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Networked production for complex applications -
Intelligent machining of hard, brittle
materials
Project carried out by the FH Nordostniedersachsen (Technical University of Northeastern Lower
Saxony) in Lueneburg, Germany
Project managers: Prof. Dr. rer. nat. Georgiadis and Prof. Dr.-Ing.
Berger
The contours of the video image transmitted over the Internet
were milled into this marble plate (photo: FH Nordostniedersachsen) |
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Industrial ceramics and other hard, brittle materials can be machined quickly and efficiently using
networked control systems and technologies for high-speed machining. Thanks to the enormous progress
made in recent years, it has become possible to link CNC controls with customers, machine manufacturers,
and suppliers by means of user-friendly communication networks.
This has made it possible to considerably increase productivity and reduce disturbance-related downtimes. An integrated machine
concept was introduced for the first time at the Hanover Fair 2000.
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This application can be accessed from the 
home page of the Automation Engineering Department at the Technical University of Northeastern
Lower Saxony, Germany.
Tele-monitoring, tele-service and tele-control
In partnership with Siemens, SNR and IBAG, the Technical University of Northeastern Lower Saxony,
Germany, presented an integrated machine concept for the machining of hard, brittle materials at the
Hanover Fair, which combined functions such as tele-monitoring, tele-service, and tele-control on a
single control platform.
The concept enables agreements with customers, material-related machining
adjustments and the optimization of production-related parameters to be performed virtually online.
The transparency of the production engineering environment, in particular for individual and small
batch tasks, is enhanced, thus improving customer orientation. The permanent link with local CNC and
PLC controllers enables warnings to be issued immediately as well as permitting direct intervention
and automatic adjustments in the process itself.
High-speed milling spindle
The machine concept is based on a modular 3-axis milling cell for the machining of hard, brittle
materials, which meet requirements relating to traversing speed (up to 20 m/min), machining accuracy
(up to 0.01 mm) and wear resistance for all movable components in the face of even the finest particles
of ceramic dust. The heart of the system is a high-speed milling spindle with a drive capacity of 7.5
kW and a speed range of between 20,000 and 42,000 rev/min. Expanded cooling and sealing air on the
front spindle bearing make the spindle suitable for particularly difficult applications.
Process visualization via the Internet with SIMATIC WinCC
All drives, sensors, and monitoring units are linked to a Sinumerik 840D CNC controller. The Sinumerik
840D, in turn, is linked to the Windows Control Center, the PC-based process visualization system from
Siemens, and the Simatic WinCC/Web Navigator (server) for implementing of the telematic functional
requirements.
The Simatic WinCC/Web Navigator makes it possible to visualize and control a system via
the Internet or company intranet. Conventional Internet connections were selected specifically as the
means for communication to the outside world in order to demonstrate the universality and world-wide
applicability of the solution. The communication mechanisms used by Simatic WinCC/Web Navigator are
based on event-driven, high-throughput transfer, resulting in excellent web performance.
Presentation at the Hanover Fair 2000
For the practical demonstration of the machine concept, a cross-link was continually maintained between
machining in the production hall and the "customer" in the exhibition booth. The performance
capabilities of the experimental concept were demonstrated by machining three-dimensional marble
reliefs in commercial CD format. In the case of complex reliefs, it was possible to generate CAD file
formats with up to 16,000 interpolation points using the VIDEOMAT image processing system (Siemens)
and transfer them to the CNC.
Before, during and after the machining phases, essential information
such as NC blocks, error status information and sensor values were transferred to a remote partner
station capable of making modifications or even stopping the machining process. During this time, the
two locations were visually and acoustically linked using two remote-controlled (SIMATIC WinCC
Guardian) Web cameras. The SIMATIC WinCC Guardians were used to link camera shots into a WinCC image
and monitor the image contents for alterations - movements, changes in color - which could lead to
generation of flags in a database.
Product development and product manufacture - although taking place
at two different locations - took place simultaneously and were closely cross-linked. The facial
contours of visitors to the exhibition booth served as models for the product, and were immortalized in
marble within minutes and 150 kilometers away.
Machining the marble relief
Carbide milling heads were used for the machining process itself. As far as thermal stress, surface
quality and tool wear were concerned, the strategy of dry machining at high spindle speeds and at feed
rates of 6m/r.p.m. proved extremely advantageous.To improve surface quality, a separation into
roughing and finishing with tool change was used for fine-resolution reliefs.
The machining time for
the marble relief shown in the picture was around 6 minutes. Other solutions for hard-to-machine
hard/brittle materials such as heat-resistant components used in the automotive and aeronautics
industries are currently under development.
Future-oriented product development
At the Hanover Fair 2000, a new and future-oriented product development method was demonstrated by
this innovative system. The product was designed and the prototype created at one and the same time.
Different knowledge centers came together under a single platform, eliminating the effects of distance.
At the same time, it was possible to show that subprocesses could be performed from different locations
on a central control system. With this system, it will be possible in many cases to eliminate
time-consuming travel and the resulting costs, while at the same time improving the productivity of
both machines and plants. |
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