Nathan Smith

Technical Support

10 years engineering experience, specializing in CNC 3 & 4 axis milling, measurement and inspection.

When it comes to milling cutters, they are generally either coated or uncoated. Both have their advantages and disadvantages, but which one is better and how do you choose between them? Let’s explore each type in more detail:

What are coated milling cutters?

Coated milling cutters have a thin layer of coating applied to their surface, this can either be done via a CVD (chemical vapour deposition) or PVD (physical vapor deposition) method. This coating can be made from various material combinations, such as titanium nitride (TiN), titanium carbo-nitride, (TiCN), titanium aluminium nitride (TiAlN) or diamond-like carbon (DLC) just to name a few. The purpose of the coating is to increase the hardness of the cutter and provide better wear resistance during the machining process. Coated cutters have a lower friction coefficient, which means they have a longer lifespan and can cut through materials faster.

What are the advantages of coated milling cutters?

Extended tool life - The coatings enhance the tool's wear resistance, resulting in longer tool life, especially when cutting difficult materials or high-temperature alloys.

Higher cutting speeds - Coated cutters can often withstand higher cutting speeds thus increasing productivity.

Reduced friction and a better finish - The coatings reduce friction and enhances lubrication between the tool and workpiece, resulting in lower cutting temperatures and improved surface finish.

Thermal insulation – Heat generation can wear tools quicker, specific coatings have been produced to withstand higher temperatures in order to protect the tool and workpiece for longer periods.

What are the disadvantages of Coated Milling Cutters?

Limited material compatibility - Some coatings may not be suitable for certain materials, so their applications might be restricted. For instance, Aluminium (and other non-ferrous metals) can stick to certain coatings which causes a build up of sticky swarf. This can result in faster tool wear, complete burn out of the tool or damage to the workpiece.

Unsuitable for low-speed cutting – Coated milling cutters are prone to chipping or peeling when used at lower speeds, therefore making them potentially unsuitable.

Higher cost - Coated cutters are generally more expensive due to the additional coating process, so if budget is a concern and performance/tool life isn’t required then an uncoated cutter could be an option.

What are uncoated milling cutters?

Uncoated milling cutters, as the name suggests, do not have any coating on their surface. They are commonly used for low cost general-purpose milling operations on ferrous metals or they are the preferred choice for higher performance non-ferrous applications such as Aluminium.

What are the advantages of uncoated milling cutters?

Ideal for non-ferrous applications – A polished, uncoated milling cutter will offer high performance machining on non-ferrous applications such as Aluminium. Some coatings can stick to these types of material which can cause swarf issues that affect tool life and workpiece finish.

Cost-effective – For general purpose applications, uncoated milling cutters are generally more affordable than coated ones. Therefore these are ideal for anyone on a budget.

Versatility - They can handle a broad range of materials and applications in general purpose economy machining.

Easy to resharpen - Uncoated cutters are relatively easy to resharpen when they become dull.

What are the disadvantages of uncoated milling cutters?

Lower tool life - Uncoated cutters may have a shorter lifespan compared to coated ones, especially when machining harder or more abrasive materials.

Cannot withstand higher temperatures - The lack of a coating can lead to higher cutting temperatures, which may affect tool life and surface finish.

Unsuitable for higher speeds & feeds – Due to the accelerated risk of tool wear with uncoated cutters, this mames them unsuitable for high speed or high feed milling applications.

Coated Vs Uncoated - which is better?

The answer to this question depends on the specific cutting application and the materials being worked on. Coated milling cutters are generally preferred for high-speed machining and cutting through tough materials, such as stainless steel or titanium. They offer better wear resistance and longer tool life, which can save money in the long run. However, coated cutters are more expensive than uncoated ones, so the cost-benefit analysis must be carefully considered.

Uncoated milling cutters are typically used for softer materials, such as aluminium or brass. They are cost-effective and can be used for a wide range of general purpose applications. However, they are not as durable as coated cutters and may need replacing more frequently. 

Summary

In summary, both coated and uncoated milling cutters have their place in a workshop. Choosing the right one depends on the specific cutting application and material being worked on. 

Cutwel supply a wide range of coated and unocated milling cutters from leading brands YG-1, Korloy & Karnasch.

For machining softer materials, like aluminium, you would usually use an uncoated milling cutter. Aluminium swarf tends to be sticky or long chipping therefore you can encounter various issues which can lower your tool life or affect your surface finish should you not use the appropriate tool.  Our Alumininum Milling Cutters include the Alu Power, Alu Power HPC,  A+, and Alu-Splitter milling cutters.

If you're machining stainless steel, cast iron, steel or titanium, we have a huge range of coated carbide milling cutters to help with your applications. Some of these include: V7 Inox, Kennametal Harvi I TE Milling Cutters, X-Power Pro Milling Cutters, X5070 Blue Milling Cutters and lots more!

Need more help?

Please contact our expert technical team who can provide advice on your application and help you with tool selection. Please call 01924 869 615, email sales@cutwel.net or fill in the form below!

Carbide milling cutters for general machining a wide range of materials

Low cost HSSE milling cutters for general purpose applcations

For high performance and general purpose aluminium milling applications