Micromilling strategies for machining thin features

Micromilling of metal structures with ‘thin’ features represents a major challenge towards broadening the use of this technology in a range of microengineering applications, for example in producing multi-channel microstructures, housing for mechanical microdevices, and surgical instruments. The most common thin features seen in microengineering products are ribs and webs. This research identifies the main factors affecting the reliability of micromilling technology when employed for the machining of microcomponents incorporating thin features. The general principles that should be followed in designing machining strategies for such features are discussed in this article. Taking these general principles into account, new strategies are proposed to reduce the negative effects of identified factors on part quality and, at the same time, to overcome some of the problems associated with the use of conventional machining strategies for micromilling of ribs and webs. To implement and verify them, initially the milling operations were programmed manually, and then a special CAM module was developed for their automatic generation. Finally, this article reports the validation of the proposed strategies for machining thin features, which was carried out on a specially designed test part

A study of micro-electro discharge machining electrode wear

This paper studies the influence of factors contributing to electrode wear during the micro-electro discharge machining (EDM) process. The paper proposes a method for calculating the volumetric wear ratio based only on geometrical information obtained from the process. The objective of the work is to investigate the suitability of micro-EDM electrode wear compensation methods. Electrode shape deformation and random variations in the volumetric wear are studied as two main factors affecting the applicability of wear compensation methods as well as indicating the accuracy achievable with micro-EDM. EDM drilling and EDM milling are regarded as separate processes as they require different approaches in investigating and implementing the results of the study

Bulk Metallic Glass based Tool-Making Process Chain for Micro- and Nano- Replication

Existing and emerging micro-engineered products tend to integrate a multitude of functionalities into single enclosures/packages. Such functions generally require different length scale features. In practice, devices having complex topographies, which incorporate different length scale features cannot be produced by employing a single fabrication technology but by innovatively, integrating several different complementary manufacturing techniques in the form of a process chain. In order to design novel process chains that enable such function and length scale integration into miniaturised devices, it is required to utilise materials that are compatible with the various component manufacturing processes in such chains. At the same time, these materials should be able to satisfy the functional requirements of the produced devices. One family of materials, which can potentially fulfil these criteria, is bulk metallic glasses (BMGs). In particular, the absence of grain boundaries in BMGs makes them mechanically and chemically homogeneous for processing at all length scales down to a few nanometres. In this context, this research presents an experimental study to validate a novel process chain. It utilizes three complementary technologies for producing a Zr-based BMG replication master for a microfluidic device that incorporates micro and nano scale features. Then, to validate the viability of the fabricated BMG masters, they are utilized for serial replication of the microfluidic device by employing micro-injection moulding

Layer based micro-machining: new approach for tool-path generation

This paper proposes a new tool-path generation approach for layer-based micro machining (“conventional”, laser or EDM milling). With this approach, the laser spot non-conformity or EDM tool wear is compensated for by varying the layer machining angle and start point while the material removal volumes are represented by a sequence of 2D slices. Tool-path generation is performed taking into account the specific requirements of 3D micro-machining. The capabilities of the developed CAM system have been verified experimentally

A Novel Approach for Size Up-Scaling of Nickel Master for the Replication of Micro and Nano Features

This paper proposes a novel approach and a process chain for precision assembly of nano imprinted Ni shims on a larger Ni master plate and fixing them using laser welding. The capabilities of micro-manufacturing technologies (milling and assembly) were combined with those of nano-manufacturing to stitch produced Ni shims on a template in order to achieve a relatively large area for further imprinting using Roll-To-Roll (R2R) technology. The results of two setups are shown and analysed with the main sources of errors pointed out. Laser welding of the assembly tests were carried out in order to investigate the best of the welding path geometries commonly used in "macro" world