BUEs are built-up edges formed due to the accumulation of work-piece material against the rake face of the tool.
How are BUE formed?
During machining, the upper layer of the work-piece metal experiences a large shear force as it comes in contact with the tool-tip and an amount of the metal gets welded to the tool-tip. This is due to work hardening of the metal layer. The metal adhered to the tool becomes so hard that it is difficult to remove.
Why are BUE formed?
BUE formation is common under a few conditions which are :
Low cutting speed
Work hardeneability of work piece material
High feed rate
Low rake angle
Lack of cutting fluid
Large depth of cut
In which materials is it observed easily?
BUE formation is usually noticed in alloys such as Steel rather in pure metals.It is also observed in soft materials like soft pure Alumunium, hot rolled low carbon steel.
What are the effects of BUE?
There are a few basic effects caused by the BUE formation like :
Change in tool geometry
Change in rake steepness
Reduction in contact area between the chip and the cutting tool.
What are the advantages of BUE?
BUE formation can have a few advantages on the cutting tool and ease of machining like :
Slight increase in tool life
Reduction in power demand.
What are the disadvantages of BUE?
The count of disadvantages is actually more than the advantages it has on the machining process.
Poor surface finish
Problems in dimensional control of the process
Leads to flank wear (damaging the flank face)
How can the BUE formation be prevented?
BUE formation is a common machining problem but there's a soluion to every problem.Here are a few prevention steps to reduce BUE formation
Increasing cutting speed
Use of cemented carbide tool in place of HSS tool
Introduction of free machining materials ( loaded or resulphurized steel)
Application of an appropriate lubricant at low cutting speed