The cutting process – A tribological nightmare 05:09

The basics of metal cutting are not too difficult to understand. You need a cutting edge, a work piece and a machine that rotates the work piece or the cutting edge depending on method. But, to really understand the whole process is a lot more challenging.

The first thing is to understand the cutting process as a tribological system, which can be defined as a system with surfaces in mechanical contact under relative movement to each other. Depending on the work piece material, type of machining strategy, machine rigidity, cutting tool material, tool coating, coolant, edge preparation, etc., the different types of tribological systems are very different from one to another and every change in the system can completely change the behaviour of the tool wear and tool deterioration.

Another thing that does not make the situation easier is the fact that a materials outer layer usually set the mechanical wear behaviour. But on a cutting insert, where a coating is applied on top of the bulk material (carbide, ceramic or PCBN), the wear behaviour is changed when the coating is worn off. But despite that, a coating can heavily increase tool life due to improved wear resistance, improved resistance to chemical wear or simply a change of friction between the chip and the insert.

To make this discussion even more complex, the cutting zone can be divided into different tribological subzones, where the material in the chip shows different behaviour depending on speed, feed, edge geometry and so on.

Still, nothing is mentioned about the material variation of the work piece. Even if the material composition is well within the tolerances of the specification, the material behaviour can differ hugely between batches depending on many other things.

To really understand a specific cutting process to make the best choice when it comes to insert geometry, grade and edge preparation, it is of outmost importance to realize all of these possible influences of the cutting process. So, to get the most out of the products when it comes to optimizing, contact the product specialists.

For more information, please contact your local Seco representative, or our Advanced material (PCBN/PCD/CERAMIC) team.

Author: Stefan G Larsson Product Specialist SECOMAX PCBN/PCD/CERAMIC SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340572 Mobile +46761367807 e-mail:stefan.g.larsson@secotools.com