Cutting modes and tool life

When processing by cutting, it is necessary to achieve an optimal combination of processing performance and tool durability. Insufficient tool life increases equipment downtime when replacing tools, which leads to a decrease in productivity. If the cutting mode is too gentle, the tool life will increase, but the processing time of the part will increase, which also reduces the efficiency of equipment use and overall productivity. To ensure the efficiency of processing, it is necessary not only to choose the right tool, but also to choose the optimal parameters of the cutting mode, which we will talk about today.

Durability is the time to reach the permissible wear value of the cutting tool.

There are three main turning parameters, each of which affects the durability of the tool cutting speed feed and cutting depth. By changing these parameters, we can achieve the best result for us.

Cutting speed (Vc) - the maximum speed of movement of the cutting edge relative to the workpiece (measured in m/min).

Feed (fn) the tool when turning is equal to the distance by which the cutting edge moves along the axis of the part in one revolution (measured in mm / rev).

The cutting depth (ap) is half the difference between the machined and machined diameter of the workpiece (measured in mm).

Power consumption (Pc) is the power required to carry out the cutting process (measured in kW).

The specific cutting force (kc) is numerically equal to the cutting force assigned to 1 mm2 of the section of the cut layer (it is a constant value for each processed material, measured in N/mm2).

                                                      

Effect of cutting speed (Vc)

Cutting speed is too high

• Intense wear on the back surface

• Poor quality of the treated surface

• Rapid lunkoobrazovanie

• Plastic deformation

Cutting speed is too low

• Build-up

• Low processing efficiency

Feed Effect (fn)

Feed too high

• Loss of control over chip formation

• Unsatisfactory quality of the treated surface

• Hole formation, plastic deformation

• High power consumption

• "Welding" chips

• Chip edge damage

Feed too low

• Drain chips

• Low processing efficiency

Effect of depth of cut(ap)

Cutting depth is too large

• High power consumption

• Cutting plate breakage

• Increased cutting forces

The cutting depth is too small

• Loss of control over chip formation

• Vibrations

• Excessive heating

• Low processing efficiency

Taking into account the geometry пластины and grades of hard alloy for various types of operations when choosing the cutting speed, it is necessary to take into account the type and hardness of the material to be processed, the desired nature of the chips throughout the cutting path, cutting depth and feed, the rigidity of the SPEED technological system (machine-device-tool-part) and processing conditions (intermittent cutting and vibration).

Productivity is limited by roughing - by power consumption, while finishing - by the quality of the surface being treated. When working on low-power equipment, the cutting speed should be reduced in accordance with the capabilities of the machine. The required processing quality is achieved using modern tools and technologies that allow you to work with high feeds without loss of quality.

In the most general case, the durability and the corresponding elements of the cutting mode should be such that the productivity of the operation is maximized at a minimum cost and ensures a given quality of processing. Optimal performance is ensured by working at large cutting depths and feeds at moderate cutting speeds.

Literature used:

1) High-performance metal cutting. Textbook SANDVIK COROMANT 2003 Vinogradov D. V.

2) Technical manuals and catalogs of Dormer, Pramet, Sandvik Coromant, Seco, Tungaloy.

3) Recommendations for the purpose of cutting modes and tool selection. 2010 M.A. Bolotov, A.N. Zhidyaev, N.D. Pronichev, A.I. Khaimovich.

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