What does the E in HSS-E mean?

HSS (High Speed ​​Steel):

HSS is a type of tool steel characterized by high hardness, wear resistance, and heat resistance.

It gets its name from its ability to maintain its hardness ("red hardness") even at the high temperatures generated by high-speed cutting (approximately 500-600°C).

"E" stands for "Efficiency":

HSS-E is a special grade of high-speed steel, distinguished by the addition of cobalt (Co).

The addition of Co significantly improves the steel's high-temperature performance (red hardness) and wear resistance.

This ensures that HSS-E tools maintain a longer tool life and greater stability under more demanding machining conditions (such as cutting more difficult materials, at higher cutting speeds, or for longer continuous machining times), significantly improving machining efficiency.

Main Features and Applications of HSS-E:

Main Alloying Elements: In addition to the common tungsten (W), molybdenum (Mo), chromium (Cr), and vanadium (V) elements found in high-speed steel, Cobalt (Co) is a key characteristic, typically present in an amount between 5% and 10%.

Advantages:

Extremely high hardness and wear resistance.

Excellent hot hardness, with slower performance degradation at high temperatures.

Good resistance to temper softening.

Disadvantages:

Due to the cobalt content, it is slightly less tough than ordinary high-speed steel and more brittle.

More expensive.

Typical Applications:

Used for machining high-hardness, high-strength materials such as high-temperature alloys, titanium alloys, and hardened steel.

Used for manufacturing complex tools for high-speed, heavy-duty cutting, such as drills, milling cutters, taps, and broaches.

Comparison with Other High-Speed ​​Steels:

Ordinary HSS (such as M2): Versatile and cost-effective, suitable for most general machining applications.

HSS-E (such as M35): Contains cobalt and offers high performance, suitable for more demanding machining applications.

HSS-E VAP (or similar): Based on HSS-E, it also features a surface coating (such as TiN or TiAlN) for even better performance and longer life.

In summary, the "E" in HSS-E directly points out the core advantage of this material: higher efficiency and performance achieved by adding cobalt to meet more stringent metal processing needs.