Success Story: Technological support for HELLER CylinderBoreCoating
The process control VM and the electrical generators of ELMA-Tech support the arc spraying coating technology HELLER CylinderBoreCoating resp. Daimler NANOSLIDE®
The coating technology NANOSLIDE®, developed by car producer Daimler AG together with Gebr. Heller Maschinenfabrik GmbH, was once again in the public eye on the occasion of the awarding of the German Future Prize 2016 by the German Federal President.
A three-headed research team from Daimler / Heller competed among the nominees for a total of 3 project teams with the project "The vision of the smooth drive - coating halves energy loss".
Even if the German Future Prize 2016 was not awarded to the Daimler / Heller research team, this does not in any way reduce the success of a fascinating technology, in whose development current sources and above all the process control of ELMA-Tech are decisively involved.
It's all about this: Coating of cylinder bores of aluminium lightweight crank-cases for car engines using twin-arc spraying (Copyright: ©vladimirfloyd/Fotolia)
The coating method
"By means of twin-wire arc spraying technology the cylinder surfaces in the aluminium crankcases are coated with an extremely thin layer based on an iron-carbon alloy.
The result is a very wear-resistant nano to ultrafine material structure with micropores, ensuring lubrication during operation. As a result, heavy grey cast iron liners in the aluminium crankcases that can be several millimetres thick are eliminated.
The result is a surface as smooth as glass, providing up to 50 percent less friction between piston, piston rings and cylinder surface and a weight reduction of several kilogrammes.
Meanwhile, the process incorporates numerous inventions and ideas and is protected by more than 90 patent families and more than 40 patents." (Quoted after: https://www.heller.biz/fokus/)
Wire arc spraying in use (Copyright by courtesy of Gebr. Heller Maschinenfabrik GmbH)
Industrial process safety with the virtual machine (VM)
An essential element of the Heller CBC coating process is the complex and extremely fast energy control of the arc wire spraying process in which central parameters such as current, voltage, wire feed and process gas flow have to be optimally matched to each other and to each phase of the coating process.
The fully electronic ELMA-Tech welding generator, which is used for this purpose, is precisely taking this demanding lead.
The core component of all ELMA-Tech developments and welding generators is the Virtual Machine (VM), which has been developed by the world-renowned welding technician Prof. Dr.-Ing. Peter Puschner. Since 1997 the VM – meanwhile in the third generation - is leading joining processes in thousands of machines in many industrialized countries.
This is a microprocessor-based control system especially for fast-running processes. It combines the advantages of the two main control systems, which are now on the market, namely the cyclic PLC controllers and the traditional, usually sequentially operating microcontroller controllers with event-driven real-time operation systems.
Their typical disadvantages such as either relatively slow or very scattering reaction and response times are avoided in the VM: The static and dynamic control implemented in the VM evaluates the rapidly changing process states from the drop formation to the detachment of the wire by the atomization process - sequences which are played in the thousandth range of seconds - and responds to each different state in the range of its cycle frequency of 20 kHz , thus within 50 microseconds.
In other words: Depending on the process state, the VM provides up to 20,000 different generators with optimum characteristics for a high-quality and optimal coating result. For this purpose it uses a database which is designed as an expert system with all necessary physical parameters, which describe such generators in terms of their dynamic and static operating behavior.
Conceptually, the VM is an interruption-free, cyclically rotating processing system for processes. The external control and regulating electronics are connected via special I/O modules integrated into the VM and are also cyclically operated. Via a further interface, user-specific adaptations can be transferred to the "process processing". For the actual sequence control this takes place uninterrupted.
The control concept of the VM allows to configure the current source completely new in static and dynamics with a cycle time of 50 μs. It follows the teachings of the Puschner patent issued worldwide for synthesizing the static and dynamic behavior of electronic welding generators.
The parameters for statics and dynamics are selectable in real-time in physical quantities, so that a 100% reproducibility of the process control is given. This makes it possible to optimally adjust the current source characteristics for different process requirements in a phase-related manner and to meet the requirements of the arc or its plasma.
Constant current sources / electronic generators for the Heller CBC
ELMA-Tech constant current sources of the type VARIO 800 DC LDS are used in many different designs for this coating process.
The VARIO 800 LDS is suitable for surface coating with electrically conductive metals and shows excellent spray properties in all materials (eg copper, zinc, zinc / aluminum 85/15, aluminum, aluminum bronze, aluminum nickel, aluminum magnesium) , Chromium-nickel, steel alloys, etc.)
All electrically conductive wires and cored wires can be used to a maximum attainable melting rate of 6 to 30 kg / h depending on the material and the spraying system.
The use of filler wires makes it possible to process hard materials in addition to materials such as carbon steels, chromium and high-alloy steels.
Since mid-2011, ELMA-Tech has been able to supply approximately 60 of these constant-current sources, including VM process controllers, to Heller for worldwide applications in the area of the Heller CBC.
Video: Here the presentation of the innovation on the occasion of the nomination of the project team for the German Future Prize 2016 (in german)