Se refiere a que la máquina automática corta el metal con tal precisión y calidad que no es necesario pulir o eliminar las asperezas manualmente. En el siguiente texto, el fabricante (Grand Die) quería reducir el tiempo de fabricación e instaló un centro de mecanizado EDNC43S para producir rodetes automáticamente (subrayo las partes más relevantes):

• BENCH-FREE FINISH Using the EDNC43S, Grand Die completely eliminates the need for benchwork on the impeller with Makino’s new High Quality Surface Finish (HQSF) technology. “From EDM to shooting parts, the impeller mold requires no benchwork whatsoever” ... (Grand Die Gets Bench Free, http://www.moldmakermag.com/0402feature1.html )

Y más adelante habla de "bench-free molds." Como dice el colega, esto es posible porque se obtiene un acabado sin relieve.

En este otro caso, al describir un centro de mecanizado Makino D500 de cinco ejes (separados en 2+3):

• the simultaneous movement of all five axes [...] prevented most five axis machines from reaching accuracies that many molds required. [...] The 2+3 method provides manufacturers with the best potential for bench-free machining. (2+3 Machining, http://knol.google.com/k/makino-machine-tool/2-3-machining/1... )

Por último, dos más:

• our high-speed machining enabled us to cut directly into hardened steel (RC52-55) using cutters as small as .25mm, creating a bench-free finish. (Mold Making Technology, http://auroracadcaminc.com/index.php/mold-making )

• To achieve the highest possible surface quality in large molds you will need a machine and tooling up to the task, allowing you to dramatically reduce secondary EDM work and manual finishing time. [...] A variable geometry horizontal machine designed for 2+3 machining of large, complex molds. It has superb accuracy and the ability to achieve bench-free surface finishes. (Solutions for Your Large Mold Machining Challenge, http://www.tusdec.org.pk/projects/gtdmc/solutions/tutorials/... )

Saludos,

Daniel