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Coatings on Cutting Tools

Metal Cutting Tools Get a New “Coat”

Men (and women) have been cutting metal in machine shops since the late 19th century. They started with crude ideas and methods which have progressed to the current “high tech” technologies of today. The constant during these progressive years has been the cutting tool itself. The actual product that contacts the raw metal, cuts and removes chips from the raw stock, creates the finished work piece. Cutting Tools have evolved over the years from high carbon steel, to high speed steel, to cobalt, to carbide, and for specific applications, diamond and ceramics.

In the late 1970’s a company named Balzers started applying a very thin film to cutting tools, thus improving their overall life, in some cases, by 400%. This process is called “surface treatment” or “tool coating” and is used widely in today’s machine shops and manufacturing facilities.

There are several processes used to apply surface treatments, but the (2) main types used for cutting tools are PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition) and these are readily available from special coating facilities located throughout the world. My goal with this article is to share with the reader some common PVD and CVD choices, and reasons to utilize each.

The right surface treatment on cutting tools can increase tool life, decrease cycle time and enhance surface finishes. However, choosing the right coating can seem overwhelming at best. Each one has some distinct advantages and disadvantages depending on your individual set of machining in the machining process.

Coatings have several characteristics to be aware of:

Microhardness HV
Abrasion Resistance
Friction Coefficient
Max Service Temperature

Hardness
A high surface hardness from your coating is one of the best ways to increase tool life. Coating hardness is measured in units called HV, (Hardness Vickers). TiN is the start point with a hardness of about 2300 HV, followed by TiCN at 3000 HV, TiALN at 3500 HV and AlTiN ringing in at about 4000HV. Tools coated with these coating ZANUSSI ZCG554NX1 would work best in ferrous and non ferrous materials, such as stainless steel, carbon steels and aerospace materials like Inconel and the like. With a surface hardness near 10,000 Vickers, CVD diamond coatings
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