A series of software modules developed by Open Mind for five-axis CNC milling using its Hypermill and Hyperform products represents a major step forward in computer-aided manufacturing (CAM). As distinct from other five-axis programming software products, the new modules are easy to use, provide rapid program generation, exhibit high levels of process reliability and offer improved as-machined surface quality. Before embarking on the development, Open Mind identified in existing software from other vendors certain shortcomings which needed to be addressed.
Foremost was the inability of most to support reliable automatic collision checking, so as much or more time had to be spent on process simulation as on programming.
This in turn led to problems in applying five-axis machining to deep cavity work where it has much to offer.
As a result, a high proportion of five-axis work within manufacturing industry tended to use three interpolative and two positional axes to machine discrete features rather than the entire component.
Open Mind collaborated with the Fraunhofer Institut in Germany to develop a more complete solution to five-axis program generation.
It is based on a patented mathematical model which uses leading curves which define the inclination of the tool and therefore the machining axis position.
By comparing the leading curve against the polyhedral surface model of the component it is possible to detect whether the tool and its holder will come into contact, i.e collide, with the surface.
If this is the case, the angle of the tool is adjusted to compensate.
However, if a collision remains unavoidable then the cutter retracts to a safe position and a display advises a change in the tooling specification.
As the software includes a reliable collision-checking algorithm, the need for external simulation is eliminated so programming time is minimised.
Likewise, the program can utilise all of the machining axes to optimise cutting conditions so the run time of the machining program is reduced and the machined surface is of good quality.
It may also prove possible to machine cavities and surfaces completely in a continuous program, as a result of which the number of set-ups can be reduced while the need for electric discharge machining to finish details in deep cavities may be reduced or even eliminated.
Open Mind five-axis modules are suitable for mould and die, turbine blade and aerospace machining.
They make use of some or all of the specialised machining strategies developed to take advantage of the basic concept.
These are five-axis finishing, Z-level finishing, five-axis equidistant finishing, five-axis rest machining, five-axis top milling and side wall access relief (SWARF) cutting, and five-axis ISO machining.
Both dedicated and general-purpose post processors are available for use with the software.