Five-sided machining on show

Five-sided machining of up to 20 similar, or totally different components in the same machine setting, is being demonstrated at the Brackley headquarters in Northamptonshire of Traub Heckert UK.

Five-sided machining of up to 20 similar, or totally different components in the same machine setting, is being demonstrated at the Brackley headquarters in Northamptonshire of Traub Heckert UK.

The demonstrations are being performed on the latest Hermle C800U vertical machining centre which has been fitted with the patented Albech, NC-driven trunnion-based indexing unit in order to form a flexible machining cell able to achieve high levels of accuracy and productivity.

The production system, which is fully controlled by the latest Heidenhain iTNC 530 control system, has five component positions on each of four faces of the indexing unit and each station is able to independently rotate through +5 degrees of centre line.

At each component station, parts can be accommodated within a diameter of 140mm and with a total weight of up to 50kg per face of the unit.

The ability to machine on five faces of a component in a single clamping is not only a major solution to reduce operational sequences, lead times and costs, associated problems such as refixturing are also reduced and higher geometrical relationships can be maintained between features of a component.

In addition, the ability of the C800U to machine different components in a single cycle means sets of parts can be completed in 'one-hit' ready for assembly.

The C800U is the mid-range gantry construction CNC vertical machining centre of the Hermle range with spindle options up to 40,000rev/min.

The design eliminates any spindle overhang typical of a C-frame machine construction and provides a very stiff production structure.

Each of the three main axes are achieved by moving the spindle and the relative motions are therefore divorced from any influence of component weight variations held on the indexing trunnion unit.

The Hermle C800U gantry bridge has three separate guideways, the third being central to and set back from the two outer guideways which, in effect, halves the bearing span.

By placing a single drive unit in line with the central carriage on the bridge this reduces any angular reaction force on the two outer guides while forces on the central guide are vertical.

The mineral cast bed ensures low thermal expansion with excellent shock and vibration absorption and is designed with the guideway axes and drive components positioned outside and above the machining area.

As a result, contamination from swarf and coolant on the guideways is eliminated.

The tool changer is positioned just behind and close to the spindle, negating the need for a change arm.

The 30 tool capacity disc magazine rotates in a horizontal plane and is driven by an AC servo motor through planetary gearing with a chip to chip tool change time of six seconds.

Tool exchange takes place through an opening in the rear of the machine.

Working volume is 800 x 600 x 500mm with an acceleration of 5m/s2 to rapid traverse rates of 35m/min.

Positional accuracy is within 0.008mm.

Spindle power is 25kW giving 10,000rev/min as standard with options of 16,000, 24,000 and high speed 40,000rev/min.

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