What Is a Coated Abrasive?

The surface coating of high-speed steel tools is a new process that uses physical vapor deposition (PVD) to coat the surface of the tool with a hard film such as TiN to improve the performance of the tool. The coated high-speed steel is a composite material, the matrix is high-speed steel with good strength and toughness, and the surface layer is a material with high hardness and high wear resistance. TiN has high thermal stability, low friction coefficient with steel, and strong bonding with high-speed steel coating. The surface hardness can reach 2200HV and is golden yellow.

The hardness of high-speed steel tools is 62HRC-70HRC (766HV-1037HV), and the physical vapor deposition (PVD) method is used to coat TiC or TiN coatings of 2m-6m, which can increase the surface hardness of the tool to 2000HV-3200HV (above 83HRC) exceed

High-speed steel cutting tools have excellent comprehensive properties in terms of strength, toughness and processability, and the manufacturing process is relatively simple, the cost is low, and it is easy to sharpen sharp

There are many grades of high-speed steel, and each has its own characteristics and application range. Using it as a tool material should be reasonably selected based on the properties of the processing material, the type of manufacturing tool, the processing method, and the rigidity of the process system. The selection principles are as follows:

1) The price of ordinary high-speed steel is low, and it is mainly used for processing ordinary steel, alloy steel and castings. High-performance high-speed steel is mainly used for processing difficult-to-machine materials such as stainless steel, high-strength steel, and heat-resistant steel.

2) Compared with complex tools, general tools have simpler manufacturing process and lower manufacturing accuracy. Considering the large proportion of material consumption in tool costs, ordinary high-speed steel is commonly used.

1) High tool life and cutting productivity. The life of coated high-speed steel tools can generally be increased by 2 to 3 times than that of uncoated tools. For example, the life of coated drills can be increased 3 to 10 times; coated taps can be increased 5 to 10 times; coated gear cutters can be increased 3 to 6 times; coated extrusion dies can be increased 6 to 10 times. When the tool life is unchanged, the cutting speed can be increased by 20% to 30%, or even 1 to 2 times. In addition, the feed rate of coated high-speed steel tools can be increased by 10% to 20%, so the cutting efficiency can generally be increased by 50% to 100%. Production practice shows that the cutting speed of TiN coated gear tools can be increased by 30% to 50%, and the feed rate can be increased by 10% to 20%, and it has no adverse effect on the tool life.

2) Less cutting force and torque, less tool breakage. When using coated drills and taps, the friction factor is reduced and the chip adhesion is reduced, which can reduce the axial force of the drill and the torque during drilling or tapping by 20% to 40%, which greatly reduces the chipping of the tool.

3) High processing accuracy and surface quality. When drilling with a coated drill, because the built-up edge can be reduced or eliminated, the expansion of the hole diameter is significantly reduced, and the accuracy of the hole is improved (grade 1-2), and the surface roughness can be approximately smaller than that of the uncoated drill. 50%, reaming and deburring can often be omitted when drilling. The coated drill can process difficult-to-machine materials such as mild steel, corrosion-resistant nickel alloys, and high-temperature alloys.

When processing with a coated reamer, not only can the surface roughness be significantly reduced, but as the cutting speed and feed rate increase, the surface roughness of the coated reamer only increases slightly, while uncoated tools During the process, the surface roughness increased sharply. Coated reamer works well when machining high-alloy tool steels such as aluminum, mild steel, stainless steel, gray cast iron, and prone to build-up edge. When using a coated tap to tap a thread, the surface roughness value of the thread can be reduced by about 50%. At the same time, the possibility of abrasion on the surface of the thread is reduced due to the reduction of the built-up edge, which can prolong the life of the standard tap hole. ^[2]