polishing. Some form of structural elements can also be obtained using lithographic methods or lasers. Compared with metal sheet processing, these methods are not yet common in cutting. A theoretical basis for this method is that the microstructure can reduce the heat transfer between the chip and the tool and reduce the thermal load on the tool.

Polishing of PVD coatings. The polishing process belongs to the modification of the surface morphology. There are various different methods of polishing the ground or coated surface. In addition to the Truva polishing method for high-volume parts, there are brush and sand blasting methods commonly used in the production of tools. None of these methods are novel and have been used for many years in the production of cutting inserts, such as broccoli-like surface structures for polishing thick CVD coatings. Polished cutting inserts showed very even wear after cutting for 6 minutes. The unpolished blades exhibit parallel microscopic cracks, which can lead to rapid widening of the wear band and early failure of the tool.

These polishing methods are also now commonly used for PVD coatings. As on the surface of a PVD-coated hole-machining blade, structures known as "droplets" in the PVDARC process can be seen. These droplets act like stones in the river bed, hindering the removal process of the chips, which is particularly disadvantageous in the hole processing. If the chips can be removed quickly and with less friction, the contact time between the chip and the tool is reduced, and the heat transferred to the tool is also reduced. Unimpeded chip removal results in less cutting forces and prevents bites and plugging of the chips in the drill bit and cutter pocket. The quality of polishing depends on the choice of polishing method and the adjustment of process parameters.

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