Methods for Performance Evaluation of Computer Numerically Controlled Lathes and Turning Centers
|Publication Date:||1 January 2012|
This Standard establishes requirements and methods for specifying and testing the performance of CNC lathes and turning centers. In addition to clarifying the performance evaluation of lathes and turning centers, this Standard seeks to facilitate performance comparisons between machines by unifying terminology, general machine classification, and the treatment of environmental effects. The Standard defines testing methods capable of yielding adequate performance results for the majority of turning centers and is not intended to replace more complete tests. It is not the intent of this Standard to place limits on, or to enforce 100%-testing of, any individual machine tool in accordance with this Standard. This shall be the subject of contractual agreement between the Supplier and the User.
The actual specification for turning centers is divided into the following six logical areas:
(a) General Definitions. Definitions provided in this Standard are generally consistent with the usage in other referenced documents related to machine tools and metrology, although some are specific to their use in this Standard.
(b) Machine Environmental Specifications and Responses. Environmental specifications and responses include thermal, electrical, and vibration specifications and tests, as well as requirements on utility air and other externally supplied services.
(c) Machine Accuracy Performance as a Machine Tool. Machine accuracy performance as a machine tool includes positioning accuracy and repeatability for linear and rotary axes, angular error motion of linear axes, spindle axis of rotation analysis, machine thermal tests, critical alignments, and contouring performance using circular tests.
(d) Machine Cutting Performance and Short-Term Reliability. Machine cutting performance and short-term reliability includes tests of spindle idle run losses and maximum metal-removal capability. Additionally, the machine is run for approximately 24 h to determine short-term reliability.
(e) Additional Machine Performance. Additional performance sections are provided for axis of rotation alignment, tail stock alignment, subsystems repeatability, tool-setting performance, CNC performance, and machine performance as a measuring tool.
(f) Machining Test Parts. This Standard provides for the machining of test parts for a particular manufacturing application. These test parts shall be fully specified as part of the original purchasing agreement between the User and the Supplier. Such specification shall include, but not be limited to, material, tooling, machining sequence, and inspection procedure.
This Standard is rather comprehensive, and for smaller, less-expensive machines, a shorter series of tests for conformance to specification is given in Nonmandatory Appendix B.