To meet the needs of its aerospace customers, DMG is focusing on innovative technologies, and on a Centre of Excellence as the first port of call for the national and international aviation industry. 

Although the aviation industry is affected by the global financial crisis, the aerospace sector remains an attractive market for high tech machine tool manufacturers such as DMG. The trend is towards using parts made from materials that provide superior mechanical properties but with lower specific weight. In particular, the economical machining of metals, including aluminium and titanium alloys and advanced composite materials poses a real challenge for manufacturers.

With its Aerospace Centre of Excellence, DMG claims it is meeting these challenges with its services ranging from technology, process and product development to seminars, workshops, machine demonstrations and test machining.

Crucially, Deckel Maho offers adapted modules, which can be used to individually adapt its standard machines with modular components to meet the requirements of the aviation and aerospace industry. The innovative duoBlock series is such a modular system – suitable for use with HPC or HSC with 5-axis milling technologies, permitting combined technologies such as milling and turning to be performed in one clamping position.

The machines can be further adapted by fitting various milling spindle heads to the dynamic triple guided slide. For example, 5-axis simultaneous milling or mill/turn operations can be optimised by an optional A or B axis configuration of the spindle heads. For combined milling and turning, the swivel headstocks can be fitted with either turning or milling tools via the HSK interface.

Milling spindles for horizontal housing and swivel heads in the B axis configuration are available as patented 5X torqueMaster variants with transmissions for high torques of up to approximately 1,500Nm. The B axis milling head 5X torqueMaster is claimed by DMG to be the only swivel type milling head with integrated transmission that can swivel through 190° degrees in around 1.5 seconds without any reduction in milling performance. A axis heads with various motor spindles, which can be swivelled from -25° to 120°, offer an alternative right-angled arrangement of the head swivel axis in relation to the linear axes.

Improvements and adaptations

Special powered aerospace spindles fit into the housing of all duoBlock machines with a longitudinal traverse range of 800mm to 1,600mm. These aerospace spindles deliver up to 100kW at a torque of 180Nm and a maximum rotational speed of 15,000rpm with the HSK A100 tool mounting. They have also proven ideal for HSC and HSP machining of materials that are difficult to machine such as titanium alloys and aerospace spindles, with a rating of 85kW at a torque of 40Nm and a maximum rotational speed of 30,000 rpm with HSK A 63 tool mountings are available as an alternative.

Adaptation of the machines makes further improvements possible. The duoBlock concept also provides the basis for the universal machine series – with or without palletiser - for combined milling and turning. The milling and turning machines are predominantly used in the manufacture of engines for the aviation and aerospace industry.

The use of thermally optimised torque motors, which are integrated in the NC table assembly group, permit table rotational speeds of up to 800rpm with a turning diameter of 900mm for workpieces weighing up to 1,000kg. Table rotational speeds of 250rpm are possible on the large duoBlock milling and turning machines with a longitudinal traverse of 1,600mm at a turning diameter of 1,600mm and a load of up to 3,000kg.

Cooling compressors for heat dissipation on the machine are used: on the headstocks in the motor spindle and gear variant; in the linear axis drives with ball spindle or in purely linear motors; in the torque motors of the milling and turning centres; and in all switch cabinets. Further options include active cooling measures for coolant lubricant or cooling air treatment. 

Machining essentials

Software tools are also becoming increasingly more important and on Deckel Maho machines, a number of option are available: Application Tuning Cycle (ATC) for adjusting machining behaviour to the cutting process; intelligent spindle monitoring for reducing the milling spindle's tendency to vibrate; adaptive feed control; CNC cycles (HPC, TPC) for avoidance of the influence of milling head or NC table offsets, combined with precise determination of the respective turning centre and ; 3D quickSet for monitoring and correction of axis precision.

When rationalising production in the aviation and aerospace industry, it is particularly important to reduce set-up times and this can be achieved through the use of pallet changers, which are compatible with all Deckel Maho machines. This converts the universal machines into universal machining centres by permitting simultaneous machining and loading of workpieces. If automatic production is required for longer periods at night or over the weekend, it is necessary to connect a pallet accumulator to the universal or horizontal machining centre.

Integrated solutions are particularly advantageous and the capacity of such manufacturing cells is on average three to seven pallets. If several workpieces or components of one family are to be produced fully automatically in a mixed job, DMG recommends linking the manufacturing cells, for example, via a linear pallet storage system. A CNC level control system controls the entire organization of such a flexible production system and for machining workpieces in small and medium sized batches, two to six machines are usually linked together to achieve the highest level of production automation.

Efficient chip disposal is particularly important given the high proportion of cutting involved and the large volume of chips produced during production in the aviation and aerospace industry. Suitable measures for efficient chip disposal are: the design of the machine compartment and booth with walls that are vertical or as steep as possible; the avoidance of chip accumulation; targeted use of coolant lubricant for cooling and chip disposal; guided blast air flows for dry machining; wide chip conveyors; additional conveyor screws, which are shielded from the machine bed by profiled sheets; the treatment of the coolant lubricant in such a way as to prevent clogging and ; process monitoring of chip disposal via video cameras, rinse flow meters and temperature control of the coolant lubricant.

DMG
www.gildemeister.com