During 2000, Open Mind introduced what was billed as the first true 5-axis CAM (computer-aided manufacturing) software for CNC milling. This is distinct from producing programs which interpolate fewer axes simultaneously while the others are merely positioned. Now the company has gone a stage further with its new Segment Optimisation software for which a worldwide patent is pending.
The German company, whose UK subsidiary is in Wantage, realised that it is inefficient to machine in full 5-axis mode all the time.
Some areas of the component can usually be milled faster by interpolating three or perhaps four axes simultaneously and clamping the others.
There are also accuracy implications.
If a 5-axis machine tool is not particularly rigid, better tolerances and surface finish can be achieved by 3- or 4-axis rather than 5-axis milling.
The ability is retained to revert during a cycle to 5-axis machining as often as is expedient, such as for undercutting, finishing complex components or rapidly reorientating the tool for the next cut.
The latter has the effect of keeping the tool close to the workpiece at all times, so maximising the proportion of the cycle time that metal is being cut.
As the tool adjustment angle changes over a very short section of the tool path, it is generally possible to achieve higher average machining feedrates with this method.
Tool inclination is optimised before starting the next segment of 3- or 4-axis machining, so there are no grooves at the boundaries.
Moreover the milled surface is just as accurate as one which has been machined in true 5-axis mode, sometimes better according to the application and the machine tool.
This 'best of five' approach is what segment optimisation enables.
Each 5-axis tool retraction, automatic collision check and repositioning followed by 3+2, 4+1 or 5-axis machining of the next segment in the tool path are calculated automatically within the Open Mind software using special NC programming algorithms.
Many factors are taken into account such as machine construction, kinematics, control technology and the degree of look-ahead especially for high-speed machining.
Five-axis simultaneous machining with segment optimisation guarantees the same high process safety as 3-axis machining with Open Mind's products, notably hyperMILL and hyperFORM.
When calculating the tool paths, the entire surface model is included in the collision-check.
This enables the user to enjoy all the advantages of 5-axis machining while also benefiting from uncomplicated NC programming, for which preparation times are considerably reduced as the collision check is carried out automatically and without the time and cost penalties of using third party products.