KNUX 160405 R-M1 UE6020 Mitsubishi Carbide Insert: Technical Analysis for Maximum Efficiency in Steel Machining
Introduction
Achieving high productivity in metal cutting is not solely dependent on having a powerful CNC machine. One of the most critical factors determining machining performance is selecting the correct indexable carbide insert. A different carbide grade or chipbreaker geometry used in the same toolholder can double tool life—or, conversely, render the insert unusable within minutes.
For this reason, professional manufacturing facilities select cutting inserts not only by consulting catalogs but also by evaluating the workpiece material, cutting parameters, machine rigidity, workholding conditions, and overall production cost.
In this article, we examine the Mitsubishi Materials KNUX 160405 R-M1 UE6020 carbide insert from a mechanical engineering perspective, covering its geometry, coating technology, chipbreaker design, application areas, and machining performance in detail. The KNUX 160405 R-M1 is a negative turning insert designed primarily for steel machining, featuring the M1 chipbreaker and UE6020 CVD-coated carbide grade.
Technical Analysis of the KNUX 160405 R-M1 Code
Every marking on an indexable insert identifies a specific technical feature.
KNUX
 
 
K – 55° parallelogram insert geometry
 
 
N – 0° clearance angle (negative insert)
 
 
U – Hole configuration and tolerance specification
 
 
X – Special insert design

160405
 
 
16 – Cutting edge size
 
 
04 – Insert thickness (approximately 4.76 mm)
 
 
05 – 0.5 mm nose radius

R
Indicates right-hand cutting geometry.
M1
A Mitsubishi chipbreaker optimized for medium machining and semi-roughing operations, providing reliable chip control across a wide range of steel applications.
UE6020
A CVD-coated carbide grade featuring TiCN / Al₂O₃ / TiN multilayer coating technology, offering an excellent balance between wear resistance and edge toughness for ISO P steel machining.
Why Choose a Negative Geometry Insert?
The KNUX series features a negative insert geometry.
Compared with positive inserts, negative inserts provide a larger wedge angle, resulting in:
 
 
Stronger cutting edges
 
 
Higher resistance to impact loading
 
 
Improved reliability during heavy roughing
 
 
Reduced risk of edge chipping

Negative inserts are particularly suitable for machining:
 
 
Forged components
 
 
Castings with scale
 
 
High-strength alloy steels
 
 
Large-diameter shafts
 
 
Interrupted cutting applications

UE6020 Carbide Grade
Insert performance depends not only on geometry but also on carbide grade.
The UE6020 grade combines:
 
 
Fine-grain tungsten carbide substrate
 
 
Optimized cobalt binder
 
 
Multilayer CVD coating technology

Its coating consists of three functional layers:
TiCN Layer
 
 
High hardness
 
 
Low friction
 
 
Excellent abrasion resistance

Al₂O₃ Layer
Acts as a thermal barrier, reducing heat transfer into the carbide substrate and significantly extending tool life at higher cutting speeds.
TiN Top Layer
 
 
Reduces friction
 
 
Improves chip flow
 
 
Enhances surface finish

How the M1 Chipbreaker Works
During cutting, the workpiece material undergoes severe plastic deformation ahead of the cutting edge.
Without proper chip control:
 
 
Long continuous chips form
 
 
Chips wrap around the workpiece
 
 
Surface damage may occur
 
 
Automated production can be interrupted

The M1 chipbreaker features specially engineered grooves that curl chips into a controlled radius before breaking them.
This provides:
 
 
Short, controlled chips
 
 
Reliable unattended machining
 
 
Reduced operator intervention
 
 
Improved production safety

Recommended Workpiece Materials
The UE6020 grade has been developed primarily for ISO P steels.
Typical applications include:
Carbon Steels
 
 
C35
 
 
C45
 
 
CK45
 
 
C60

Structural Steels
 
 
S235
 
 
S355
 
 
ST37
 
 
ST52

Alloy Steels
 
 
16MnCr5
 
 
20MnCr5
 
 
42CrMo4
 
 
34CrNiMo6
 
 
AISI 4140
 
 
AISI 4340

Under suitable cutting conditions, it can also be applied to selected stainless steel grades.
Evaluation from a Manufacturing Engineering Perspective
For a manufacturing engineer, the most important criterion is not the purchase price of an insert but the cost per machined component.
Consider two inserts:
Insert A
 
 
Tool life: 20 minutes

Insert B (UE6020)
 
 
Tool life: 35 minutes

Although Insert B may have a higher purchase price, it offers:
 
 
Fewer tool changes
 
 
Reduced machine downtime
 
 
Increased production capacity
 
 
Lower labor costs

As a result, the total production cost per part is often significantly lower.
Professional manufacturers therefore evaluate inserts based on cost per part, not simply purchase price.
Example Machining Application
Workpiece
Material: 42CrMo4
Hardness: 280 HB
Diameter: Ø160 mm
Operation
 
 
Rough turning
 
 
Depth of cut: 3 mm
 
 
Feed: 0.35 mm/rev
 
 
Cutting speed: 220 m/min

Under these machining conditions, the M1 chipbreaker provides:
 
 
Stable chip breaking
 
 
Reduced vibration
 
 
Balanced cutting forces
 
 
Improved tool life

Actual machining parameters should always be optimized according to machine rigidity, coolant supply, and workholding conditions.
How to Increase Tool Life
Proper application is just as important as carbide grade.
To maximize insert life:
 
 
Use a rigid toolholder.
 
 
Clamp the workpiece securely.
 
 
Avoid excessively low feed rates.
 
 
Maintain continuous and adequate coolant supply.
 
 
Minimize tool overhang.
 
 
Select cutting parameters appropriate for the workpiece material.
 
 
Ensure unrestricted chip evacuation.

These practices help reduce edge chipping and uneven wear.
Common Wear Mechanisms
Flank Wear
The most common and predictable wear pattern.
Symptoms include:
 
 
Reduced surface finish
 
 
Increased cutting forces
 
 
Dimensional inaccuracies

Crater Wear
Occurs on the rake face.
Main causes:
 
 
High cutting temperatures
 
 
Diffusion wear

Built-Up Edge (BUE)
Occurs when workpiece material adheres to the cutting edge, especially at low cutting speeds.
Effects include:
 
 
Poor surface finish
 
 
Dimensional variation
 
 
Irregular chip formation

Chipping
Localized fracture of the cutting edge.
Typical causes include:
 
 
Machine vibration
 
 
Interrupted cutting
 
 
Incorrect feed rates
 
 
Poor workholding rigidity