1. Micro-nano manufacturing
2. Precision manufacturing
3. Hybrid manufacturing
4. Energy efficient manufacturing

Machines, components and instruments

This research involves the development of ultra-precision machine tools and instruments, air bearings and nanopositioning systems. Current projects focus on the development of an ultra-precision five-axis grinding machine, ultrasonic piezo-motors and aerostatic bearings. The developments on air bearings have led to the spin-off company LAB motion systems. Another spin-off, Xeryon, develops piezo motors based on the vast experience of our research group in this field.

Machining processes

The development of micro-systems and precision machines requires research of micro-machining and ultra-precision machining processes. Our research currently focusses on the improvement of micro-EDM milling, Micro-ECM, ELID-grinding and ultra-sonic assisted micro-machining.

Micro-EDM milling research aims to predict the tool wear on-line by techniques such as pulse counting and to compensate the estimated wear in real-time in order to achieve micrometer dimensional tolerances. The development of new Micro-ECM tools enables very localised material removal. Investigation of ELID-grinding and ultra-sonic assisted micro-machining processes, on the other hand, aims to improve the surface finish of hard-to-machine ceramics, down to a few tens of nanometers.

More information: Micro- and Precision Engineering

Laser micro-machining

Ultrafast lasers enable the fabrication of high-quality parts with minimal thermal damage due to their ultrashort pulse duration (typically less than 10 picoseconds). Ultrafast lasers find applications in a wide range of fields including microelectronics, medical devices, optics, microfluidics, precision mechanics, tribology and microtooling. They can be used for various manufacturing processes including surface structuring and surface treatment, micro/nanomachining (cutting, milling, drilling, polishing), thin film scribing and additive manufacturing.
Femtosecond (fs) laser team at MaPS focuses on the research and development of fs laser processing of materials such as metals, ceramics and composites for several applications. 
More information: Laser Micro-Machining

CAD/CAM and Multi-axis machining

Machining complex shaped components in an efficient way requires the use of multi-axis milling strategies. Therefore, improving the performance of tool path planning by CAD/CAM software for 5-axis milling operations is an important topic. Since the operations performed by these multi-axis machines become more complex, a good machine simulation, simulating the NC code on a virtual machine is important to detect possible collisions or other problems.
 

Electric Discharge Machining (EDM)

PMA has a long history of research in the field of Electric Discharge Machining. Wire-EDM, die sinking EDM and milling EDM operations have been investigated in close cooperation with Agie-Charmilles. The most recent years the main objective has been to investigate the machining of novel high-tech materials, in close cooperation with the material science department of the KU Leuven (MTM). Understanding the material removal processes and optimizing machining parameters for technical ceramics and other recent developed materials is key to machine these difficult to machine materials in an efficient way.
 

In-Situ Process Monitoring 

In milling of complex parts, tool vibrations and instable process conditions often lead to increased tool loads and accelerated tool wear, which would severely affect the machined surface and the accuracy. Therefore, monitoring of the tool condition becomes of great importance to realize efficient and precision machining. The main objective of this research is to develop an in-situ tool condition monitoring system based on acoustic emission detection. The investigation mainly focuses on multi-axis machining and ultrasonic-assisted machining of difficult-to-cut material such as hardened steel and titanium alloy.

Hybrid manufacturing processes are based on the simultaneous and controlled interaction of process mechanisms and/or energy sources/tools having a significant effect on the process performance. These processes have a large influence on the processing/manufacturing characteristics resulting in higher machinability, reductions of process forces and tool wear, etc. Due to the combined action of processes, it also has an important – and most of the time – positive effect on the surface integrity of machined parts. This paper gives a definition and classification of hybrid processes, followed by a description of principles and future perspectives, benefits on productivity, effects on surface quality and applications of common hybrid processes.
 

Ultrasonic assisted grinding

Ultrasonic assisted grinding combines the rotation and feed motion of a conventional milling operation, with ultrasonic vibration in vertical direction. The tool has a milling-tool like shape, however it consists of abrasive grains in a metalic binder. This process is used for machine hard and brittle materials (ceramics, hardened steel). The combination of the rotating motion with the ultrasonic vibration results in lower process forces, less tool wear and a self-dressing effect of the tool. 

