Selected Aspects of Precision Machining on CNC Machine Tools

Abstract

The work is new due to the type of process used—ultrasonic precision machining—to determine the possible effect of spindle heating (long-term machining) on the precision of the flat surface. It was carried out on a precise ultrasonic machining machine, and the material of workpiece was ceramic Al2O3. A flat surface was machined. Such an experiment has not been feasible until now. The experiment was divided into two days. On the first day, the machining time was 4 h. It is a long enough time to create a temperature-steady state. On the second day, with a cold tool and cold machine tool, we continued where we left off on the first day. This is how we monitored the accuracy of the dimensions of the workpiece on the plane surface. We have achieved the following: The average interface depth achieved values of 0.007089 mm and 0.003667 mm for cold and heated spindles, respectively. It means that when the spindle is not heated, the depth of the interface is higher by 93% (almost double the depth). The average standard deviation of the interface depth is 0.001683 mm and 0.000997 mm for cold and heated spindles, respectively. It means that when the spindle is not heated, the process is not as stable, and the standard deviation is higher by 69%.

Experimental Evaluation of Flexible Fixture Stiffness for Steering Knuckles When Loading a Milling Machine Tool

“…They provide a rigid and stationary position of the workpiece during machining, which guarantees the accuracy of the dimensions and geometry of the finished part [10]. The correct design of the fixture determines the method of fixing the workpiece, the use of technological capabilities of the machine tool, the choice of cutting parameters [11], and the trajectory of the tool [12]. It significantly affects the setup time of mechanical operations [13].…”

Influence of Machine Tool Operating Conditions on the Resulting Circularity and Positioning Accuracy

“…For example, in terms of volumetric accuracy, it is the maximum magnitude of the error vector between the working volume of the machine. There are several types of factors influencing machine accuracy [13,15,16]:…”