The service life of carbide end mills

The service life of carbide end mills

The life of carbide end mills is affected by many factors, including materials, cutting parameters, working conditions and tool management. Reasonable use can significantly extend the life. The following are the key points:

I. Core factors affecting life

1. Material to be processed

- Soft steel (such as 1018): The tool wears slowly and has a longer life.

- Medium hard steel (such as 4140 quenching and tempering): Due to work hardening, wear accelerates.

- High hard steel (such as D2 mold steel ≥60HRC): The life is greatly shortened, and special coatings (such as AlTiN) are required.

2. Tool parameters

- Coating: TiAlN (high temperature resistant) is suitable for hard steel; TiN is more suitable for soft steel.

- Edge treatment: Chamfering or passivation treatment reduces the risk of chipping.

- Chip groove design: Large chip grooves are suitable for soft steel, and small grooves enhance the cutting rigidity of hard steel.

3. Cutting parameters

- Too high speed/feed: Causes thermal wear (craters) or chipping.

- Too low parameters: Increases friction rather than cutting, shortens life.

II. Expected life reference for different materials

Material hardness	Typical life (cutting minutes)	Failure Mode
Mild Steel（<30HRC）	60–120+	Uniform wear on the flank
Medium hard steel（30–45HRC）	30–60	Blade tip breakage + thermal cracking
High hardness steel（>45HRC）	10–30	Coating peeling + macro chipping

III. Practical strategies to extend tool life

1. Optimize cutting parameters

- Hard steel: Reduce linear speed (Vc=50–80m/min) and feed (fz=0.03–0.08mm/tooth).

- Soft steel: Increase parameters (Vc=150–250m/min, fz=0.1–0.2mm/tooth), but avoid built-up edge.

2. Cooling and lubrication

- Hard steel/deep cavity: High pressure internal cooling (＞7MPa) is preferred to prevent thermal shock.

- Dry cutting: Only for coated tools, and the temperature must be strictly monitored.

3. Tool path optimization

- Trochoidal milling: Reduce full-edge engagement and dissipate heat more evenly.

- Progressive machining: Step milling replaces full-depth cutting.

4. Maintenance habits

- Regular cleaning of the chip groove: Avoid chips from rubbing the tool again.

- Pre-wear inspection: Stop the machine every 20 minutes to observe the condition of the cutting edge.

Fourth, warning signs of the end of life

- Cutting force mutation: The machine tool load increases abnormally (the spindle current increases).

- Surface quality decreases: The burrs increase and the finish becomes worse.

- Abnormal noise/vibration: It indicates that the cutting edge is worn or broken.

- Chip color change: Blue oxide chips indicate overheating.

V. Comparison of life of cemented carbide vs. other materials

Tool type	Soft steel life ratio	Hard steel life ratio	Cost ratio |
Cemented carbide	1×	1×	1×
Powder metallurgy high-speed steel	0.3×	Not applicable	0.5×
Ceramic/CBN	Not applicable	3–5×	5–8×

Suggestion: For small batches and multiple varieties, choose cemented carbide, and for large batches and high hardware, consider CBN coating.

VI. Failure case analysis

- Problem: Tool life is only 15 minutes when processing 42CrMo (35HRC).

- Reason: Vc=120m/min is too high, resulting in thermal failure of the coating.

- Improvement: Reduce to 80m/min, and the life is extended to 45 minutes.

Summary: The life of carbide end mills ranges from **10 minutes to several hours**. The key is to maximize economic benefits through parameter adaptation, cooling optimization and path planning. Recording each processing data and gradually establishing an in-plant database is the most reliable.

Contact us or send inquiry：

Changzhou Hiboo Tools Co., Ltd.

Email:sales01@hiboo-tool.com

Website: www.hiboo-tools.com