The specific cutting force is nonsense because it does not account for the most important parameters of the cutting process. Listen again – IT IS NONSENCE! And now explanations:
The current practice of relaying on machining database for the purpose of anticipating process outputs such as the cutting force, temperature, tool life, etc. is highly unsatisfactory. A recurring theme at the CIRP-sponsored International Workshop on Modeling of Machining Operations being held since 1997 concerns the urgent need for reliable and robust predictive models of practical cutting operations so as to avoid the need for very large machining databases. As a result, industrial and academic communities have collaborated through a project coordinated by National Institute for Standards and Technology (NIST) of the USA so as “ assess the ability of state-of-the-art machining models to make accurate predictions of the behavior of practical machining operations based upon the knowledge of machining parameters typically available on a modern industrial shop floor.” There are have been suggestions to develop a House of Models consisting of models that are declared by CIRP to be “fit to use” in the metal cutting industry. The intent was as usually great though no new ideas were proposed. This was mistake No. 1, which eventually kills this project.
Realizing that there is no way to develop a suitable predictive analytical model for metal cutting (although in my opinion it just lays ob the surface but the so-called specialists in metal cutting have too large blinds on their eyes), the specialist in metal cutting returned to the old “trial-and-error” experimental method, originally developed in the middle of the 19th century along with incorrect Taylor equation. Its modern form, known as the “Unified or Generalized Mechanics Approach”, has been pursued by Armarego and co-workers for years and then spread as the mechanistic approach in metal cutting developed at University of Illinois at Urbana-Champaign. It was developed as an alternative to the metal cutting theory because the latter did not prove its ability to solve even simplest practical problems. This approach widely utilized the specific cutting force.
The problem with the specific cutting force is that it does not account for the specific cutting conditions. It is insensitive to the type of carbide, tool geometry, type of coolant used and many-many other important parameters of the cutting process.
IMPORTANT IS that even if it is determined experimentally for a set of specific cutting conditions, it is still of next to zero value because nobody knows how to measure cutting force PROPERLY. In 2001 NIST with the support of the CIRP International Competition on “Assessment of Machining Models” conducted a very important test to determine the cutting force and other cutting parameters. The experiments were replicated at four different leading machining laboratories while utilizing the same tubular workpieces and cutting tool (both were selected from the same batch). And what do you think was the result? Surprise – 50% (at best) variation in the cutting force. And these were the best laboratories.
Should I continue or you’ve got the message?
Regards
Viktor
Viktor
