Tom Beaumont

Product Training Manager

18 years engineering experience, specialising in 3 & 4 axis CNC milling, turning and horizontal boring.

Carbide and HSS are two popular substrates used in the manufacturing of milling cutters. Each material has its own strengths and weaknesses, and the choice between carbide and HSS milling cutters depends on various factors such as the type of material being machined, the desired cutting speed, tool life requirements, cost considerations and your machine set up/capabilities.

What is HSS?

HSS stands for High-Speed Steel. It is a type of tool steel that is known for its excellent balance of hardness, toughness, and wear resistance, making it suitable for a wide range of machining applications.

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% Cobalt (or HSSE) – A type of high-speed steel alloy that contains 8% cobalt. It is a tool steel that has excellent hardness, wear resistance, and heat resistance properties. The addition of cobalt makes the tool more durable and capable of withstanding higher temperatures during cutting operations.

HSS 5% Cobalt (or HSSE) – A type of high-speed steel alloy that contains 5% cobalt. This type of HSS is known for its excellent combination of hardness, toughness, and wear resistance. Having 5% cobalt makes the tool more robust.

HSS – The lowest grade of high speed steel without any cobalt content. Not commonly seen in metalworking anymore due to newer substrates being developed that are higher performing.

Why would you use HSS?

You would use HSS Milling Cutters mainly when you have a manual machine.

HSS milling cutters are designed for machining soft materials such as softer steels, aluminium and brass. They have a high working hardness with excellent toughness whilst remaining sharp during prolonged use. They are relatively affordable and provide a good balance between durability and efficiency.

However, one of the downsides of HSS milling cutters is their limited cutting speed. They are not as hard as carbide, so they cannot withstand the same level of heat and speed without losing their cutting edge. Additionally, HSS milling cutters are typically not suitable for cutting hard materials like stainless steel, which can quickly wear down the cutting edge.

What is carbide and what are the different types of carbide?

Carbide Milling Cutters are made from a combination of tungsten carbide and cobalt, making them significantly harder than HSS. They are a popular choice used by many engineers in CNC machining.

The different types of carbide include:

Micrograin Carbide - This refers to carbide materials that have relatively larger carbide grains, typically in the range of 0.2 to 2 micrometers. The larger grain size provides increased toughness and impact resistance, making micrograin carbide suitable for applications that involve interrupted cutting, difficult-to-machine materials, or heavy machining operations.

Ultrafine Carbide – This refers to carbide materials with smaller carbide grain sizes compared to micrograin carbide. The grain size typically ranges from 0.1 to 0.5 micrometers. The smaller grain size provides improved hardness and wear resistance, making ultrafine carbide suitable for applications that require high precision, fine surface finishes, and extended tool life.

Nanograin Carbide – This takes the concept of grain size reduction even further, with grain sizes typically in the range of a few nanometers (less than 100 nanometers). The extremely small grain size enhances the material's hardness, wear resistance, and overall strength. Nanograin carbide is used in applications that demand exceptional performance, such as high-speed machining, fine finishing, and cutting of very hard materials.

Why would you use carbide?

This substrate material is ideal for machining hard and abrasive materials such as titanium, stainless steel, and cast iron. Carbide can withstand high temperatures and maintain its cutting edge for more extended periods, making it highly efficient.

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

However, carbide cutters are more expensive than HSS cutters. They are also brittle and can crack or fracture if subjected to excessive stress or impact. For this reason, carbide cutters require a high level of precision during handling and cutting, which makes them unsuitable for manual machines or unstable cutting conditions.

What other substrates are available?

Powder metal is another substrate that is commonly used in various milling applications. This can include general milling, profiling, slotting and more. Powder metal is often more cost-effective than solid carbide cutters while still delivering excellent performance. With high wear resistance, long tool life is achieved.

Powder Metal Milling Cutters can withstand higher cutting speeds, making them suitable for high-speed machining applications. Powder metal also offers similar performance to carbide with the toughness of HSS. Therefore, it is ideal to use for when HSS wears too fast and where carbide is too brittle.

What types of Milling Cutters do Cutwel supply?

Cutwel have the UK's largest of milling cutters for UK next day delivery. We have milling ranges available for every application, material, size & performance. See below for a brief overview of our best selling Carbide, HSS & Powder Metal milling cutters.

Our best-selling carbide milling cutters are the K2 Carbide and K2 Carbide Multiple Helix Milling Cutters from global supplier YG-1. Great for machining steel up to 45HRC, stainless steel and cast iron, the K2 carbide range provides consistent and reliable performance in general machining conditions. 

Our HSS Milling Cutters should be considered where additional toughness is required. For unstable or manual machining, our YG-1 range provides exceptional value and tool life, suitable for steel and non-ferrous materials.

When HSS wears too fast or when carbide is too brittle, YG-1's OnlyOne is the ideal option, providing great performance on steel, stainless steel and cast iron. This powder metal milling cutter can be used on CNC and manual machines, even in unstable cutting conditions.

Summary

When it comes to choosing between HSS and carbide milling cutters, your decision will largely depend on the materials you will be cutting and the conditions under which you will be doing it. No matter which substrate you choose, it's essential to keep your milling cutters well-maintained to ensure optimal performance and longevity.

To sum up, if you are machining softer materials and need an affordable and durable milling cutter, HSS would be the ideal option if using a manual machine. However, if you require that next step up in performance or you are machining hard and abrasive materials carbide milling cutters are the go to substrate.

HSS, Powder Metal & Carbide milling cutters for general machining steel, stainless steel, cast iron & non ferrous materials

Carbide milling cutters designed for high performance milling at high speeds & feeds and in the toughest machining conditions

Coated and uncoated HSS milling cutters for steel and non-ferrous materials.