Coatings can be a bit overwhelming. Here are some things to consider when choosing whether or not to have your tools coated and which type of coatings to choose.

The Physical Vapor Deposition (PVD) Process
When coating tools, Super Tool uses the Physical Vapor Deposition (PVD) process because it allows for more aggressive machining while maintaining the strength and hardness of the steel bodies. The PVD process is a vacuum process that shoots charged particles at the tool causing an atomic reaction. A beam of electrons is shot at the tool causing them to bond with atoms on the surface. This creates a hardened coat around the coated area of the tool giving it great strength and durability. PVD coating can also create smoother and sharper cutting edges, which helps to reduce edge build up and can improve the finish cut of the tool.

The Four Main Coating Types
There are many coatings to choose from. We offer the four main types: Titanium Nitride (TiN), Titanium Carbonitride (TiCN), Zirconium Nitride (ZrN), and Aluminum Titanium Nitride AlTiN.  The following chart can help you determine which coating to use for the operation your tool is performing.

MATERIAL MACHINED  

DRILLING

REAMING

COUNTERBORING

MILLING

WET (Coolant)

WET (Coolant)

WET

(Coolant)

DRY

 

WET (Coolant)

DRY

 

Non-Ferrous (Soft)

ZrN

TiCN/ZrN

ZrN

ZrN

ZrN

ZrN

Non-Ferrous (Hard)

ZrN

TiCN/ZrN

ZrN

ZrN

ZrN

ZrN

Cast Iron

AlTiN

TiCN/AlTiN

AlTiN

AlTiN

AlTiN

AlTiN

Low Carbon Steels

AlTiN

AlTiN

AlTiN

AlTiN

AlTiN

AlTiN

Medium Strength Steels

AlTiN

AlTiN

AlTiN

AlTiN

AlTiN

AlTiN

High Strength Steels

AlTiN

AlTiN

AlTiN

AlTiN

AlTiN

AlTiN

High Temperature Alloys

AlTiN

AlTiN

AlTiN

*

AlTiN

*


Why Coat Tools
Coating tools can improve the tools productivity in the following ways:

  1. Thermal Insulation – the build up of heat as the tool is cutting is one of the main reasons tools can break down. Coatings create an insulation barrier to help reduce the amount of heat that is generated during operation by pushing the heat back to the chip. Insulation can also allow the user to increase the feeds and speeds at which the tool is run.
  2. Mechanical Strength – Under normal operation, the roughness of the tools cutting edge and the abrasion from the chips cause the cutting edge to dull. With coating, friction is reduced and hardness of the tool is increased which causes the chips to flow easier and reduces tool wear.
  3. Chemical Resistance – Tools experience all sorts of chemically reactive forces during operations (i.e. heat, coolant, and the material of the workpiece itself). Coatings help to prevent the degradation of the tool (loss of tool life) by helping to repel these forces and improve cutting quality.

These are just a few reasons to consider coating your tools. Remember, having a coating put on your tools will increase the price and may lengthen the delivery time if it is not a stocked item, however, the extended life of the tools and better finish of the tools can be worth the wait.

 

Chadd Brown
Super Tool, Inc.

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  1. Applying a coating to a tool allows the user to substantially increase speeds and feeds while minimizing tool wear. Selecting the correct coating and its attributes can mean the difference between a successful operation and one that shows little to no difference.

  2. Tom Walz says:

    Very nice chart. Thank you.

  3. MP Krishnan says:

    Why Milling is mostly done dry?
    Can using a coolant improve tool life of Milling inserts (both PCD & Carbide) ?
    (esp. w.r.t milling of Aluminium component)

    • brednane1981 says:

      Dry machining is frequently used in milling applications when using high performance cutting tools such as carbide. While liquid coolant offers advantages including temperature cooling, lubrication, and chip clearing improperly applied liquid coolant can do more damage than good.

      It is difficult to genuinely flood carbide milling cutters whether it is an end mill, slitting saw, face mill, etc… With the high rpm rates used the teeth are continuously subjected to wet then dry then wet again which results in uneven cooling of the tool. Carbide is highly susceptible to micro-cracking due to the thermal shock of this uneven heating and cooling.
      Once the micro cracking begins, the tool fails. Therefore, dry machining is typically used in milling applications.

      When dry milling keep in mind that heat buildup can generate additional problems. Often instead of liquid coolant, the machinist will switch to compressed air as a coolant in these applications.

      When it is possible to truly flood the tool with liquid coolant there can be significant improvements in tool life and stock removal rates.

  4. john hook says:

    thank you for the information on the use of lubricants for milling . it was very informative.