In-line monitoring of cut surfaces in interrupted cutting operations.

Todays market of machined products is characterized by an ever increasing demand in high-quality products, which can be assured by low levels of variability of process conditions. This mostly concerns precise and ultraprecise machining operations, but also more traditional operations are interested, which are far to be completely optimized in terms of obtainable quality of cut surfaces. The paper presents a system developed in order to monitor in-line the quality of cut surfaces in interrupted machining operations, in particular devoted to sawing of metal tubes. The presence of burrs above an acceptable limit at the cut surfaces entrance and exit is an index of the fact that the blade teeth have reached unacceptable levels of wear and therefore have to be changed to still guarantee high quality products. The automatic recognition of unacceptable presence of burrs can provide the machine controller with feedback about the need of blade change without the operators aid and, moreover, can reliably predict the residual tool life. In the paper, first the problem will be outlined, then the concept of the system presented together with the software developed for the cut surfaces geometry acquisition; later on, the control chart developed for reliable and automatic monitoring of the process is proposed and main results presented and discussed.