Cemented Carbide and HSS are common base materials used in the manufacture of end mill

.ss‍Both have advantages and disadvantages. The choice of endmill made of carbide and HSS depends on various factors. Such as the type of material being machined, required cutting speed, tool life requirements, cost considerations, and machine setup/machine capabilities.

What's HSS?

High-speed steel is a tool steel with high hardness, high wear resistance and high heat resistance, also known as high-speed tool steel or sharp steel.

It is widely used in various cutting and machining applications in industries such as manufacturing, metalworking and engineering.

What are the different types of HSS?

HSS 8%Co,---It's the HSS alloy containing 8% cobalt. It is a tool steel with excellent hardness, wear resistance and heat resistance. The addition of metallic cobalt makes the tool more durable and able to withstand higher cutting temperatures.

HSS 5%Co---It's the HSS alloy containing 5%cobalt. This type of HSS is known for its excellent combination of hardness, toughness and wear resistance. 5% cobalt HSS are even stronger.

High-Speed Steel – The lowest grade of high-speed steel without any cobalt.It is no longer common in metalworking as new substrates with higher performance are being developed.

Why choose HSS?

When you have a manual machine tool, you will primarily use HSS End Mills

HSS end mill cutters are designed for machining soft materials such as machining soft steel, aluminum, and brass. They have a high working hardness and excellent toughness while maintaining their sharp edges during long periods of use. They are relatively inexpensive and offer a good balance between durability and efficiency.

However, one of the disadvantages of HSS End Mills is their limited cutting speed. They're not as hard as carbide, so they can't withstand the same heat and hold a cutting edge at the same turning speed. Additionally, HSS milling cutters are usually unsuitable for cutting hard materials like stainless steel because they quickly wear out the cutting edge.

What's the carbide and the different types?

Carbide end mills are made from a combination of tungsten carbide and cobalt, it's much harder than HSS. They are the dominant choice used by many engineers in CNC machining.

Carbide types:

Microcrystalline carbide: Refers to carbide materials with relatively large carbide particles, typically in the 0.2 to 2 um range. Larger grain size increases toughness and impact resistance, making microcrystalline carbides suitable for interrupted cuts, cutting difficult materials, or heavy machining applications.

Ultrafine Carbide - This refers to carbide materials with smaller grain sizes compared to microfine carbides. Grain sizes are typically between 0.1 and 0.5 microns. Smaller grain sizes provide increased hardness and wear resistance, making ultrafine carbides suitable for applications requiring high precision, fine surface finishes, and extended tool life.

Nano carbides - This further reduces the concept of grain size, which is typically in the range of a few nanometers (less than 100 nm). The extremely small grain size increases the hardness, wear resistance and overall strength of the material. Nanocarbides can be used in applications where specialized properties are required, such as high-speed machining, finishing and cutting extremely hard materials.

Why choose carbide ?

It is the ideal tool material for machining hard and abrasive materials such as titanium, stainless steel and cast iron. Carbide can withstand high temperatures and maintain its cutting-edge performance for a longer period of time, making it efficient.

Carbide End Mills can also achieve faster cutting speeds than HSS milling cutters, making them an excellent choice for high-speed cutting operations.

However, carbide tools are more expensive than HSS tools. They are also brittle and can crack or break if subjected to excessive pressure or impact. As a result, carbide tools require a high degree of machine tool accuracy in handling and cutting, which makes them unsuitable for manual machines or unstable cutting conditions.

Any other tooling material?

Powder metallurgy metal is another substrate that is commonly used for a variety of milling applications. This can include general milling profiles, grooving and many more different types of machining. Powdered metal is often more cost-effective than solid carbide tools, while still offering excellent performance. Their high wear resistance enables long tool life.

Powdered metal endmills can withstand higher cutting speeds, making them suitable for high-speed machining applications. Powder metallurgy metals also have similar properties to carbides, with the toughness of high-hardness alloys. This makes it ideal when HSS wears too quickly and carbides are too brittle.

Conclusion

When it refers to choosing HSS or carbide end mills, your decision will depend heavily on the material you will be cutting and the machining conditions. Regardless of which tool substrate you choose, it's important to keep your milling cutter well-maintained to ensure optimal performance and longevity.

To summarize, if you are machining softer materials and need an affordable and durable milling cutter, if you have a manual machine tool then an HSS HSS milling cutter would be the ideal choice however, if you need to go a step further in terms of performance or if you need to machine hard wear-resistant materials, carbide milling cutters are the way to go.