PMA has two DMG Sauer machines (70-5 and 20) and built up a lot of experience with the Ultrasonic Assisted Grinding of ceramics (ZrO₂, SiC, B₄C, Al₂O₃)
 

Ultrasonic assisted turning

Based on the knowledge from the Ultrasonic Assisted Grinding, a special tool holder for a lathe has been developed at PMA, in order to apply ultrasonic vibration to the cutting tool. This tool holder, using a piezo-actuator to realise the vibration, has been tested for the machining of hard and brittle materials such as borosilicate glass and ZrO₂.

The developped vibrating tool holder system is capable of performing both tangential as radial vibration assisted turning. Less chipping, less tool wear, higher achievable cutting depth are some of the benefits of this technology.
 

Integrated laser hardening

Conventionally, laser hardening is performed as a batch process, at a hardening facility. This however introduces a lot of time loss and logistics into the manufacturing chain. In order to speed up the lead time for prototypes and small serie products, laser hardening is integrated into the machining center. This allows to harden the work piece on the machine, omitting the need to unclamp it, transport it to the hardening facility, wait until the part is scheduled in, transport back to the machining facility, reclamping & re-alligning the component (accuracy loss!), before it can be finished by for example a grinding operation.

A special laser-tool head, based on a standard HSK-63 tool holder, has been developed. This allows to perform laser hardening operations inside a still fully functional 5-axis milling center. 

ECM Milling 

ElectroChemical Machining (ECM) is an established technique in the industry. This machining process mainly finds its use in applications where very hard metals are to be machined. In addition, electrochemical machining is known for the low roughnesses that can be achieved. Other aspects of this technique are the lack of tool wear and no occurrence of a heat affected layer after machining.

One of the problems with ECM is the complex electrode design. To overcome this specific problem of ECM, research was done to use a generic cylindrical tool. An appropriate name for this new machining technique is electrochemical milling. Besides that, other research is going on to overcome problems like the formation of a passivation layer,… This research will combine an ECM milling operation, with a mechanical milling operation.
 

ELID grinding

ELID-grinding is a precision manufacturing processes to realize mirror-liked surfaces. Unlike polishing, tools used in ELID grinding are wheels with small grain size than polishing pads. Therefore, the efficiency can be improved dramatically. Meanwhile, with in-process dressing, grinding wheel can keep sharp edges of grains even during a long processing cycle.

The oxide layer generated by dressing electrochemical reaction provides a friction effect on materials’ removal, which is similar like polishing. And the protrusion heights of grains decrease with the increasing thickness of oxide layer. This multi-effect between workpiece and wheel leads to a mirror surface of nano-scale roughness.

 

4. Energy efficient manufacturing

Sustainable Manufacturing: Energy-efficient Approach for Machining Processes

Substantial environmental impact induced by continuously rising energy and resource consumption in industry has urged industrial enterprises to reform their current manufacturing towards an environmentally conscious scheme. To accomplish this aim, reducing production energy has been acknowledged as one of the essential tasks. As machine tools dominate the energy consumption during production, reducing the energy consumption of machine tools can effectively mitigate the environmental impact of manufacturing and cut down the production cost. The main objective of this research is to enhance the energy conservation of machining processes, and three main subjects are involved: parametric modeling of machining processes, development of energy-efficient machining strategies, and energy simulation in CAM system. For parametric modeling, the energy consumption of machining processes is modeled at machine level. For development of energy-efficient machining strategies, a surface roughness based approach is developed to optimize the machining settings for both unit processes and process chains. To simulate the energy consumption of machining processes in CAM system, an operation-mode based approach, which incorporates material removal simulation to precisely track energy of cutting material, is developed and validated. With this approach, energy-efficient computer-aided manufacturing can be achieved and the process settings can be optimized before the workpiece is loaded onto the machine for execution.