Why Carbide Tools Break/Shatter
Solid carbide end mills are extremely high-performance tools in CNC machining, offering high rigidity and good resistance to high temperatures. However, compared to HSS tools, carbide is more brittle, and under certain conditions, end mills can break suddenly.
Understanding the main causes of end mill breakage can help prevent production defects and reduce tool costs.
1. Vibrations during machining
One of the most frequent causes of end mill breakage is excessive vibration.
Vibrations can occur for several reasons:
• poor workpiece clamping
• incorrect tool clamping in the tool holder
• excessive tool overhang from the tool holder
• low rigidity of the clamping system
Vibration produces alternating stresses on the cutting edges, which can rapidly lead to the appearance of microcracks and subsequently tool breakage.
2. Incorrect cutting parameters
Cutting parameters play an essential role in the tool's lifespan.
Frequent problems:
• feed rate too high
• spindle speed too low
• depth of cut too high
• excessive tool load
These situations can generate cutting forces far exceeding the tool's limits.
3. Excessive tool wear
A worn end mill becomes more vulnerable to breakage.
As the cutting edges wear:
• cutting forces increase
• temperature in the cutting zone increases
• microcracks appear in the material
If the tool continues to be used under these conditions, breakage becomes inevitable.
4. Mechanical shocks
Carbide end mills do not tolerate mechanical shocks well.
Breakage can occur when:
• the tool suddenly enters the material
• there are frequent interruptions in cutting
• the tool hits a hard spot in the material
• there are errors in the CNC program
Mechanical shocks can cause instantaneous cracks in the carbide structure.
5. Insufficient cooling
Excessive temperature is another factor contributing to end mill breakage.
Frequent causes:
• insufficient coolant flow
• poor chip evacuation
• material buildup on the cutting edge
High temperatures accelerate wear and can lead to damage of the PVD coating.
6. Machined material
Some materials are more challenging for carbide tools.
Examples:
• very hard steels
• mold steels
• stainless steel
• abrasive materials
In these cases, it is important to use tools with appropriate geometry and coating.
How to prevent end mill breakage
To reduce the risk of breakage, it is important to:
• use correct cutting parameters
• reduce tool overhang from the tool holder
• use precision tool holders
• regularly check tool wear
• use PVD coatings suitable for the material
Carbide end mill reconditioning
Worn end mills should not be discarded immediately. In many cases, they can be reconditioned through CNC grinding and reapplication of the PVD coating.
Through reconditioning:
• tool geometry is restored
• cutting edges are resharpened
• the tool can be used again in production
The cost of reconditioning is usually 50–70% lower than purchasing a new end mill.
Professional Services – Sefira
SEFIRA offers complete reconditioning services for solid carbide end mills, drills, and other cutting tools.
The process includes:
• high-precision CNC grinding
• honing of cutting edges
• industrial cleaning
• high-performance PVD coatings
• dimensional inspection
📧 info@sefira.ro
📞 +40 712 333 902
More information about services can be found at www.sefira.ro