What kind of drill is drilled by 40Cr heat treatment with hardness above 40 degrees?
Machining method of high hardness workpieceHigh hardness steel, hard powder metal, super heat resistant alloy and bimetallic material are more and more widely used in industry.
The products made from these materials are almost indestructible, and they pose new problems: how can they be processed into the final product in the most economical way?. It is gratifying to note that the tool suppliers have made new progress in developing milling and turning the blades of high hardness materials. At present, the coated carbide, metal ceramic, polycrystalline boron nitride (CBN), and polycrystalline diamond (PCD) material blades have been applied. The special shape of these advanced materials, the blade of the surface of the special coating attached to the process, can withstand mechanical impact and wear when the heat generated. However, the use of these blades requires additional external conditions, one of which is the close coordination of experienced tool suppliers.
A good example is the successful milling of a sintered barium carbide gas turbine blade using a coated carbide blade in a small batch process. When the cutting speed is 120sfm, the cutting is completed in only 5-10 minutes. In high volume machining of high hardness materials, 15-30 minutes of blade life is acceptable. But for small quantities of workpieces, shorter tool life and constant replacement of the tool are not major drawbacks. However, it is important to extend the life of the blade during full load production, which reduces tool change time, tool change, machine efficiency, and productivity. Now, carbide inserts can be used for machining turbine blades. If the amount of processing is large, CBN blades with higher hardness and higher cost should be adopted.
On the other hand, putting a blade on a large cutter is not necessarily a costly mistake. The cost of the CBN blade is 8-10 times that of the carbide blade. In the use of these advanced material blades, if the cutting speed and feed is not correct, will affect product quality and tool life. Because it is difficult to realize the stock reserve, it is necessary to evaluate the processing benefit and the whole process. Value from the whole process, if we consider the adjustment and replacement of the blade time, even if the use of carbide tools with low cost to meet the requirements of tolerances and surface accuracy, so the cost is expensive. Only when the production capacity, processing cycle and blade performance are well coordinated can the actual machining capability eventually be formed.
The cost of the blade is relatively low, and the cost of cemented carbide blade is about 3% of the total processing cost,CBN blades are reinforced and guided, and they can prevent edges from chipping when machining materials with a hardness of more than 50RC.CBN blades make up 5-6%, so using cheap blades is a wrong way to save money. The use of advanced materials in the short term can recover the investment, and the waste rate is very low.
