scope:

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 percent 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.

Sections 2 and 3 of this Standard reference documents that are used herein and provide a listing of symbolism. The first part of Section 4 is a glossary covering technical terms used throughout the Standard which might require explanation. The second part of Section 4 defines common machine classifications and provides guidance for developing other classifications.

The actual specification for CNC lathes and turning centers is divided into six logical areas:

• General definitions and machine classifications

• Machine environmental specifications and responses

• Machine accuracy performance as a machine tool

• Machine cutting performance and short-term reliability

• Optional machine performance

• Machining test parts

General definitions and machine classifications include definitions of common terms, machine types, machining ranges, position resolutions, and other general specifications, as required.

Environmental specifications and responses include thermal, electrical, and vibration specifications and tests, as well as requirements on utility air and other externally-supplied services.

Machine accuracy performance as a machine tool includes positioning accuracy and repeatability for linear and rotary axes, angular error motion (yaw) of linear axes, spindle axis of rotation analysis, machine thermal tests, critical alignments, and contouring performance using circular tests.

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 hours to determine short-term reliability.

Optional 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.

Also optionally, this Standard provides for the machining of test parts for a particular manufacturing application. These test parts are to be fully specified as part of the original purchasing agreement between user and supplier. Such specification shall include, but not be limited to, material, tooling, machining sequence, and inspection procedure.

This Standard does not address issues of machine safety.

This Standard is rather comprehensive. A guide for using it is given in Appendix A. Further, for smaller, less expensive machines, a shorter series of tests for conformance to specification is given in Appendix L.

Specification Forms

Any specification described as complying with this Standard shall include at least those items specified in Forms 1, 2, 3, and 4. Optionally, special tests, as required in Form 5, shall be included.

Alternatives

Where specifications use definitions and procedures different than those in this Standard, the alternative items shall be identified and made part of the machine specification. Such procedures should follow the philosophy outlined in this Standard and be specified in equivalent detail.

This Standard allows parts of the environmental test section to be deferred or bypassed, and only the performance test to be carried out. This alternative is allowable only if it is acceptable to both the user and the supplier and if deferred according to the procedures outlined in Section 6.1.