What does coating on a carbide tool increase?

The main purpose of coating is to further improve the wear resistance of cemented carbide and to extend the life of alloy tools.

 

1) Improve the performance of carbide-cutting tools;

2) The need for high-speed cutting and high-speed machining;

3) The need for machining of difficult-to-machine materials such as aviation heat-resistant alloys, composite materials, and hard materials.

When carbide (including a series of carbide products, such as carbide materials, carbide blades, carbide cutting tools, carbide wear-resistant parts, carbide moulds, etc.) is used, The complex stress on the surface and thermal wear during high-speed operation will cause the carbide material (especially the carbide blade) to wear very seriously, which will lead to the dulling of the carbide blade edge and greatly reduce the service life of the carbide material. , thereby greatly reducing production efficiency.

In some special industries, some cemented carbide products often have high hardness, but the toughness cannot be met. The toughness meets the requirements, but the hardness does not meet the usage requirements. The wear resistance and service life are often unsatisfactory. So how can we make cemented carbide truly have high toughness and high hardness at the same time?

That is to carry out coating treatment on the surface of cemented carbide. The surface of cemented carbide is coated with a special material with higher hardness and bending strength than cemented carbide – a rare precious metal. Including TiN, TiC, Ti (C, Min), TiBN, TiB2, Al2O3, Ti (C, N) (CVD), TiN (PVD), etc., to improve the hardness and bending strength of the cemented carbide surface method. Since the coating material has higher hardness and wear resistance than cemented carbide, the wear-resistant life of cemented carbide can be doubled after coating treatment.

Carbide coating is actually to modify the surface of cemented carbide. The physical modification of cemented carbide is mainly through the coating method, which forms a single or multi-layer structure on the surface of the cemented carbide base material, thereby imparting hardness. New properties of alloy materials.

 

coating on carbide tool

 

What are the 2 main coating methods on carbide inserts?

 

Tool coating technologies can generally be divided into two categories: chemical vapour deposition (CVD) and physical vapor deposition (PVD).

 

1) Chemical vapor deposition (CVD)

 

CVD technology is widely used in the surface treatment of carbide indexable tools. CVD can realize the deposition of single-component single-layer and multi-component multi-layer composite coatings. The bonding strength between the coating and the substrate is high, the film thickness is thick, up to 7~9um, and it has good wear resistance. Coating method When using CVD coating, the cutting edge needs to be passivated in advance (the radius of the blunt circle is generally 0.02~0.08mm, and the strength of the cutting edge increases with the increase of the radius of the blunt circle), so there is no uncoated blade on the cutting edge sharp. Therefore, the PVD method should be used for tools that produce thin chips for finishing and require sharp cutting edges. In addition to being coated on ordinary cutting inserts, the coating can also be coated on the entire tool. It has now been developed to be coated on welded carbide tools. CVD-coated tools are suitable for high-speed roughing and semi-finishing in medium and heavy-duty cutting.

 

2) Physical vapor deposition (PVD)

 

Physical vapour deposition (PVD) uses physical methods such as evaporation or sputtering to remove materials from a target source and then deposits these energy-carrying vapour ions onto the surface of a substrate or part through a vacuum or semi-vacuum space to form a film layer. Compared with the CVD process, the PVD process temperature is low (as low as 80°C) and has basically no effect on the bending strength of the tool material below 600°C; the internal stress state of the film is compressive stress, which is more suitable for hard Coatings for precision and complex cutting tools made of high-quality alloys.

There are two main methods of PVD technology: vacuum cathode arc physical evaporation and vacuum magnetron ion sputtering.

 

(1) Vacuum cathodic arc physical evaporation (ARC)

 

The vacuum cathodic arc physical evaporation process involves stimulating a high-current, low-voltage arc on the target and generating continuous metal ions. The ionized metal ions evaporate with an average energy of 60~100eV to form a highly excited ion beam, which is deposited on the surface of the plated workpiece in a vacuum environment containing other inert or reactive gases. The ionization rate of the vacuum cathode arc physical evaporation target is about 90%, so compared with vacuum magnetron ion sputtering, the deposited film has higher hardness and better bonding force.

 

(2) Vacuum magnetron ion sputtering (SPUTTERING)

 

In the vacuum magnetron ion sputtering process, argon ions are accelerated and hit the cathode target with a negative voltage. The collision of ions and the cathode causes the target to be sputtered out with metal ions with an average energy of 4 to 6 eV. These metal ions are deposited on the plated workpiece placed in front of the target to form a coating film. Due to the lower energy of metal ions, the bonding force and hardness of the coating are correspondingly worse than those of the vacuum cathodic arc physical evaporation method. However, due to its excellent surface quality, it is widely used in the field of surface functional and decorative coatings.

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