Coated cutting tools and their applications
Before beginning a carbide cutting operation many considerations are made, like using a coated cutting tool or noncoated cutting tool and coolant. It’s well known that carbide does well with heat yet not always remembered that intense fluctuations in its thermal temperature can shock the tool or the part, impacting overall tolerance. Therefore, many manufacturers would recommend flooding your operation, at what cost though? You could be using a lot of coolants.
As we mentioned in our last blog, innovation has been the drive behind our modern tools and by 1971 coatings became the standard. Each coating services a specific purpose but the deciding factor should fall on the use of your tool. To bring more understanding to the advantages to coatings here are five points of discussion to have with your coating provider:
Selecting a coating with high surface hardness will indefinitely increase tool life. Compared to the uncoated tool and coolant you typically can run coated tools at speeds two to three times higher. If you are looking for a coating that offers good adhesion, resistance to chipping, and a great level of toughness either go for Titanium Nitride(TiN) for short runs or Titanium Carbo-Nitride (TiCN) for the long run.
Increased heat means decreased coating life or complete coating failure. A higher lubricity can also allow for higher speeds than that of their non-coated counterparts. It’s important to look for reduced coarseness or irregularities to help keep friction down. Specifically, in carbide cutting the tool will allow the chips to fall or slide away from the tool face and generates less heat.
In many operations, although a material may not be hard, elements and processes are added to the project that could begin to form lobes or attempt to break down the cutting edge. If you are looking to protect against abrasion consider Zirconium Nitride (ZrN.)
4. Seizure free properties
Poor coolant or concentration is often the cause of lock ups or Build Up Edge (BUE). As materials start bonding to the tool, like aluminum, it will grow larger and larger and eventually need to be scrapped. A seizure free property like Chromium Nitride (CrN) will prevent chemical bonding between the cutting material and tool.
Treatments can begin to break down at oxidation temperatures. Typically, the protection is intended to transfer the heat away from the tool and into the chip and sometimes the part. For operations that will reach high temperatures, it had been a safe bet to go with Titanium Aluminum Nitride (TiAlN) or Aluminum Titanium Nitride (AlTiN) coatings. The new up-and-coming Aluminum Chromium Nitride (AlCrN) has since proved to be more effective in efficiently adhering to one another and protecting the tool. However, these three coatings are extremely consistent in long milling operations.
At the end of the day, the coating you select can make the difference in long and dynamic operations. Cost-effective coatings are dependent on several variables, as you may have noticed there are several variations for every operation. But when it comes to cutting costs and increasing productivity coated carbide cutting tools are the way to go. You should always check for newest and leading coatings available for your operation.