Power package – Maximising productivity and accuracy

Power package – Maximising productivity and accuracy

According to DMG MORI, its new fourth-generation DMC 80 FD duoBLOCK universal machining centre provides the perfect base for demanding five-axis-milling operations and mill-turn machining

Five-axis simultaneous machining is increasingly emerging as a key technology. In addition, automation and combined milling and turning are becoming ever-more important. With nearly 4,000 duoBLOCK machines successfully sold, DMG MORI has dictated this development.

The increased trend towards automation is also apparent by the increase of duoBLOCK universal machining centres with pallet changers. One of these models is the DMC 80 FD duoBLOCK, which demonstrates further enhanced flexibility and productivity while boasting improvements of 30% in its core characteristics of precision, performance and efficiency. 

A re-engineered machine concept
The fourth-generation DMC 80 FD duoBLOCK universal machining centre has a newly developed B-axis milling head. It has an extended swivel range of 250 degrees, with a swivel of 70 degrees in the negative direction. The larger axis bearing results in a 20% increase in stiffness. The extended swivel range and reduced interference contour, in conjunction with the cable conduit integrated into the housing, enable an even wider range of customer-specific complete machining operations to be carried out. Idle times are reduced thanks to shortened B-axis movements, and the extended life of the integral cables has a positive effect on the reliability of the machines.

At the present time, only DMG MORI is able to supply the unique combination of a redesigned B-axis with an even stiffer and more accurate milling/turning table and pallet system. With these unique selling points in the market, the DMC 80 FD duoBLOCK will open up further applications to an extent that has not been seen before.

Enhanced machine rigidity
In its fourth generation, the duoBLOCK machine concept, which has proven its worth time and time again, has been made even more stable thanks to the verifiable increase of 30% in rigidity. With a work area that has been increased in size by 8% to 715 cubic centimetres, and a Z-axis traverse of 850mm, the DMC 80 FD duoBLOCK has an increased overall rigidity, despite its reduced footprint. This is due to structural optimisation, with a wider machine bed and columns, and the use of high-quality castings made from GGG60 ductile cast iron.

In addition, the supporting surfaces of the inherently rigid machine bed have been enlarged, with larger-sized 55mm linear guides fitted on the Y-axis, and 50mm diameter ballscrews incorporated. These measures, along with the larger bearings in the B-axis and C-axis, result in a gain of approximately 20% in overall rigidity in the DMC 80 FD duoBLOCK fourth generation.

This makes it possible for heavy-duty milling to be carried out with the powerMASTER 1000 spindle and the HSK 100 toolholder interface in the B-axis. This set-up has a power of 77kW, the maximum speed is 9,000rpm, and the torque achieved is 1,000Nm. Thus equipped, the B-axis provides an increase in power of 130% compared with previous motor spindles, and therefore offers milling performance in a completely new dimension. In comparison with the competition, the fourth-generation duoBLOCK universal milling centres achieve a 75% greater material removal rate during five-axis milling.

Further options for the duoBLOCK are motor spindles with the HSK 63 tool interface, for high-speed cutting (HSC machining) up to 20,000rpm. Alternatively, torqueMASTER gear-driven spindles with 1,300Nm at 8,000rpm and 37kW for HSK 100 can be used when carrying out high-performance cutting operations (HPC machining).

Long-term precision
With the increased rigidity of the 4th duoBLOCK generation, an almost-constant overall machine temperature is achieved with the DMC 80 FD duoBLOCK during chip removal. This is achieved through a strengthened structure, a thermo-symmetrical design and additional cooling measures. Additional cooling channels in the machine bed and column, together with the liquid cooling of the feed drives on all linear axes, including that of the rotary table with C-axis motor, reliably dissipate the heat produced during chip removal.

The previous cooling measures in the milling head and the electrical cabinet have been adapted to suit the re-engineered machine structure. In spite of the increase in power, all these coordinated measures lead to a balanced temperature level in the machines. As is common with all DMG MORI machines, electronic compensation devices eliminate the residual displacement caused by temperature or the effects of static or dynamic forces.

The devices included as standard are supplemented by the effective use of the Spindle Growth Sensor (SGS) to prevent axial spindle displacement. The option of careful temperature control of the coolant during machining is also recommended. The combination of all these measures leads to a 30% improvement in workpiece accuracy when milling or milling and turning with the DMC 80 FD duoBLOCK.

Optimised production and idle times
Both the production time and the idle time of the DMC 80 FD duoBLOCK have been investigated and optimised. The focus here was on redesigning the tool and workpiece change­over in parallel with production on the fourth-generation duoBLOCK machines.

The first point to mention is the use of space-saving wheel magazines. With 123 tool pockets, the space required is reduced by approximately 40%. The parallel arrangement of a maximum of six wheel magazines with a total capacity of 363 tools (for special option) pockets satisfies the increasing number of possible applications of the DMC 80 FD duoBLOCK and the global upward trend in process automation. Short traverse distances and cam-controlled changers enable short times to be achieved when changing and presenting tools during production.

The idle times of the machine and that of the pallet changer have been improved by increasing the table speed of the fourth axis to 40rpm in rapid traverse, and re-engineering the sequence. Additional devices for an enhanced process automation, which are familiar from the duoBLOCK high-performance, can be selected from the DMG MORI modular system and connected accordingly.

The same applies to the systems from DMG MORI’s proven external partners. The use of pallet magazines, loading gantries and robots as well as the integration of the universal machining centres into flexible manufacturing systems is therefore fully in keeping with the current trend, and enables unattended automatic operation to be carried out.

The 8% larger work area with the 6% longer vertical travel of 850mm is easily accessible from the side and from above. In spite of the enlarged work area, the footprint has been reduced to 21.4sqm. The user-friendly ergonomics of the machine have been further improved with the re-engineered machine design, enhancing ease of operation through an easily accessible set-up station. These prerequisites are very important for effective workpiece fixturing and for seeing into the work area to observe the machining process. Automation devices external to the machine can also be readily connected to the enclosures by means of suitable interfaces.

The DMC 80 FD duoBLOCK is equipped with the CELOS app-based interface, a 54.6 cm ERGOline control operator terminal and Siemens software. CELOS from DMG MORI simplifies and accelerates the process from the idea to the finished product. CELOS apps provide the user with integrated management, documentation and visualisation of order, process and machine data. CELOS is compatible with production planning and scheduling (PPS) and enterprise resource planning (ERP) systems, can be networked with CAD/CAM applications, and is ready for future-oriented CELOS app extensions.