Turning processing chapter-tool shape and tool life

26 September 2021

Tool life is the total cutting time of a new tool from the start of cutting until the tool is scrapped. In numerical control machining, tool life refers to the time that the tool tip cuts the workpiece or the actual length on the workpiece surface during the cutting process from the beginning of machining to scrap the tool tip. Tool tip processing time is the main evaluation index for tool company to calculate tool life.

pcd and pcbn cutting tools

Generally, the service life of the tool is 15-20 minutes for continuous processing of each blade. Tool life is measured by each company in the laboratory under relatively ideal conditions. According to different workpiece material, different cutting depth and feed, according to each blade continuous processing 15-20 minutes to calculate, calculate the relationship between the corresponding linear speed and feed, that is, constitute the corresponding cutting parameter table.

In the workpiece processing cost, tool cost accounts for a very small proportion. When the linear speed is reduced, even if the tool life is increased, the number of workpiece processed by the tool will not necessarily increase, but the workpiece processing cost will increase. Therefore, it is necessary to understand correctly that it makes sense to increase the number of parts processed as much as possible while ensuring the tool processing life as much as possible.

Cutting edge damage pattern:

Type

No.

damage pattern

Major damage structure

Initiate mechanical action

 

 

1~5

Flank wear

The scratching action of the hard particles contained in the material to be cut causes abrasion.

6

Small Collapse

Small breakage due to large pressing force or vibration of the tool and other factors

7

Collapse

Large-scale chipping caused when the endurance of the cutting edge is too large due to mechanical shock

Initiate thermochemical action

 

8

Rake face wear

Dissolution and diffusion caused by high temperature cause the tool to be carried away with the chips by the alloyed surface

9

 

Plastic deformation

Deformation caused by softening of the tool tip due to high temperature

10

 

Thermal cracking

Thermal fatigue occurs with intermittent cutting heating and cooling cycle changes

 

11

Built-up tumor

A part of the material to be cut becomes very hard metamorphic material and sticks and accumulates on the tip of the tool

 

---Miya Ma/Yvonne Feng

---Yvonne Feng


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