1. Selection of cutting parameters
Reasonable cutting parameters can give full play to the advantages of PCBN tools.
Refer to the table below for cutting parameters. (The parameters should be adjusted appropriately according to the actual processing conditions and workpiece type)
|Grey Cast Iron||500~1500||0.5~0.8||0.25~1.0|
|Chilled Cast Iron||50~120||0.1~0.6||0.1~1.2|
|Hardened steel (45~65HRC)||60~150||0.2~0.3||0.6~2.5|
|Surface hardening alloy (>35HRC)||80~240||0.12~0.25||0.5~2.5|
|Cemented carbide (Co%>17%)||2040||0.1~0.25||0.1~0.5|
2. The requirements of PCBN tools for machine tools and clamping
Due to the large radial force during cutting, the machine tool power and system rigidity are required to be high. In order to prevent chattering, collapse and deformation during processing, the overhang elongation of the tool should be as small as possible. When one end is clamped, it is recommended that the ratio of length to diameter is 2:1, and the maximum is not more than 4:1. If there is tailstock support, the overhang length can be increased appropriately.
3. Dry or cooling
The main advantage and feature of PCBN material is dry cutting. PCBN inserts can maintain excellent cutting ability even at 1000℃ during cutting. High tool life under heavy interrupted cutting occasions.
Cooling is required under special occasions:
① In the case of mandatory intermittent;
② When thermal stability is required;
③ When cutting large workpieces, it is necessary to reduce the cutting temperature in time.
Note: If cooling is added, it cannot be interrupted during the entire cutting process.
4. PCBN tool geometry and life
PCBN cutters generally adopt negative rake angle, larger back angle, negative chamfering and grinding treatment to enhance cutting edge strength and wear resistance. In addition, it is very important to accurately determine the life of PCBN. If the tool wear is severe, the cutting force and cutting temperature increase, and it is difficult to control the size and surface integrity of the workpiece during cutting. It is recommended that the wear of the flank face of PCBN tools is 0.3~0.6mm (the minimum value is used during finishing).
5. PCBN tool processing recommendations
For workpieces with high hardness and irregularity, it is recommended to rough-turn the chilled layer with HN blades first, and chamfer at the cutting-in and cutting-out ends to reduce the impact force of the PCBN tool and prevent the cutting edge from chipping and causing failure