Today, powder metallurgy has made great progress, not far from the world’s hardest material diamond.
It sounds incredible, but one of the hardest materials in the world is made of powder.
From powder to blade, we can uncover the mystery of cemented carbide blade production for you.
Tungsten oxide is mixed with carbon and processed into tungsten carbide in a special furnace, which is the main raw material of all cemented carbide.
Tungsten carbide is an extremely hard and brittle material, which is used as the main component of cemented carbide.
When tungsten carbide is mixed with cobalt, cobalt is very important to the properties of cemented carbide.
The more cobalt, the better toughness of cemented carbide; on the contrary, the harder and more wear-resistant.
The weight ratio of different components is carried out with the highest accuracy.
The error of a batch of 420 kg raw materials should not be more than 20 G.
Mixing is a precise metallurgical operation
Finally, the mixture is ground into a fine and delicate powder in a large ball mill.
The mixture must be spray dried to obtain the correct fluidity.
After grinding, the particle size of the powder reaches 0.5-2.0 um.
After pressing, the blade looks very similar to the real cemented carbide blade, but the hardness is far from the standard.
The robot transmits the pressed blade to a disc made of heat-resistant material.
For hardening, the blade is heat-treated at 1500℃ for 15 hours.
Through the sintering process, the melted cobalt and tungsten carbide particles are bonded together.
There are two things to do in the process of sintering furnace: the blade shrinks obviously, and the correct tolerance can be obtained only when the shrinkage is accurate;
Secondly, the powder mixture is transformed into a new material with metallic properties and becomes cemented carbide.
Now, the blade has reached the expected hardness, but not to the extent that it can be delivered.
Before the next step of production, we will carefully check the size of the blade in the coordinate measuring machine.
Only by diamond grinding can the carbide inserts have accurate shape.
The blade is grinded according to the geometric angle.
Most grinders have built-in measuring controls to check and measure the blades in several stages.
The cutting edge is treated to obtain the correct shape to achieve the maximum wear resistance required for machining.
These blades can be brushed with a special brush with a silicon carbide coating
No matter what processing method is used, the final result must be checked.
90% – 95% of all blades have some kind of coating.
It is necessary to ensure that there are no foreign particles on the blade surface, so as to prevent such particles from adhering to the coating, thus affecting the performance of the tool.
Chemical vapor deposition (CVD) and physical vapor deposition (PVD) are two kinds of coating methods. The choice of coating method depends on the material and processing method.
The thickness of the coating depends on the application of the blade, and the coating determines the durability and life of the blade.
The technical know-how is that there are many very thin coatings on the surface of cemented carbide, such as titanium carbide, aluminum oxide and titanium nitride, which can greatly increase the service life and durability.
If CVD method is used to coat the blade, put the blade into the furnace and add chloride and oxide in the form of gas together with methane and hydrogen
When the temperature reaches 1000℃, these gases interact with each other and also act on the surface of cemented carbide, so that the blade can obtain a homogeneous coating only a few thousandths of a millimeter thick.
Some coated blades have a golden surface and become more valuable. Their durability is five times higher than that of uncoated blades.
PVD is used to spray the blade at 400℃.
Final inspection, marking and packaging
The blade passes the automatic inspection, and then we will mark the material laser on the blade, and finally pack it.
The blade box is marked with product information, serial number and date, which is a promise to ensure excellent quality and service for users.
After packaging, the blades can be delivered to customers.